Film and digital resolution compared

Wow, that is a ton of homework in the first post. Great work.

I speak from a layman point of view, where I think for "regular joe's", printing from these digital files will not yield much difference at small sizes. We would have to print really large to notice the subtle differences.

I doubt I can tell the difference from a 8R print of a D800 versus a D3.
 
What Shutter Type Most Accurate Record of Image

What Shutter Type Most Accurate Record of Image

Focal plane shutters move accross the plane and copals open and close somewhat like an iris. some others exist like Minolta Minolina P's. What part of the image is recorded first and last? With shutters moving at 1/8000 of a second compared to 1/60 a lot can change during the exposure in the latter that does not in the former - there is not much discussion about this here.
 
Well, this has been my experiences.

In summary, usually the largest enlargement I make with 35mm B&W film is 8 by 10. I have rarely made a few 11 by 14. That's in inches! Same with slides. Medium format I have made pretty good 16 by 20 enlargements.

I have a Canon digital DSLR and have made 40 by 30 inch prints. Try doing that with 35mm film, any type.

Thanks for your information. Appreciate your effort for analysis.
 
Bill Clark said:
In summary, usually the largest enlargement I make with 35mm B&W film is 8 by 10. I have rarely made a few 11 by 14. That's in inches! Same with slides. Medium format I have made pretty good 16 by 20 enlargements.

I have a Canon digital DSLR, one which is the monster sized, and have made 40 by 30 inch prints. Try doing that with 35mm film, any type.
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I've had good luck doing occasional 13x19 prints from 35mm color. I have one very stunning 13x19 print of the Chicago River that I did using Walgreens rebranded Agfa scanned at max res on the K-M SD 4.

I have another very nice night shot at 13x19 done on Fuji 800, same scan but cleaned up a bit in Neat Image.
 
I rather expected this when I started researching an upgrade from digital and realized the advantages of film. But now I have to wonder if I still want to make optical paper prints, or go K7 with a good printer. Not sure I am ready to even think about laser-scanning photo paper...

So much for sleeping tonight, dammit! :bang:
 
Bill Clark said:
I have a Canon digital DSLR and have made 40 by 30 inch prints. Try doing that with 35mm film, any type.
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I still recall seeing a poster that Canon sent to its dealers some 25 years ago, hyping the abilities of its 85mm f/1.2L. I was struck by the detail and the very low level of grain. It really looked like a large format image, but it was taken with an EOS 35mm. And this was a 20" x 30" poster, at least.

Another example of 35mm's capabilities. I was at a camera show one day -- this was also about 25 years ago -- and one of the dealers who was a good friend of mine walked up to me and handed me two 8x10 B&W glossies. They were both photos of the same subject -- a small, country church with clapboard sides and a steeple. He asked me if I could tell which was shot with a 4x5 and which was shot with a 35mm. I examined them briefly and then correctly indicated which was which. He asked how I told the difference. "The grain," I said. The 35mm image's grain was more pronounced, otherwise the detail in the two images was equivalent. I asked him about the cameras he used. I don't recall which 4x5 it was anymore, but the 35mm was a Leica IIIg with a 50mm f/3.5 Elmar.

So what I'm getting at is, with a 35mm camera and the right lens and film, it is definitely possible to get image quality bordering on that of a large format camera/lens.

BTW, I found the OP's opening comments very interesting. I had derived the first formula he gave for determining the theoretical resolution capability of a given type of film in megapixels some 15 years ago, but I found his additional discussions to be very informative. They were helpful in explaining to me why it is that I can't get digital like quality from fine grained slides that one would think shouldl compare favorably to even relatively modest megapixel output cameras. In my own tests, however, I've found that often the limiting resolution factor with film is the grain.
 
I shoot a lot of film formats, from 35mm to 11x14 and most in between. And quite a bit of digital. Resolution is not what I'm trying to get out of Large Format, though it's very readily there. For me with LF it's tones, dynamic range, and the look of the lens aberrations, perspective, depth of field.

35mm is pretty disappointing if you are chasing resolution, compared to a 5x7 or 8x10 contact print. The advantage of 35mm is portability and rapid shooting, same as digital. I find it funny that we try to get ultimate sharpness out of tiny lenses, blowing up a postage stamp sized negative many times in a print or on screen. Whereas some LF shooters take an inherently sharp system, and enjoy the softness and tones.

Here is a 6 1/2 X 8 1/2 negative contact print I made yesterday, from a 1909 Cooke lens.

18418511924_10eb41e635_c.jpg
 
Very high quality results are possible, but you better be using the best film, an excellent lens, and a tripod with 35 mm. There is no room for error.

In the linked thread I recently posted a Velvia 100f 35mm slide scanned with an em-5 mark ii in 40 mp mode. There are gobs of detail present and I needed all 40 mp. Soon as I get a chance I will re-scan this photo and others at 1:2 (double) resolution to see where that gets me.

http://www.rangefinderforum.com/forums/showthread.php?t=149510
 
Thanks.
You should see 4x5 or 5x7 Velvia! It's like a stained glass window in a chapel in France, when held up to the light. Fantastic for scanning. But yes, this is a 35mm forum, so I'll stop.
 
I enjoyed Rich's theoretical treatment and the discussion about film vs digital!

Every theory needs to be tested for validity against experimental data. So let's do this! I took the same picture of a park in plenty of light with a digital and analogue camera, using the exact same lens and a heavy Gitzo tripod.

