> I've bought the famous Pentax Zoom A 70/210 4 but i'm a little bit > disapointed because there are > pincushion distortions. > When I take a picture, for exemple, of a painting, the borders are deformed. > > Is it normal ? For me it's important because I do a lot of architectural > photos.
As I understand it it is quite normal and perhaps unavoidable for zooms to have pincusion or barrel distortion in some portion of their focal length ranges--all the big expensive Nikon and Canon stuff has it. Since I don't shoot anything that requires distortion-free performance I don't notice it. Note that many PRIMES have some barrel or pincusion distortion too, even 50s. You might see if there is one focal length, probably near the middle of the range, in which the zoom shows no distortion or less distortion. Most of the Nikon zooms I've read reviews of apparently have a spot somewhere in the middle of the range that is distortion free, but have barrel distortion wider than that and pincushion distortion longer than that. Apparently that is about as good as it gets with zooms. I'm curious what the gigantic 80-210/4.5 SMC-T lens could do! DJE
