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more photography
26-Mar-2009, 15:23
Hi

I have just purchased a new Epson V750 and plan to scan 4x5 vlevia, what is the best and native resolution of this scanner without interpolation.

Keith S. Walklet
26-Mar-2009, 15:37
The manufacturer claims a max optical of 6400spi. You'll need to scan in two pieces for color with 4x5 at that resolution, resize them to 3200 and join them in Photoshop. The best results are wet mounted IMO. Lots of threads about various approaches.

Jeremy Moore
26-Mar-2009, 15:55
By scanning a 35mm microfilm target to test the optical limitation of the scanner I decided to scan at home at 2400ppi on the V700. I also tested quite a few of these and the numbers varied based on the scanner from as low as ~2100 to as high as ~2500 in our lab.

PenGun
26-Mar-2009, 16:25
Focusing the beast is a black art. Many never get it focused AFAIKT. Have fun.

Keith S. Walklet
26-Mar-2009, 16:57
Jeremy, are you referring to the true resolution (as often referenced by Sandy) or an actual scanner setting?

I find it necessary to use the beast's ;-) max optical setting (6400spi) and wet mount to achieve the best true resolution.

Big Fish
26-Mar-2009, 20:31
Try the Silverfast website. There is a special Epson Scanner section.

Best...

Big Fish

z_photo
27-Mar-2009, 04:04
speaking of silverfast, what version of their software is the weapon of choice? i cannot get their demos to run

more photography
27-Mar-2009, 07:54
Hi looked every where, whilst you could scan at 12800, there must be an optical resolution, I have read 1600 and other places 2400, not sure which one or is somewhere in between, as I want to scan at he larges with most optimum resolution possible.

Ken Lee
27-Mar-2009, 08:15
I'm no expert, but I have consistently read that people who test the recent batch Epson scanners get somewhere around 2000 spi, plus or minus a few hundred, and my experience seems to bear this out. Higher settings just seem to produce larger files, but do not result in additional, usable visual data.

I set my Epson 4990 to 2400 spi. For additional detail, I shoot 5x7 instead of 4x5. It's cheaper than getting a high-end scanner, and you can make (albeit small) contact prints if you like.

BarryS
27-Mar-2009, 09:03
The top prosumer flatbeds top out at around 2400 ppi. You can scan at higher resolutions, but all you'll be getting is interpolation. One easy way to test is to make a series of scans (1800ppi, 1900ppi, 2000ppi, etc) of a flat detailed object (not film) and examine each scan for crisp detail. At some point, you'll see that the scans get bigger, but start getting softer. Since an actual object has an infinite amount of detail, the limiting factor won't be the resolution or sharpness of a piece of film.

David Luttmann
27-Mar-2009, 09:38
With the V700 and fluid mounting, I get about 2200 spi. I have found no difference with the 6400 setting and lens. The key is obtaining correct focus.

Ken Lee
27-Mar-2009, 10:09
To David's point, you can get a modest but helpful improvement in resolution, by simply raising the subject off the glass by a small amount.

This will also prevent you from seeing Newton's Rings, when the film comes in contact with the glass. Unfortunately, the effect can be seen, even when we place the film emulsion-side-down.

If you search this forum, you will find that in order to accomplish this, some people have devised a variety of do-it-yourself methods, while others use the custom "Variable Height" holders made by www.betterscanning.com (http://www.betterscanning.com/scanning/vb_advantage.html).

Jeremy Moore
27-Mar-2009, 10:23
Jeremy, are you referring to the true resolution (as often referenced by Sandy) or an actual scanner setting?

I find it necessary to use the beast's ;-) max optical setting (6400spi) and wet mount to achieve the best true resolution.

I'm talking about the setting above which the optical lens in the scanner is not resolving anymore detail, but honestly I have never tried the 6400 setting. I'm developing a bunch of new 4x5 film tonight from a recent trip so I'll scan a couple of 6400 and compare to my method of scanning.

I also found this on the Epson site which seems to suggest there is something extra at work, the "Micro Step Drive™ technology", when scanning at 6400.


