LF resolution compared to smaller formats?

[Ellis Vener]

Danny, First I would check the mechanics: Was the lens assembled correctly afete r being mounted? Does the GG line up with the silm plane in your holder? Is either out of spec? Have you trired with a different holder. iuse QL all the tim e and have tested my QL holders against a variety of differnt holders and found therewas virtually almost no difference with my cameras (Canham DLC & Arca Swiss 4x5 F-line.) with the lens (a 210mm f/5.6 Nikkor W) wide open and no difference with with the lens stopped down to f/16 and f/22. The test were ma de on Velvia QL and Velvia 4x5. Your images should be sharp. Something in your imaging system: either your camera, your holder or the combination of th e two, is wrong.

[Bill Glickman]

Danny

There has been many qualified responses above that all point to potential problems in the mechanics of the process... I agree with all of them - and you should confirm these are / are not issues in your paticular situation. It sounds as if you are astute enough to know if one of these problems exists, but many of us have been fooled before.... However, I must admit I continue to share the exact same frustration you are experiencing. I own a Mamiya 7, 4x5 and 8x10 cameras. Unfortunatly you started comparing your 4x5 work to one of the sharpest camera systems in the world...The bottom line is this... the M7 lenses are probably the sharpest lenses ever made. Some test results have recorded 140 lpmm to film! This is truly amazing, considering the very best 4x5 lens will offer maybe 75 lpmm... mainly the very new Schneider Super Symar XL 150 and 110mm. But, apart from this lens and a select few others, most LF lenses are far inferior. The Nikor 300M you used - I once saw it recorded at approx. 50 lpmm. Still not high enough to overcome the magnifcation degredation that will occur bringing the 6x7 chrome to 4x5. From my experiences with these same cameras, I have concluded that the M7 produces 11x14 (sometimes 16 x 20) prints as good as 4x5, unless I am using my Super Symar XL's, in which case the 4x5 will produce slightly better results. Of course there is many other issues regarding lenses that equate to high quality enlargements, resolution being only one of them. However, I am somewhat convinced it is very significant in this comparison you are making. After a year of using these cameras, I still am baffled how my M7 chromes out perform my 4x5 chromes. (BTW, I doubt the QL are the problem, specially if stoped down to f22 or 32, I have tested them against film holders and rarely notice a difference, Depth of focus overcomes a lot of mis alignment at the film plane at those apt. - do the math and you will see) I have now come to accept this fact and have changed my shooting method as follows... If I have the right fl lens for the M7 for proper compostion, I use that camera first... unless the shot requires movements, then I use 4x5. If the scene is so awesome, or I envision a very large print (larger than 24"), then I use the 8x10 camera. And that jump becomes truly amazing, specially when using the high res. Super symars on 8x10. Both the 4x5 and M7 pale in comparison to these 8x10 chromes. So, assuming you have no mechanical issues, then IHHO, this situation will continue to amaze you for many years. After a shoot, I still stare at my M7 chromes under a 8x loupe and marvel at the sharpness and color rendition these chromes have compared to my 4x5 chromes! Now, if only Mamiya had longer lenses available for this format..... well that is the downer, they never will... they final introduced their longest lens, a 210mm f8...its huge and very slow. So although this amazing camera system produces results unparalled to anything I have seen, as with all things in photography, it still has has a down side... very limited fl's...and no movements. (Remember, this camera is the perfect wedding camera, that is what its intent was) If the M7 had the ability of long fl's, all movements, auto foucs, auto wind, TTL flash metering... I would sell all my LF equipment and use this camera system exclusevely! But that won't happen, so back to LF! I hope this adds some light to your situation.... Take Care....

[Gary Frost]

At f45 you will get noticable softening due to diffraction. I try to make this my max stop down. Comparing to medium format, you should try to stay around f22. Another thought is the extra coverage of the 300mm lens may be causing some flare and loss of contrast from the extra non-image forming light bouncing around inside the camera. Use a hood. Comparing my APO Sironar S 150 with my Fuji GW690 90mm lens, I don't see any loss of sharpness going from medium to 4X5. I do see a softening at f45 though. Do more testing and maybe try another lens. I have a Fuji 240 f9 A that is an excellent performer but not quite as good as the APO Sironar S. It will cover 8X10 so using a hood helps improve contrast in many situations. I also use a QL holder, as well as standard holders, and have not had any problem with it.

