So I was pretty excited about the new Tamron 24-70 lens with vibration compensation. I couldn’t wait to put it up against my Sigma 24-70 HSM and see just how much of an improvement it was. Unfortunately, things did not quite work out the way I hoped. What I found was that the Tamron was indeed a lot sharper at f/2.8 than the Sigma at all focal lengths. It stays sharper until around f/5.6, and after that center sharpness evens out between the two lenses. Unfortunately, I found that my Tamron exhibited poor performance compared to the Sigma towards the edges of the image. The edge performance did not seem particularly bad in close focus test shots. But I started to notice it quite a bit on scenes with distant focus, especially at infinity. In fact in some instances it looked so bad on the Tamron that I’m wondering if I got a bad copy. For now, I am returning this lens. I may try another copy in the future depending on what I see from other people’s reports.
Here are a few samples, shot with a Canon 5D Mark II.
Over the past two days I shot around 200 photos at various apertures and focal lengths, and the results were pretty similar. The Tamron was always way better wide open, and definitely sharper up to f/5.6 in the center, but its edge performance looks worse when both lenses are stopped down.
As far as the other features of the lens…
Does the vibration compensation work? Yeah, it does. But I didn’t really spend a lot of time testing it out, I was more concerned about the sharpness issue and spent most of my time on that.
Regarding geometric distortions, the Tamron in my estimation looks a lot like the Sigma. Moderate moustache-style distortion at the wide end, mild pincushion distortion at the telephoto end, and pretty negligible in the middle focal lengths.
The lenses were fairly close in most other areas as well. Color and contrast were very similar, with perhaps a slight edge in contrast going to the Tamron. Vignetting at f/2.8 is fairly heavy on both lenses at all focal lengths, with the Tamron slightly worse in this regard. (Vignetting I’d say is noticeable but mild at f/4.0 and almost imperceptible at f/5.6). Autofocus performance is pretty good with both lenses, and perhaps a tad snappier with the Tamron.
Ok, I didn’t want to have to go here, but here are brick wall shots. The Tamron was at 36mm and the Sigma was at 34, but close enough. The results were pretty much the same throughout the focal length range.