LF versus smaller format optics, which is better pixel for pixel?

[chris jordan]

Hi guys, really interesting thread, thanks for all the thoughts. In the original question I tried to eliminate the film grain/format size issue by specifying that the 8x10 camera has a high resolution digital back mounted on it. I am trying to equalize all other factors and compare only the optics. What I'm hearing is that 35mm optics outperform 8x10 by a lot, which is what I suspected. I am curious if 35mm optics outperform medium format as well? So let's say the LF camera has been eliminated from the playoffs, and now we run the same test with a top-quality 35mm and MF rig side by side, each with a 200mm lens, same aperture and exposure, focused on a distant target. We import both raw images into Photoshop and crop the MF photo down to the size of the 35mm and compare the resolving power of the two systems. Would 35mm still win, and by how much?

[voigtf64]

great thread, but I have just discovered a game changer , the Sigma DP Merrill Foveon series of cameras , these are producing {and this is my observation) large format quality images in both detail and tonal gradation, OK so they are
dreadful on battery usage and asa speed, but for an old film person like myself they are what I have been missing in current technology, not perfect there is a potential to burn out highlights, but really give them a look ,the DP1, DP2 and DP3, mind blowing capability.

[chris jordan]

voigt, agreed, I had a DP1 for awhile and the images were amazing, incredibly rich and lush feeling, I loved that camera. For me the low megapixels limited it to being my personal snapshot camera, but rumor has it that there's a much higher resolution version of that technology in the works, possibly from several different companies at once. Fingers crossed.

[Corran]

If you equalize all sensor technology (same sensors, just with more area for different formats) the answer is obvious. The best lens wins.

[paulr]

Back to the OP's somewhat theoretical question, I think the very best small format lenses of mid- to long focal lengths would win this today.

Quality of lenses in the small digital camera world is all over the place, but the best models are insanely good.

The very best wide angle lenses are probably the Schneider and Rodenstock lenses for medium format technical cameras. If you compare the MTF curves of these lenses to the same companies' LF lenses, the differences are almost obscene.

[paulr]

Now that amateurs who dare to spend $4000 in digital photographic equipment (without any idea of any future return-on-investment) can get a 36 Mpix silicon sensor, with sensor pixel pitch @5 microns, hence capable of detection 100 cy/mm, the old comparison between film formats, to say the least, has to be re-examined from scratch.

Here's a comparison from actual prints. I've been making 60" prints from 36 megapixel files from one of these 5 micron pixel pitch cameras. They look significantly better than 50" darkroom prints from 4x5 (TMX 100 negatives). They look roughly comparable to 50" digital prints from desktop scanned 4x5 negatives. I'm willing to bet that they don't look as good as digital prints from high quality drum scans of 4x5, although I haven't tried.

The film here really isn't the limiting factor. TMX has good modulation (high signal / noise ratio) at least up to 150 lp/mm and possibly well beyond. Getting the detail off the film is the hard part. Drum scans are required if you're printing big and want the best possible quality. And here's the catch: the cost of 20 drum scans equals the price of my camera. Never mind the price of film and processing.

As far as I'm concerned, that dslr was an incredible bargain. It's paid for itself a few times over in the 3 years I've had it.

[Jim Andrada]

And now Canon is offering a version of the 5D with a 50 megapixel sensor.

Regardless, I like film better!!!!! Don't bother me with facts, my mind's made up! Then again a 50Mpx camera paired with a Zeiss OTUS sounds like something that would be worth a try. I read a few reviews of the OTUS and people were complaining about the price, but compared to a $40k video zoom or even a $5k video prime, the Otus isn't bad.

[mmerig]

Here's a comparison from actual prints. I've been making 60" prints from 36 megapixel files from one of these 5 micron pixel pitch cameras. They look significantly better than 50" darkroom prints from 4x5 (TMX 100 negatives).

Hmm, 5 micron pitch at 42.3 X enlargement would be 120 dots per inch of pixels or "grain".

60 inches*25.4mm/inch/36 mm = 42.33
42.33 * 5 microns = 211.66 microns
211.66 microns /1000 microns/millimeter = 0.21166 millimeters
25.4 millimeters/1 inch/0.21166 millimeters = 120 pixels (dots) per inch

Of course these calculations don't take into account Bayer filter arrays (which could make it worse).

