Did you look at the negatives as well as the prints? Better yet use a
fine grained slide film like Velvia or Kodachrome 64. A print is a
second generation image subject to degradation from the lens in the
printer and the grain in the paper. Did you look for other optical
qualities besides sharpness? I wouldn't be surprised if the zoom at
35 mm exhibited some pincushion or barrel distortion for instance.
Were the images sharp to the very corners? That a 50 mm prime and a
"normal" zoom at 50 mm are pretty close is not surprising since the
zoom ought to be about at its best in the middle of its range. You
say you did the tests at f/8. Any lens is going to render close to
its best performance at such an aperture. Test them again wide open--
I'll bet you start to see some differences then. After all, the only
reason to have lenses in the f/2.0 f/1.8 range is so that you can
rely on them wide open when you need it. I'll bet you see some corner
degradation on the zoom at f/4.0.
I use a "normal" zoom for bright daytime work, but out comes my F/2.0
35mm for street photography in the late afternoon or in the shadows.
Also if straight lines toward the edges of the frame are of
importance to you (as they might be in photographing buildings) the
35 mm prime may do a better job than the zoom. So the primes probably
have their uses after all and you don't have to feel silly for having
bought them even if, under the best of circumstances, the zoom does
just about as well.
Tony Galt
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