thanks otc. i have been experimenting with the flash both mounted and using slave flash as secondary for fill-in, with Gary Fong's diffuser. I realised that keeping my Sigma's len wide open at f2.8 is better than pointing the flash (1:1) at the object.
also, is it true that i can get even better pictures using a PRIME len like Pentax SMC 100 F f2.8 Macro?
Lancer, I suppose you are referring to wide open at f2.8 without flash than using flash at varying aperture of your sigma lens, with two flashes.
I do not have sigma 17-70 and pentax f 100 f2.8, so can't really comment. Really one is a zoom and the other is a prime with macro 1:1. Different focal length serves different functions. 17-70 is more of a walk-about lens and can double as portrait lens. SMC 100 f2.8 is a macro lens and I believe is a superb one for macro, that goes 1:1. As a portrait, I believe is tact sharp, even at f2.8. Hey.... must check with Fengwei on this cos he own these two lenses before.
otc