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  1. #21

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    To clarify - photodo provides an adequate compromise in testing for the average person because the average person does not have the critical requisites or technique neccessary to challenge the potential of the lenses reviewed in photodo. In other words, the average person does not have the visual experience to see the actual differences in outcome, and he makes so many mistakes in the course of his work that the lenses are rarely used in an optimal manner; comparisons in practice become impractical, so, the scope of photodo's tests fosters irrelevance: just more optical bench-racing. So in that regard, photodo is at least entertaining to those looking for issues they can pursue outside of the practice of photography - seat-of-the-pants optical benchracing.

    In many regards photodo "won't do". For example, they test all lenses at infinity. Most pictures are not made at infinity, and a daunting error in this regard is the outcome of their tests for macro lenses which are made for subjects specifically NOT at infinity.

    Further, wide-open work is not properly evaluated by photodo's testing, nor is miminal aperture. Photodo doesn't test large format lenses, either, because they don't fall within the average consumer's concerns. But who really cares? Not the amateur. A pro might care, but the pro knows to take photdo with a grain of, ah, silver.

    But the real point is not about photodo in particular, it concerns the irrelevance of the MTF metric for persons who understand and seek certain lens qualities which may not be lp/mm metric-obsessive, for example certain color qualities, the virtues of certain aberrations, and so-forth.

    Finally, as we all know, for good reasons, photodo does not attempt to evaluate the manufacturing consistency of a lens source, nor the materials quality, durability. Brand Z lens might just come off as MTF equal (in the sense of the compromise) as good as Brand A, but it's internals go off kilter in short order, or just plain breaks.

  2. #22

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    Well, JJ since you are bound and determined to follow thru on this MTF discussion please identify the abberations that do not effect MTF.
    Claire (Ms Anne Thrope is in the darkroom)

  3. #23

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    Quote Originally Posted by Claire Senft
    Well, JJ since you are bound and determined to follow thru on this MTF discussion please identify the abberations that do not effect MTF.
    Your question points directly to three parts of my position: first, MTF is not all that matters; second, obsessing on MTF is irrelevant because most lenses are adequate and most persons' technique won't exploit the potential of the lenses; third, persons so obsessed or deluded will, just as you have, pursue MTF benchracing issues regardless of the content of the post that set them off: you didn't read what I wrote. "Bound and determined" my butt. I wouldn't be wasting my time discussing this stuff if I weren't, FAPP, bedridden at the present. I wouldn't be as grumpy, either. I'd be out of here working.

    There are no military resolution charts on gallery walls. Very few memorable pictures are technically perfect. Obsolete, horrific MTF quality lenses can be beautiful - their qualities speak to part of the photographic language. It is up to the photographer to use them, or not, as they please. There never will be an esthetic photodo, thank God.

    (All that said, there is part of my effort, one minor project, that is concerned with ultra-high quality LF, but it's only a small part of my concerns and I will abandon it for meaningful work as appropriate.) Oh, and I know this is the RF forum. I use a LF RF camera, too... but some subject drift is acceptable.

  4. #24

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    I hope you get well fast JJ but you did not answer the question.
    You make several points with which I am in agreement...but I will never tell you which they are.

    Have a nice day.
    Claire (Ms Anne Thrope is in the darkroom)

  5. #25

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    Quote Originally Posted by Claire Senft
    I hope you get well fast JJ but you did not answer the question.
    You make several points with which I am in agreement...but I will never tell you which they are.

    Have a nice day.
    The answer is too obvious - MTF takes into all the things a benchracer wants to talk about, and usually all they want to talk about.

  6. #26

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    But I am not a benchracer. And I would like to know. As far as photodo is concerned, I too have my problem with them. The MTF grading is optimized for a 4x6 print. I am not much interested in making 4x6 prints. Things I see in their favor: They are a Hasselblad distributor but when one looks at the Rollei tests they have given the highest marks to a Schneider lens. When it comes to the highest score ever given out is was given to a Canon lens. They have several very nice articles to read...good for the grumpy, bed ridden person, as well as others to read.

    So JJ can you tell us which abberations do not influence MTF tests or did you perchance misspeak or you are ingnorant of which they are?
    Claire (Ms Anne Thrope is in the darkroom)

  7. #27
    David A. Goldfarb's Avatar
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    I think JJ and Ed Zimmerman's point is not that there are aberrations that don't influence MTF, but that aberrations that produce a lower MTF value might produce a better image for reasons apart from sharpness, contrast, and resolution. One might reasonably prefer a lens with a lower photodo score over a lens with a higher score.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  8. #28

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    Quote Originally Posted by Claire Senft
    So JJ can you tell us which abberations do not influence MTF tests or did you perchance misspeak or you are ingnorant of which they are?
    I had answered your question before you asked the second time. See below. Is it not clear that I won't be provoked into benchracing bull?

  9. #29

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    OK I am going to give it a rest. Having made your purchase the die is cast and it is up to you how well it is used. To my way of thinking the only abberation not influencing MTF is distortion and that is listed seperately. In addition to that field illumination is also important.

    Unless as a result of damage or of a faulty lens slipping thru the system one is fortunate because almost any lens made in the last 30 years is quite a marvelous instrument.

    If one wants to be a fanatic abiut lens quality, in my opinion, they should do it with enlarging lenses because that is the most important lens you are likely to own.

    Please, no remarks about CZ enlarging lenses.
    Claire (Ms Anne Thrope is in the darkroom)

  10. #30

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    Quote Originally Posted by Claire Senft
    [...]
    If one wants to be a fanatic abiut lens quality, in my opinion, they should do it with enlarging lenses because that is the most important lens you are likely to own.
    Uh oh! Here come the ULF contact printers!

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