Well as most of you would be aware, I purchased the Sigma 120-400 f4.5-5.6 APO DG OS whilst I was in Canada (about 6 weeks ago now).
Well I guess as there have been a few posts recently enquiring about these I would post up a review.
Lens Construction - 21 Elements in 15 Groups
Angle of View 20.4 - 6.2 degrees
Number of Diaphragm Blades 9 Blades
Minimum Aperture F22
Minimum Focusing Distance 150cm / 59.1 in.
Maximum Magnification 1:4.2
Filter Size Diameter 77mm
Filter Size Bayonet-type Hood
Diameter 92.5mm X Length 203.5mm - 3.6 in. X 8 in.
Weight 1750g - 61.7 oz.
Corresponding AF Mounts
SIGMA, CANON, NIKON, PENTAX (1*, 2*), SONY (1*)
Having had this lens for 6 weeks now and having fairly limited time for use these are my observations, true to my belief.
AF Speed - Can be slow, particularly if you are changing large distance between objects, this can however be overcome by giving the focus ring a tweak as you are zooming. The HSM focus motor allows for full time Manual Focus even when set to AF.
However once focus in the "zone" it is quick to make minor adjustments.
[b]Stabiliser[/] - Seems to take a moment to kick in initially, but I would think that it does give the rated / touted 3 stops or maybe a bit better.
Build Quality / Finnish - This lens is finnished with Sigmas new matt black finnish, with an almost velvet feel to it. I haven't managed to scratch it yet and it does seem / feel to be quite rugged.
The build feels rock solid to me. The OS and focus switches slide freely and yet are quite firm and decisive. The zoom ring although a little stiff when first out of the box has freed up little now and is quite comfortable to use. The zoom and focus rings are are both easy to use yet firm in their operation giving that feeling of quality.
100% crop, minor sharpen, minor levels, no other processing
If I can get it right, I think this lens will certainly get it right.
Value For Money - This is very subjective, would I, myself get a better picture from an "L" series lens. I doubt it at the moment. At half the price of the 100-400 L am I happy with the quality versus price, Extremely.
For the budget conscious shooter who wants that bit extra length with stabilization you would have to look seriously at this lens.
I hope this helps someone who may have been thinking about this lens