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Thread: f64

  1. #181
    Drew Wiley
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    Re: f64

    Sorry for the typos... I have just spent a lot of money getting that tendonitis in my fingers partially fixed. But the same comment I made to Sal applies to those
    allegedly definitive tests by Perez and KT. They aren't scientifically valid either. Do you REALLY think that kind of casual "batch" testing is more tightly controlled than how modern lens manufacturers with serious engineers and machining equipment define their own quality control ?????????????????? Nonsense.

  2. #182

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    Re: f64

    Anecdotal evidence which points us to look in a certain direction is great and helpful. As they say... Who knew ?

    That being said, I have to agree with the wisdom of testing multiple samples under controlled conditions. When we remove all the variables, what seems to us like unshakeable evidence may indeed shake out.

    It may be true that certain lenses - or certain focal lengths in certain lenses - are reliably superior, but the only way to prove it is to actually prove it.

  3. #183
    Drew Wiley
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    Re: f64

    Yeah, and one has to look at what lens manufacture has been by the "big four" ever since the mid-60's. The quality controlled equipment by any one of them probably runs into many millions of dollars. Sure, some lens designs are inherently better than others for certain purposes, and each might have their forte.
    For example, the Nikkor M has only six air/glass interfaces, plus multicoating - the ultimate evolution of the tessar design. So the contrast and hue differentiation are superb. But other kinds of lenses are superior at other things, like a big image circle, or macro to infinity versatility. Nobody has a perfect batting average. There were unanticipated cement issues with the 80 and 110 Apo Symmars for example. Back when the big camera stores still had pro staff and knowledgeable
    salesmen, I once heard one of them remark that he had never seen a bad Fuji lens. I believe it.

  4. #184
    Jac@stafford.net's Avatar
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    Re: f64

    Quote Originally Posted by Drew Wiley View Post
    These simply aren't scientific results. You'd have to design an optical bench and have something truly flat as your target.
    We humans are not scientific targets. We do not expect our view to be flat. We interpolate. And we do not see everything in terms of resolution. If we view an image we like, we do not refer to lens designs to understand why.
    .

  5. #185

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    Re: f64

    Quote Originally Posted by Drew Wiley View Post
    These simply aren't scientific results. You'd have to design an optical bench and have something truly flat as your target...
    They aren't and were never intended to be "scientific results." They're relevant results for those who shoot 8x10 landscapes at or near infinity. No, neither I nor anyone else interested in replicating the results has to design an optical bench or have something "truly flat" as a target. An Edmund chart, taped tightly to a fence, 50 feet from the camera, along with natural elements near it, is the perfect target for a real-world test.

    Quote Originally Posted by Drew Wiley View Post
    ...as far as "batch variation" in fully modern manufacture is concerned, "the usual suspect", I doubt it unless your statistical sample base is significant (non single uses has that kind of quantity of anything), and unless you first rules out the other suspects...
    For a significant period during my engineering career, I performed statistical quality control functions. I'm completely familiar with the concepts and practice. I always mention sample variation when discussing lens performance here. The 300mm f/5.6 Nikkor W's performance at f/45 and f/64 was so much better than the other tested lenses, I'm willing to wager (based on experience) that its 'winner' status cannot likely be attributable to sample variation.

    Quote Originally Posted by Drew Wiley View Post
    ...The reason I typically carry a Fuji 360A in that focal length is that I'm an opportunistic shooter. I frequently encounter subjects near macro, where this lens or a G-Claron is going to perform significantly better than a general purpose lens. Or I might have an architectual subject, or be in the redwoods, where I need dramatically more rise than something like a 300M. But at the same time, I might carry an old 360 Zeiss process tessar as well, because I prefer its out of focus rendering where selective focus is the name of the game...
    Neither a 300mm f/9 Nikkor M nor a 360mm lens of any type was part of my comparison. Scenes at macro range were not part of my test. Selective focus was not part of my test. My test was to evaluate sharpness of landscape subjects at near-infinity infinity distances when exposed at f/45 and f/64. That is all. And my results confirm what was stated in the OP.

    Quote Originally Posted by Drew Wiley View Post
    ...a more relevant test, and a necessary one to pin down this given subject fairly, would first be to evaluate what is happening in those filmholders. Film sags, acetate typically more than estar, and 8x10 significantly more than 4x5. Your center to edge findings with an ordinary holder are automatically defeated by this very fact...
    There's no further test necessary to "pin down this given subject fairly." To reiterate, my holders are all depth checked and hand-picked. There is no significant depth variation between their centers and edges. There is no film sag. The 8x10 Kodak polyester-based film I used is, in my experience, the most rigid available. I've previously depth-checked it after loading into these holders and, when held vertically, reflections in the emulsion from linear objects were straight. Everything had a long time to reach equilibrium with environmental conditions.

    Quote Originally Posted by Drew Wiley View Post
    ...That isn't science; it's rolling the dice and then blaming something else.
    You can wave your arms until they fall off, but it doesn't change the fact that my results confirm the OP. A 300mm f/5.6 Nikkor W at f/64 is vastly sharper than the other lenses I compared it to, and more than sufficiently sharp to make very crisp enlargements where the other lenses would suffer. Remember, I own all those other lenses, and use them in varying circumstances for different reasons. I've not until now made pictures with them at f/64 and don't plan to in the future. I've not packed the 300mm f/5.6 Nikkor W great distances and don't plan to in the future. But, if I want to make a photograph on 8x10 film of a subject at distance, need great depth of field and can do this close to my car, I wouldn't hesitate to use the 300mm f/5.6 Nikkor at f/64. It's the only lens among those I tested that I'm willing to say that about. And it confirms the OP's contention.

