Re: Top-end digital concerns
Hi Clement,
my answer will not satisfy you at all, because I am quite the opposite of you regarding technical details. I don't invest my time in understanding all the technical aspects of a DSLR camera, but just use it as a tool for my purposes. There are limitations, but compared to 35mm film, a camera like the 5D or the 1Ds Mark II/III has nothing but advantages. With 35mm lenses, you couldn't stop further down than f/16 either without getting diffraction issues. This is not different with FF DSLR bodys.
Again, I do not care much about technical details, but I just see the excellent results from my 1Ds III and that is enough. For me, with prints up to 1m large, the only (but very important) advantage of LF over DSLRs are the movements. If I could have the movements on a DSLR (more than with a few tilt-shift lenses), I probably wouldn't use a LF camera any more.
Re: Top-end digital concerns
Hi Clément
Following your post, the question relevant to large format users are
- since digital is supposed to deliver better images than film with he current "35mm" (24x36mm) and medium format silicon sensors (now close to the 41x56 = 645 film size), with a better work-flow and (hopefully) with a better cash-flow (for professionals), is there any future for even 6x8 cm silicon chips and above ?
- if large format silicon chips appear, the question of 3 micron pixel size is less important provided that we have enough pixels to saturate even a one terabyte hard disk with 2-3 images ;)
Regarding smaller pixel size, we should always make a difference between
- pixel pitch or pixel grid periodicity, commanding the rules for the sampling theorem
- pixel surface, commanding the number of photons per exposure for a given illumination and exposure time, hence commanding the physical signal to noise ratio.
Sure, in Bayer patterns both pitch and aperture size are related for practical reasons, but both phenomena are formally different. Reminder : the commercial pixel count for a Bayer pattern is the total number of pixels all colors combined, in fact the actual pitch for red pixels is twice as big as the basic Bayer pattern pitch.
I see a great deal of interest in tiny subpixels as exposed below.
Regarding the sampling theorem I prefer not to speak in terms or Airy disks but in terms of cut-off period or cut-off spatial frequency.
With film we are in a situation of the cut-off period of best films is far above what can pass through a top-class large format lens. So in a sense, all LF users are very happy with a detector which is much better than the lens ! So why not the same for digital photographic imaging, not only for military or aerospace use (or both ;) ) ?
The absolute cut-off period for a diffraction-limited lens si N*lambda where N is the f-number and lambda is the average wavelength of visible light ; in fact taking the worst-case at 0.7 microns (the actual limit of sensitivity fr the human eye) we get an ultimate cut-off period of 0.7 N.
The sampling theorem states that you need 2 samples per optical period to avoid aliasing and moiré effects.
Take a state of the art view camera lens, e.g. a solid modern 150mm for 4x5", consider that it is diffraction-limited at f/16, the diffraction cut-off period is about 11 microns (0.7 * 16), the corresponding cut-off spatial frequency being about 90 cy/mm, a figure hardly reached by any view camera lens covering the 4x5" format. Modern color film are capable of recording fine details above 100 cy/mm but with a vanishing contrast.
I recenty read that Sony has announced silicon chips for mobile phones with 12 Mpix on a sensor with 7mm of diagonal, 3288 x 2468 pixels ; this yields a pixel pitch of 1.7 micron (we know nothing from these figures about pixel surface, smaller than 1.7 x 1.7 micron square !)
http://mobilearsenal.com/new/sony_12...r_mobiles.html
So a pixel pitch of 1.7 microns yields a cut-off period of 3.4 microns, this corresponds to a diffraction-limited lens at about f/5. For a fixed-focal length for a mobile phone, if it is not a wide-angle, why not ? But sure, we are now entering a situation where the optical diffraction cut-off frequency of the lens is the actual limit.
To me this is a blessing since in this perspective we can forget about anti-aliasing filters. Good by also to anti-moiré post-processing software as advertised by Hasselblad !
Compare with the situation we have in LF on film.
