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Scanner comparisson page and drum scan limits?
I have been looking at the scanner comparisson page http://www.largeformatphotography.info/scan-comparison/
And it got me thinking.... the scanning comparison page we were looking compares the scans at 2400ppi, the highest optical resolution of the v700 (which I am contemplating purchasing), however the drum scanners can go beyond 8000ppi!!! Even at the 2400ppi the drum scans are so much cleaner than the flatbed or the flextight which lies in between in my opinion. The comparisson image was a 4x5 film that * had a 10x enlargement if printed at 240ppi 40x50 print! I am wonder how much data does the 4x5 hold if the tango is so much cleaner. In other words at which ppi is the practical resolution of the film reached with the drum scan?....
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Re: Scanner comparisson page and drum scan limits?
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
l2oBiN
In other words at which ppi is the practical resolution of the film reached with the drum scan?....
It really depends on the lens and film combination you're using but first of all on what's practical to you.
Take a sharp Zeiss lens on high resolution 35mm film like Spur Orthopan UR (ASA 12) which is based on an Agfa microfilm emulsion, and you're able to get finer detail on film than any scanner can detect. Recently we did a test comparing this combination to Fuji Acros on 4x5" shot with the 110XL. The 35mm microfilm was surprisingly close in terms of overall detail. You would need something in the range of 14,000 spi optically to get the finest information from that microfilm digitized.
On 8x10" I found the best lenses offer diffraction limited resolution on film at f/22 in the center for high contrast detail. So getting all the detail into the file requires a scan of up to 3500 spi resulting in a 5.5 GB file. Of course for lower contrast detail the effective resolution on film is lower.
With their smaller image circle 4x5" lenses are usually slightly sharper. So 4000-4500 spi will probably be sufficient to get all the detail.
But in practical terms with normal modern fine grained films you'll get most of the information from the film with an optical scan at 2000-4000 spi provided that the scanner still has a high MTF within that range. It's only areas with high contrast detail that require higher sampling resolutions.
If, however, you're planning to print really large it's always better to scan at least to the desired printing resolution. The tonal transitions are much nicer when scanned optically from film than interpolated by software.
BTW when it comes to scanner resolution the latest Flextight X5 is in the same league as the best drum scanners for 35mm film. It was tested recently at ScanDig and came out with an effective resolution of 6900 ppi. Unfortunately the text is in German only, but when you scroll down you can take a look at the scan sample of the USAF1951 target.
-Dominique
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
l2oBiN
In other words at which ppi is the practical resolution of the film reached with the drum scan?....
It depends on the quality of the drum scanner, and its ability to set the aperture to match the grain size on the film. There is a huge difference between flatbeds and drums. Flatbed's scan blurry, and the image is then sharpened (sometimes quite successfully for the size). Drum scanner's start out sharp. You can get 8,000 ppi out of them, but of course, that depends on how you quantify it. There are a lot of variables, and where one of us is clear about one part of the equation we may be not so clear about another. What I can tell you is that things look better in a scanner capable of 8,000 (or 3 microns) vs one that is set to 4,000. In sharpness, with test targets, a Premier beats a Tango hands down. In real life scanning with real film it's hard to quantify, harder to prove and as sharpening gets better, sometimes hard to justify. However, the old rule of "can't get more than 4,000" isn't true, in my opinion.
I have been fortunate to have a drum scanner, I like to start out sharp. Contrary to what Dominique referred to, an Imacon/Hassleblad is closer to a flatbed scanner - in that it uses ccd technology. It has a better lens than most flatbeds and the results are better. But it does not match a drum scan.
There is one other issue that I will mention that is a pet peeve of mine. We constantly talk (ok, haggle) about resolution. We have a lot of sharp lenses these days, skilled camera operators who know how to tip a front standard (for example) and good film and developers. My scanner gets all the sharpness the film has, I zoom in to the grains and can see it. The amount of sharpness in a digital print from a scan of this type is limited by the printers ability to put down dots in a tight enough pattern, without the slightest banding, overinking, etc.
The real issue for me has been full tonal reproduction. There are some inherent conversion issues that plague the digital world. A PMT (photo multiplier tube) is capable of picking up a few photons of light inside the dark box. They are extremely sensitive, sensing about 20K steps per channel or 64K for RGB. The ccd's pale in comparison. Consider what you work with in Photoshop, where you have steps from 1 to 255. That's quite a dip in tonal representation. Getting "all of the juice" requires a strategic approach.
Many people make a scan to look like the print they are going to make. This is a mistake. I was doing some scans with a friend last night and we were playing with pulling out the tonal separations inherent in the film. As we raised and lowered the midtones, we could see some of the tones blending together. We moved the values until they separated, which may have been lighter or darker than the actual print in that area. The clear goal is to supply the raw materials (tonally separated) so that someone can make a great print from the scan (after a little adjustment).
As has been said many times on this forum and others, this is the reason that "a scan is not just a scan". The operator is the key vs the machine. Working with someone on a long term basis to pull out all the "juice" from your work is the answer to a lot of these questions, especially for people who want exquisite prints. (Or practicing one's self - with a good drum, if finances allow.)
There is nothing wrong with doing one's own scans. Anyone can learn, of course. However, while I am not sure your question is the right one to ask, there is certainly more than 2,400 in the film, on a couple of fronts.
This was a longer answer than the question, I apologize for the long-windedness and I hope the info is useful to some.
Lenny Eiger
EigerStudios
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Re: Scanner comparisson page and drum scan limits?
If a large format lens delivers 60 lines per millimeter on film, we consider it pretty good.
Since there are 25.4 mm per inch, that is 60 x 25.4 = 1524 lines per inch. To effectively resolve 1524 lines per inch, we need a scanner that can resolve 3048 lines per inch, isn't that right ?
Given an image made with such a lens, if we scan at greater than 3000 spi, what are we getting ?
Or is my math wrong ?
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Ken Lee
Given an image made with such a lens, if we scan at greater than 3000 spi, what are we getting ?
Or is my math wrong ?
Wen you have a device that can see in to the grains - and can reproduce them as samples you get what the film has. I have seen this kind of math used to describe things, way too often, but it simply does not match to real life...
Once again, the conversation is about sharpness. What about tonal reproduction?
Respectfully, I just don't think this is right, or the whole picture.
Lenny
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Re: Scanner comparisson page and drum scan limits?
Ken raises a critical point and one that has been nagging me. I think his math is correct if one talks about lines per mm on a high contrast target (that is near 100% contrast). But what about a target that has much less contrast say 50% or 25%, or even a sine function target?
