100m 2.8 v 85mm 1.8
Be keen on your thoughts. I've had my 85 1.8 for almost two years, and love the shallow DOF, even on my APS-C 60D. However I've not been entirely happy with it. Yes it is sharp wide open, as the reviews say, but my problems are threefold:
the amount of CA (purple fringing) at 1.8 is quite horrendous in high contrast areas
In low contrast areas (e.g. focusing in shade in in evening), it has a propensity to front focus. This is not a camera/lens calibration issue.
The closest focusing distance, 0.85m, is prohibitive when photographing children & toddlers
So, for these reasons, I'm considering the EF100 2.8 USM macro. Of course the I'll miss that shallow DOF, though I believe 2.8 will be ok for my portrait intentions. And, 160mm as opposed to 136mm probably wont make a big difference.
Any other considerations here to be aware of? How do you find this macro for portraits, CA and accuracy of focusing?
p.s. I can't justify the L series primes at this stage, and the EF-S 60mm has too close a working distance for the macro photography I intend to get more involved in.