If you read the actual MTF data of a fine-grained color slide like PROVIA 100F, you find that the MTF curve of this film is very close (up to 60 cy/mm) to the MTF curve of a 7-micron pitched sensor fitted with an anti-aliasing filter cutting off at 70 cy/mm, except that film transmits fine details with a low contrast well above 100 cy/mm.
Since you are French you can read my article here and check by yourself.
http://www.galerie-photo.com/film-co...esolution.html
But we can use (B&W) films for which the MTF extends above 200 cy/mm, the Gigabit(TM) film was available in 4x5" ! So why not doing the same with digital sensors ?
Regarding tiny pixels, I see a great interest in them since it gives a total freedom to the digital imaging software engineer to do as much pre-processing as thay can inside the camera, or inside the digital back before delivering the actual image file to the end user.
Once the software is developed, it is costless to duplicate it. And the computations are secret and proprietary, do not expect any details about that.
In Europe we do not recognize software patents, so all pre-processing tricks, at least for the European market, will be secret know-how. And if a company is issued a software patent for digital image pre-processing valid only on the US, taking into account that you have to disclose a minimum of technical details in a patent, this would mean that the patent is kept secret for European readers ! ;)
So on the contrary I'm expecting that zillions of tiny pixels will continue to be both a marketing gimmick for the years to come, and a blessing for software engineers. It will give them so much freedom in pre-processing, that the question of the optical diffcation cut-off frequency wil be more or less marginal.
I'm thinking of all kind of intelligent pre-procesing software based on smartly combining pixels together, in a adaptative way, testing locally the shapes and intensities in the image, in order to reduce noice where it is the most visible and to enhance egde sharpness ad libitum.
Instead of good old Fourier methods based on a spatially invariant linear processing, I see a heavy use of all kinds of non-linear and adaptative image pre-processing techniques based on brute-force methods with zillions of pixels !
Re: Top-end digital concerns
You're taking an interesting approach to this problem. As attracted as I am to technical detail, I'm taking a more emperical approach to this question. But, this may be all the more appropriate, since my interest is more in the low end.
I've been doing a lot of reading, and here are a couple of conclusions that I've drawn:
As for 35mm DSLR full-frame cameras, the current high-end DSLR's in the low 20's megapixels offer about as much resolution as current, high-end DSLR zoom lenses can handle. Maybe one can go a little higher with fixed focal length lenses.
I spoke with Schneider LF technical people, and it was their opinion that at 22 megapixels, one could use traditional LF lenses and not expect to gain that much by "upgrading" to the Digitar type lenses. (I'm thinking in particular of the Mamiya 22mp digital back.) They emphasized that a lot could be accomplished, size-wise and otherwise with a back like that. Above 22p, they recomended more sophisticated lenses.
So, given the expenses involved, this is the direction towards which I'm heading. 22mp can do quite a lot. It'll take a while, but at least I have a plan. While I found an older style Arca 6x9 camera for a reasonable price, I've recently run across a way I can adapt this back to my 4x5. Etc.
About three and a half years ago, I purchased the only full-frame camera that I could afford. There were only two: the Canon 1Ds and the just discontinued Kodak DSLR in either a Nikon or a Canon mount. I wanted to use a 24mm PC lens, so I needed full frame, to get the best wide-angle advantage of that lens. Given the hefty discount, I chose Kodak in a Canon mount. It has it's weaknesses and strengths. It's low ISO, but I use it only on a tripod like a VC. One thing I like, it has no anti-aliasing filter. This gives it excellent color and resolution characteristics. (Until moire interferes.) One advantage to this camera, is that it's good preparation for using a digital back, since they also do not have anti-aliasing filters.
But, there are negatives with the 35mm DSLR approach. Movements are more limited, given the few number of lenses that can be PC controlled. The exposure chamber is small, so DSLR's are more subject to flare,especially in overcast situations. (I hate flare!)
