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  1. #21
    Alan Klein's Avatar
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    I don't normally do closeup work. But my Mamiya RB67 medium format is really very capable of that and has bellows adjustment markings on it to make adjustments. Are those accurate or do you have to do more?

  2. #22

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    Quote Originally Posted by StoneNYC View Post
    I was assuming it was some kind of PDF you could print and cut out that's what I was looking for so I saw the pages with math on it I just didn't bother :-0
    You kids are going to drive me crazy. Post 15. Click and print, then cut out with scizzors. Ignore all of the others since they have words and numbers.

  3. #23
    StoneNYC's Avatar
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    Quote Originally Posted by BrianShaw View Post
    You kids are going to drive me crazy. Post 15. Click and print, then cut out with scizzors. Ignore all of the others since they have words and numbers.
    Hahhaa!!! It's true, we are lazy, we grew up with calculators instead of slide rules, never learned to count with beads like you old folks

    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  4. #24
    StoneNYC's Avatar
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    Quote Originally Posted by Alan Klein View Post
    I don't normally do closeup work. But my Mamiya RB67 medium format is really very capable of that and has bellows adjustment markings on it to make adjustments. Are those accurate or do you have to do more?
    I have the same Mamiya RZ67 and the chart works fine, it's a wonder to me they didn't incorporate the same sort of chart on all modern LF cameras, it seems kind of like a no brained to me, but no one's done it yet, I mean the least they could have done was added ruler markings on the field camera bodies so you didn't have to carry one in the field, sometimes I wonder about these engineers... Lol
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  5. #25

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    Quote Originally Posted by StoneNYC View Post
    I have the same Mamiya RZ67 and the chart works fine, it's a wonder to me they didn't incorporate the same sort of chart on all modern LF cameras, it seems kind of like a no brained to me, but no one's done it yet, I mean the least they could have done was added ruler markings on the field camera bodies so you didn't have to carry one in the field, sometimes I wonder about these engineers... Lol
    Probably better to ask the marketing guys than the engineers. Engineers love numbers, and scales, and marking, and all sorts of technical stuff. Marketing guys are better at figuring out what the majority of users want and need and will pay for. But if you wonder about engineers, start a thread and ask away. Me and my kind will be glad to give you an education. Just have a slide rule ready so you can understand the lesson and do your homework. [as you say: ]

  6. #26
    MattKing's Avatar
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    Quote Originally Posted by StoneNYC View Post
    I have the same Mamiya RZ67 and the chart works fine, it's a wonder to me they didn't incorporate the same sort of chart on all modern LF cameras, it seems kind of like a no brained to me, but no one's done it yet, I mean the least they could have done was added ruler markings on the field camera bodies so you didn't have to carry one in the field, sometimes I wonder about these engineers... Lol
    Maybe because it only works if the lenses used were made by the camera's manufacturer, and explicitly identified as working with the scale.

    The idea about the ruler is good though.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  7. #27
    StoneNYC's Avatar
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    Quote Originally Posted by MattKing View Post
    Maybe because it only works if the lenses used were made by the camera's manufacturer, and explicitly identified as working with the scale.

    The idea about the ruler is good though.
    Thank you Matt for noting that the ruler idea is a good one, it's sort of seems obvious to me

    But as far as the lenses are concerned yes each lens is different, but please correct me if I'm wrong because obviously I don't know as much about this stuff, but wouldn't all lenses have the same bellows distance? So correcting for it would be the same and would only depend on focal length? So you could easily have a scale that showed 65, 75, 90, 100, 127, 135, 150, 180, 210, 300, 350, 400, 500

    It could be simply a little slide out that you pull out to measure and would have the chart right in the side just like the RZ/RB have?

    If someone had an odd size, they could simply interpolate between the two different sizes and get relatively the correct compensation?

    Or am I totally off base here?
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  8. #28
    MattKing's Avatar
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    Stone:

    How would you deal with telephoto lens designs, or retro-focus lens designs?

    The scale on the camera can only measure how far the lens board is from the film plane. The actual focal length of the lens is measured from the nodal point of the lens to the film plane (when focused at infinity) and with large format lenses, the distance between the nodal point and the lens board will vary with the design of the lens, its construction, and possibly the shutter used.

    In many cases (telephotos, retro-focus design), the nodal point is actually effectively outside the physical body of the lens - it certainly isn't a consistent distance from the lens board.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  9. #29
    StoneNYC's Avatar
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    Quote Originally Posted by MattKing View Post
    Stone:

    How would you deal with telephoto lens designs, or retro-focus lens designs?

    The scale on the camera can only measure how far the lens board is from the film plane. The actual focal length of the lens is measured from the nodal point of the lens to the film plane (when focused at infinity) and with large format lenses, the distance between the nodal point and the lens board will vary with the design of the lens, its construction, and possibly the shutter used.

    In many cases (telephotos, retro-focus design), the nodal point is actually effectively outside the physical body of the lens - it certainly isn't a consistent distance from the lens board.
    Well I guess I've been measuring wrong... In any case, it can't be too far off from that? Within an inch? I don't even know what retro-focus means...
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  10. #30
    MattKing's Avatar
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    Quote Originally Posted by StoneNYC View Post
    Well I guess I've been measuring wrong... In any case, it can't be too far off from that? Within an inch? I don't even know what retro-focus means...
    For some telephoto lenses, the nodal point is a long way forward of the front element and way outside the body of the lens.

    And retro-focus construction is most often used for wide angle lenses. In that case it results in the nodal point also being outside the lens itself, except in this case it is behind the rear element. - some times a considerable distance behind.

    Unless you know where those nodal points are, you cannot measure the distance between them and the film plane, and therefore cannot use single measurements from a fixed plane to determine an exposure calculation.

    That is when the various tools that involve measuring magnification (e.g. using a ruler in the field of view) are most useful.

    And that is why you can't build a scale on the camera for this purpose.

    EDIT: for certainty and clarity, I mention that a "telephoto" lens is not the same as a long lens - it is a lens that is shorter than its focal length.

    A bit of random googling yields an example of the Nikkor 1200mm f/18 lens which is focused at infinity when the bellows it is mounted on is extended to just 755 mm - about 450 mm or 18 inches less than the focal length of the lens.

    The lenses you are using may not be strongly telephoto, or strongly retro-focus, in which case the nodal points may all be near the middle of the lenses.

    But in any event, a scale on the camera wouldn't work.
    Last edited by MattKing; 11-16-2013 at 01:30 AM. Click to view previous post history.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

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