How much resolution can I expect to get copying color slides and film with a 26 MP camera?

[jonikon]

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives. My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera. I get that the weak link here is the slide or negative, but 6MP of useable resolution seems a bit low to me. Hopefully someone must have figured this out by now.

 

[Sittatunga]

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives. My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera. I get that the weak link here is the slide or negative, but 6MP of useable resolution seems a bit low to me. Hopefully someone must have figured this out by now.

The big problem with copying colour slides is excessive contrast. That's much less of a problem with the huge dynamic range of a digital camera compared to most film than it was for duplicating slides. Your 26MPx camera will start to resolve the grain of the film, particularly if it's colour negative film or pushed HS Ektachrome or Tri-X. It's the grain that limits the ultimate resolution of film (hence the popularity of Panatomic-X for landscapes and Lith film for copying). But it's also the grain that gives the various films their individual characters, so your 26MPx certainly isn't overkill. I find that a 1" sensor 20MPx compact will give more detail in any light than any 35mm camera using colour negative film.

 

[ishwanu]

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives.

Yes, I know there's no point in digitizing my own slides at anything beyond 24mp.

My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera.

That could be true with many real-world slides, especially ones shot with less than stellar lenses. But I think 12mp might be more accurate with good gear under ideal circumstances.

 

[bmoag]

Opinions vary about the usable resolving power of 35mm film. Most of what I've read seems to wildly exceed what you can see for yourself when digitizing film.

Much depends on what you plan to do with the digitized film other than pixel peep the grain.

In general after scanning umpteen color negative 35mm I would say the 6mp thing is not far off, but may overestimates what is really usable in most color negative 35mm materials. As dpi/sensor megapixels increase the digitizing does more for the grain than it captures usable picture information. Some monochrome and transparency materials can yield usable picture info at somewhat higher resolutions but all have a ceiling.

You can still read that the dynamic range of color negative film exceeds digital I always found that laughable even in the early days of film scanning and early raw digital capture. When you digitize film you are taking a picture of a picture, digitizing film obviously yields better results than scanning a print but the principal is the same. Using a macro lens and digital camera will yield better dynamic range than most flatbed scanners or the old dedicated film scanners but, again, there is a limit to usable pictorial information vs just a better picture of the film grain.

So in my humble 24mp is indeed overkill for digitizing 35mm film but using a dSLR is the optimal way to digitize 35mm film for most of us. if you don't like the file sizes you can downsize them in post with no loss of usable image quality.

 

[bjn70]

Hopefully someone must have figured this out by now.

Yes but there seem to be a lot of different opinions. My opinion was that my 6MP D70S was roughly equivalent to my old SLR film images. I've read other opinions that said 8MP but more recently I've read that you can't capture all of the resolution of film even with a 24MP sensor. I've digitized a lot of my own slides with a Nikon D7200 and Nikon 105mm f4 macro lens. IMO my results were in the 6MP or less range.

 

[Gato Amarillo]

It would vary hugely depending on the quality of the film original - what film, how good a lens it was shot with, the skill of the photographer, and so on.

6 MP seems like a good general answer. Maybe twice that from Kodachrome shot by an expert, maybe much less from a typical family snapshot made with an Instamatic.

I don't think there is any way to really say, but a 24MP camera and a good lens should get you about all there is to be had.

Gato

 

[Overrank]

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives. My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera. I get that the weak link here is the slide or negative, but 6MP of useable resolution seems a bit low to me. Hopefully someone must have figured this out by now.

I’ve recently posted in the film forum some example digitisations of a slide made with different resolution digital cameras - https://www.dpreview.com/forums/thread/4741864 These are with modern colour slide film shot recently

There are details on the slide that needed a 45MP camera (or a 4000dpi scanner) to resolve. You will lose some resolution through the camera/lens arrangement - I’ve found on tests that I only get around 60% of the linear resolution. As with digital cameras there’s a sweet spot of usable information, and more than that isn’t required in most cases - 24 MP seems a resonance compromise.

 

[PhotoTeach2]

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives. My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera. I get that the weak link here is the slide or negative, but 6MP of useable resolution seems a bit low to me. Hopefully someone must have figured this out by now.

My personal experience scanning negative/slide film back in the 90's indicated that grain could be discerned in ISO (then ASA) 100 film at about 4000dpi, thus I concluded that 16mpx was about equivalent when digital cameras started to be introduced.

ASA 25 was somewhat higher at about 5000dpi (aka 24mpx) ...

It appears the manufacturers knew that also since the mpx "wars" seemed to stop at 24mpx, (until recently).