Digital is expensive. A I kind of implied, the direction I'm taking is more driven by what I can achieve, what's available, and a principle of diminishiing returns as one scales the digital ladder.
Re: Top-end digital concerns
A short time ago I commented upon this exact aspect of sensors, yet there were no responses:
http://www.largeformatphotography.in...1&postcount=21
The main issue really is the pixel cell site dimension. While I think a near 4x5 sensor could be possible, there would not be any advantage in having it near 6µm pixel sizes. Without doing the math on this, I would propose that 9µm might be a reasonable limit, and allow some usable apertures and image quality.
One could cram even more pixels into a sensor than can be found on a Nikon D3X, but to do so would sometimes be even more of a compromise of image quality. It would also mean that smaller apertures would degrade image quality even more.
Another possible approach would be doubling of cell sites; imagine a future D6X with close to 52MP sensor. The only practical way to do that would be to double up (or more) the captures, then interpolate into a smaller result. A few small video cameras do that; they have sensors near 5MP and group together four or more adjacent pixels to create a more sensitive signal to produce a lower resolution HD result.
However, I think that the current D3X really is at the performance limit; to go further would have extremely low improvement in optical resolution (not file sizes). I really feel that with the Canon 1Ds Mark III and Nikon D3X, those companies need to concentrate more on improving colour and sensitivity, and give the uberMP race a rest for a while.
Ciao!
Gordon Moat Photography
Re: Top-end digital concerns
Quote:
Originally Posted by
Aender Brepsom
Hi Clement,
my answer will not satisfy you at all, because I am quite the opposite of you regarding technical details. I don't invest my time in understanding all the technical aspects of a DSLR camera, but just use it as a tool for my purposes. There are limitations, but compared to 35mm film, a camera like the 5D or the 1Ds Mark II/III has nothing but advantages. With 35mm lenses, you couldn't stop further down than f/16 either without getting diffraction issues. This is not different with FF DSLR bodys.
Again, I do not care much about technical details, but I just see the excellent results from my 1Ds III and that is enough. For me, with prints up to 1m large, the only (but very important) advantage of LF over DSLRs are the movements. If I could have the movements on a DSLR (more than with a few tilt-shift lenses), I probably wouldn't use a LF camera any more.
Strange how people see things differently. I also have a 1DsmkIII, I'm sort of disappointed with it, not that it does not perform very well, it does mostly. It leaves me thinking it should be better, hence a return to LF for me for the fun side of photography. The more pixels I have in 35mm cameras the more I like film. I've not found any Canon lenses to get me excited either. The latest range of pixel packed 35mm just leave me cold, all those pixels help highlight digital faults and make me realise how good film is and how I took it for granted.
Kevin.
Re: Top-end digital concerns
Quote:
Originally Posted by
Gordon Moat
...I think that the current D3X really is at the performance limit; to go further would have extremely low improvement in optical resolution (not file sizes). I really feel that with the Canon 1Ds Mark III and Nikon D3X, those companies need to concentrate more on improving colour and sensitivity, and give the uberMP race a rest for a while.
Thom Hogen seems to reach the same conclusion in his review of the D3x (http://www.bythom.com/nikond3xreview.htm). Some excerpts:
...I would say that f/11 is that last aperture you can use and still have an expectancy of getting near maximal resolution (a term I loosely used before: diffraction limited aperture). Go smaller than f/11 and no amount of careful sharpening will restore the semblance of acuity at and near the Nyquist limit. Moreover, you'll lose signficant contrast, and most people perceive contrast in conjunction with sharpness (i.e. more contrast is perceived as "sharper"). If you're a stickler for detail, don't stray past f/8...For my landscape work, I won't be afraid to use f/11, but if I can get to f/8 I will.
...Indeed, I think that the serious landscape shooter almost certainly needs to consider using the PC-E lenses on his D3x and using the Scheimpflug principle to get depth of field, not solely aperture. If you need to go to f/16 for depth of field in your landscape work, I'm not so sure that you shouldn't just use a D700 and use panorama stitching to get more pixels, despite what that means for moving subjects.