[Glenn Kroeger]

Bill's post brings up another important issue... film. It may be that at f/8, Mamiya 7 lenses can resolve 140 lp/mm, but NOT on color film. Look at the MTF curves for Velvia and Provia F. By 50 lp/mm these films are very low contrast. This is not to say that they cannot resolve more lp, but you will see soft separated lines, not crisp edges... the film just doesn't have the high frequency response to render this fine detail crisply. So 4x5 buys you a 50% linear size increase over 6x7. Even if you can get medium format lenses that resolve more than 50% better than 4x5, that's unlikely to occur at the f stops normally used in landscape work, where lenses in both formats are diffraction limited. Consider shooting at f/16 on your 6x7. Diffraction limits resolution to about 90 lp/mm but Velvia cannot record that (at real world contrast ratios). For equivalent depth of field, you would shoot the 4x5 lens (assuming a 1.5 ratio of focal lengths) at about f/24 (22+1/3) with a diffraction limit of about 60 lp/mm which Velvia CAN record. So the 4x5 will still hold an edge in detail, but barely.

The real question is whether the extra detail in 4x5 is usable! With digital enlargement (Tango scanner, LightJet 5000) about the maximum usable scanning density is 150 pixels/mm or 3800 ppi. That corresponds to a maximum resolution of 75 lp/mm. I've run tests with identical images, and with careful application of unsharp masking, there is virtually no difference in DETAIL in 20x24 inch prints from 6x7 and 4x5. There IS a difference in grain and tonal smoothness in areas of smoothly varying tone such as sky.

So the bottom line is not to expect TOO much from 4x5. It is slightly better than 6x7 in capturing detail given real film and lenses. But that slight edge is not going to show up, in color photography, in 16x20 or smaller prints if you use the best digital enlargement techniques. If you use traditional printing, there will be some difference in a 16x20 print. The big advantage of sheet film is the ability to push or pull process individual sheets, and the ability to crop with abandon and still make wonderful 20x24 prints. And on the light table, 4x5 chromes are more satisfying than 6x7.

[Patrick Chase]

This is a reply to Bill Glickman's comments:

In my experience, resolutions higher than about 60 lp/mm are pretty much mythical beasts in ANY film format. One reason already pointed out is the resolution of the film itself. A second is the fact that diffraction typically ends up limiting you to far less.

Let's look at that "140 lp/mm" Mamiya lens that Bill raves about as an example: Simple theory and a bit of math tells us that such resolution is only obtainable at apertures of f/4.5 or wider even if the lens is otherwise perfect in all respects. By f/8 you're limited by diffraction alone to about 85 lp/mm, and at f/22 (a reasonable opening for near-far lanscape shots in 6x7) you're limited to 57 lp/mm. All of a sudden the pathetic-sounding 50 lp/mm resolution of that Nikkor M (or Danny's Fuji, which is a pretty similar lens) begins to look like it might really be a non-issue after all. At the f/45 opening that Danny used in his test, the diffraction-induced resolution limit is about 30 lp/mm. He'd might as well have been using a Wollensack or a polished Coke-bottle bottom at that point.

Furthermore, the human eye is only sensitive to spatial frequencies out to about 7 lp/mm (and even that's rather optimistic for anybody over age 30), so I seriously question Bill's ability to perceive anything past ~50 lp/mm through an 8X loupe. I know I can't (I've tested myself and others using targets of known frequencies as part of my job).

Bill, if you can see a significant difference between your 6x7 chromes and 4x5's shot with lenses as good as the Super Symmar under an 8X loupe, then I respectfully submit that there is something wrong with either your equipment or your technique. Well-executed LF work with top-notch lenses at ideal apertures should be nearly indistinguishable from perfection under magnification that weak, so no matter how good the Mamiya system is, the differences shouldn't be anywhere near as dramatic as you imply. Critical examination under a quality microscope might be another story altogether, of course...

