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  1. #1
    Curt's Avatar
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    Why No Camera Can Focus

    http://www.anstendig.org/WhyNoCameraCanFocus.html

    Any experience with or comments on this? I did in a workshop given by the, can't mention the government agency, and it was an eye opener.

  2. #2
    jstraw's Avatar
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    Unless you're dealing with a point of focus closer than the lens can focus, the point of focus is somwhere between minimum focus and infinity. The point of focus is, by definition *somewhere* in between. So *some* point is going to be in focus, even if by accident or even if it's not the point you desire. So generally speaking, no matter where the focusing ring or bellows are...*some* point is in focus. If that point can be determined then you can focus at that distance at that adjustment.

  3. #3
    David A. Goldfarb's Avatar
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    The Messraster sounds a lot like the microprism screen, which I've always found hard to use. I had a microprism spot on my Canon EF, and I've had a few SLRs with microprism rings.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
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  4. #4
    Alex Hawley's Avatar
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    Quote Originally Posted by Curt View Post
    http://www.anstendig.org/WhyNoCameraCanFocus.html

    Any experience with or comments on this? I did in a workshop given by the, can't mention the government agency, and it was an eye opener.
    To me, its a dead horse argument. What he is saying is true in the strictest respect, but obviously not in the pragmatic respect.

    Back when I was navigating a ship, we had a similar saying; you never know exactly where you are, just where you have been. But we still got there and got there safely.
    Semper Fi & God Bless America
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  5. #5
    Michel Hardy-Vallée's Avatar
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    I find that he spends an inordinate amount of time bombasticly praising his system, disparaging all others, and giving little or no experimental data. I don't care if his system is better, he's so self-sufficient that I distrust this paper.
    Using film since before it was hip.


    "One of the most singular characters of the hyposulphites, is the property their solutions possess of dissolving muriate of silver and retaining it in considerable quantity in permanent solution" — Sir John Frederick William Herschel, "On the Hyposulphurous Acid and its Compounds." The Edinburgh Philosophical Journal, Vol. 1 (8 Jan. 1819): 8-29. p. 11

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  6. #6
    David H. Bebbington's Avatar
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    Quote Originally Posted by David A. Goldfarb View Post
    The Messraster sounds a lot like the microprism screen, which I've always found hard to use. I had a microprism spot on my Canon EF, and I've had a few SLRs with microprism rings.
    His writing is rather impenetrable, but as I understand it he's saying that microprisms are too inexact, with too wide a tolerance either side of true focus before they become really noticeable. This is well known - it is a good idea (if inconvenient) to have a number of interchangeable screens (assuming your camera has this facility) and use the one best matched to your lens (which could be microprisms for large-aperture lenses, a split-image rangefinder/Fresnel for wide-angle lenses, and a plain screen for very long lenses). He repeats the word "Messraster" like a mantra, this is only the normal German word for "graticule" and I can see no reason why an inscribed grid of any kind should be an aid to focusing. In any situation with fantastically high requirements regarding focusing accuracy (mainly scientific applications), standard practice as far as I am concerned would be to use a clear screen (not matted) with an inscribed cross-hair and a high-power magnifier eyepiece. This will give you really accurate focusing (assuming your camera has the viewing plane totally coincidental with the film plane) but also a big headache if you look away from the cross-hair and try to concentrate on pictorial composition. I think Mr. Anstaendig is sadly an obsessive in a world of his own ( as are most people who say "The whole world and the standard practice of the last 150 years are all wrong, only I am right"!).

  7. #7
    Vaughn's Avatar
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    What an article....

    For most of us, 90% of the time it does not matter precisely where the exact plane of focus is. We'll be using depth of field to get acceptable sharpness where we want it. It won't matter if the plane of focus is 15 feet out or 17 feet out -- as long as the depth of field gets the foreground to the background (or infinity) sharp enough for the level of enlargement we want. And determining that is not all that exact. Perhaps I should be more careful, but it seems he is, for the lack of a better way to explain it, talking about the need to measure something in cm's that is actually meters in length.

    While there are many exceptions, most photographs do not depend on getting one particular plane in exact focus.

    I did enjoy his breakdown of the term "depth of field"...sort of sounded like saying..."What is the English translation for the German word meaning "depth of field"?

  8. #8
    FrankB's Avatar
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    Well gosh, I suppose I'd better throw these two Rollei 35's away then... :rolleyes:
    The destination is important, but so is the journey

  9. #9
    Mick Fagan's Avatar
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    What is it with musicians and photography.

    I must be doing something wrong, the only musical instrument I can play is a bell.

    Mick.

  10. #10

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    Yet somehow I keep getting pictures in focus.

    David.

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