How many mps is "enough" for camera scans?

[bags27]

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I'm using my CL (and Sigma 70 macro) to scan negatives. Great workflow and very effective on 135 film. Works well, too, with 120 film, but I feel the scans don't fully bring out the sense of depth of MF images. I've begun stitching partial shots together on PS, and it works pretty well, with the inevitably anomalies.

If I were to buy a FF camera, does the number of mps matter more than merely the fact that it's a FF, rather than crop sensor, now covering a MF negative? I realize that a 47 mps sensor captures more detail than a 24 mps sensor. But how much additional detail is there on a negative? And often the less dense sensor has greater dynamic range.

Thanks!

Edited December 31, 2020 by bags27

[frame-it]

2 hours ago, bags27 said:

I'm using my CL (and Sigma 70 macro) to scan negatives. Great workflow and very effective on 135 film. Works well, too, with 120 film, but I feel the scans don't fully bring out the sense of depth of MF images. I've begun stitching partial shots together on PS, and it works pretty well, with the inevitably anomalies.

If I were to buy a FF camera, does the number of mps matter more than merely the fact that it's a FF, rather than crop sensor, now covering a MF negative? I realize that a 47 mps sensor captures more detail than a 24 mps sensor. But how much additional detail is there on a negative? And often the less dense sensor has greater dynamic range.

Thanks!

i use my GFX50r + 90APO summicron-M + macro adapter M to scan 6x6 negatives...the negative would be almost full frame in the viewfinder..managed to get a lot of details

 

perhaps multishot mode [ if your camera has that] might help you get more detail?

[250swb]

Depends what you mean by medium format. If you scan a 6x6 with a FF camera you aren't going to use the pixels that don't cover the square format, so more pixels to start with are an advantage. If however you are scanning a 6x9 negative you will use all the pixels so a lower megapixel camera would be more or less equivalent. But a 6x6 scan with a 47mp sensor is more than enough to exceed a conventional film scanner if your setup and workflow are spot on, and a 6x9 scan at 47mp is icing on the cake.

[bags27]

I have both a 6x7 and a 6x9 and am definitely aware how very nice the 6x9 "wastes" no pixels with my CL.

Frame-it's point about multi-shot (such as the SL2 or S1R) is an interesting possibility.

Still, hard for me to think about spending a lot on a new digital camera right now, when I seem always to leave my digitals (CL and M10) at home and take film cameras out with me. I worry that the new camera will just be a scanning camera, and so trying to rationalize a used Sigma fp with 24 mps rather than a used Panasonic S1R (not a camera I think I'd otherwise enjoy)

[gbealnz]

Maybe try the M10 then?

[bags27]

6 hours ago, gbealnz said:

Maybe try the M10 then?

Thanks, Gary. When I tried 1:1, it doesn't work out well with the live view. It's very hard for me to focus it. Maybe I'll give it another try.

[Stuart Richardson]

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I will say that it depends quite a bit on your light source as well as your setup, but there is a lot more detail (and consequently tonality) in film than you might assume. I run a studio with an X5 and a V850 (solely for 8x10), and I have been trying to figure out a better way to scan 8x10, as the V850 can do a decent job, but comes nowhere close to getting the most out of 8x10. I would say that in general, film flatness and being absolutely rigid are more important than the highest end of megapixels, as the higher res you get, the great the losses from things like vibration, misalignment, flare and diffraction. I have tried scanning with both the S3, which is 65mp and the SL2 with multishot, which gives a 187mp file. The SL2 is better even without multishot, because the vibration of the shutter kills the sharpness in the S3, even with mirror pre-release. In both cases I used the 120mm APO Macro S, which is an extremely good macro lens. Overall, I think the X5 still does a better job, and does so more easily. With film scanners, I would say that most would agree that there is about 4000-5000dpi of information in slow modern films...when I say that amount, I am not talking about an Epson scanned at that resolution, I am talking about a true scanner with a lens and transport system that can get that out of the film...that is a small group, and basically limited to drum scanners, Kodak/Creo/Eversmart flatbeds and the Imacon/Hasselblad 646, 848, 949, X1 and X5. The Imacon and Hasselblad scanners can do it for 35mm, but they are only 3200 dpi for 120 and 2040 for 4x5, so they do leave resolution on the table for larger formats.

Just doing the calculation, if you assume film has about 5000dpi of "information" (by that I mean visible grain and hints of the information, though it will be very soft at that level of detail), then for 6x7 you would theoretically need about 156mp to resolve it completely. Since you will inevitably lose some detail to lens characteristics, I would say that in general, a system that can do a true 200mp with an extraordinarily good lens would be needed to get "everything". In practice, you do not need anywhere near this much to make an extremely good scan.

I would say, however, that if you are looking to make good enlargements from MF film you are going to want at least a 50mp camera with an electronic shutter, a very rigid setup, an extremely good macro lens and and still, you will leave a bit on the table. The Fuji GFX100 or Phase 100 or 150mp cameras are really going to be the best at this still. The SL2 is quite good, but multishot is not as good as single shot when it comes to pure resolution.

