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Thread: LF lens + MF camera = ?

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    LF lens + MF camera = ?

    Mathematics is not my strong side so I would like to ask how to calculate how much shift is possible when I mount a 135mm LF lens with a 150mm image circle on a MF 645 camera body, and also if the focal length and/or field of view (ie extent of the observable world that is seen through the lens) changes or not?

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    Re: LF lens + MF camera = ?

    Quote Originally Posted by lowep View Post
    Mathematics is not my strong side so I would like to ask how to calculate how much shift is possible when I mount a 135mm LF lens with a 150mm image circle on a MF 645 camera body...
    Way more than you are going to need in any practical application. Way more than your shift-mount adapter hardware is likely to allow. Remember, too, that as you focus closer than infinity the image circle expands proportionately.


    Quote Originally Posted by lowep View Post
    ...and also if the focal length and/or field of view (ie extent of the observable world that is seen through the lens) changes or not?
    The focal length is always fixed - 135mm is 135mm. As for the field of view, think of it this way: the lens projects a cone of light. You can capture as much or as little of the cone as you'd like, depending on how large a piece of film (or sensor) you put in its way. The larger the piece of film/sensor, the wider the field of view that you capture with your slice of the projected image. If you use a 24x36mm piece of film/sensor, you will get an image that looks exactly the same as you'd get with a 135mm lens made for a 35mm camera - and so on, with different formats. On 4x5 inch film, the format for which most 135mm view camera lenses are primarily intended, you get a view that's slightly wide of normal. On 645 film, you'll get a fairly narrow field of view that's typically considered well-suited to portrait applications.

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    Re: LF lens + MF camera = ?



    Thanks! Even I can understand this.

    Quote Originally Posted by Oren Grad View Post
    On 645 film, you'll get a fairly narrow field of view that's typically considered well-suited to portrait applications.
    Does this mean if I use lens shift to shoot & stitch together two images taken with a portrait-fov-style lens eg about 80mm 645 into a panorama I will end up with a field of view twice as wide as one image ie equivalent in terms of width to fov of about 40mm 645 wide angle lens?

    If yes, then what this gets me thinking about is what difference the fov of a stitched panorama image taken with a portrait style lens eg 2x80mm 645 will be from an image of the same subject taken with a wide angle fov style eg about 45mm 645 lens -- apart of course from double MP and more background & foreground on the top and bottom of the image made with the 645 wide angle lens?

    Rather than a portrait-style lens it would probably make more sense to stitch together 2 images taken with a wide angle fov LF or 67 lens that would deliver a much wider fov than a standard 645 wide angle lens, right? But the minimal focal length that at least the Zork adapter system can work with without a special custom adaption rules this out as an option.

    I agree the logical way to find the answer to these questions is to do it. To do that I need to buy a lens or an adapter for one of the lenses I already have. Before that I am trying to figure out what the different lens options can deliver to augment what I can already do with my portrait and wide angle 645 lenses

    Otherwise I may like harry potter just end up back where I started... it would not be the first time that happened

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    Re: LF lens + MF camera = ?

    Quote Originally Posted by lowep View Post
    Mathematics is not my strong side so I would like to ask how to calculate how much shift is possible when I mount a 135mm LF lens with a 150mm image circle on a MF 645 camera body, and also if the focal length and/or field of view (ie extent of the observable world that is seen through the lens) changes or not?
    Peter,

    A question is also what large format lens, and if it is suffice sharp for the exercise to be worthwhile... Just an example, my Rod Sironar-N was sharp but not digital lens sharp per say on 28MP back.

    Best regards,
    Anders

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    Re: LF lens + MF camera = ?

    Quote Originally Posted by lowep View Post
    Does this mean if I use lens shift to shoot & stitch together two images taken with a portrait-fov-style lens eg about 80mm 645 into a panorama I will end up with a field of view twice as wide as one image ie equivalent in terms of width to fov of about 40mm 645 wide angle lens?
    If you stitch a pair of portrait-orientation (i.e., vertical) 645 frames side-by-side, you end up with the equivalent of a landscape-orientation (horizontal) 6x9 frame. Based on the format diagonals, 80mm on 6x9 corresponds roughly to 55mm on 645.

    If you stitch the 645 frames together in horizontal orientation, it's not clear that it makes sense to compare with a 645 frame because the aspect ratios are so radically different. But if it's the horizonal field that you're concerned about, then yes, 80mm on a nominal 12cm (actually 112mm) is like 40mm on a nominal 6cm (actual 56mm). Just don't forget that you get only half the coverage vertically.

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    Re: LF lens + MF camera = ?

    A lens with a 150mm image circle at 645 ratio will have 90*120mm coverage.

    Since you're using a 645 body (41.5*56mm sensor) that gives you 24mm shift in each vertical direction, and 32mm shift in each horizontal direction.

    Assuming you do a 2*2 image stitch (with 30% overlap), you will expose a total area of 70*95mm, still well within the 90*120mm image circle of your lens.

    The effective field of view of any exposure depends on the focal length, and sensor size.

    While on 4X5" a 135mm lens will look like a 35mm lens on FX (or a 55mm lens on 645), the 2*2 stitch (70*95mm) will make the 135mm lens look like a 50mm lens on FX (or 80mm on 645).

    Hope this helps!

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