Archived posting to the Leica Users Group, 1998/01/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]To answer the several questions about perspective distortion: according to the books, it is an effect that is dependent on focal length and camera position only. However, try this practical test: cut out a circle of paper about the size of a basketball. From ten feet away, put it in the corner of the frame with a non-retrofocus lens like the Leica 35mm Summicron-M. Then do the same thing with a good retrofocus lens such as the Canon EF 35mm f/2. Compare the images. What you will see is that both lenses will distort the circle into an oblong, ovoid shape, but the Leica lens (in this example) will distort the circle slightly more. I can't explain this, and "perspective distortion" may well be the wrong term to apply to this exact effect. I had a long discussion-cum-argument with Arthur Kramer about this, and I ended up calling the effect "apparent perspective distortion." Whatever it should be termed, it is generally worse in the case of non-retrofocus wide-angle designs. Hope this clarifies. By the way, I'm sorry if my replies go to the Digest and don't have the proper subject header; my offline reader gives me no easy way to change the subject header of replies. At least, I haven't discovered how to do it yet. --Mike