Now if we want to resolve the fine density gradations between lines on a sine target we will need some degree of higher resolution than is simply implied by the target lines/mm - maybe a much higher resolution. The same logic also holds for small variations in density on film, that is dimensions beyond the resolving power of the taking lens. Another way of saying this; is it useful to scan at a resolution that will detect artifacts that emanate from a resolvable point on the original subject and that has been recorded on the film.
I wonder if this is something that Lenny is alluding to when he comments on the value of extreme resolution scanners that employ PMTs, like Aztec.
In fact is the issue of scanner resolution tied more to the resolving power of the film than to the taking lens?
Nate Potter, Austin TX.
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Ken Lee
Since there are 25.4 mm per inch, that is 60 x 25.4 = 1524 lines per inch. To effectively resolve 1524 lines per inch, we need a scanner that can resolve 3048 lines per inch, isn't that right ?
Given an image made with such a lens, if we scan at greater than 3000 spi, what are we getting ?
Ken, your math and assumptions are both correct, with one big caveat. 3048 is the absolute smallest number of samples necessary to represent 1524 cycles. In reality, various factors prevent your scanner from resolving every pixel perfectly. Some scanners will be able to resolve 1524 cycles per inch by increasing the number of samples (ie, scanning at 4000 DPI/SPI or beyond). However some scanners won't see any improvement, because the scanner optics or sensor are already limiting resolution at 3000 SPI. For example, my Epson flatbed will never resolve 60 lp/mm, no matter what the SPI is set to.
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Nathan Potter
In fact is the issue of scanner resolution tied more to the resolving power of the film than to the taking lens?
Nate Potter, Austin TX.
In my opinion, no, the limit to resolution is always the weakest link in the chain. In the case of a scan, the chain is 1) film, 2) lens and 4) the optical scanning resolution. I assume optimum conditions to get maximum resolution, i.e. camera on tripod, lens at best aperture, etc.
If you scan at an optical resolution beyond the potential of the film and the lens you look deeper and deeper into the film and see finer and finer grain clumps. But this is not resolution, and it is not sharpness, though depending on how it is processed it may appear to produce sharpness, when in fact is is only an illusion of sharpness that could be achieved with other methods of processing.
When I write "optical resolution" I mean the true effective resolution, not the stated resolution in dpi. As others have pointed out there is a huge difference in effective yield between various scanners.
Sandy King
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
sanking
If you scan at an optical resolution beyond the potential of the film and the lens you look deeper and deeper into the film and see finer and finer grain clumps. But this is not resolution, and it is not sharpness, though depending on how it is processed it may appear to produce sharpness, when in fact is is only an illusion of sharpness that could be achieved with other methods of processing.
Thank you - That confirms my experience when scanning 35mm film at 4800 spi with a Minolta Dimage Multi Pro scanner: once I exceeded the limit of the taking lens + film, all the rest was just... grain.
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Re: Scanner comparisson page and drum scan limits?
Well I can agree with what Sandy says but that was not quite my point. I put it poorly. So to explain another way.
If I have a very fine grain film where even clumps cannot be resolved by the scanner and in fact the resolution on the film is totally determined by the film, then is there some kind of advantage in scanning beyond the resolution imposed by the taking lens? The advantage being this kind of elusive "quality" that Lenny mentions about very high resolution scans.
Nate Potter, Austin TX.
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Re: Scanner comparisson page and drum scan limits?
As Sandy said, "the limit to resolution is always the weakest link in the chain"
Let's say we are taking a photo of the earth from outer space, with a camera that can resolve 1 meter at most. Can we read the print on a newspaper ?
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Re: Scanner comparisson page and drum scan limits?
"If I have a very fine grain film where even clumps cannot be resolved by the scanner and in fact the resolution on the film is totally determined by the film..."
Perhaps I misunderstand, but that sounds contradictory. If the film is so fine-grained that it's undetectable, then the taking lens (or the tripod) determines resolution, not the film.
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Ken Lee
As Sandy said, "the limit to resolution is always the weakest link in the chain"
Let's say we are taking a photo of the earth from outer space, with a camera that can resolve 1 meter at most. Can we read the print on a newspaper ?
Hm, well, if not it seems CSI has some explanations to do... ;)
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Lenny Eiger
However, the old rule of "can't get more than 4,000" isn't true, in my opinion.
I agree. A scanner designed for higher resolutions usually performs better at lower resolutions than a scanner being at its limit at 4,000 spi. Any idea how the old Linotype-Hell scanners performed at their stated maximum resolution of 24,000 spi?
Quote:
Originally Posted by
Lenny Eiger
Contrary to what Dominique referred to, an Imacon/Hassleblad is closer to a flatbed scanner - in that it uses ccd technology. It has a better lens than most flatbeds and the results are better. But it does not match a drum scan.
I was only comparing the X5 in terms of resolution on 35mm film. Tonality is a different story. That's where I'd prefer a high-end drum scanner any time. I was comparing X5 scans with my own ICG scans at the highest optical resolution of 8,900 spi. I really have to say that the X5 was on par. I don't know if a Premier could do so much better when even the X5 is quite close to its 8000 spi spec. If you could show some sample how a Premier scan looks at 8,000 ppi maybe the difference compared to other scanners is obvious.
Quote:
Originally Posted by
Lenny Eiger
My scanner gets all the sharpness the film has, I zoom in to the grains and can see it.
Seeing the grain pattern in a scan does not necessarily imply that you're getting all the detail. The grain clumps in a single emulsion are of various size. To detect some detail hidden in the smallest grain clumps you would have to use a very small aperture which is going to cause grain aliasing from the larger grain clumps. Your choice of aperture is a compromise between maximizing the amount of detail and minimizing artifacts. This may not be a problem for large format film because the LF lenses are unable to transfer enough contrast in the high spatial frequencies for most films to capture. But think about the resolving power of the best 35mm lenses. Choosing a high res film for these lenses can really make a difference in terms of resolving power. Like in our tests with microfilm we could record more than 250 lp/mm on film. You would require a sampling spot smaller than 2 microns and a very high MTF at that frequency to digitize these fine structures.
Quote:
Originally Posted by
Lenny Eiger
The real issue for me has been full tonal reproduction. There are some inherent conversion issues that plague the digital world. A PMT (photo multiplier tube) is capable of picking up a few photons of light inside the dark box. They are extremely sensitive, sensing about 20K steps per channel or 64K for RGB. The ccd's pale in comparison. Consider what you work with in Photoshop, where you have steps from 1 to 255. That's quite a dip in tonal representation. Getting "all of the juice" requires a strategic approach.
May I ask where you got those number about the 20K steps per PMT channel?
As far as I understand the PMT signal generates an analogue current which is routed through a log amp before going into the A/D converter where it's digitized and the steps are introduced. But in general I agree that you start off with a strong signal from the PMT.