Hardware Resolution

* 4800 x 9600 dpi, 6400 x 9600 dpi with Micro Step Drive™ technology

sanking
27-Mar-2009, 10:25
Optical resolution is determined by how many pixels the scaner can sample. A flatbed scanner with a 1200 sensors per inch can sample 1200 spi in one direction, the width of the CCD. To sample in the other direction the CCD is moved along the page, and more samples may be taken in this direction depending on the stepping motor. For example,if the scanner takes 2400 samples per inch in the direction of the movement of the head, it would be called a 1200X2400 spi scanner. Strictly speaking either of these figures could be called optical resolution, though for most scanners the first, or lowest, number is the only one that matters.

Interpolated resolution is based on how many pixels the the scanner can guess at, by inserting new imaginary pixels in between the real ones, and guessing at what light reading should be there based on surrounding pixel readings.

Effective Resolution is not a term used by scanner makers, but by people who actually test the real resolution of the scanner. The fact that the optical resolution is 1200 spi does not mean that the optics of the scanner is able to discriminate at this level. Effective resolution can be measured by scanning a target of known resolution, magnifying the image on screen and determining visually the real discrimination.

In general the effective resolution of consumer flatbeds is only about 30-40% of the stated optical resolution. Professional flatbeds do much better, ranging from about 60% with some models to 90% or more with the very best, and drum scanners in theory resolve at close to 100% of stated optical resolution.

Sandy King

sanking
27-Mar-2009, 10:38
I don't understand what Epson means by the term "micro step drive" technology.

However, when discussing the optical resolution of scanners it is often stated that the larger number is of no importance. For example, when talking about a scanner with stated optical resolution of 4800 X 9600 spi most people say that the larger figure is not important, that only the smaller figure applies. This is, practically speaking, true in most cases, but not always. In fact, the larger figure is based on the number of samples that are taken in one direction (the direction of the movement of the CCD head), and is quite real.

If you look at the image files of the targets that I recently posted in another thread on this forum, you will see that the resolution of the bars is much greater in one direction with the EverSmart Pro scan than in the other. This is due to the fact that the scanner samples 3175 spi wide, but 8025 spi in the direction of movement of the head. As you can clearly see the resolution in the direction of the head movement is quite real, and is not interpolated. So, If effective resolution based is on both horizontal and vertical bars the resolution is about 60 l/mm, but based just on the vertical bars it is over 90 l/mm.

I am going to re-post that image here so you don't have to go back to the other thread to see my point.

BTW, the 4990 also shows more resolution in the movement of the head, but not nearly as much as the EverSmart due to optical limitations.

Sandy






I also found this on the Epson site which seems to suggest there is something extra at work, the "Micro Step Drive™ technology", when scanning at 6400.

VictoriaPerelet
27-Mar-2009, 21:23
Flatbed CCD scanners (opposed to CIS scanners which have full width CMOS elements with micro lens but are not good for transparency) are using tiny sensors, very small and usually plastic lens and set of mirrors to project 8" scanline on to tiny CCD. Most of CCD's are re-branded Philips elements or similar:

http://www.kodak.com/global/en/business/ISS/Products/Linear/index.jhtml?pq-path=14426

Take Epson apart:) and you'll see set of mirrors that shrinks it to "flatbed" height and not table high machine or Imacon like tower. As almost everything related to photography depends on good glass - plastic piece is just not good enough.

That said, most of our published pics are scanned on mediocre flatbeds.

Keith S. Walklet
27-Mar-2009, 22:50
Jeremy, I know I'm often on my own with the opinion that it is worthwhile to scan at the higher resolutions, but the difference is very apparent in my sample 20x24 prints from a 35mm transparency, especially when final sharpening is applied.

I was just sharing the comparison prints made from my old 4870 scans at 1200, 2400, 4800 and 9600spi with a friend today, in fact.

His observation, "Wow, sharper, sharper, sharper, then what happened to that? Its so soft in comparison to the others, like it just falls off a cliff." which was in reference to the 9600spi sample, which on the 4870 is an interpolated setting.

