Topcon's RE Auto-Topcor 28mm 1:2.8   - introduced quite late in 1971 - is a bit of a mixed bang. The center is very sharp even at f2.8, and the extreme corners are reasonably sharp as well - but in the field resolution is going down drastically, at least wide open (at f2.8). At f4, the problem is still quite visible, and only from 5.6 on (even better at f8) the resolution is reasonably good. Similar to other manufacturers, also Topcon has problems with lateral CAs. They are quite visible and more pronounced than with the older RE Auto-Topcor 4/20mm!

		TOPCON AUTO-TOPCOR RE 28mm 1:2.8                  (7 Linsen / 6 Glieder)