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  1. #31
    StoneNYC's Avatar
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    Quote Originally Posted by MattKing View Post
    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.
    Gotcha, okay that makes sense, but at least the ruler idea make sense still, however my question now is how the heck do I know what I have on my lenses that I own now, is there a marking point that I'm supposed to look for, I don't remember seeing any of those zeros with lines through them...
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  2. #32
    Greg Davis's Avatar
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    I made this chart to go along with my lenses. It is approximate, not exact, but it works well for me. I printed it so one column is on the front and one on the back of the same page, then laminated it and put it in my camera bag.
    Attached Files
    www.gregorytdavis.com

    Did millions of people suddenly disappear? This may have an answer.

    "No one knows that day or hour, not even the angels in heaven, nor the Son, but only the Father." -Matthew 24:36

  3. #33
    Alan Klein's Avatar
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    Stone: Why do you need a chart for the RZ67? Wouldn't the built in exposure meter read less light as the bellows expands and automatically compensate for the final exposure?

  4. #34
    StoneNYC's Avatar
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    Quote Originally Posted by Alan Klein View Post
    Stone: Why do you need a chart for the RZ67? Wouldn't the built in exposure meter read less light as the bellows expands and automatically compensate for the final exposure?
    Alan, the exposure meter is in the mirror attachment, a piece that I don't use to shoot with, nor do I have anymore I sold mine because I never used it, it's too heavy and I like using the waist level finder better to take pictures with that camera. So it's of no help when exposing. That's why the pullout chart exists on the side.

    But anyway I was referring to shooting with my 4 x 5, in terms of having to calculate exposure with bellows extension.
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  5. #35
    MattKing's Avatar
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    Quote Originally Posted by StoneNYC View Post
    Gotcha, okay that makes sense, but at least the ruler idea make sense still, however my question now is how the heck do I know what I have on my lenses that I own now, is there a marking point that I'm supposed to look for, I don't remember seeing any of those zeros with lines through them...
    If your lenses are either telephotos or retro-focus designs, the "marking point" would be outside the body of the lens.

    You need to use the other tools available for this purpose unless and until you determine where the nodal point is.
    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

  6. #36
    StoneNYC's Avatar
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    Quote Originally Posted by MattKing View Post
    If your lenses are either telephotos or retro-focus designs, the "marking point" would be outside the body of the lens.

    You need to use the other tools available for this purpose unless and until you determine where the nodal point is.
    Wait I'm confused what other tools? The only tools available to me are my reciprocity timer, which asks me about the Bellas distance, however if the bells distance includes this extra space that is outside of the lens area, how can I tell where on the lens this point is? I don't see any special marking telling me where that point is like you do on a 35mm camera which has that zero with a line through it showing that that is where the film plane is, so how can I know?
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  7. #37

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    Quote Originally Posted by StoneNYC View Post
    ... a line through it showing that that is where the film plane is, so how can I know?
    That is a problem. Information like that is available but one must read and understand the specification data for the lens in question. Knowing if your lens is a telephoto design or not is essential to knowing this.

  8. #38
    StoneNYC's Avatar
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    Quote Originally Posted by BrianShaw View Post
    That is a problem. Information like that is available but one must read and understand the specification data for the lens in question. Knowing if your lens is a telephoto design or not is essential to knowing this.
    I highly doubt any of my lenses are telephoto's, even if I bought a "telephoto", it wouldn't be a real one per your specification that the link has to be longer than the extension or something like that.

    I own a 75mm f/4.5 grandagon, a 90mm f/9 Schneider super angulon and a 150mm f/5.6 Schneider super angulon, and I plan to purchase a fujinon 300mm f/8.5 C lens to complete my "kit" but the 300 is a compact lens so I don't think that qualifies as a telefoto in your new-to-me definition.
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

  9. #39

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    Quote Originally Posted by StoneNYC View Post
    I highly doubt any of my lenses are telephoto's, even if I bought a "telephoto", it wouldn't be a real one per your specification that the link has to be longer than the extension or something like that.

    I own a 75mm f/4.5 grandagon, a 90mm f/9 Schneider super angulon and a 150mm f/5.6 Schneider super angulon, and I plan to purchase a fujinon 300mm f/8.5 C lens to complete my "kit" but the 300 is a compact lens so I don't think that qualifies as a telefoto in your new-to-me definition.
    None of those are telephoto lenses. Measuring from the lensboard has always worked out well for me, as for the filmplane it's where the groundglass is.

  10. #40
    StoneNYC's Avatar
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    Quote Originally Posted by E. von Hoegh View Post
    None of those are telephoto lenses. Measuring from the lensboard has always worked out well for me, as for the filmplane it's where the groundglass is.
    Yes I know where the film plane is

    And ok, good enough for me! Lens board to film plane it is!
    ~Stone | "...of course, that's just my opinion. I could be wrong." ~Dennis Miller

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