Have to laugh, Sandy. My astigmatism makes lines going both directions look the same. A great illustration, regardless.

Jan Becket
28-Mar-2009, 01:08
I've been scanning 4X5 B/W on my V700 with Ed Hamrick's Vuescan. I have it set to scan at the max 6400 but a setting in "Output" downsamples by whatever factor you choose. I have mine set to downsample to 3200. (That extra 1,000 or so dpi above 2,400 is probably just wishful thinking...) Ed makes a pretty good case for this approach on his website. In any case, it's a solid piece of software. I'm getting better results than I did w/ Silverfast a few years ago and saving a huge bundle every year by not having to pay for upgrades.

Keith S. Walklet
29-Mar-2009, 16:02
Jeremy, to follow up my post on the incremental improvements by boosting the scanning resolution, I've attached some recent tests. These were all scanned on Leigh Perry's collaborative scan comparison transparency with Silverfast, 48bit HDR, wet-mounted on 3/16" plex directly on the platten. The file on the left was scanned at 2400 and left that way, the others were downsampled from their respective resolutions, and all three files were sharpened 400-1.0.

I usually am scanning at 6400spi. The file sizes at 6400spi are manageable (I can scan a 4x5 in two passes). I did find that the detail continues to improve with the 9800spi and 12800spi settings, but the file sizes are unwieldy.

sanking
29-Mar-2009, 17:47
Keith,

Don't you have any problem with the fluid making its way over the bed glass and into the inside of the scanner with this method of fluid mounting?

Sandy King






These were all scanned on Leigh Perry's collaborative scan comparison transparency with Silverfast, 48bit HDR, wet-mounted on 3/16" plex directly on the platten.

Keith S. Walklet
29-Mar-2009, 18:00
Sandy, not so far. The edge of the scanner platen seems to be fairly well sealed, but I take care to try and avoid using so much fluid that it runs to the edges. If I overdo it, I soak up the extra with my microfiber cloth. I am using KAMI, so it evaporates quickly, too.

My piece of plex is roughly 5x7 and sits in the middle of the bed with the mylar overhanging on the near edge to make it easy to grasp and lift. With the plex so far from the edges, it makes intercepting any excess fluid fairly easy.

falth j
1-Feb-2010, 05:04
At a workshop I attended about nine month's after the epson v750 was released, it was generally felt by the workshop hosts, and from their tests, that there wasn't much to be gained above the 2200 - 2400 setting areas in practice, and perhaps higher settings may be detrimental in some cases...

Martin Miksch
4-Feb-2010, 03:27
J...in my sample 20x24 prints from a 35mm transparency...

WOW^^

Tom Monego
4-Feb-2010, 07:16
With my V700 I found that there was no advantage to scanning above 3200ppi. Scans just took a lot more time and the results weren't any better. For a 4x5 to print at 300ppi (Canon ipf5000) 1500 ppi will get you above 16x20. At least with the V700 you can try to scan a 4x5 at 6400ppi, in one piece if you have a couple of hours. You can use Silverfast, but I have found the pro section of the Epson software to work well. The home and auto sections are worthless.
I agree focusing is a bit of a black art, the unit I have used since the scanner came out (4 years?) came fine out of the box, I was lucky. I no longer work in that job, so I'm planning on buying one a little worried about the focus calibration.

Tom

sngraphics
23-Sep-2012, 13:17
Focusing the beast is a black art. Many never get it focused AFAIKT. Have fun.

Pardon my ignorance but I have been using this scanner for a few years now and I did not realize it could be focused.
How does one go about that?

sngraphics
23-Sep-2012, 13:22
The key is obtaining correct focus.


I agree focusing is a bit of a black art, the unit I have used since the scanner came out (4 years?) came fine out of the box, I was lucky. I no longer work in that job, so I'm planning on buying one a little worried about the focus calibration.

Tom

Sorry for the second post in a row.
Pardon my ignorance but I have been using this scanner for a few years now and I did not realize it could be focused.
How does one go about that?