Edited January 2, 2021 by Stuart Richardson

[bags27]

4 hours ago, Stuart Richardson said:

I will say that it depends quite a bit on your light source as well as your setup, but there is a lot more detail (and consequently tonality) in film than you might assume. I run a studio with an X5 and a V850 (solely for 8x10), and I have been trying to figure out a better way to scan 8x10, as the V850 can do a decent job, but comes nowhere close to getting the most out of 8x10. I would say that in general, film flatness and being absolutely rigid are more important than the highest end of megapixels, as the higher res you get, the great the losses from things like vibration, misalignment, flare and diffraction. I have tried scanning with both the S3, which is 65mp and the SL2 with multishot, which gives a 187mp file. The SL2 is better even without multishot, because the vibration of the shutter kills the sharpness in the S3, even with mirror pre-release. In both cases I used the 120mm APO Macro S, which is an extremely good macro lens. Overall, I think the X5 still does a better job, and does so more easily. With film scanners, I would say that most would agree that there is about 4000-5000dpi of information in slow modern films...when I say that amount, I am not talking about an Epson scanned at that resolution, I am talking about a true scanner with a lens and transport system that can get that out of the film...that is a small group, and basically limited to drum scanners, Kodak/Creo/Eversmart flatbeds and the Imacon/Hasselblad 646, 848, 949, X1 and X5. The Imacon and Hasselblad scanners can do it for 35mm, but they are only 3200 dpi for 120 and 2040 for 4x5, so they do leave resolution on the table for larger formats.

Just doing the calculation, if you assume film has about 5000dpi of "information" (by that I mean visible grain and hints of the information, though it will be very soft at that level of detail), then for 6x7 you would theoretically need about 156mp to resolve it completely. Since you will inevitably lose some detail to lens characteristics, I would say that in general, a system that can do a true 200mp with an extraordinarily good lens would be needed to get "everything". In practice, you do not need anywhere near this much to make an extremely good scan.

I would say, however, that if you are looking to make good enlargements from MF film you are going to want at least a 50mp camera with an electronic shutter, a very rigid setup, an extremely good macro lens and and still, you will leave a bit on the table. The Fuji GFX100 or Phase 100 or 150mp cameras are really going to be the best at this still. The SL2 is quite good, but multishot is not as good as single shot when it comes to pure resolution.

Thanks so much Stuart. Although some of this is of course well beyond my ability or aspiration, this is extremely helpful in the broader mechanics of it.

[Mr.Prime]

As a recent purchaser of a 6x6 camera this thread is of some interest.

I can see and appreciate the difference between 135 and 120 film on this forum (it often comes across as obvious in the smooth tones) and other internet sites which gets me thinking I do not need high pixel count for small images and hence ‘daily’ scanning for internet use or photobooks can likely be satisfied even with an 8Mp APS-C sensor!

Then, when I want a wall sized or exhibition (ha!) print I could contract out to a professional.

[Stuart Richardson]

What is required and what is possible are two very different things. Film is a fundamentally different process, so resolution is not as easily defined as it is in digital. By its very nature, the information is contained all the way down to the molecular scale, but since it is not a mechanically perfect digital medium, there is no clear extinction resolution. It is mostly an agreed upon level at which all normally useful detail is captured. Most people that I have spoken to who are in a position to known, as well as my own experience suggests this is in the 4000-6000dpi range for most good films and camera systems. But that does not mean you need that much resolution to make a nice print. In most cases a really good 2000dpi scan will be just fine for normal sized prints from medium format. My X5 does 2040 dpi for 4x5 and I have printed 40x50 inch (100x125cm) prints from it that look superb. More important than pure resolution is the skill of the operator and the quality of the equipment/process. Having everything completely flat and in focus, plane parallel, no flare, not too much dust, a nice wide contrast range etc.

 

[bags27]

16 minutes ago, Stuart Richardson said:

What is required and what is possible are two very different things. Film is a fundamentally different process, so resolution is not as easily defined as it is in digital. By its very nature, the information is contained all the way down to the molecular scale, but since it is not a mechanically perfect digital medium, there is no clear extinction resolution. It is mostly an agreed upon level at which all normally useful detail is captured. Most people that I have spoken to who are in a position to known, as well as my own experience suggests this is in the 4000-6000dpi range for most good films and camera systems. But that does not mean you need that much resolution to make a nice print. In most cases a really good 2000dpi scan will be just fine for normal sized prints from medium format. My X5 does 2040 dpi for 4x5 and I have printed 40x50 inch (100x125cm) prints from it that look superb. More important than pure resolution is the skill of the operator and the quality of the equipment/process. Having everything completely flat and in focus, plane parallel, no flare, not too much dust, a nice wide contrast range etc.

 

So very helpful, Stuart. Thanks much!

[Stuart Richardson]

You're welcome!