[Ellis Vener]

Bill, the camera you want is the Fuji 680 III. No rear movements, but ample fron t standard movements for a plethora of lenses from about 55mm to 500mm. And because the film format is 6x8 cm it is an even better match if you are tryi ng to fill every last mm of an 8x10 or 11x14 piece of paper. And the lenses are, in my opinion, better than the Mamiya lenses for the RZ67 cameras.

[Bill Glickman]

Ellis, I agree with you comment about Fuji 680 III, it is the only MF camera system that resembles LF. Two things prevented me from going with that system, the first is the size of camera and lenses, they are huge...the camera body is way bigger than my 4x5 body and also is not back pack friendly. The other reason was the poor lens resolution test results that were done by C. Perez, linked to this page. But I did take a good hard look at it...

As for the Mamiya 7 chromes vs. the 4x5 chromes, I respectfuly agree with most of the comments above. Being anal, I had to go re check my chromes after the above threads... and although I do not claim to be quite as scientific in my approach as some of the very knowlegable posters, I will say this for certaninty, and I know it somewhat defy's the math above... My M7 chromes withstand a 16x loupe with no loss of sharpness, and yes, most were shot at f8....although grain does become a slight issue at 16x, I will concede that, but I am hoping photoshop can clean the grain issue up. Now, my 4x5 chromes, none withstood the scrutiny of 16x, my best shots with the Super Symar XL's and some with the fuji 240 f9 mentioned above (the best lens I have next to the SS XL's) will withstand about 10x, my other LF lenses such as Nikor 75mm, Nikor 360W, Nikor 450M, were in the 6-8x. These are averages based on several hundred chromes. Of course there is exceptions to everything, these are AVERAGES. I did this to help express what is going on with my camera and lenses, not to offend anyones camera system or lenses.

I only use Velvia film, considering its high resolving power compared to other color films, this may be the reason the difference is apparent. I have to admit, this has been, and still is quite surprising to me - so Danny I fully appreciate you amazement. As one poster suggested, we have to be careful not to ask tooooo much from 4x5. I fully agree with that statement... Of course the 8x10 chromes withstood the same loupe magnification as the 4x5, but with double the format size, it just beats everything, including my back and shoulders! I welcome anyones comments, until this thread, I finally came to the conclusion as well as other Professional Photograhpers that informed me of the M7's amazing lenses... this is just the way it is.... nothing is wrong... I have performed gg/film alignment test so many times, I am convinced they cameras are right on the money. Also all of my LF cameras are brand new Toyo's, and all use new toyo film holders. I have done everything possible to rule out any error prone areas in both technique and camera mechanical operation...

[N Dhananjay]

Actually, MF may score over LF even in the area of film alignment. Many (if not all) MF cameras have a pressure plate to hold the film flat - something which isn't done with LF (barring expensive vacuum backs). The larger film size of LF also perhaps contributes to the film bowing out of GG position. So even with a GG in the right place, you can have alignment issues.

I don't think comparing resolutions across formats is going to be frightfully conclusive - just far too many variables involved (aspect ratios, focal length differences which contribute DOF on film, different apertures one typically shots at which affects both DOF as well as sets resolution limits due to diffraction). And all of this still doesn't take into consideration the fact that an enlargement system will bring its own set of idiosyncracies (including diffraction) to bear.

The biggest draw for me to LF (at least in terms of sharpness, for the moment leaving aside advantages due to movements and grain and contact printing) is the fact that enlarging losses do seem to get worse with larger enlargement ratios, especially with real enlarging systems. In other words, I suspect that loss of sharpness is not linear. So if you have 100 lppm on film, a 2X enlargement may give you a loss of 50 lppm + another say 5 lppm due to enlarging system inperfections, leaving you with about 45 lppm. A 4X enlargement however is not a linear extrapolation of this i.e., it is not just a loss of 75 lppm to enlargement + another 5 lppm to the enlargement system imperfections. Your losses to the enlargement system add up too and thus you lose not just 75+5 lppm but a greater amount. Most of the time, enlargement systems are diffraction limited, especially once you get to large enlargement ratios. A long distance from lens to paper means smaller effective apertures, more distance for light rays to bend and bounce around the place etc. Thus the preference for smaller enlargement ratios => larger initial negs to begin with. However, please bear in mind that I am just speculating at this point. I have not actually seen tests (nor, needless to say, have I attempted them). Food for thought....