 

[D Cox]

I digitised my 35mm films some years ago, using a Sony NEX-5n and an Olympus 80mm macro lens on a bellows. That lens is designed for 1:1 copying.

The NEX-5n is 16 Megapixels, and I don't think copying the films again with a higher resolution sensor would give visibly better results.


a

I think this is Kodachrome.

It is definitely worth while to use a good macro lens.

Don

 

[MoreorLess]

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives.

Yes, I know there's no point in digitizing my own slides at anything beyond 24mp.

My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera.

That could be true with many real-world slides, especially ones shot with less than stellar lenses. But I think 12mp might be more accurate with good gear under ideal circumstances.

Its hard to be totally exact but yeah with low ISO film(mostly Fuji slide film at ISO 50-100 and Ilford 100) I feel that 12 MP does seem like a rough guide, I'd guess some would say a little more, some a little less.

I do think there is reason to digitise film beyond that level though as more finely resolved grain structure does I think make for a more pleasing image, espeically if you were intending to print something fairly large.

Digital I would tend to try and avoid hitting the resolution(or indeed the DR) limit as the artifacts which become visible most would deem to be unpleasant but film I think people fine them much more tolerable and maybe even desired.

Using a Crystal Scan 7200 I tend to scan with a 50 MP output but actually store the images at 25 MP because its not good enough to resolve much grain beyond that.

 

[Sittatunga]

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives.

Yes, I know there's no point in digitizing my own slides at anything beyond 24mp.

My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera.

That could be true with many real-world slides, especially ones shot with less than stellar lenses. But I think 12mp might be more accurate with good gear under ideal circumstances.

Its hard to be totally exact but yeah with low ISO film(mostly Fuji slide film at ISO 50-100 and Ilford 100) I feel that 12 MP does seem like a rough guide, I'd guess some would say a little more, some a little less.

I do think there is reason to digitise film beyond that level though as more finely resolved grain structure does I think make for a more pleasing image, espeically if you were intending to print something fairly large.

Digital I would tend to try and avoid hitting the resolution(or indeed the DR) limit as the artifacts which become visible most would deem to be unpleasant but film I think people fine them much more tolerable and maybe even desired.

This is reminiscent of the CD versus vinyl debates of the late 1970s. Analogue recording (images or sound) tends to roll off smoothly near its limits. Digital has a hard cutoff and can also show posterisation, particularly in skies. However, with 12 bit, 14 bit or 16 bit RAW formats, it is possible to disguise this using tone curves when outputting to 8 bit jpegs.

Using a Crystal Scan 7200 I tend to scan with a 50 MP output but actually store the images at 25 MP because its not good enough to resolve much grain beyond that.

 

[lumigraphics]

I'm able to get excellent 40MP scans from medium format film with an Epson Photo 4990 flatbed and about 60MP from 4x5 transparencies. As a baseline for comparison.

 

[Michael Benveniste]

I get that the weak link here is the slide or negative, but 6MP of useable resolution seems a bit low to me. Hopefully someone must have figured this out by now.

Let's run through some rough math, starting with the MTF curve from Velvia 50:

https://asset.fujifilm.com/www/us/files/2020-03/64873257f4644939d7bd75d95600a561/AF3-960E.pdf

I read about 48 cycles/mm at MTF50, if you interpret cycles as line pairs, that works out to 96 lp/mm. Square that and multiply by 36 and 24, and it works out to roughly 8 megapixels. If the original shot has a fairly compressed dynamic range you might be able to get away with the far right end of the curve (60 lp/mm), which works out to about 12 megapixels.



In reality, you are going. to get less than that because of sampling error, film flatness, and imperfect optics. In addition, if your slides are mounted, you won't capture the full 24x36mm. And remember, this is Velveeta 50 -- with a faster film like Astia or Provia you can expect a bit less. It also assumes that the original image was reasonably sharp to begin with. So while 6 megapixels is perhaps a bit low, in real life you shouldn't expect much more than that.

-
Light travels at 2.13085531 × 10^14 smoots per fortnight. Catch some today!

 

[ishwanu]

My personal experience scanning negative/slide film back in the 90's indicated that grain could be discerned in ISO (then ASA) 100 film at about 4000dpi, thus I concluded that 16mpx was about equivalent when digital cameras started to be introduced.

That would yield about 24mp from a 35mm frame rather than 16.

ASA 25 was somewhat higher at about 5000dpi (aka 24mpx) ...

That would yield about 36mp from a 35mm frame rather than 24.

It appears the manufacturers knew that also since the mpx "wars" seemed to stop at 24mpx, (until recently).

