Tamron 28-75mm f2.8 DI v Sigma 24-70mm f2.8 EX v Contax Zeiss 35mm f2.8
[published 2004]

The motivation for this test was to establish whether a zoom could replace the 35mm Distagon f2.8 I commonly use for architectural shoots. Trolling about on location, the perfectly convenient lens for shooting exteriors would be a 35-70mm zoom that doesn’t short change the 1Ds II optically, but unfortunately the world’s best suffers from quite strong barrel distortion at the wide end. Otherwise, it is perfect.

I’ve had the Sigma 24-70mm f2.8 DG EX Macro for a while now, and really want to like it, despite its bulk and noisy autofocus. It seems sharp enough in everyday use, and it’s a fraction of the cost of the Canon, but its strong and variable distortion also put it out of the picture for architectural use. Its natural competitor, then, is the Tamron 28-75mm f2.8 DI. Equally fast, much lighter and smaller and currently everyone’s favourite lens.

But can it cut the mustard against the benchmark Distagon, only once outperformed thus far by its zoomier brethren – and only that for a gnat’s hairsworth of resolution? With some trepidation, mindful of legion horror stories about Tamron’s quality control, I opened the Tamron’s box and went to work….

Test frames shot with a 1Ds II at ISO 100, RAW processed through C1 and saved for web with BoxTop Pro JPEG. Modest identical USM applied to each image. 100% crops shown.
Full frame / distortion

Here’s the full frame: familiar target. The Zeiss 35mm f2.8 is exemplary for controlling distortion with a little correctable barrelling, so it’s the one to beat: mouse over each image to compare the rendering of the Tamron and Sigma zooms…

Full marks to the Tamron; Sigma nul points – horrible wavey pincushion distortion. In fact, bearing in mind that a) I’ve not bothered to set up a properly rectilinear test target! and b) the Distagon has a little barrel distortion, the Tamron if anything is more neutral at 35mm than the prime. This could be interesting…
35mm / f4: centre frame
Tamron 28-75mm at 35mm / f4 (100% crop: centre frame)

Contax Zeiss Distagon 35mm / f2.8 (100% crop: centre frame)

Sigma 24-70mm at 35mm / f2.8 (100% crop: centre frame)

Tamron 28-75mm zoom and Zeiss 35mm prime practically neck and neck, and both way ahead of the Sigma still. Let’s see if the gap shrinks when we stop them all down the f11…

35mm / f11: extreme corner

Tamron 28-75mm at 35mm / f11: 100% crop, extreme corner

Contax Zeiss Distagon 35mm / f11: 100% crop, centre frame

Sigma 24-70mm at 35mm / f11: 100% crop, centre frame

At last! A reasonably sharp shot from the Sigma! Yellow, distorted, and still lagging behind the competition, but acceptable. But even stopped down the Zeiss 35mm f2.8 retains a clear advantage over the excellent Tamron. Interestingly, the Distagon hardly gets any sharper between f4 and f11. Like most Zeiss lenses, it peaks at f8. Finally, centre frame crops at f11 – no surprises expected…

35mm / f11: centre frame

Tamron 28-75mm at 35mm / f4: 100% crop – centre frame

Contax Zeiss Distagon 35mm / f2.8: 100% crop – centre frame

Sigma 24-70mm at 35mm / f2.8: 100% crop – centre frame

As you might expect, little to choose between them here, maybe even the Tamron shades it?