Since I know from 35mm film experience that I can't get traditional near-to-far landscape compositions in full focus at f/8 (and frequently not even at f/11), it would seem that to achieve optimal landscape resolution with a 20+MP DSLR kit, I'd be limited to three tilt/shift lens focal lengths (with limited coverage compared to their LF film counterparts); above and beyond that, I'd have to shoot planar or limited depth-of-field subjects. A lot of folks are perfectly happy shooting 4x5 film with just three lenses (90, 150, and 240 are roughly comparable to the DSLR tilt/shift focal lengths), but I'm not. And stitching is of limited appeal since most of my subjects involve moving objects.
So it would seem that 35mm DSLR's can intrinsically achieve some LF film landscape photography objectives, but not all; and that further ratcheting up the megapixels will achieve little to no benefit due to diffraction. Apparently the only way in the foreseeable future to achieve all LF film camera capabilities with digital capture is to use a technical camera with a digital back. A used 22MP digital back can be cost-effective if one is happy with a maximum 16x20" print size (it would yield roughly 260DPI, which is close to the optimal 300+ DPI used by most inkjet printers), or can shoot subjects amenable to stitching. But the higher capture resolutions required for larger native print sizes are just not cost-effective at this point.
The potential of digital capture is certainly intriguing (the faster shutter speeds by itself would enable a variety of shots not possible with LF film), but for now I'm waiting until the MF digital market shakes out and prices come down quite a bit. And with a deep recession underway, that could take a long time.
Re: Top-end digital concerns
Clement,
I think there are a lot of numbers out there. Some of them mean something and some of them don't. For commercial work, the convenience of digital and the small target size (magazine page) make it very easy to choose - for most.
I am a fine artist, and I like to print up to 40 inches, in black and white. There is no digital camera that comes close to my needs. I use an 8x10 camera and when I drum scan the image I have a 568 megapixel file. (24, 39, 50, mgpxls is no comparison.) I tried going down to 4x5 (and 6x7), I have a scanner that is exceptional, and should be able to make a file that equals an 8x10. It clearly doesn't. It isn't a matter of numbers. In my case its more a matter of film "real estate".
If print quality is important to you in your work, and you print larger than 15-20 inches on occasion, then film might be a good option.
I would say you might want to rent a top end digital camera for a day and see what it can do. Get a high end drum scan of the same image and compare, with your work in mind.
Lenny
Re: Top-end digital concerns
Thanks all for sharing your experience / point of view.
Everyone here but me noticed the “slip of the tongue” I made about units in my first message. It is of course micrometers and not nanometers. The mix-up came from an article about interferential filters involving tons of light wavelength values I red just before starting the topic.
Whatever.
Quote:
Originally Posted by Aender Brepsom
With 35mm lenses, you couldn't stop further down than f/16 either without getting diffraction issues. This is not different with FF DSLR bodys.
Good point. But what I red about digital diffraction quality fall-off often sounded like there is no image at all after diffraction limit aperture.
I wanted some feedback on this point from top-end digital users.
Quote:
Originally Posted by Aender Brepsom
I just see the excellent results from my 1Ds III and that is enough. For me, with prints up to 1m large.
I definitely need to see such prints.
Quote:
Originally Posted by Emmanuel BIGLER
Regarding tiny pixels, I see a great interest in them since it gives a total freedom to the digital imaging software engineer to do as much pre-processing as thay can inside the camera, or inside the digital back before delivering the actual image file to the end user.
Quote:
Originally Posted by Emmanuel BIGLER
So on the contrary I'm expecting that zillions of tiny pixels will continue to be both a marketing gimmick for the years to come, and a blessing for software engineers. It will give them so much freedom in pre-processing, that the question of the optical diffcation cut-off frequency wil be more or less marginal.
I’m afraid I can’t share your enthusiasm on this point.