I think 120 dpi would not look that good to me on a print. If I optically (darkroom) enlarge an FP4 4 by 5 negative to about 50 inches, the grain is not noticeable without magnification. The grain is quite noticeable without magnification if I do the same enlargement with a 135 format FP4 negative taken of the same subject at the same time.

I can post examples if anyone is interested, although my flatbed scanner subdues the detail on both prints somewhat.

[Emmanuel BIGLER]

From Nodda Duma

... as an imaging system designer, I need better angular resolution than 100 microradians, I simply choose a more appropriate focal length, f/#, and focal plane array. Usually the trade off is in field of view.

I agree with Nodda Duma: with our photographic lenses, usually we love to get a one-shot image (no stitching) and we like to have a minimum of field of view!

If I had to design a military surveillance camera, without disclosing here anything top-secret, I can tell you that 7 mm for the entrance pupil is far too small: if I had an unlimited budget and unlimited storage space at home & no problems for transportation of the huge instrument, I would vote for a telescope lens in the genre of the Hubble space telescope, coupled with some kind of scanning system. For landscape images this would be THE ultimate, as they often say in commercial ads we love to read

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From Ken:
How do we determine that 7mm is the diameter of the entrance pupil ? Why is 1/10,000 radians the desired limit ? How does that relate to what the eye can detect ? What happens when we enlarge the image ?

Hi Ken.

I did not mean that 7 mm was anything optimum nor ultimate. I just wanted to put some realistic numbers to play with the basic diffraction limit and see where we are. I forgot to mention, but most of us know this, that the resolution limit for the human eye is close to the diffraction limit. If we take a size of 2 mm for our entrance pupil in daylight, we get, @.7 microns of wavelength, something like .7/2000 ~= 1/2850 ; one minute of arc is 1/3440.

Regarding the size of the entrance pupil vs. the diffraction limit, I have already mentioned here that if we make a compilation of the best f-numbers for state of the art standard photographic lenses for film use, lenses available in the 1980's, we get a trend as follows:

best f-number = (focal length in mm) / (8 mm)

This corresponds to a constant entrance pupil of 8 mm for all formats!

However, in a recent discussion as Ken knows,
http://www.largeformatphotography.in...al-f-stop-quot
one of our readers quotes a Zeiss source, the critical "f-stop" for a CZJ F/4.5 - 180 mm Tessar being f/12.
But we need to stop down a little more in rdre to get a better homogeneity in the field, we sacrifice resolution at the center to slightly increase resolution in the edge. 180/8 yields about 22 which is a significantly smaller aperture than f/12. The situation is what we are facing all the time in LF photography, if we want to somewhat shift or tilt, we need more image circle and at f/12 probably the 180 mm tessar will be somewhat limited.
Hence if we do not take into account film grain & resolution, all those lenses deliver the same angular resolution in object space, with the same useable field of about 50° to 60° (can go up to 80° for some standard view camera lenses). So there is no advantage of any kind using a bigger camera, except of course film grain that becomes, in relative values, negligible with bigger film formats. However one cannot extrapolate this "8 mm" trend to smaller formats, however for sure you will hit the "f/1.0 wall" quickly when focal lengths and formats get smaller and smaller.

May be the most recent standard 150 mm view camera lenses for the 4x5" format can be stopped down to f/16 and not f/22, for those family of lenses the trend would be something like (f in mm) / (11 mm) i.e. a bigger entrance pupil and a better angular resolution.


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From PaulR:

Here's a comparison from actual prints....the cost of 20 drum scans equals the price of my camera.

Paul, many thanks for sharing your experience with us, yes this is were we are now in the real world as far as good prints are concerned. And it is better to face this reality: if we love our film camera it is for many good reasons, but not to outperform recent digital cameras.

This a problem when a friend comes to you and asks you to help him choosing a classical medium format film camera or a large format camera. Before entering the discussion, we should explain him that if he tries to scan his images with an amateur-grade scanner, he will never outperform what he actually gets with a recent digital camera, at least with film in medium format.

A possible answer for B&W could be: use the traditional wet darkroom, do not try to scan. But even with an amateur-grade flatbed scanner, for a 8x10" final print, I have several good friends faithful to their film cameras who will never go back to the wet darkroom, the digital darkroom being so flexible!