My Sigma 70-300 APO DG Macro review from another site:
flare control: 5
tested on digital: Yes
review date: April 8, 2006
Tokina 80-200 ATX Pro f2.8 , Minolta 70-210 f4, Minolta 70-210 f4.5-5.6, Vivitar 70-210 f2.8-4, Ozunon 70-210 f4.5. Tamron 28-300XR, Sigma 28-200D
-1:2 macro @ 200-300mm
-Size & Weight
-DG Coatings & DI
-macro switch takes a bit to get used to
-front element rotates when focusing
Let me start by saying this optic rocks! This is the APO DG with the red ring and cool finish. It looks good, it feels good, and it delivers at all focal ranges. Don't let anyone kid you this lens produces excellent results. I shoot this baby wide-open and at 300mm and it can knock the old beercan for a loop on most days especially when shooting under harsh conditions.
As far as physical features go his thing has a sweet tack finish and a nice manual focusing ring. The zoom feel is smooth and the lens is very light weight. She does telescope to a very long lenth when at full telephoto w/hood attached, but then she is transformed into a nice small package to stow with the included reversable plastic hood when it's time to put her away.
The advantages this lens seems to have over some older glass in this range is the new DG caotings and APO glass seem to be reducing flare, abberations, and other lens distortions pretty well. The AF is not the fastest but it is not slow either. The lens delivers decent enough bokeh and looks pretty sweet at f5.6.
On a 5d/7d body with AS this lengs can deliver some eyepopping results with image quality easily rivaling some old Minolta favorites. The macro function is a tremendous bonus as it does 1:2 right from this lens without adding a diopter.
I could go on and on about this lens but I will just suggest that if you are looking for a 70-xxx zoom lens and you want to spend USD $200.00 or less for a new lens this one may not be able to be beat.
As you can see I have many lenses in this range and while this one may not focus quite as fast as a $600-2000 pro lens, under many conditions the Sigma 70-300 APO DG Macro can deliver comparable image quality. One note I would make is his lens seems to perform much better at the long end than the reported performances of some of it's earlier incarnations.
This lens is a real keeper and is one of my favorites.