One thing though that made me wonder was a comment by Karl Hudson in the ScanHi-End newsgroup where he made a statement about the Tango being able to resolve down to 4 microns with a 15.9 micron aperture.
Quote:
Originally Posted by Karl Hudson
Also remember there has to be SOME light falling on the photomultiplier to get any kind of dynamic range. How many photons can pass through 3 microns? I have no idea but I'm sure a lot more pass through a 15 micron aperture ...and after all the PMT's are going to "white out" on clear drum and set the 6 volt peak signal there. Then it's going to block the light and adjust the op amps to zero volts offset there. What's in between is your dynamic range. The less light you have to start with on white-out, the less dynamic range your scan will have.
It got me thinking how useful a 3 micron aperture really is if it compromises the signal's dynamic range. Maybe this is another factor besides the grain aliasing causing the noise you get on 3 micron scans. How often do you actually use the 3 micron aperture?
Quote:
Originally Posted by
Lenny Eiger
Many people make a scan to look like the print they are going to make. This is a mistake. I was doing some scans with a friend last night and we were playing with pulling out the tonal separations inherent in the film. As we raised and lowered the midtones, we could see some of the tones blending together. We moved the values until they separated, which may have been lighter or darker than the actual print in that area. The clear goal is to supply the raw materials (tonally separated) so that someone can make a great print from the scan (after a little adjustment).
If you're working with 16 bit/channel, is there any advantage applying the tonal separations in the scanner software compared to what you could do with a raw scan in Photoshop?
Damn, with all these quotes the my original post went over 10,000 characters. Sorry about the length.
-Dominique
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
sanking
In my opinion, no, the limit to resolution is always the weakest link in the chain. In the case of a scan, the chain is 1) film, 2) lens and 4) the optical scanning resolution. I assume optimum conditions to get maximum resolution, i.e. camera on tripod, lens at best aperture, etc.
It is not that simple that the system resolution is limited by the weakest link in the chain. It's rather a function of contrast of all the links combined, and the weakest link reduces the overall contrast more than the others. Please see below my response to Nate's post where I'm going to elaborate on that point further.
Quote:
Originally Posted by
sanking
If you scan at an optical resolution beyond the potential of the film and the lens you look deeper and deeper into the film and see finer and finer grain clumps. But this is not resolution, and it is not sharpness, though depending on how it is processed it may appear to produce sharpness, when in fact it is only an illusion of sharpness that could be achieved with other methods of processing.
That's correct, but it's hard to define where the resolution of a lens and film combination stops because the variance is huge depending on the contrast at hand. When you're photographing a test target with a line pattern it may give you an idea what your capture system is capable of when it comes to 2-4 stops contrast. The great work of Chris Perez and Kerry Thalmann may serve as a base as well for LF lenses and TMX or similar film. And when you're scanning the MTF of the scanner needs to taken into account. A scanner that maxes out on a scanner test target at 60 lp/mm will probably be unable to detect some barely resolved detail on film at that frequency.
Quote:
Originally Posted by
Nathan Potter
Ken raises a critical point and one that has been nagging me. I think his math is correct if one talks about lines per mm on a high contrast target (that is near 100% contrast). But what about a target that has much less contrast say 50% or 25%, or even a sine function target?
Now if we want to resolve the fine density gradations between lines on a sine target we will need some degree of higher resolution than is simply implied by the target lines/mm - maybe a much higher resolution. The same logic also holds for small variations in density on film, that is dimensions beyond the resolving power of the taking lens. Another way of saying this; is it useful to scan at a resolution that will detect artifacts that emanate from a resolvable point on the original subject and that has been recorded on the film.
I wonder if this is something that Lenny is alluding to when he comments on the value of extreme resolution scanners that employ PMTs, like Aztec.
In fact is the issue of scanner resolution tied more to the resolving power of the film than to the taking lens?
Nate Potter, Austin TX.
For real world photography it is an interesting question how a lens, a film and a scanner perform on a target of lesser contrast. A sine target gives a much more realistic result about the performance than a simple line target, but these are very expensive.
When I tested my ICG drum scanner with a high contrast scanner target it was able to resolve more than 160 lp/mm. But with a test target shot on film the effective resolution was much less because the contrast of the finest detail on film was too low for the scanner to detect at the highest spatial frequencies. Thus I'd take the lp/mm values from scanner tests with a grain of salt though it might work as a relative comparison between the machines. But it's really the MTF that is important. Unfortunately these are not published. A drum scanner's MTF depends on the mechanical precision, the optics and the effective aperture. A real world photograph has much lower contrast in high spatial frequencies. To detect the highest spatial frequencies captured on film you would need a scanner that has a close to 100% MTF on those frequencies.
Example:
Let's just say we're trying to record some detail at 60 lp/mm that has a contrast of one stop. At f/22 and 1:20 magnification ratio a perfect diffraction limited LF lens transfers 14.7% contrast for that frequency. A modern slide film like Fuji Astia 100F transfers about 38% contrast at 60 cycle/mm according to the published MTF. I'm taking a transparency film for this because it doesn't compress the tonal range like most negative films do. So our one stop real contrast in the scene becomes just 1/18 of a stop on film if everything else is perfect. The scanner needs a very high MTF at the 60 lp/mm frequency to detect that sort of detail. A high res drum scanner has the necessary optics and mechanical precision to capture such fine detail. But the higher you go with your desired resolution you'll see that even the best drum scanners have their limitations. If you take negative film with its compressed tonality it's even harder for the scanner to detect those very subtle differences in density where the finest detail is hidden.
As Ben pointed out oversampling helps to get a more precise image of the lower spatial frequencies. I can see it even in blurry areas with no detail at all that the tonal transitions are nicer if the scan was made at a higher optical resolution. If your desired print size requires a scan beyond 4000 ppi than I would always recommend to scan for the native resolution of the printer.
Last week I was scanning very old 35mm slide film from the 60s that is going to be blown up to 2 x 3 meters. I used the maximum optical resolution of the scanner at 8,900 ppi which is enough for a 105 ppi print at that size. The client told me the printer wants 195 ppi. I could have used the 12,000 ppi setting of my scanner but it is in fact only 12,000 x 6,000 so I found the 8,900 x 8,900 to be the best solution I could offer, also considering scanning hours and file size.
Lenny, would you have used the 16,000 x 8,000 setting of your Premier in a similar case?
-Dominique
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
SCHWARZZEIT
BTW when it comes to scanner resolution the latest Flextight X5 is in the same league as the best drum scanners for 35mm film. It was tested recently at
ScanDig and came out with an effective resolution of 6900 ppi. Unfortunately the text is in German only, but when you scroll down you can take a look at the scan sample of the USAF1951 target.
