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Thread: Perspective Difference - Fullframe+80mm vs 1.6+50mm

  1. #1

    Default Perspective Difference - Fullframe+80mm vs 1.6+50mm

    For this query im having quite abit of trouble phrasing what im trying to get at so please bear with me. I was taking a look at whether upgrading to FF was practical for my own personal usage but i stumbled across this dilemma. What id like to know is that does the fovcf have any effect on the perspective of an image thats taken, taking into consideration to use different focal lengths to counter the effect of 1.6fovcf.

    Eg, 5dmkII+80mm and a 7D+50mm (assuming the physical discrepancies of the lenses are close to identical. Barrel distortion/Pincushioning etc), i presume that distance required to frame a subject identically in each case will equate to the same distance that the camera would have to be away from the subject. Eg ~5m to frame a face only portrait of a person. Correct me if im wrong.

    The other thing is the difference in the final picture for either setup considering the main subject has been framed nearly identically in both cases. Assuming the same resolution is used, and the point of focus is the same, are the angle of lines in the picture any different? Or is there any inclusion/exclusion of elements in the picture? (eg. stray tree branches in the background barely getting into the frame). This is assuming that both lenses exhibit similar physical discrepancies in the lens designs such as barrel distortion/pincushion. (Unlikely but just too simplify things)

    I know this question might have been rearing its head time and time again. But even after googleing i still could not come up with any substantial assumptions to put this curiosity to rest. I would love to try out an experiment with both cams but alas i have not the funds to own that much equipment.
    Last edited by Nashaz; 2nd November 2010 at 01:11 AM.

  2. #2

    Default Re: Perspective Difference - Fullframe+80mm vs 1.6+50mm
    This should help you

    Do note Nikon is 1.5x instead of 1.6x

  3. #3

    Default Re: Perspective Difference - Fullframe+80mm vs 1.6+50mm

    Much appreciated!

  4. #4

    Default Re: Perspective Difference - Fullframe+80mm vs 1.6+50mm

    In your example (FF with 80mm lens and 1.6x crop sensor cam with 50mm lens), yes, the fields of view would be the same (barring discrepancies in actual focal length, sensor size etc). You'd get the same framing at the same camera-subject distance.

    Shot from the same position, the perspective would be the same too. Perspective (the relative sizes of objects and different distances, and the converging lines effect) is only dependent on camera position. Focal length, sensor size, etc are irrelevant.

    Some examples:

    the pix of the old man aren't that useful, but the building pix later on demonstrate the point.
    Now, this demo is with diff focal length lenses on the same camera, but the writer is cropping the wide angle images to get the same FOV as the longer lenses, which is essentially what happens with a crop-sensor camera anyway. HTH

  5. #5
    Senior Member ZerocoolAstra's Avatar
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    Mar 2008
    rainy Singapore

    Default Re: Perspective Difference - Fullframe+80mm vs 1.6+50mm

    agree with Edwin Francis. If both shots (from FF and crop) are taken with the exact same camera-subject distance, then there should be no difference in the perspective.

    So a 50mm lens on a 1.6x crop body should theoretically give you the same FOV (and perspective) as an 80mm lens on a FF body if both shot from exactly the same position.
    But like you, I lack the apparatus to test it out for myself
    Exploring! :)

  6. #6

    Default Re: Perspective Difference - Fullframe+80mm vs 1.6+50mm

    Thanks for the clarification guys!


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