JBelthoff
23-Sep-2012, 15:38
Pardon my ignorance but I have been using this scanner for a few years now and I did not realize it could be focused.
How does one go about that?

You don't focus the scanner. You raise or lower the film holder either using the Epson plastic things that came with the holder, (Not so efficient), or use something like the Better Scanning holder which can be found here: http://www.betterscanning.com/

Hope that helps.

-- JB

sngraphics
23-Sep-2012, 15:54
[QUOTE=JBelthoff;935363]You don't focus the scanner. You raise or lower the film holder either using the Epson plastic things that came with the holder, (Not so efficient), or use something like the Better Scanning holder which can be found here: http://www.betterscanning.com/

Yes, that did help, and thank you very much John for clearing that up for me.


The more pressing question I had was, what is the native resolution for this scanner?
And if there is a difference in native resolution between scanning reflective and transparencies.
Because I see this thread is mainly about scanning transparencies but most of what I scan is reflective.

Also what are other "safe" alternatives to the Native resolution?
eg. if native is 6400 is 50% a good 2nd option or are there "Good Steps" like 4800, 3200, 2400

Any input, info or advice would be much appreciated.

Lenny Eiger
28-Sep-2012, 11:57
Also what are other "safe" alternatives to the Native resolution?
eg. if native is 6400 is 50% a good 2nd option or are there "Good Steps" like 4800, 3200, 2400

Any input, info or advice would be much appreciated.

Most people on this forum would agree that the native resolution, or let's just say, maximum optical resolution, is between 2000 and 2400. Scanning at any number higher than that will not yield anything more.

Lenny

architorture
28-Sep-2012, 13:55
I do not doubt that the max optical resolution of the v700/v750 is ~2400dpi. But the only definitive source I've seen for that figure did not state at what scan resolution the test was done.

In my own tests (with my v700), I have found a clearly visible quality difference between scanning at 2400spi and scanning at 4800spi to downsample to 2400dpi in photoshop.

these images are small 100% portions of a 4x5 negative, mounted to the betterscanning glass mounting station. The last image is for comparison - a 2000spi scan from a Flextight X1 or X5 (i don't recall which - 2000spi is the max available resolution on a 4x5 negative though).

IMO, the difference between 2400 and 4800 is obvious and significant...

(The lasersoft imaging watermarks are because these were done when I was testing the demo of silverfast 8)

epson v700 4800-2400
81133

epson v700 2400
81134

imacon 2000
81136

Perhaps this is a result of a process that is essentially just some capture sharpening? I don't know. I don't have a way to measure any quantitative difference.
But to get a better result than the imacon, for 30-50 times less cost? sounds good to me!

Brian C. Miller
30-Sep-2012, 23:50
I'm in the "your mileage may vary" crowd, because the scanner will be within the manufacturing tolerances, but there's a low side and a high side. I've found that my 750 will give a definite difference between 3200 and 6400. Here's a sample and a crop in the Lounge at 6400 (link (http://www.largeformatphotography.info/forum/showthread.php?43423-safe-haven-for-tiny-formats&p=937617&viewfull=1#post937617) or link (http://www.largeformatphotography.info/forum/showthread.php?43423-safe-haven-for-tiny-formats/page428)). Is my 750 better than my 3200? Yep! Would I still send off my film to Lenny? Duh, of course! But to say that a certain model tops out at X, I must recommend that you have to test your scanner for yourself.

sngraphics
3-Oct-2012, 03:56
Most people on this forum would agree that the native resolution, or let's just say, maximum optical resolution, is between 2000 and 2400. Scanning at any number higher than that will not yield anything more.

Lenny

Thank you for your reply Lenny.
After doing some testing with my V750 I might have to agree with architorture.
I am seeing differences at higher resolutions.
Pretty much the same results as the samples architorture provided.
I have to mention that almost all the scanning that I do here is of reflective material and that I use SilverFast and I profile my scanner a few times a year.
Not sure if reflective makes any difference because I've noticed that pretty much most of the posts here are in reference to film/negatives/transparencies.