-Dominique
The text came up in English for me! Guess something out there knows whether we speak English or German?
Sandy
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Re: Scanner comparisson page and drum scan limits?
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
SCHWARZZEIT
It is not that simple that the system resolution is limited by the weakest link in the chain. It's rather a function of contrast of all the links combined, and the weakest link reduces the overall contrast more than the others.
-Dominique
I am going back a long ways, but I believe system MTF is the product of the discrete component MTFs. Improving the weakest link is often the easiest way to get a proportional improvement.
More generally, the expert eye has always been the best judge. Scanner SNR is directly related to so many factors that providing a broadly applicable quality metric would be very difficult. I do not recall ever seeing a thorough analysis back when PMT and CCD scanners were relevant to some lucrative markets. People bought what made their data look good - as they do today I guess.
Practically, I believe a PMT-based system can be engineered to have better SNR at small apertures than any area-based detector. LN2-cooled or amplified CCDs can actually detect single photons and have some advantages (primarily speed), but a PMT-based detector is more sensitive (better SNR) at low flux levels.
I am sure the engineers on this board can put it better but here's my simple summary. At anything under NASA price levels, PMTs maintain better SNR at small sampling apertures. This yields better MTF = perceptually better rendition of intensity variation overall and less visible "grain" in light image areas. Drum scanners are a fast way to position a PMT over large areas so we like 'em for LF. Wish I had a drum to play with today.
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Ron Marshall
Some scan comparisons (scroll down)
What item in particular please ?
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
sanking
The text came up in English for me! Guess something out there knows whether we speak English or German?
Sandy
That's great. Somehow I must have missed that they have the review text up in different languages.
-Dominique
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
peter ramm
More generally, the expert eye has always been the best judge. Scanner SNR is directly related to so many factors that providing a broadly applicable quality metric would be very difficult. I do not recall ever seeing a thorough analysis back when PMT and CCD scanners were relevant to some lucrative markets. People bought what made their data look good - as they do today I guess.
It probably wasn't necessary to do a scientific analysis outside of an engineering level. There was the Seyold Report where a bunch of prepress scanners were evaluated.
I agree that the expert eye is the best judge. Looking at the scans from different machines and playing around with the files, trying to see where the limitations are is probably the best you can do to make a buying decision.
The scanner comparison page on this site is also a great resource to get an impression. But I guess some differences would be more obvious if the scans were done at a higher resolution. One more suggestion would be to host the original scans somewhere for those interested to play with the files. Today hosting space is much cheaper than it was when this comparison started.
Quote:
Originally Posted by
peter ramm
Practically, I believe a PMT-based system can be engineered to have better SNR at small apertures than any area-based detector. LN2-cooled or amplified CCDs can actually detect single photons and have some advantages (primarily speed), but a PMT-based detector is more sensitive (better SNR) at low flux levels.
I am sure the engineers on this board can put it better but here's my simple summary. At anything under NASA price levels, PMTs maintain better SNR at small sampling apertures. This yields better MTF = perceptually better rendition of intensity variation overall and less visible "grain" in light image areas. Drum scanners are a fast way to position a PMT over large areas so we like 'em for LF. Wish I had a drum to play with today.
Thanks for your input, Peter. As Lenny pointed out the influence of the scanner operator should not be underrated.
-Dominique
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
SCHWARZZEIT
Any idea how the old Linotype-Hell scanners performed at their stated maximum resolution of 24,000 spi?
Sure. They didn't. For starters, I don't mean to pick on you, or make you defend yourself. Just in case you feel that way, this isn't personal at all.
I used to be very upset at Imacon's quoting of certain numbers that were actually out of range. They suggested their DMax was 4.8, I believe, which exceed the max on film, of 4.6. How did they actually get that result? I railed against them in forums for lying to us about their capabilities. That is, until one fellow took the time to explain to me how they got their result. There was a mathematical formula based up the probable capabilities of such a device with its components, etc. It was theoretical number. They were quoting theoretical while others were quoting tested values. It got worse, when Epson suggested it can do 6400 real resolution, which we all know is too high. Now its all just a mess of one kind of disinformation vs another.
In conversations with Aztek they said that their stepper motor was capable of 18,000 steps around the circumference of the drum. That means that they could have taken samples and produced a much higher number of pixels. Phil Lippincott said to me that he decided against this because he felt the other components could only do 8,000 and he would rather have delivered 8,000 real samples vs some other result, theoretical or otherwise. The long winded point I am trying to make is that there are two sets of numbers. One is the theoretical capabilities of the scanner and the other is the real resolution in real terms as measured by say, a piece of film.
I had occasion to work on an old Hell 299 (I think that's the number) and was probably the first person to make enlarged negs for platinum printing with a scanner - back in 1980. I'm familiar with that scanner. I also am familiar with the 3400 series, and their scans aren't up to par with later drum scanners.
Quote:
Originally Posted by
SCHWARZZEIT
I was comparing X5 scans with my own ICG scans at the highest optical resolution of 8,900 spi. I really have to say that the X5 was on par. I don't know if a Premier could do so much better when even the X5 is quite close to its 8000 spi spec. If you could show some sample how a Premier scan looks at 8,000 ppi maybe the difference compared to other scanners is obvious.
I have an assistant who did a lot of work with 4x5 scans on an Imacon before he found me and we spent some time comparing the scans. They aren't bad. But they aren't drum scans. They were a bit soft. I am curious as to what ICG you have. I'd love to see a scan off a 380... just to see how good it is.
I am happy to supply some samples. I'm not sure what format. It appears that one doesn't see it unless one is looking at the whole thing.... As much as I appreciate the efforts here on the scan comparison, I find it very difficult to make real sense out of it. When things are compressed that much, the differences disappear.
Quote:
Originally Posted by
SCHWARZZEIT
May I ask where you got those number about the 20K steps per PMT channel?
Haddon Stevens Lippincott. Phil passed away a couple of years ago and Haddon is now the head of the firm.
Quote:
Originally Posted by
SCHWARZZEIT
One thing though that made me wonder was a comment by Karl Hudson in the ScanHi-End newsgroup where he made a statement about the Tango being able to resolve down to 4 microns with a 15.9 micron aperture.
This is what's frustrating. There are 24,500 microns in an inch, roughly. One might not imagine that at 15.9 microns you would not resolve to 4,000, but only 1597.5. The micron settings are different for different scanners. I usually do chromes and b&w negs at 13, they start to get soft at 16. I wouldn't claim that I could do my best work at 16. But Karl might.... because the way the settings they have things are different. I have been told that it is fixed at 11 microns, then told it isn't. I don't know Karl personally and have no reason to doubt him.
