This article, 35 mm, medium format, or large format?, on the Photodo website compares on film resolution across formats:
http://www.photodo.com/nav/artindex.html
This article, 35 mm, medium format, or large format?, on the Photodo website compares on film resolution across formats:
http://www.photodo.com/nav/artindex.html
I think this is based mostly on the different normal working apertures. 35mm lenses get used at faster F/stops then LF. That lets them have better resolution numbers at those F/stops. How many LF lenses are at the limits of diffraction when stopped down normally ? But when you add in the different enlargement factor things start to change.Originally Posted by Gordon Moat
Did you have some sort of comment on these Eric? I've actually spent quite a bit of time looking at these results. While Chris has gone to a hell of a lot of effort to get these numbers, my feeling is that it was a deeply flawed study. There's no control in place to objectify focus accuracy or many other factors. There would appear to be only a single trial for each lens (when there ought to be, say, 10). Only a single sample of each lens was used. The one common trend that I DO see in the numbers - is a linear drop in resolution with Focal Distance (notice I did NOT say focal LENGTH). I think that's something interesting to think about. My guess is that the degradation to resolution number with focal distance would be a diffraction byproduct (the further away you measure the amount of diffraction - the greater the diffraction becomes). So - "what is my point?" you ask...? I'm trying to suggest that the numbers you see have nothing so much to do with 'lens quality' so much as being built into the format itself - esp. where focal distance varies so greatly. Just a thought.
Lenses for smaller formats do outperform lenses for larger formats.
If for the sake of eliminating uhelpful variables you only look at the best lenses in each format, it will still be true: lens performance (in terms of mtf, at the film plane) declines as format size increases. The decline is more than made up for by increased film area, which is why we bother with larger formats. But your large format lenses would not compete with medium format lenses when used on medium format film.
People hate to believe this, because it sounds like some kind of conspiracy against us--but it's nothing like that. It's simple optics. Lenses for larger fomats need to have a larger angle of coverage. Getting more coverage out of a lens constitutes a major design criterion, one that requires compromises in other areas.
It's the reason that Schneider's and Rodenstock's digital lenses show so much higher MTF performance than their large format counterparts. It's not magic; they just cover much less.
Schneider gives us the best examples, because they actually publish all their MTF charts. I know the origninal poster didn't want to get into this, but I don' know how else to clearly show the difference without conducting a massive and pointless test.
You can compare their best lenses for 8x10 with their best lenses for 4x5, their best for large format digital, and their best for medium format (for the Rollei 2-1/4 cameras). Performance increases significantly with each step down in format size.*
A Schneider tech rep showed me this principal taken to an extreme. It was an image made by a new Schneider digital lens that resolves (at MTF 50) over 200 line pairs per milimeter. This is over four times what we typically see from 4x5 lenses. The catch is that it's designed for a miniature digital sensor ... its coverage area is smaller than the fingernail on your little finger. So it's always give a little, take a little.
*This may not hold true consistently with wide angle lenses (super angulon, super symmar xl, etc., comparing 8x10 to 4x5 ... for reasons i don't understand).
Paul, this is by no means an attack... but what you're saying isn't even rational. You predicate your entire argument on something you refer to as 'coverage' without even defining it. IF what you're saying is true, then clearly, in Chris Perez' numbers you'd see the Grandagons and the Nikkor-SWs having the worst numbers - and you'd see the big 450-600 Ms and teles with much BETTER numbers. It sounds to ME as though you've been listening to a poorly informed salesperson. I have absolutely no emotional investment whatever in proving large format superior in any way. I really don't even care that much about resolution in my personal work (I care more about concepts - another story) - but I'm just not sold on that. I think maybe the photodo.com article/experiment is probably the most illuminating yet. But IF we're actually talking about GLASS here - it is, or SHOULD be simply an issue of curvature and quality control of a given lens design. I seriously doubt that quantum effects come into play. It simply doesn't make sense to me that a scaled-up design manufactured to the same tolerances would have less inherent resolution unless limited by an extraneous factor, as previously mentioned. If you can clarify what you're trying to put across, Paul, I'm happy to listen.
Sure, I'll try.
By coverage, I'm talking about image circle size at a given focal length. If you compare a 210mm lens designed for 4x5 with one designed for 2.25, the large format lens will be designed with a much, much larger image circle ... to cover the film and to allow for movements. This design parameter requires major compromises in other areas.
Here are a few places you can compare for yourself:
http://www.schneider-kreuznach.com/f...L/sr_apo_L.htm
(here you can download mtf charts for the apo symmar 120 and 150 mm lenses)
http://www.schneider-kreuznach.com/foto/dig2/dig2.htm
(here you can download mtf charts for the 120 and 150mm digitar lenses ... be sure to notice the higher resolutions used for these--the lowest resolution, 20lp/mm corresponds to the highest resoulution on the apo symmar chart)
http://www.photodo.com/nav/prodindex.html
(this is a long list of independently performed MTF tests on many large and medium format lenses. If you scroll down to Rollei, you'll find test results for a 150 mm Schneider lens for 2-1/4. This chart uses a third set of resolutions, but it overlaps enough with the others to give you an idea).
The other tests on the photodo site will let you do some general comparisons between medium format lenses and small format. There are a lot of dogs in the 35mm world, and a few in the medium format world, so I think you'll learn most by comparing just the best examples of each.
Many thanks to all of you who contributed an answer to my question.
It seems that I can get away with using MF on the back of my Ebony with LF lenses but I would have to think about the appropriate lens and film combination.