  • Nikon D600 (full-frame 24 Mpixel sensor) + Nikon AI-S 50mm f/1.4, stopped down to f/8.
  • Nikon FE2 with Ilford FP4 (ISO 100) + Nikon AI-S 50mm f/1.4, stopped down to f/8.

I then converted the 24 Mpix digital image to monochrome for comparison with the FP4 b/w film. Otherwise, the picture is completely untouched and I made no changes in Photoshop. The FP4 negative was scanned with a Plustek 8100 film scanner at 5,000 dpi. The result from the scan is a 66 Mbytes 16-bit TIF vector file which is equivalent to a 33 Mpixel JPG file (6888x4788 pixels, 8 bit). I'm therefore oversampling any information that is in the negative. Below are low-res versions of the two images (no cropping).

Next, I decreased the resolution of the original full-frame 24 Mpixel digital file to 16 Mpixel, 12 Mpixel, and 8 Mpixel so we can compare them to the scanned full-res FP4 analogue picture. I then picked a region at the column of the statue in the park (marked by a red box) where you can see a street sign in the background. The street sign says: "Capitol St NE 1100." Below are crops from these files so we can compare them. The upper row gives crops of the full-frame 24 Mpix, 16 Mpix, 12 Mpix and 8 Mpix digital images. In the lower row you see the same crop of the full-res scanned FP4 analogue image 4 times for ease of comparison with the digital images above. Let's have a look what we see in the crops:

  • 24 Mpixel digital image: the street sign is super sharp; no pixels are visible even at this high zoom level.
  • 16 Mpixel digital image: the street sign is still sharp; you start to see pixels.
  • 12 Mpixel digital image: the street sign is still legible; pixels become prominent.
  • 8 Mpixel digital image: unable to read the street sign, heavy pixelation.
  • FP4 analogue image: you can barely read the street sign due to the low resolving power of the film. In terms of the amount of information that is stored in the analogue film, it is similar to the 8 Mpix digital file (you can barely read "Capitol 1100", but not "St NE"). However, in terms of overall appearance, the analogue film is somewhere between the 12 Mpix and the 16 Mpix digital image. Now, this is hard to quantify because our eyes and the brain that interprets the information are analog "image processing" organs and favor analogue information (such as film) over digital. I'd argue that you could enlarge a film image to a larger size than a digital image that has stored the same amount of information as the analogue film image because our brain prefers a bit of blurriness over pixelation.

Caveats: you might criticize that I used a film scanner (Plustek 8100) that is not on par with professional drum scanners. However, I have had negatives scanned on a drum scanner by Northcoast in "enhanced scan mode" (3339x5036 pixels) and believe that my scans are of higher quality. But to be fair, if you'd find the perfect film/developer combination to reduce grain as much as you can, and used a high-quality drum scanner, you might be able to push the results a bit further than I did.

My conclusion from this experiment is:

A 35mm ISO 100 analogue film image stores the same amount of information as an 8 Mpix digital image.
In terms of overall appearance and quality, a 35mm ISO 100 analogue film image is equivalent to a 16 Mpix digital image.

Coming back to Rich's analysis, you did a great job and my experiment shows that you overestimated the quality of film by only 25% (20 Mpix vs 16 Mpix).

Looking forward to your comments!

D600_FP4.jpg


FP4_all_Mpix.jpg


(click on the above image to enlarge)
 
gnuyork said:
...
I was able to enlarge scans of 35mm slide film to nearly four feet wide and have a good usable print, albeit not as sharp as smaller prints, but I was surprised how well they held up. ...

There's no way I could do this with the 5DmkII images, or even the D800 for that matter. ...
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Perhaps you can't, but I can and do on a daily basis (there's a 29x44" print printing at the moment). I regularly print images this large and larger from both 35mm film scans (typically Velvia and Velvia 50 scanned with an Imacon scanner) and digital images (most from a D800). As a general rule, the D800 images appear a bit sharper* and are always smoother (lower noise, ...).

* sharpness - Sharpness doesn't exist in the real world. It is a figment of the viewer's imagination that is a computer (read: brain) generated impression based on a range of attributes including, but not limited to, resolution, luminance contrast, and color contrast.
 
Dwig is right: A D800 has 7300 x 4912 pixel. If you blow such an image up to four feet wide, you'd get 10 pixel per millimeter (linear), which would look very sharp, even if the printer doesn't interpolate.
 
Dwig said:
* sharpness - Sharpness doesn't exist in the real world. It is a figment of the viewer's imagination that is a computer (read: brain) generated impression based on a range of attributes including, but not limited to, resolution, luminance contrast, and color contrast.
Click to expand...

sharp·ness
/ˈSHärpnəs/
noun
the quality or state of being sharp. :D
 
Rich,

Thank-you for posting and starting this discussion. From time to time I've seen other posts around internet about resolving power of film vs digital etc. but never really understood it, & often got further confused, so I appreciate your work on this.

Given my understanding of optical theory is pretty limited, may I ask how the equation R = 4r^2hw/10^6 is derived? (Is there an online source you can point me to, so that I can do some background reading....?) -- thanks
 
RichC said:
So, no replies - presumably, then, you all agree with me!
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No, it's just that we're all out here trying to remember when was the last time we saw algebraic formulas and level 2 section headings in a forum post.

Nice post, you obviously put some good work into it.

I'll tell you what, though: While you guys are in here pondering this stuff, I'm going to put some hot coffee in a spillproof mug and go make some photos. D810 in one hand, M7 in the other.

Good luck.
 
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