    There's neither 'blaming something else' or 'rolling dice' involved. While my test conditions were not in accordance with your idea of 'science,' they were totally controlled for this practical, relevant comparison. Again, I encourage anyone who owns these lenses to conduct their own tests and post the results here. My money is on most, if not all, 300mm f/5.6 Nikkor Ws exhibiting far less diffraction blur at f/64 than people expect. I look forward to hearing from those who follow up, not just those who speculate and pontificate.

  6. #186
    fishbulb's Avatar
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    Re: f64

    Quote Originally Posted by Drew Wiley View Post
    Those of us who routinely carry Fuji A and C lenses know what utterly superb performers they are, even in smaller 4x5 applications demanding still greater enlargement. But diffraction is the great equalizer.
    It is sad that people still believe the "diffraction is the great equalizer" myth. It has been proven many times to be empirically false.

    A lens that has fewer optical aberrations will appear sharper than another lens, even when stopped down. Likewise, a higher-resolution film/sensor will be sharper than a lower resolution film/sensor, even when stopped down.

    Even under the severe diffraction at f/64, a sharper lens will outperform a less sharp lens. Just go and test a 1800's meniscus lens against a modern computer-designed lens, and see which is sharper at f/64...

    For example, there are some good articles on the lens rentals blog (this one too). Or for the impact of sensor resolution, see here.

    You can also see this in lens review online. Compare, for example, the old Sigma 50mm vs. the new Sigma 50mm art. Same test camera, same conditions, same tester, same methods. Even stopped down to where diffraction is killing resolution, the better lens is still the better lens.
    -Adam

  7. #187
    Drew Wiley
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    Re: f64

    If this is your red line, Sal, then you're utterly wasting your time even nitpicking lenses. I've run 8x10 tests precision filmholder versus conventional where plane
    variations in the latter (due to film bowing or sag in the vertical position, not a bad holder itself) was a far greater factor than anything related to one modern lens
    versus another, or even minor diffraction issues. Unless someone here is an optical engineer, I'd suspect that optical manufacturers in the 1920's had better testing gear than any of us do. Having sold machinist equip at one time, and been on a first name basis with even NASA opticians, I'd suspect quality control today is pretty astounding when it comes to pro lenses. Yes, I do respect the cumulative know-how of the many users on forums like this, and the associated reputations or characteristics of certain lenses via lots of real world experience. But to go around saying you have no sag in your holders is utter nonsense. Hold up your holder and film in various positions with a strong linear light source (like bare fluorescent tube), with the darkslide removed. The light will be wavy or distorted. I personally check non only my holders, but the camera back itself with a bar of precision ground flat stock and a depth micrometer through it; in other words, tolerances within 1/1000 inch. That does zero to keep the film itself truly flat. When I contemplate big enlargements, or something critical like
    an enlarged dupe in the lab, a precision vac holder makes all the difference in the world. In the field, I routinely use adhesive holders for 8x10 color work (I rarely print b&w larger than 20x24, which is a very modest enlargement for 8x10). Some sheet films are stiffer than others, and some camera angles (like
    pointing downward) are more prone to sag than others; but it is always there to some extent. There is a reason that astronomers used glass plates rather than
    sheet film in the old days. Otherwise, they'd be wasting their time. And yes, you are rolling the dice. You refuse to acknowledge the weakest link in this fashion
    of testing. Might as well be throwing darts with fogged up glasses.

  8. #188
    (Shrek)
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    Re: f64

    Quote Originally Posted by fishbulb View Post
    A lens that has fewer optical aberrations will appear sharper than another lens, even when stopped down.
    Especially when stopped down. Look at a simple diagram of the light rays through a lens wide-open vs. at f64 to see why. Aberrations and surface defects are magnified the more you stop down.

  9. #189
    Drew Wiley
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    Re: f64

    Back to the "us versus them" opinion dept: How many of you saw in print when Sinar formally published that the weakest link in image sharpness was the flatness of film in the holder itself? Of course, people like Sinar-Bron knew absolutely nothing about quality control or precise machining, did they? Even Swiss watches are made with soggy cardboard and a bandsaw blade connected between a willow stick and a hound dog tail. But that's back when they tried to market an alternative platen-back 4x5 holder, which was so damn expensive it never caught on, along with the more practical adhesive system for 5x7 and 8x10 holders which people quickly learned to clone far more affordably, and had a distinct applications for. And people knew how to make even more precise vacuum holders for at least studio applications right along. There are a few minor tricks to it; but any thoughtful shop dude can do it. Yeah, unless I am after some special pictorial effect in a given lens, I buy the best I can afford. But I know that all this nitpicking is an utter waste of time unless the other variables like consistent
    film plane flatness and good lens shading are likewise controlled.

  10. #190

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    Re: f64

    Quote Originally Posted by Sal Santamaura View Post
    ...I look forward to hearing from those who follow up, not just those who speculate and pontificate.
    Also not those who repeat irrelevant information without having read what I wrote that already addressed it.

    Let those reading this thread judge for themselves. Some appear to be doing just that.

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