I've been looking at OM Zuiko 100/2.8 and the 135/2.8 and 135/3.5 for a cheap light prime option for my 5d. I already have an OM 50/1.4 and like it a lot.
Is the 100 a much better performer than the 135's? It seems to go for a much higher price (relatively speaking, of course - they're all cheap alternatives to standard AF lenses), which seems strange to me, unless it's just in higher demand because it's better than either of the 135s.
I currently have both of the 135's and should be getting the 100 next week. I'll perform some non-scienticfic tests to see which one I should keep and post it here.
So far, both the 135's are pretty sharp although the 2.8 has a more contrasty color rendition.
the 100/2.8 is just more popular. Both 2.8s are good, perhaps the 100 slightly better than the 135 but that's a fairly minor difference I'd think. Get them both! They are cheap enough...
I have 100/2.8 and 135/3.5.
I much prefer the 100mm because of size and slightly better IQ.
100mm goes for $100-$150, pretty cheap for what it is/does.