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  1. #1

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    What determines neg. size? 6x4.5 and 6x6

    I'm a bit confused on something.

    What determines the negative size/aspect ratio with 120 film? In other words, what determines if it's 6x4.5 or 6x6?

  2. #2

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    The camera.

    David.

  3. #3
    Dave Miller's Avatar
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    The size of the mask in the camera through which the image is formed on the film. It's nothing to do with the film itself.
    Regards Dave.

    An English Eye


  4. #4

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    Quote Originally Posted by hammy View Post
    I'm a bit confused on something.

    What determines the negative size/aspect ratio with 120 film? In other words, what determines if it's 6x4.5 or 6x6?
    First, all sizes are nominal, and almost invariably, the actual size is smaller than nominal.

    The maximum image width on 120 film is 56-58mm. The image can be any length, but typical choices are 40-44mm (645 = 15-on or 16-on), 56-58mm (6x6 = 12-on, 11-on in some very old cameras), 67-72mm (6x7 = 10-on), 78-80mm (6x8 = 9-on, rare), 80-88mm (6x9 = 8-on, the original 120 format), 110-120mm (6x12 = 6-on) and 170mm (6x17 = 4-on).

    Any camera can be built for any format; some accept different backs or use masks for multiple formats.

    Cheers,

    R. (www.rogerandfrances.com)

  5. #5

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    Thanks.

    That's what I thought.

    So my Hasselblad 500C, it's 6x6?

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    Quote Originally Posted by hammy View Post
    Thanks.

    That's what I thought.

    So my Hasselblad 500C, it's 6x6?
    Usually but 645 backs are available. Measure the gate with a ruler and you'll know. Or count the exposures...

    Cheers,

    R.

  7. #7

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    Quote Originally Posted by Roger Hicks View Post
    Usually but 645 backs are available. Measure the gate with a ruler and you'll know. Or count the exposures...
    Or measure the size of the images on a processed roll of film.

  8. #8

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    Hasselblad backs are usually referred to by the number of exposures per roll - 12 (look through a hole in the back to advance film to #1 frame) or A12 (auto stop at first frame). Both are 6X6 frame size and take 12 images per roll of 120. There are also 16 and A16 backs for 6X4.5 frame size, and 16 exposures/120 roll. There is an A24 for 24 exposures 6X6 on 220 film (not many 220 films left on the market). The back you probably want to avoid is the 16S which was designed for 4.5X4.5 "Superslides". Finally there is a 70mm 6X6 back which takes many exposures per roll, but the choice of 70mm films is rather limited.
    If you are shopping for an additional back for your 500C, the A12 back seems to be most common on the used market. Myself, I get along fine with the older non-auto 12 backs. This may be the style back you already have with your 500C. They tend to be less expensive than the A12. 16 and A16 backs are much less common on the used market, but there are some available if the 6X4.5 and 16 exposures per roll are important to you.

  9. #9
    Photo Engineer's Avatar
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    Lens has some part in this too.

    A 70 mm lens for a 35mm camera will not work properly on a 645 camera where 70 mm might be considered normal. Even if the mounts were the same, the image would not be correct due to vignetting among other things.

    PE

  10. #10
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    Quote Originally Posted by Photo Engineer View Post
    Lens has some part in this too.

    A 70 mm lens for a 35mm camera will not work properly on a 645 camera where 70 mm might be considered normal. Even if the mounts were the same, the image would not be correct due to vignetting among other things.

    PE
    Lens vignetting could prevent the frame area from being completely exposed but it has no role in determining what that area is.

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