Sigma 24-70mm F2.8 EX DG Macro A-mount lens review by chych
|chych#2608 date: Aug-6-2007|
flare control: 4
|ownership:||I own this lens|
|compared to:||KM 24-85/3.5-4.5|
Tamron 90mm macro
|price paid:||360 (new)|
+Non-rotating focus ring
-Two-step MF mode
-Small hood for APS-C
-24mm a little long
-Slight misalignment at 70mm
|comment:||I had been previously using a KM24-85mm with great results, however I wanted just a little bit more speed in my zoom lens for indoor photography, with and without flash. The 50/1.7 is of course, good for this, but I wanted the convenience of a zoom. I also like the 50-85mm range for portraits, so I did not bother with the Tamron 17-50/2.8 or Sigma 18-50/2.8 lenses, but I do want some wide angle (not a 28-70 zoom). Hence I got the Sigma. Suffice to say, I'm very happy with this lens.|
Image quality is generally excellent. Sharpness is excellent from 24-50mm wide open. There appears to be a slight centering defect/back focus at 70mm, and is slightly soft at f2.8 with some LoCAs (manual focusing removes the LoCAs but it's softer) - this goes away at f4. At 50mm/f2.8, this lens is better than the KM 50/1.7 at f2.8; less CA and is sharper. There is slight CA in this lens, mostly wide open, but nothing a bit of post-processing can't fix. Colors are excellent, though Bokeh can be a little incoherent (not as good as the Tamron 90 macro). It is better in every regard than the KM 24-85mm.
The build is quite good and the lens is sturdy, with a mix of metal and plastic. The lens exterior has a soft felt-like touch, which I've come to like. The lens is huge and blocks the pop-up flash (though I rather like the size of the lens, feels good in the hands). The lens also blocks the A700's red lamp if the hood is on. The zoom ring is a little stiff initially, but gets better over time; I'd prefer the zoom and focus ring to be switched though. The hood is small for APS-C, and there is occasionally some flare issues. The 82mm filter is annoying, but I plan on using a 77mm polarizer on it with a step-down ring; should work with APS-C.
The lens does have a some barrel distortion. I measured about -2.5% at 24mm, and 1.5% at 70mm. Also, 24mm is a little longer on this lens than it is on the 24-85. I measured the magnification of the lens as 1:3.4, better than what is stated (80mm object on a 23.6mm sensor is 1:3.4).