In article
>Without getting too technical, could someone explain in layman's terms >why fixed normal lenses (35mm, 2 1/4, etc.) are always being touted as >being extremely sharp and highly corrected?
>Is it really easier for a manufacturer to produce a high quality optic >in the normal and/or short telephoto range, than say a moderate to long
>telephoto or a wide angle?
Yes to the second question. You can see why, if you look at the problem:
When you build good long lenses, you are trying to deliver to the film about the same lines-per-millimeter of information as the normal lens, but you are using much less (due to the narrower angle) of the subject
as source material, so the resolution of that (reduced) subject material
must be higher in order to transmit to the film the desired amount of image information. In other words, for a given image size and quality,
the longer lens must be sharper than the shorter within the angle of
view that is to be used for making the image. If that is still confusing, try it a different way: We have two lenses. one is a 50mm that will just resolve 20 fence posts across a 35mm frame. The other is
a 150mm lens that will just resolve the same 20 fence posts across a
4x5 frame at the same distance (each is a normal lens for its format). You grab the 150mm and stick it on the 35mm camera as a long lens, but discover that, while you now have a narrower look at the fence (with about 6 fence posts showing), you are at the limit of resolution for the long lens at 6 posts instead of the 20 for the normal lens.
Not too good. This does not cause the wide-angle to be super sharp, because it is hard to spread a uniformly high quality rendering of a subject over a wide image angle. Images through lenses tend to be worse near the edges of the lens than in the center, and when you require
(in order to cover a wide angle of view) that the lens edges be much
wider than normal, the problems in designing good, even lenses multiply.
Hope this helps, and does not contain too many errors made by the
non-technician author.