On the other hand, some would say that you resolve on the amount of microns you have and I would say not. When I scan at 13, I shouldn't be able to get more than 2,000 resolution on anything. But that isn't how it works. I get much more. As you stated, one can't scan at 3 microns or you will anti-alias. But how does one explain the results? Either there is no more after 2,000 or there is a lack of understanding on the actual process. I would suggest the latter.
Quote:
Originally Posted by
SCHWARZZEIT
If you're working with 16 bit/channel, is there any advantage applying the tonal separations in the scanner software compared to what you could do with a raw scan in Photoshop?
I think there is. Especially with DPL. Can I prove it? Probably with time I could. However, I can tell you that if I get things right in the scan, things separate well and the prints are fairly easy to make. I just did something off a raw scan and I ended up with 14 adjustment layers. There is a huge loss in going to Photoshop. It's going from 20K separations down to 250. If you give it tonal ranges that are separated in the way you want it to be, there is a real benefit when the conversion happens. I am stating my opinion, rather than stating it as a real fact. It's whats worked for me so far. I'm still learning.
Lenny
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Lenny Eiger
Sure. They didn't. For starters, I don't mean to pick on you, or make you defend yourself. Just in case you feel that way, this isn't personal at all.
I didn't take it as personal offense. On the contrary, I do welcome real honest opinions, and hopefully we can all learn from each other.
Quote:
Originally Posted by
Lenny Eiger
I used to be very upset at Imacon's quoting of certain numbers that were actually out of range. They suggested their DMax was 4.8, I believe, which exceed the max on film, of 4.6. How did they actually get that result? I railed against them in forums for lying to us about their capabilities. That is, until one fellow took the time to explain to me how they got their result. There was a mathematical formula based up the probable capabilities of such a device with its components, etc. It was theoretical number. They were quoting theoretical while others were quoting tested values.
Yes, it is the theoretical Dmax value for any 16 bit/channel workflow. It doesn't take into account any CCD noise issues. I haven't tested a Flextight scanner for real Dmax. I heard they are doing quite ok compared to the Nikon Coolscan film scanners. FWIW, a client of mine who owns an Imacon 646 told me that the drum scan I did for him of a Velvia 50 slide had much better shadow detail than he could get from his Imacon. But I haven't compared it myself.
Aztek has an honest approach by giving the real Dmax value in their public specs for the Premier.
Quote:
Originally Posted by
Lenny Eiger
It got worse, when Epson suggested it can do 6400 real resolution, which we all know is too high. Now its all just a mess of one kind of disinformation vs another.
I see your point, and of course I'd prefer the manufacturers to state some true optical resolution for their machines but it seems they rather give the specs for their stepper motors and let the customers in the dark. But drum scanner manufacturers are no real exception on this.
So in the end we have to see for ourselves how these machines perform and draw our own conclusions if the quality is worth the money.
Quote:
Originally Posted by
Lenny Eiger
I had occasion to work on an old Hell 299 (I think that's the number) and was probably the first person to make enlarged negs for platinum printing with a scanner - back in 1980. I'm familiar with that scanner. I also am familiar with the 3400 series, and their scans aren't up to par with later drum scanners.
These scanners were probably made for a different set of computer hardware. It's only for a few years since we're able to process huge files. It's still very time consuming.
Quote:
Originally Posted by
Lenny Eiger
I have an assistant who did a lot of work with 4x5 scans on an Imacon before he found me and we spent some time comparing the scans. They aren't bad. But they aren't drum scans. They were a bit soft.
I guess there are differences between the newer and older Flextight models.
Quote:
Originally Posted by
Lenny Eiger
I am curious as to what ICG you have. I'd love to see a scan off a 380... just to see how good it is.
I have a 370HS. When I bought the scanner from ICG I asked them about the difference between the 370HS and the 380. I was told that the 380 has a slightly faster top speed at 2,000 rpm on lower res scans. But I wouldn't see a difference in the quality of the scans. Exactly the same optics and components are used to build both machines. This came directly from ICG.
I could supply some scan samples if you like.
Quote:
Originally Posted by
Lenny Eiger
I am happy to supply some samples. I'm not sure what format. It appears that one doesn't see it unless one is looking at the whole thing....
I think a crop where you personally think that it's representative in showing how sharp the scanner sees the grain at 8,000 spi would be great. But I know what you mean that it's more impressive to see the whole scan.
Quote:
Originally Posted by
Lenny Eiger
This is what's frustrating. There are 24,500 microns in an inch, roughly. One might not imagine that at 15.9 microns you would not resolve to 4,000, but only 1597.5. The micron settings are different for different scanners. I usually do chromes and b&w negs at 13, they start to get soft at 16. I wouldn't claim that I could do my best work at 16. But Karl might.... because the way the settings they have things are different. I have been told that it is fixed at 11 microns, then told it isn't. I don't know Karl personally and have no reason to doubt him.
On the other hand, some would say that you resolve on the amount of microns you have and I would say not. When I scan at 13, I shouldn't be able to get more than 2,000 resolution on anything. But that isn't how it works. I get much more. As you stated, one can't scan at 3 microns or you will anti-alias. But how does one explain the results? Either there is no more after 2,000 or there is a lack of understanding on the actual process. I would suggest the latter.
I'm sure there there's something else than just interpreting the aperture size as the smallest resolvable spot. The aperture is a hole in a disc, so how does the micron number describe the hole? It could be the radius, the diameter or something else that defines the spot size. I asked this question several times and was always told that it is the diameter. If it is the diameter of the analysis spot than the smallest resolvable detail could be as fine as half that size because the spots can overlap. This way smaller details are resolved with some loss in contrast, just like diffraction spots.
Another approach could be that the analysis spot is optically magnified before it is projected onto the resolution aperture, and the solution is probably different for each manufacturer. It seems that we cannot draw conclusions on the absolute resolving power of the scanner just from the aperture size.
BTW, in Phil Lippencott's scanner test the Tango came out with an optical resolution of 4096 ppi.
Quote:
Originally Posted by
Lenny Eiger
I think there is. Especially with DPL. Can I prove it? Probably with time I could. However, I can tell you that if I get things right in the scan, things separate well and the prints are fairly easy to make. I just did something off a raw scan and I ended up with 14 adjustment layers. There is a huge loss in going to Photoshop. It's going from 20K separations down to 250. If you give it tonal ranges that are separated in the way you want it to be, there is a real benefit when the conversion happens. I am stating my opinion, rather than stating it as a real fact. It's whats worked for me so far. I'm still learning.
