len10@ihuxw.UUCP (L. C. Dombrowski) (03/21/84)
I have to add to Ken Reek's comments on wide angle lens dis-
tortion. Barrel distortion (straight lines looking curved
near the edges of pictures) is quite common in wide angle
lenses. From what I understand, the problem is tougher to
compensate for in very wide angle lenses (like 15-24mm non-
fisheye types) and in the new variable focal length lenses
which go down to short focal lengths. But where as lens
sharpness cannot be determined simply by looking through the
lens while mounted on a camera, objectional barrel distor-
tion IS easy to detect simply by focusing on ceiling/wall
corners, placing them in the four edges of the viewfinder,
and looking to see how straight they appear. This was one
test which helped me select my Tamron 17mm wide angle.
Len Dombrowski
AT&T Bell Laboratories
Naperville, Illinois