As my experience suggests, fortified by others within this forum, it seems that film (especially colour) has become the limiting factor, for at least some modern Apo- LF lenses. In which case, these (and possibly all but the longest) LF lenses can be used for MF landscape applications where appropriate, e.g., long shots where an LF lens used for LF landscape applications would have to be 800mm or more in focal length to cover the same area and thus bordering on impractical. With the advent of some fine-grained films such as the re-introduction of Adox films, the enlargement potential seem to be much improved for MF format using the sharpest LF lenses (as well as, of course, MF lenses, but they cost a lot). Then there’s the very sharp Schneider Apo-Digitars and Rodenstock equivalent; the Schneider 180mm and 210mm will cover 6x9cm with a little movement left - but these lenses are another story. Just as a final thought; as promised I'd field test my Schneider Apo-T-X 400mm against my Canon 300mmL IS (the latter at 3/4 distance so same size on the digital sensor). Although this was not a test to end all tests, I couldn't see much difference!, although focusing the Schneider wasn't easy. I tested them three times just in case there was a focus error, no change. I put the lack of difference down to the compromises in current 35mm lens design more than anything. The incorporation of an image stabilising mechanism (all Canon’s non-IS lenses outperform their IS equivalents by some margin); the limiting factor of the digital sensor used; and the fact it is an slr lens (it doesn't butt up close to the image plane as in, say, the rangefinders, and there is integral focusing). It seems that some 35mm manufacturers nowadays are going for practicality in the field rather than out-and-out image quality, especially as digital sensors have limited resolution (compared with fine-grained film) meaning that any extra resolution the lens has is largely wasted (although not entirely, for reasons beyond the scope of the forum). This is a route that MF lens designers should not go down as some LF lenses seems to be directly competing with them now, and all can be adapted to fit MF cameras if push comes to shove.
Thanks to those for saving me a few thousand dollars/pounds (I think I would have erred on caution anyway) and many thanks again to the rest who contributed. Very much appreciated.
Now I just need to find out the best roll film holder to fit my Ebony ...
Last edited by Sam Martin; 26-Jun-2006 at 15:44.
I wouldn't think too much in terms of limiting factors ... the physics of image degradation doesn't usually work that way. There's an image chain, in a sense, but it's not limited by a weakest link (unless the link is incredibly weak). Rather, every link has the capacity to degrade the image. The less degradation along the way, the better.
Also, a lot of modern films have mtf characteristics that blow away just about any lens. None of our LF lenses can come close to recording all the detail that something like tmax 100 is capable of recording (just as one example).
Sam,
If working with a roll-film back is acceptable to you, then I strongly suggest you go that route for general landscape shooting. The availability of camera movements (particularly tilt and swing, which can enable use of a larger aperture than otherwise possible) will frequently offset any resolution differences (if any) versus standard MF. And particularly if you use color film, I doubt lens differences will play much of a role anyway. I recall discussions saying that color film has maximum resolution of around 60 lpmm in typical real world situations (even with non diffraction-limited apertures), which seems consistent with my field experience. My Mamiya 7 might be a smidge sharper at f/8 or f/11 versus a top-notch LF lens when shooting color, but not by much, certainly not enough to compensate for the lack of movements. I used to get very frustrated shooting landscapes with the M7 due to the frequent need to stop down to f/16 or worse to achieve adequate depth of field, which really killed lens performance. I've had far fewer such frustrations shooting LF.
JW,
I listed the Chris Perez links since they provided the only quantitative comparison I am aware of between MF and LF lenses. I agree that the test data is limited; it is only one data point of many needed to evaluate a lens. I evaluate my lenses using multiple test shots (close focus, infinity focus, no rise, extensive front rise, shoot at/near sun to test lens flare), sometimes using multiple apertures to truly put the lens through its paces. If Chris were to do all this across the board, it would take many years! But testing lenses at 1:20 distance-to-focal length magnification seems a useful data point, relevant to at least a certain portion of many photographers' work.
Sam - The best roll film holders appear to be those which allow for the straightest path of travel directly before the holder aperture (opening) regardless of format (6x6, 6x7, 6x9, 6x12). I've done a LOT of googling on the topic. The very best performers appear to be the Sinar Zoom II (prohibitively expensive), the Horsemans (good choice) - and the upset winner - surprisingly - because they're so cheap... are the Singer/Graflex RH series holders. I have a 70mm 6x7 version. But plan to get others. From what I gather, the Graflex is at least as good as the (way more expensive) Sinar. Though it's far more rudimentary and less fashionable.
The way I look at glass is thus; lens manufacturers aren't using a different kind of glass, tighter tolerances or a set of scientific laws (physics) to make small vs. large format lenses. Each manufacturer is going to use the highest performance design it can come up with for a given focal length. In the end, there's no substitute for experimentation. I'll bet you, dollars to doughnuts - that if you use a highly vaunted 35mm format lens (Nikkor, Leitz, Zeiss etc. - of course it won't cover) - around 85-105 mm and you compare that with a current MF/LF offering by Fuji, Nikkor, Schneider or Rodenstock - and using the best, most consistent procedures you possibly can to test - that your results will be identical in the center of the frame at least - provided you use the same aperture for all - say, f/5.6 or 8.
In short - I'd say it's really not worth losing sleep over. And in 99% of the cases, vibration and flawed user technique are going to totally obfuscate any differences that COULD exist between two half-decent lenses designed for different formats. The most important thing, and the big challenge, appears to be - to get a good sample of whatever lens you decide on.
Yours truly,
Jonathan
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