I think the difference may be that some corrections can be done more easily in a dedicated scanner software beforehand. Thus it's much easier to get to the print file from a preadjusted scan than working from a raw scan file. On the other hand I like the idea that I have the full unmodified gamut of a raw scan to work with. I only made a few tests where I compared a preadjusted scan with a raw scan after both files went through Photoshop. The results were very close, and I couldn't really decide which I liked better.
It's not that you have only 250 separations per channel in Photoshop. Internally a 16 bit file has roughly 16K values per channel. If you have 20K separations to work with in DPL then your Premier must have a greater than 16 bit A/D converter. Otherwise you would lose some steps during A/D conversion.
-Dominique
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
SCHWARZZEIT
So in the end we have to see for ourselves how these machines perform and draw our own conclusions if the quality is worth the money.
Yes, "you're on your own" is the response we are getting because there is no independent testing agency. Aztek's testing was apparently independent, but it is old. Their efforts were not supported by the rest of the industry, in fact one scanner maker told them to take off the results or they'd be sued. FLAAR, which attempted to be such an agency, or at least promote it that way is corrupt. Their endorsements are bought and paid for.
This said, there are a lot of factors. I have a scan sample someone gave me from a Scanmate 11,000 that should not be possible. The samples are too tight for their "stated resolution". Did the fellow do some post-processing - I don't know. The scan project here undertaken by Leigh Perry was an attempt to make a real comparison, but there is quite a bit of downsizing and post processing done. Really mediocre (being polite) scanners show up as quite reasonable on the web.
Quote:
Originally Posted by
SCHWARZZEIT
It's not that you have only 250 separations per channel in Photoshop. Internally a 16 bit file has roughly 16K values per channel. If you have 20K separations to work with in DPL then your Premier must have a greater than 16 bit A/D converter.
-Dominique
They have told me its a 16 bit. Must be the effects of rounding numbers up and down... for discussion.
Regarding raw vs adjusted at scanner scans- one thing the software does (DPL) does that's great is that they have a "CMS" file attached to each scan. This gets loaded into the scanner at scan time and adjusts the range of the scanner. This is very different from doing a raw scan, like most scan software does. The pro version allows you to create your own cms file/profile for each image. It's not needed for most chromes, and only some color negs, but its great for b&w negs. It's like having a different scanner for each image. At least that's what I've been told and the premise I am working on. It appears to be working that way, but there's plenty I don't know...
Lenny
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Re: Scanner comparisson page and drum scan limits?
I am reading this thread with great interest. One point of discussion I do not understand is separation. How does a 16-bit number have less than 20,000 "separations" ?
_ .. --
Tim
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Tim Povlick
I am reading this thread with great interest. One point of discussion I do not understand is separation. How does a 16-bit number have less than 20,000 "separations" ?_ .. --
Tim
Tim,
I am curious myself. According to latest Photoshop we are in 16 bit - so there should be 65,536 possibilities, if my math is correct. However, when we move a curve up and down, we only have 0-255 as choices. This would appear quite sledge-hammer-ish as a tool. In terms of b&w, I also don't think my printer can separate out that many tones. My gray ramps are perfectly smooth, but the resolution is low - 1440x1440. So if I only have the tones that can be generated with that resolution, I believe its quite limited. I don't know what the number would be... do you?
Lenny
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Re: Scanner comparisson page and drum scan limits?
One has to ask whether any monitor can accurately render that many shades per channel, and whether we could even see them if it could :)
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Ken Lee
One has to ask whether any monitor can accurately render that many shades per channel, and whether we could even see them if it could :)
Agreed. The key, IMO, is to get as many shades on the paper as possible. (I try not to imagine the monitor is of any use at all. I only look closely at the print, which is what open would do in a darkroom.) To get as many shades, one needs good ink, and good eyes. It helps a great deal if the scan's zones are separated... in my experience so far...
Lenny
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Re: Scanner comparisson page and drum scan limits?
If I recall correctly, printer drivers for inkjet are 8-bit only.
This means that we have lots of room to get things right in the deep color space - before things get collapsed by the printer, the driver, the RIP, and ultimately, by the even more limited gamut of the paper/ink combination.
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Lenny Eiger
Tim,
I am curious myself. According to latest Photoshop we are in 16 bit - so there should be 65,536 possibilities, if my math is correct. However, when we move a curve up and down, we only have 0-255 as choices. This would appear quite sledge-hammer-ish as a tool. In terms of b&w, I also don't think my printer can separate out that many tones. My gray ramps are perfectly smooth, but the resolution is low - 1440x1440. So if I only have the tones that can be generated with that resolution, I believe its quite limited. I don't know what the number would be... do you?
Lenny
Hi Lenny,
Your math is correct, there are 64k possibilities (separations?). As to the photoshop, I think if you are in 16-bit mode the tone curve is presented to the user as 0 to 255 they are expanding it to 16-bit internally and I see your point that in so doing one has only a crude control over the curve that is 16-bit with an 8-bit control. If they allowed user input of a curve one would generate the desired curve to perfection, but that would be a 64k table to fill. Ouch. My only suggestion is be very precise with the curve tool in PS. Maybe someone can suggest a better suggestion.
I checked the Hamamatsu site concerning the PMT's spec's. I don't have the PMT number used in our Premiers but a PMT I looked at had the following features. If one took dark current as a "step" and maximum current as the max limit as the number of steps, then you ended up with a PMT that had 20,000 steps. Interesting result (matched Haddon's number). A more interesting was take the minimal value the PMT could sense and use that as step size. To my way of thinking this is the proper value to use. The PMT then had 6,000,000 steps. In otherwords, a 22-bit DAC could realistically be used to capture a color channel. That would yield 66-bit RGB. No way to print that :-)
_ .. --
Tim
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Lenny Eiger
They have told me its a 16 bit. Must be the effects of rounding numbers up and down... for discussion.
Lenny, I confused the number of values in 14 bit and 16 bit. My mistake! 64K values is of course correct for 16 bit. So a 16 bit ADC is sufficient for the 20K separations of the PMT.
Quote:
Originally Posted by
Lenny Eiger
Regarding raw vs adjusted at scanner scans- one thing the software does (DPL) does that's great is that they have a "CMS" file attached to each scan. This gets loaded into the scanner at scan time and adjusts the range of the scanner. This is very different from doing a raw scan, like most scan software does. The pro version allows you to create your own cms file/profile for each image. It's not needed for most chromes, and only some color negs, but its great for b&w negs. It's like having a different scanner for each image. At least that's what I've been told and the premise I am working on. It appears to be working that way, but there's plenty I don't know...