 

[Overrank]

My personal experience scanning negative/slide film back in the 90's indicated that grain could be discerned in ISO (then ASA) 100 film at about 4000dpi, thus I concluded that 16mpx was about equivalent when digital cameras started to be introduced.

That would yield about 24mp from a 35mm frame rather than 16.

It’s about 21.4MP but I’ve found it to be roughly equivalent to a 45MP camera when you account for all the losses in the system when using a camera (based on measurement of high contrast targets ). The real problem is the source material (image) rather than film resolution issues.

ASA 25 was somewhat higher at about 5000dpi (aka 24mpx) ...

It appears the manufacturers knew that also since the mpx "wars" seemed to stop at 24mpx, (until recently).

 

[ishwanu]

My personal experience scanning negative/slide film back in the 90's indicated that grain could be discerned in ISO (then ASA) 100 film at about 4000dpi, thus I concluded that 16mpx was about equivalent when digital cameras started to be introduced.

That would yield about 24mp from a 35mm frame rather than 16.

It’s about 21.4MP

Yes, that's more precise, but 24mp cameras are easier to find.

but I’ve found it to be roughly equivalent to a 45MP camera when you account for all the losses in the system when using a camera (based on measurement of high contrast targets ). The real problem is the source material (image) rather than film resolution issues.

That last sentence is the key part. With my own slides that were shot using mainstream gear under a wide range of conditions, I get virtually nothing of use beyond 24mp.

I do have a way to photograph a small section of a 35mm slide at the equivalent resolution of a 130mp camera with no AA filter. I think I tried it once, but maybe it's time to try again.

 

[PhotoTeach2]

My personal experience scanning negative/slide film back in the 90's indicated that grain could be discerned in ISO (then ASA) 100 film at about 4000dpi, thus I concluded that 16mpx was about equivalent when digital cameras started to be introduced.

That would yield about 24mp from a 35mm frame rather than 16.

It’s about 21.4MP but I’ve found it to be roughly equivalent to a 45MP camera when you account for all the losses in the system when using a camera (based on measurement of high contrast targets ). The real problem is the source material (image) rather than film resolution issues.

Overall resolution is obviously limited by the weakest-link, but I suggest the film "grain" is a final determinate of its resolution. My experience was that I could not discern grain @ 3000dpi, but it was EASILY discernable @ 4000dpi, (thus the determinate number was somewhere in between 3 & 4000dpi -- aka 16mpx by estimate).

ASA 25 was somewhat higher at about 5000dpi (aka 24mpx) ...

It appears the manufacturers knew that also since the mpx "wars" seemed to stop at 24mpx, (until recently).

 

[PhotoTeach2]

My personal experience scanning negative/slide film back in the 90's indicated that grain could be discerned in ISO (then ASA) 100 film at about 4000dpi, thus I concluded that 16mpx was about equivalent when digital cameras started to be introduced.

That would yield about 24mp from a 35mm frame rather than 16.

But the film grain was (easily) DISCERNABLE @ 4000dpi ... which means it was BEYOND the actual film resolution, (which I concluded was between 3000 & 4000dpi -- thus about 16mpx).

ASA 25 was somewhat higher at about (between 4 & 5000dpi (aka 24mpx) ...

That would yield about 36mp from a 35mm frame rather than 24.

It appears the manufacturers knew that also since the mpx "wars" seemed to stop at 24mpx, (until recently).

 

[Richard B99]

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives. My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera. I get that the weak link here is the slide or negative, but 6MP of useable resolution seems a bit low to me. Hopefully someone must have figured this out by now.

 

[Richard B99]

Oops...

I believe my 26MP camera with a good macro lens can out-resolve the detail in my old color slides and color negatives. My question is what would be the comparable resolution of the resulting image in terms of MP's? Someone told me not to expect any better image quality than a 6MP digital camera. I get that the weak link here is the slide or negative, but 6MP of useable resolution seems a bit low to me. Hopefully someone must have figured this out by now.

Simply put, you won't get any more resolution that the original photos and that de[endis on the emulsion and lens. She years back, I copied my fathers slides (shot on sometimes discoloured faded Agfachrome and with a simple old post war camera with zone focussing and no stabilisation or auto focus, I can say the a Z6 with a MF Nikon 105mm on its 24MP sensor was more than sufficient to capurre the original slide details. Certainly to the point that I read;ised that the originals were showing decentreing on the original lens. I was quite confused with thet for a while, thinking that there was something wrong with the exceptionally good Nikor lens before I worked out it was just a "bit better" that the original.

Still the photo books I gave to relatives went down really well. even with the decentrerd lens showing perfectively!