Or maybe I do not fully understand your point here.
Tiny pixels won’t give any freedom to pre-processing engineer. It will give them a lot of hard work… and for what result: An opaque and artificial enhancement of a poor quality native capture.
I can’t see any good in such system. But maybe I am too old-fashion on this.
Once again, it does not seem to aim optimal quality nor user best interests but just marketing matters.
Quote:
Originally Posted by neil poulsen
I spoke with Schneider LF technical people, and it was their opinion that at 22 megapixels, one could use traditional LF lenses and not expect to gain that much by "upgrading" to the Digitar type lenses. (I'm thinking in particular of the Mamiya 22mp digital back.) They emphasized that a lot could be accomplished, size-wise and otherwise with a back like that. Above 22p, they recomended more sophisticated lenses.
So, given the expenses involved, this is the direction towards which I'm heading. 22mp can do quite a lot. It'll take a while, but at least I have a plan. While I found an older style Arca 6x9 camera for a reasonable price, I've recently run across a way I can adapt this back to my 4x5. Etc.
Thank you for sharing your discussion with Schneider technicians. I wasn’t aware of that statement.
My question here would be: why not spare a reasonable amount of money and buy a 1Ds III or D3 instead of that 22Mpx back you are speaking about?
I read you plan to use such a back on your current 4x5” camera or on a 6x9 arca.
But is it the only reason?
I hope there is a quality step between 22mpx 35mm digital cameras and 22mpx digital back. And I understand it is your bet here.
Moreover I imagine that you plan to use movements on such a digital back in order to optimize the sensor native file size instead of stretching 35mm cameras file with perspective tool on Photoshop (like A LOT of photographers do).
But what is the reality of quality question here?
How leaf or hasselblad hope to sell more 22mpx digital back at such prices when 20mpx 35mm cameras are currently buyable second-hand?
I am aware that I’m exaggerating a bit, but you got the idea.
I am curious to hear your point on that.
Quote:
Originally Posted by Gordon Moat
However, I think that the current D3X really is at the performance limit; to go further would have extremely low improvement in optical resolution (not file sizes). I really feel that with the Canon 1Ds Mark III and Nikon D3X, those companies need to concentrate more on improving colour and sensitivity, and give the uberMP race a rest for a while.
Anyone else having this “deja vu” feeling?
Some years ago I clearly remember specialized journalists making that statement after the latest Kodak-fuji-canon-nikon-whoever 35mm digital camera release.
But the mpx race is still here.
Here too, I exaggerate. I am aware that there is a big quality step between two years old DSLRs and currents.
But the strange feeling I have about quality not being the main concern of producers still lingers on after those years. And I don’t see it stop tomorrow.
Quote:
Originally Posted by Noeyedear
Strange how people see things differently. I also have a 1DsmkIII, I'm sort of disappointed with it, not that it does not perform very well, it does mostly. It leaves me thinking it should be better, hence a return to LF for me for the fun side of photography. The more pixels I have in 35mm cameras the more I like film. I've not found any Canon lenses to get me excited either. The latest range of pixel packed 35mm just leave me cold, all those pixels help highlight digital faults and make me realise how good film is and how I took it for granted.
Maybe that is close to the “strange feeling” I just spoke about.
Most of the DSLRs I tryed made that impression to me: “it should be better”
Those image screaming “DIGITAL”.
Those chromatic aberrations.
This poor dynamic range. Etc…
And very often for work, there is no time, clients want tons of images so they can have the illusion of choice, they want everything immediately.
So disappointing.
The quality doesn’t seem to be the main concern here either. Except maybe in fine art photography, but that’s another world.
As you say film is for the “fun side of photography” the side we keep for ourselves.