Ok, I think I get how the CMS files work. On my ICG scanner there are basically just two hardware modes that define the range. One is called standard range which is good for all but very dense negatives and the other is called extended range where the full 4D+ range of the scanner engine is used. The hardware difference between these modes is that they calibrate to different values. Or in other words there's a difference in gain. I think the CMS files work similarly on your Premier but you can adjust them precisely to the density range of your original. Whether you really see a difference in the final print file is a different matter.
Quote:
Originally Posted by
Tim Povlick
As to the photoshop, I think if you are in 16-bit mode the tone curve is presented to the user as 0 to 255 they are expanding it to 16-bit internally and I see your point that in so doing one has only a crude control over the curve that is 16-bit with an 8-bit control. If they allowed user input of a curve one would generate the desired curve to perfection, but that would be a 64k table to fill. Ouch. My only suggestion is be very precise with the curve tool in PS. Maybe someone can suggest a better suggestion.
On an 8-bit curve in PS you may be able to see the change of single values. On a 16-bit curve smaller adjustments would be invisible when the changes are lost on its transfer to the display device. If however you feel that you need finer adjustments on your curves you may reduce the opacity of each curve layer or fade the adjustment after applying the curve directly to the image.
-Dominique
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Re: Scanner comparisson page and drum scan limits?
really? You guys really find moving mid tone value, oh say, 124, up to 125 too sledge-hammerish? You really want a curve tool that has tens of thousands of steps because 124 to 125 was just overwhelming? You put those two prints next to each other and the difference is not only visible but far to great?
Man, I'm losing touch with these discussions more and more each day...
Tyler
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Tyler Boley
really? You guys really find moving mid tone value, oh say, 124, up to 125 too sledge-hammerish? You really want a curve tool that has tens of thousands of steps because 124 to 125 was just overwhelming? You put those two prints next to each other and the difference is not only visible but far to great?
Man, I'm losing touch with these discussions more and more each day...
Tyler
I agree with you Tyler. Sounds like these guys are working on some planet other than Earth because they are discussing subtleties of tonal values way beyond the capability of the human eye.
Sandy King
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Re: Scanner comparisson page and drum scan limits?
Recently, my neighbor asked me to photograph his house and then use Photoshop to colorize sections of it so that he could determine a paint choice. He gave me some paint samples to match.
My spectrophotometer reads to tenths, but photoshop curves/readouts are whole digits. Being off by a couple of tenths was clearly visible. Thus, for some things, such as very close tolerance color matching, Photoshop is a bit of a sledgehammer. I've never found this to be a problem doing regular printing.
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Re: Scanner comparisson page and drum scan limits?
by the way, "16 bit" Photoshop mode works in 15 bit + 1 unit, 32,769 values per channel.
Tyler
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Tyler Boley
Really? You guys really find moving mid tone value, oh say, 124, up to 125 too sledge-hammerish? You really want a curve tool that has tens of thousands of steps because 124 to 125 was just overwhelming? You put those two prints next to each other and the difference is not only visible but far too great?
Man, I'm losing touch with these discussions more and more each day...
I promised myself that I wasn't going to add my voice to yet another thread like this (emphasis on another). Oy, failed again. But yeah, what Tyler said.
I would only add that the tones on the print are the result of the entire system, not just photoshop. I wonder how much an effect paper batch variability, ink batch variability, ambient temperature and relative humidity, etc., have on the tones. I suspect it's a significant fraction of the difference between 124-125.
So are you guys making new profiles for every print you make? Sorry, please don't answer that. If you are, I don't want to know.
I'll leave this thread with a story. I seem to remember a story Fred Picker told, went something like this. When he was a hungry young photographer, he worked (apprenticed?) for some excellent darkroom printers. And Fred, being Fred, could be a PITA at times. So one of the experienced old guys challenged him to print as many individual shades of gray as he could. Take as long as he needed, use whatever techniques he liked.
Turns out Fred was able to come up with something like 54 or 55 distinguishable shades of gray. Try as he might, that's where he seemed to top out. This surprised and impressed his teachers, but Fred was usually one to exceed other peoples' expectations, apparently.
My take on this is that the number of tones you can make might be interesting but it's only a small part of what makes a photograph.
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Re: Scanner comparisson page and drum scan limits?
Peter, forgive me but I'm not following... tenths of what? Most Photoshop tonal tools work in 256ths, that won't more than cover your couple of 10ths by orders of magnitude?
Tyler
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Tyler Boley
Peter, forgive me but I'm not following... tenths of what? Most Photoshop tonal tools work in 256ths, that won't more than cover your couple of 10ths by orders of magnitude?
Tyler
Sorry, I made a mistake. My spectro reads to hundredths. So for example, one paint chip measured L 95.26, a 0.39, b 1.76, but entering lab numbers in Photoshop is limited to whole numbers. Using L 95, a 0, b 2 did not produce a visually matching color.
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Re: Scanner comparisson page and drum scan limits?
Guys, before you jump all over everyone-- there is some serious compression of tones that happens on occasion, at least. I'm not sure where exactly it occurs. I assume its in Photoshop, but it could be in the rip. There's a certain effect that I get when I use an 8x10 piece of film that adds an extreme amount of textural quality. I think it should be able to happen at smaller formats, certainly 4x5, given resolution of lenses, excellent film and developers, the best kinds of scanners, etc. All the stuff we all use.
I realize the eyes can only go so far, monitors only os far, etc. I continue to struggle to get more than I am getting from smaller film...
This doesn't have to do with world views...
Lenny
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Re: Scanner comparisson page and drum scan limits?
Unfortunately, the printer and the paper/ink combination have a limited gamut, but before we squeeze the final image into that limited gamut, it's best if our tools distort the color space as little as possible, all along the way.
Not distorting, translates to retaining as many steps as possible.
Nobody is claiming that we can see or manage all those subtle steps.
We just want to retain as many as possible, so that things remain as "analog" as possible, as long as possible.
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Re: Scanner comparisson page and drum scan limits?
Attached is a step wedge chart in 8 bit. Perhaps my eyes just suck, but if there is a huge difference between 2 adjacent tones (1 full step apart), then it is not apparent to me on my monitor or on paper. I'll provide the full res .psd file if anyone wants it.
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Re: Scanner comparisson page and drum scan limits?
The problem isn't when we view a complete 256-step wedge.
The problem is when we start out with a small color space, and proceed to make lossful adjustments. This introduces gaps, or banding. With further adjustments, banding become increasingly apparent.
256 tones is nice to finish with (and that's all we can ever get in the end, because printer dirvers are only 8-bit), but if we start out with only 256, the number of steps can only decrease as we perform adjustments.