In any case, there's many more qualities to a photograph than lppm. I mean, pictures from ages past probably used lenses of even more limited sharpness. Doesn't seem to diminsih their appeal.

DJ

[heidis]

Thanks for the outpouring of time and effort to my question! I really do appreciate every one of your responses, and would like to reply to some of the points that have been raised.

First of all, I spoke to Ron Wisner this morning. I sent him the 2 4x5 chromes in question, and he examined them upon receipt today. He confirmed that they should indeed be considerably sharper than they are, regardless of having shot them at f/32 and f/45, and asked several questions that could have affected their quality, i.e. did I use any type of filter (no) and other points that I covered in my earlier posts to this column. He asked me to take a test shot using another lens, with the suggestion that my Fuji 300mm could be defective. His comment was that the softness looked like that caused by diffraction that would occur at a much smaller aperture than I used, e.g. f/64 or smaller, but specifically *didn't* think that f/32 or 45 would cause so soft an image. Ron also suggests that smaller format shots with a high-quality lens will indeed surpass one on LF *in terms of absolute picture area* - i.e. cut out a 6x7 piece of a 4x5 chrome, both shot with the same fl and f/stop, and compare them directly - but that the 6x7's quality shouldn't be only slightly superior rather than a vast amount.

Over lunch hour today, I did a simple test shot of trees with a lot of small twigs in my back yard. I used a different lens - 150mm Super Symmar XL, which should certainly give the sharpest possible image, which this time I shot at f/16 on Velvia Quickload. I focused very carefully and rechecked focus after removing the QL holder - all was still as it should be. I should have the film back from the lab on Wednesday, at which point I'll examine it closely and report my findings in this column and to Ron Wisner. If it's indeed a lot sharper, I'll believe that Ron's theory of a defective lens may be correct, and will take up his offer to send the lens to him for testing.

Following up on some posts to this column...

I'm not planning at the moment to make prints of my shots. In smaller format I shoot only transparency film, and am doing likewise on 4x5. At some point, I may buy some negative film just to have it on hand if I foresee "something special" coming up. Enlarged print size is therefore not something that affects me at this time, but I can observe similar effects by viewing my chromes with 8x vs 3.6x loupes.

Ellis - I haven't tried a different QL holder (or any other holder for that matter), simply because this is the only holder I presently have. If today's test shot also turns out soft, I'll have to think that the holder may be at least partly at fault.

Bill - I'm intrigued by your comments re: Mamiya 7 vs LF. I will have to try shooting some negative on each (which I've never done), just out of curiosity, and compare same-size resulting enlargements, once this LF soft-focus problem is resolved! I could have compared an area of one of my 35mm shots for sharpness with the 8x loupe instead, but I used 6x7 simply because the format was closer in size, for whatever that's worth.

I'll keep everyone posted as the saga continues...thanks again for your interest

[Glenn Kroeger]

Danny:

Glad you are making progress. Two thing I thought I would add. If your Fujinon 300C is at fault, it is not a problem with all Fujinon 300C. I have owned both a Nikkor 300M and a Fujinon 300C and found them both to be very sharp. If anything, my Fujinon was a bit more contrasty than my Nikkor, although I never tested resolution.

Second, I would agree with one of the previous posts that flare from the large image circle is a real issue. I know many LF photographers that insist that shading the lens with their hat or dark slide is enough. But for color work, a good bellows lens shade really improves image contrast, and therefore the impression of sharpness. MF and 35mm lenses today have flare baffles built into their designs, but with LF you have to do it the old fasioned way with an adjustable hood. Now that Lee makes several versions of their self supporting bellows hoods, including ones that fit Cokin holders, it is pretty easy to deal with a lightweight adjustable hood.

Let us know how this turns out!