Kirk Gittings
3-Oct-2012, 09:23
If one is not testing the scanner with a test target you are just guessing and I suspect many people, desiring more resolution, see it when its not really there. I can't remember who but someone loaned me one from this site when I was testing mine and it solved my problem of "wishful thinking resolution". The couple of 750s I have tested effectively topped out at about 2000. 2400 was not there.

sanking
3-Oct-2012, 18:06
If one is not testing the scanner with a test target you are just guessing and I suspect many people, desiring more resolution, see it when its not really there. I can't remember who but someone loaned me one from this site when I was testing mine and it solved my problem of "wishful thinking resolution". The couple of 750s I have tested effectively topped out at about 2000. 2400 was not there.

Kirk is about spot on. I have one of those chrome on glass resolution targets and just tested the V700, after first adjusting for optimum plane of focus. I did the tests with the film holder selected, which would activate the better of the two lenses. What I found, and it is consistent with previous testing of this machine, is that scanning at maximum resolution (6400 dpi) results in a modest increase (about 20-25%) in real resolution compared to scanning at 2400 dpi. Specifically, here are the results.

Scan at 2400 dpi -- Actual resolution = about 32 lpm, or 1600 dpi.
Scan at 6400 dpi -- Actual resolution = about 41 lpm, or 2100 dpi.

My criteria for reading the target results is the point at which one can see separation of both the vertical and horizontal bars.

BTW, similar testing of the Epson 4990 with the same target indicated a maximum resolution of about actual 1600 dpi when scanning at the maximum of 4800 dpi.

Sandy

genotypewriter
3-Oct-2012, 18:55
... just tested the V700, after first adjusting for optimum plane of focus ...

Hi Sandy... How did you adjust the height? And what soft of a precision are we talking about here?

Thanks,
G

sanking
3-Oct-2012, 19:54
Hi Sandy... How did you adjust the height? And what soft of a precision are we talking about here?

Thanks,
G

The only way to adjust the height for best plane of focus is by trial and error. If you are working with a target you scan at a certain height, note the resolution, adjust the height lower or higher, scan again and note the resolution. If you do this, adjusting the plane from about 1.5 mm above the glass to 4.0 mm above the glass, you will eventually find the height that gives the best resolution. With my scanner this plane is about 3.0 mm above the glass, when using the lens that is activated when you choose film holder. The plane of best focus of the other lens, which is activated when you choose film area guide, is much closer to the glass, with my scanner about 1 mm above the glass.

The precision as stated is quite high, assuming your criteria for evaluating the resolution of the scanned target is same as mine, i.e. there is discrimination between the horizontal and vertical bars of the target.

You don't need a resolution target to adjust for the plane of best focus. A sharp negative works fine for this. But you need some kind of target to describe the sharpness in dpi or lines per millimeter.

Sandy

genotypewriter
5-Oct-2012, 01:21
Thanks Sandy,

I do this already to a precision high enough the film is in the DOF even with some adjustments. Haven't bothered doing this with 8x10 film but I should.

Regards,
G

Robert Budding
5-Oct-2012, 05:10
Kirk is about spot on. I have one of those chrome on glass resolution targets and just tested the V700, after first adjusting for optimum plane of focus. I did the tests with the film holder selected, which would activate the better of the two lenses. What I found, and it is consistent with previous testing of this machine, is that scanning at maximum resolution (6400 dpi) results in a modest increase (about 20-25%) in real resolution compared to scanning at 2400 dpi. Specifically, here are the results.

Scan at 2400 dpi -- Actual resolution = about 32 lpm, or 1600 dpi.
Scan at 6400 dpi -- Actual resolution = about 41 lpm, or 2100 dpi.

My criteria for reading the target results is the point at which one can see separation of both the vertical and horizontal bars.

BTW, similar testing of the Epson 4990 with the same target indicated a maximum resolution of about actual 1600 dpi when scanning at the maximum of 4800 dpi.

