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Thread: Yet another DSLR magnification question.

  1. #1

    Default Yet another DSLR magnification question.

    yes yes...... this has been talked about. But still, I need some help for a better understanding of this relatively simple, yet often confused subject. For the following example/question, a DSLR with a 1.5x magnification is used.

    Am I right to say that....

    1) when i use a 50mm lense on a DSLR, the amount of BOKEH would be equivalent to that of a 50mm lense in 35mm form, even though the image has the angle of view of a 75mm equivalent now ? i.e. for an equivalent focal length for a DSLR, bokeh would be less?

    2) there is a distortion in depth when u use different focal lengths i.e. wide angle lense exaggerates depth, and telephoto lenses seem to compress images. So if you use a 100mm (35mm form) lense on a DSLR (so u get equiv. of 150mm), you get a 150mm image with the compression of depth of a 100mm lense ? And when u use a 17mm lense on a DSLR (u get 25.5mm), you get the exaggeration of depth of a 17mm lense even though you get an image of a 35mm camera fitted with a 25.5mm lense.

    Please comment. Cheers.
    Last edited by marcwang; 28th July 2003 at 07:57 PM.

  2. #2
    Senior Member
    Join Date
    Jan 2002


    For the first question, do you mean a 50mm lens on both bodies, or a 50mm on one and a 75mm on the other?

    For the second question, the physical characteristics of perspective are those of the original physical lens. Note however that you are also extracting detail from the middle 1.5x of the frame where perspective is less pronounced.

  3. #3


    same lenses on the camera .. i.e 50mm on both cameras.

  4. #4


    sorry, yet another magnification question to add.

    3) for marco lens, does the magnification increase the size of the object on sensor(film)? etc, will a 50mm macro that produces 1/2 size will be 5/8 size on a 1.6 magnification, 100mm that produces life size will be 1.6 times larger then rite?

  5. #5


    For DSLRs, perhaps the term magnification factor is misleading, although most of the data seems to suggest this. A more accurate term to use would have to be crop factor.

    So with a 17mm lens, the camera still takes the photo with a 17mm lens perspective, but because the CCD/CMOS is not as big as the 35mm film, the image gets cropped, giving the the same size at 17mm * 1.6 (for canon) = 27mm perspective, but it is in reality, still a 17mm shot, and has the characteristics of a 17mm shot.

    This URL provide more details to this issue.



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