On the other hand, if we start with 64 thousand tones per channel, we could lose 1000 steps and they wouldn't likely be noticed. If we start with 256, it doesn't take many losses to become apparent. It's a familiar look when (8-bit) JPG files are overly "corrected" by amateur digital photographers. That's why higher end cameras allow Raw capture, and modern imaging software supports it. Google 16 bit Workflow to learn more.
Performing adjustments in a large color space, prevents banding. That's why we convert to the smallest color space, last - just as we do with sharpening.
http://www.kenleegallery.com/images/tech/steps.jpg
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Ken Lee
The problem isn't when we view a complete 256-step wedge.
The problem is when we start out with a small color space, and proceed to make
lossful adjustments. This introduces gaps, or banding. With further adjustments, banding become increasingly apparent.
256 tones is nice to
finish with (and that's all we can ever get in the end, because printer dirvers are only 8-bit), but if we
start out with
only 256, the number of steps can only
decrease as we perform adjustments.
On the other hand, if we start with 64 thousand tones per channel, we could lose 1000 steps and they wouldn't likely be noticed. If we start with 256, it doesn't take many losses to become apparent. It's a familiar look when (8-bit) JPG files are overly "corrected" by amateur digital photographers. That's why higher end cameras allow Raw capture, and modern imaging software supports it. Google
16 bit Workflow to learn more.
Performing adjustments in a large color space, prevents banding. That's why we convert to the smallest color space, last - just as we do with sharpening.
http://www.kenleegallery.com/images/tech/steps.jpg
Starting with 256 discrete tones, but working in 16 bit will not introduce many, if any, banding issues. I'm quite familiar with 16 bit.
Working in a large color space, such as Prophoto RGB, will encourage more banding, because the tonal neighbors must be spaced further apart than with a small color space (both color spaces will have the same total number of discrete tones) - your gamut is wider but the tones must be spaced wider as well. If you are working with a low gamut image (such as a foggy scene), you are better off working in a small color space, such as Adobe sRGB, because the tonal values will be closer together and have a lower probability of banding.
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Ken Lee
Is that right? If we have a 16 bist per channel RGB image, aren't the number of colors/shades equal no matter whether we use sRGB or ProPhoto? Isn't what happens is that the number of steps are the same, but there's bigger jumps between the steps in ProPhoto, since the same number of steps has to cover a bigger area, as it were. If so, then aren't you more likely to see banding with the larger color space? I'm sorry if I have this wrong, as I'm no color space expert.
Oops. I see that Greg types faster than I do. :)
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Re: Scanner comparisson page and drum scan limits?
[QUOTE=Ken Lee;626685]Performing adjustments in a large color space, prevents banding. That's why we convert to the smallest color space, last - just as we do with sharpening.
This is not correct (see my previous post). Working in a larger color spaces encourages banding. Working in higher bit depth discourages banding.
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Re: Scanner comparisson page and drum scan limits?
Yes, I stand corrected. I meant bit-depth. Not color space.
My post should have read as follows
...Performing adjustments in higher bit-depth, prevents banding. That's why we convert to the smallest bit depth, last - just as we do with sharpening.
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Re: Scanner comparisson page and drum scan limits?
And my conment was directed to the other comments about "124, up to 125 too sledge-hammerish". You have to look pretty carefully to detect the difference in 1 step on a step wedge. In a "real" photo, and without a direct A to B comparison, it would be pretty darned difficult for a human to reliably identify that a few pixels ended up 1 value off and had a few neighbor pixels with the same value. If an entire section of pixels all ended up with the same value that would be different, but I think it would be pretty rare for that to happen.
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Lenny Eiger
Guys, before you jump all over everyone-- there is some serious compression of tones that happens on occasion, at least. I'm not sure where exactly it occurs. I assume its in Photoshop, but it could be in the rip. There's a certain effect that I get when I use an 8x10 piece of film that adds an extreme amount of textural quality. I think it should be able to happen at smaller formats, certainly 4x5, given resolution of lenses, excellent film and developers, the best kinds of scanners, etc. All the stuff we all use.
I realize the eyes can only go so far, monitors only os far, etc. I continue to struggle to get more than I am getting from smaller film...
This doesn't have to do with world views...
Lenny
Lenny, two givens-
1) "some serious compression of tones... ...happens on occasion"
2) the Photoshop curves tool has control points in increments of 256, both
in and out, no matter the number of levels in the
file.
One has little, if anything, to do with the other.
another two-
1) world views
2) facts
Again, one has little, if anything, to do with the other.
As a note of interest perhaps, your multi K setups will indeed
differentiate between more than 256 levels of gray (given enough room on
the paper), unfortunately StudioPrint converts to 8 bit on the fly behind
your back, before continuing on with the magic it does. Don't ask me to
write the novel required to explain how I arrived at that. So, there is
one bottleneck, though I don't think the problem you mention is at that
point. Still, I'm in agreement that there should be no downscaling of
levels of gray anywhere in the data path if at all possible, but PS tools are a different issue.
Peter, I had no idea you were referring to LAB, that's an entirely
different can of worms, and you are right about the increments of control
points available with it in PS.
At risk of offending you as you may be well aware already, there are other
perhaps more useful tools. Despite it's silly Tron like interface, i1
Share (free) will let you measure in accurate LAB values and tell you the
equivalent RGB value in any selected working space, for example.
Tyler
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Re: Scanner comparisson page and drum scan limits?
Quote:
Originally Posted by
Tyler Boley
Lenny, two givens-
1) "some serious compression of tones... ...happens on occasion"
2) the Photoshop curves tool has control points in increments of 256, both
in and out, no matter the number of levels in the
file.
As a note of interest perhaps, your multi K setups will indeed
differentiate between more than 256 levels of gray (given enough room on
the paper), unfortunately StudioPrint converts to 8 bit on the fly behind
your back, before continuing on with the magic it does. Don't ask me to
write the novel required to explain how I arrived at that. So, there is
one bottleneck, though I don't think the problem you mention is at that
point. Still, I'm in agreement that there should be no downscaling of
levels of gray anywhere in the data path if at all possible, but PS tools are a different issue.
Tyler
There's part of this that is just interim, or incomplete thinking. I've been working for a long time to get to a fully textured appearance. I have been successful at getting there with an 8x10 camera. However, I believe I should be able to get there with a smaller piece of film - at least one as large as 4x5. Somehow it doesn't work that way - at least not yet. There's a smoothness I haven't gotten to. I'm grasping at straws to figure out where the bottleneck is. I have very smooth gray ramps in my environments but the magic is only there with the big camera - at least so far. More testing to come.
I do know that StudioPrint is 8 bit. They just told me, thankfully no novel needed.
My statement about world views had to do with the comment you made about "losing touch with these discussions every day..." It was an attempt at levity.
Lenny