Sebastian, It is true that pinholes do not distort perspective in themselves; the pinhole's image is dependent upon the relationship of the point (pinhole) to the plane of projection (film).
The distortion you are seeing, assuming that the pinhole is placed on the perpendicular to a (flat, not curved) film, is due to the fact that you are not viewing the image from a point corresponding exactly to the position of the pinhole when the image was made. In fact, you will probably be unable to view it that way, because unless you are using a very large camera, your eye would have to be very close (impractically close) to the image. Also, since our eyes don't see that way, you would not be able to see it all at once, so in order to see one side and then the other, you would have to change the location of the eye. If you could place your eye in that close position, it would be a lot farther from the eye to the edges of the image than to the middle, and those areas at the edges that seem enlarged when viewing from normal viewing distance, would then appear normal. I hope this is not too confusing. This applies to images made with wide angle lenses as well. The effect can be quite disconcerting, but it is not distortion. The oft-mentioned linear distortion of lenses is, for practical purposes, not really worth the mention anyway, because it is not generally visible with well-corrected contemporary optics. It is one of those things that is true mostly in theory but of very little practical importance. Larry Bullis In some books you can read that the pinhole makes no linear distortion as a normal lens does ? But the pictures of my super-wide angle pinhole camera (141°) are on the edges very distorted ! (e.g. clouds , "zoom-effekt" ) What does linear mean ? ---------- Get your own FREE, personal Netscape Webmail account today at http://home.netscape.com/webmail/