Sandy

Sounds as if you're really testing software interpolation and not optical resolution.

http://scantips.com/basics07.html

sanking
5-Oct-2012, 09:43
Sounds as if you're really testing software interpolation and not optical resolution.

http://scantips.com/basics07.html

Flatbed scanners typically have one resolution if measured in the direction of the movement of the step motor, and another if measured at right angles to the movement (width of the CCD). When you scan a resolution target that contains only horizontal and vertical bars, assuming the target is aligned with the movement of the CCD, data is sampled directly and no interpolation is needed. Interpolation takes place with data that is sampled on the diagonal.

That said I am not a software engineer and accept that my understanding of this could be uninformed.

Sandy

Kirk Gittings
5-Oct-2012, 10:11
Does this interpolation give more resolution? No, of course not. There is no added detail present from the original photograph. It's just a larger image, which simply repeats existing data, and at best it's a mix of real and faked data. You can blow it up in your photo editor later, same thing. Interpolated images have a vague unsharp look. The added intermediate 105 value blurred the "edge" between the 100 and 110 values in adjacent pixels.

rdenney
5-Oct-2012, 10:49
The issue is not the spacing of the sensels, but their size. The sensels on an Epson see a big fuzzy spot. The higher the scan resolution, the more those big fuzzy spots overlap. Each one might still be subtly different, but at some point the fuzzy spots overlap so much that they don't add anything useful by being more plentiful.

If you evaluate the resulting file in terms of line-pairs/mm or MTF using a proper test target, then the spatial frequency of the fuzzy spots won't matter, as long as there is enough of them to fill in the gaps. All that will matter is the spatial frequency of the detail.

Someone already did this (was it Ben Syverson?), and found that the Epson does not provide a good modulation transfer at spatial frequencies greater than about 1500-2000 effective pixels/inch. But I do seem to recall that one still needed to oversample the negative to attain that outcome. So, it's reasonable to think we might overlap those fuzzy spots closely together and then summarize them into crisper spots using downsampling, or oversample and then limit enlargement to make sure we don't go beyond the scanner's capabilities. But I would never think that the scan resolution should be the same as what we expect the spatial frequency at good MTF to be. I routinely sample at 3200. Do I get more than if I sample at 2400? I dunno. But I'm sure that I don't get less, and it provides some resolution headroom so that I can be sure that I'm getting everything the scanner can deliver.

I also don't enlarge from Epson scans more than 4X happily. Let's do the math. If we get 1500 pixels/inch at good MTF, that is 60 pixels/mm, or 30 line-pairs/mm. If we want 8 line-pairs/mm in the print to provide the most sharpness a viewer can see even on close inspection, then we can print at 30/8=4x. If we set that standard at 5 line-pairs/mm in the print (which is as good as I can see in good light even with the bottom lens in my trifocals), we can go up to 30/5=6x. Most here are pretty confident in their Epson scans (at least in terms of resolution) up to a 4x enlargement, so my math lines up with that experience exactly.

But we still may choose to scan at a higher sampling rate as a strategy to ensure that we get the highest spatial frequency at good MTF possible. I really don't have a problem sending a file to the printer with a pixel density of 1000 or 1200 pixels/inch. My hard disk is big enough.

Rick "who often scans at 2400 and gets good 4x enlargements" Denney

architorture
6-Oct-2012, 17:33
FWIW, just last week I did another quick run-through of the different scan DPI settings with a recent 4x5 negative. I scanned a small portion at 2400, 3200, 4800, and 6400, then downsampled in PS with bicubic sharper to 2400dpi.

The results unfortunately confirmed my previous observation: with my scanner, 4800spi gives the best results for detail, evaluated subjectively of course. I have no idea what actual dpi it is resolving (other than that I believe it looks better than the Imacon's 2000dpi scan).

If I were to rank each setting in order, from best to worst, it would be as follows: 4800 > 3200 > 6400/2400. Interestingly, the 6400spi setting looks worse.

I was really hoping that 3200 would be indistinguishable from 4800 so that the scans would run faster, but alas, it was clearly not up to snuff :(

Here's a thought: anybody want to do a "collaborative scanner resolution chart test" similar to the collaborative test that is on the site's main page? If someone has a resolution chart they are willing to lend, we could send it around between people and test many machines quantatively... then we could really be talking apples-to-apples!

