PHOTOOG Photography writings by Olivier Giroux

25Aug/080

Comments on the Dpreview review of Sigma Fifty

It's been about two months since we first heard about Sigma's 50mm f/1.4 lens. I wrote a piece following the announcement here, and compared MTF further here.

Now that Dpreview and Photozone have both had a chance to take a look, here’s a mix of results from “Sigma Fifty” and its Canon/Nikon competition. These are the FX results from Dpreview. I’ll briefly mention DX (incl. Photozone's) results below.


Sigma, Canon and Nikon at f/1.4.

Wide open the Sigma Fifty pretty clearly dominates. This is what it was designed to do and why it’s such a big bucket of a lens. The poor performance in the corners is almost certainly due to a 2-stop (!!) light fall-off (colloquial vignette). Don’t be too bullish about the Canon or Nikon either, they have 2.7 stops of fall-offs.

The Nikon lags throughout the test but here at f/1.4 the gap is just staggering, especially when you consider that the Sigma/Canon are paired to a 21MP 1Ds-III and the Nikon is on a 12MP D3.


Sigma, Canon and Nikon at f/2.

Both the Canon and Nikon improve tremendously around f/1.8 but the Sigma continues to rule the pack through f/2~f/2.8. The Sigma’s center resolution here is just enough to quench the DX format over most of that frame. Light fall-off is now ~1 stop for the Sigma and ~1.5 stops for the Canon/Nikon.


Sigma, Canon and Nikon at f/5.6.

Stopped down all three are solid performers, but the Sigma is at its limits on the 1Ds Mk-III. Somewhere around f/4 the Canon comes out way ahead. It looks like the Canon 50mm f/1.4 has resolution to spare up to ~30MP beyond this aperture. The Nikon has just a bit more resolution still in it, but recall that it’s sitting on a 12MP sensor only here (but colors are normalized so it’s still apples-to-apples there). Light fall-off is nothing to worry about from f/4 onwards for any of them.

What’s the DX performance like?

It’s a mixed bag. Used stopped-down the Sigma Fifty is just good enough to quench DX sensors, and at any aperture has even behavior across the whole frame without any light fall-off. Wide-open it’s not quite as sharp as the Sigma-30 however.

Comparing the results of the Sigma .vs. the Zeiss in the Photozone tests (note: crossing shooting platforms hurts comparison) I believe they are roughly equivalent for most purposes. I would select the Sigma for center-axis sharpness at f/1.4 but probably pick the Zeiss for anything else.

A word about the Bokeh

Back a few months when this lens was announced I was a bit worried about the bokeh, because it's typically not Sigma's strong suit. You’ll want to check out this small collection of images then: http://www.motleypixel.com/reviews/index.htm Certainly that’s not bad. Based on these and other images (on Flickr) I conclude that the bokeh is marginal at f/1.4 but improves suddenly at f/2. From f/2 onwards the bokeh is soft and “relaxed”, I can’t find anything bad to say about it.


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