That sounds like a young professional photographer discovering the market of commercial photography. Actually that sounds correctly because that is exactly what it is. :)
Quote:
Originally Posted by Eric Leppanen
Since I know from 35mm film experience that I can't get traditional near-to-far landscape compositions in full focus at f/8 (and frequently not even at f/11), it would seem that to achieve optimal landscape resolution with a 20+MP DSLR kit, I'd be limited to three tilt/shift lens focal lengths (with limited coverage compared to their LF film counterparts); above and beyond that, I'd have to shoot planar or limited depth-of-field subjects. A lot of folks are perfectly happy shooting 4x5 film with just three lenses (90, 150, and 240 are roughly comparable to the DSLR tilt/shift focal lengths), but I'm not. And stitching is of limited appeal since most of my subjects involve moving objects.
So it would seem that 35mm DSLR's can intrinsically achieve some LF film landscape photography objectives, but not all.
This is very interesting.
So why SO MANY professional keep buying DSLRs with PCE lenses? If it is that hardly limited?
Only because they are lazy to carry a large format gear or a tripod?
Only to spare few k $?
I mean the Nikon d3x is worth 8000$!
1Ds III 7000$ or so!
PC-E optics between 1500 and 2000$!
The total gear kit is in the 11k – 14k range!
When you can find used H3D-II at 16k on EBay!
Here too, I can sense I lack some field reality experience.
Quote:
Originally Posted by Lenny Eiger
I use an 8x10 camera and when I drum scan the image I have a 568 megapixel file. (24, 39, 50, mgpxls is no comparison.).
Just a little technical comment here: I often read those comparisons between sheet film drum scan files and digital back files.
What is ignored to serve the superiority of film is that your drum scanner scans the grain. So that is not 568 Mpx of plain detail. To me the comparison is hedged.
If a scanner could deliver a 1000 Mpx of the same sheet of film would you announce that you have a 1Gpx details? 2 times more detail than you have on your current 568mpx files?
Of course not. The detail cap of film is way under those values. But the thing is we are so used to see grain enlarged that we do not consider it as a lack of detail.
But in the other hand, we do scream “unacceptable” on the minor little jpeg artefact on digital enlargements. It is both cultural and subjective.
Even though I plainly agree with you that an 8x10 is above current digital quality at same print size.
I'm not saying digital backs could achieve what you achieve with your drum scanned 8x10".
Just making it clear because I don't want a digital vs film war in this topic.
Just wanted to point that to me, such comparisons are wierd.
Quote:
Originally Posted by Lenny Eiger
I think there are a lot of numbers out there. Some of them mean something and some of them don't. For commercial work, the convenience of digital and the small target size (magazine page) make it very easy to choose - for most.
[…]
If print quality is important to you in your work, and you print larger than 15-20 inches on occasion, then film might be a good option.
Yes, that is an excellent point. All this has to be related to the print size and the print technology used.
A photographer working for daily newspapers can jump into digital with a 5 years-old DSLR and still having caped quality for his print size / offset quality prints.
But actually, if I start such a topic, it is because I need to deliver files for up to 2.5m large (close to 100 inches) prints. And at digital speed: meaning very short amount of time.
Unfortunately film isn’t always doable. And my quality exigency forbids me to use a stretched 35mm digital file.
And that is the point of that thread: a top-end digital quality solution.
regards,
CA.
Re: Top-end digital concerns
Quote:
Originally Posted by
Clement Apffel
Yes, that is an excellent point. All this has to be related to the print size and the print technology used.
A photographer working for daily newspapers can jump into digital with a 5 years-old DSLR and still having caped quality for his print size / offset quality prints.
CA.
The flaw with your conclusion here is that images that used to be targeted for printed media are passé. News papers, large and small, are dropping like flies, at least here in the USA. Staffs have been slashed to the bone and the survival schemes for traditional printed news outlets have been to position their daily publication for output to the web, though they are still trying to understand how to monetize this form of publishing. This increases their need for DSLRS that can transmit files directly to a PC for more or less instant uploads to the editing desk. The old days of photo journalism are over by and large and so are the old technologies and tools.
Don Bryant