Brian C. Miller
7-Oct-2012, 03:18
Here's a thought: anybody want to do a "collaborative scanner resolution chart test" similar to the collaborative test that is on the site's main page? If someone has a resolution chart they are willing to lend, we could send it around between people and test many machines quantatively... then we could really be talking apples-to-apples!

I like that idea. My "test target" is a sign on a crane, which is legible at the 6400spi setting. The other easily obtainable target is the USAF test target. There's also a number of other test target PDF files out there, but the problem is that they are subject to being printed on my printer. (An Epson 2200 can make a nice print, but the test targets don't look that good)

Anybody remember the Spirograph? (Apparently the current models are not up to the standard set by the original) Doodle a pattern with one of those and photograph it along with the USAF target.

Leonard Evens
7-Oct-2012, 10:00
You have to distinguiish between the sampling rate and the resolution. 6400 ppi means that the scanner collects 6400 samples per inch. That would correspond to (6400/2)25.4 ~ 126 line pairs per mm. But the optical system of the scanner can't actually resolve that well. As others have pointed out, it is more like 2200 ppi or (2200/2)/25.4 ~ 43.3 lp/mm. Since modern large format lenses and films can do a lot better than that, it follows that the scanner is the limit on the resolution you can expect.

Assuming that an average person can resolve 5 lp/mm at about 10 inches, that seems to say that if you viewed an 8 X enlargement of a 4 x 5 negative at 10 inches, the results would still look sharp. Of course some people can do considerably better than 5 lp/mm, and the calculations ignored the resolution limits of the printer. So taking those factors into consideration, it would seem that someone looking closely at a 16 x 20 print made from a scan might possibly find it sharp. Of course, if the viewer got back to a reasonable distance, a larger print would still look sharp.

Kirk Gittings
7-Oct-2012, 11:32
FWIW. I know this thread is about resolution, but res is only half the issue with these scanners. I own a 750 but virtually never use it for files for exhibition prints. Why? Because besides resolution limitations these scanners lack the ability IME to extract all the shadow/highlight info from a negative processed for normal silver printing which is my basic MO. You can exp/process a neg pretty flat and they will scan OK, but I want a neg that will print well on silver too. So since I have access to an IQSmart, I use that for files aimed at exhibition or for a rally primo scan I send it to Lenny.

But back to resolution limitations. I put a ton of work into a file and while I rarely print above 16x20 why would I want to limit my print size to that size given all the work involved (I actually am never happy with a 750 scan for prints above 11x14-they just look mushy to me unless you over-sharpen them and that adds another look I don't like? So I archived a worked up file at 30x40 from an IQSmart or Lenny to cover any eventualities.

Ken Lee
7-Oct-2012, 12:53
If 4x5 isn't good enough on an Epson, then try 5x7 or 8x10: there are plenty of pixels to choose from :-)

I like Tim Parkin's piece about the questionable utility of scanning LF at resolution greater than 2000 spi,

Kirk Gittings
7-Oct-2012, 14:58
If I understand him I don't really agree with him. Understand he is talking about scanning at 2000 vs. larger ON A DRUM SCANNER not on an Epson-two different propositions entirely and not relevant really to this thread as there is nothing you can do on an Epson to scann actual grain on a 4x5. IME with drum scans when you have actual grain clearly defined IMO you need less overall sharpening and end up with a more traditional look to the image that if you scan below the grain resolution and end up sharpening grain clumps in an to attempt to achieve the same sharp feel. One looks traditionally sharp and the other looks digitally sharpened.

sanking
7-Oct-2012, 17:16
Resolution is what it is. If real resolution of 2000 dpi is not high enough to see grain clumps with an Epson flatbed then it will not be enough with a drum scanner. With most slow and medium speed films you need a minimum of about 3000 dpi to see grain clumps. You might be able to see grain clumps at 2000 dpi if scanning a high speed film, or a film that has been over-exposed or over-developed.

Sandy

amilne
7-Oct-2012, 20:12
Boy, am I glad I don't print over 8x10, mostly.