Here’s a post I wrote a year ago, but never actually completed! The pictures were taken on Sun 28 June 2009.
Less depth of field than I like at f2.8 – I should have stopped down
One or two of the pictures here and from the chariot festival earlier in the day don’t quite have enough depth of field for my taste; having just got a new Sigma f2.8 24-70mm I wanted to see what I could do with it, particularly wide open. The shot above was taken at f2.8, and although the cyclist and the wall are sharp, the buildings on the other side of the river are a little soft. In this case it may help the picture, but generally I think I prefer things sharp. The lens does pretty well wide open, but stopping down to f4 or more does just add a little edge on sharpness and also reduces the vignetting you can see in the images above and below, both or which are uncorrected. Of course it’s a simple job to correct this in Lightroom.
Some noticeable vignetting on FX with the Sigma DX lens
I was also working with a Sigma 55-200mm f4-5.6 DC lens, one of the lightest lenses I own at around 350g, which I’ve had for several years. I’ve never thoroughly tested this on the D200 and D300 I’ve used it on, but certainly the results seem at least one tad sharper than those from the Nikon 18-210mm, perhaps hardly surprising given its much smaller zoom range.
I tried this lens on the D700, but as it is a DC lens, designed for the smaller FX format I expected to have to switch the D700 to FX format. To my surprise it seems to give pretty good results on the large FX format too, especially at the longer end. It has now been replaced by the slightly heavier 50-200mm f/4-5.6 DC which I’ve not tried and may or may not have a similar coverage.
Comment added on June 27 2010
I’ve used various Sigma lenses over the years, and particularly those in the EX range seem generally to be excellent performers and most of them have proved pretty robust. The Sigma 12-24mm EX (now replaced by a similar but improved model) is certainly good on the DX format, and the results are ok on FX, except that the 12mm end does really go too far on full-frame 35mm. The occasions where a rectilinear lens with a focal length of less than 16mm really works are few and far between – not a criticism of the lens but it is just a little too extreme.
It’s also a lens with an exposed very curved front element, impossible to use a filter for protection. Mine lasted for around 3 years before it began to have too many little defects to be really usable – giving vaguely soft areas or excessive flare whenever it was used against the light. The good news is that is wasn’t hugely expensive to have the front element replaced with a new one – I think about a fifth of the cost of a new lens, but the slightly bad news was that it took around a couple of months for the new part to arrive here to be fitted.
I’ve written before about the problems that developed with the Sigma 24-70mm. Eventually I got a replacement lens from Japan and everything seemed ok for a couple of weeks. Then I was taking pictures on a family visit to Richmond Park and the lens jammed again, refusing to zoom past around 30mm. Cursing I packed it up and sent it back to Sigma, getting a phone call a couple of days later asking what the problem was because it seemed to be working perfectly. I think the shaking in the post must have managed to free whatever was jamming it. I told them what it had done and they promised to check it out before sending it back, and I hope the problem is now solved, but although it seems to be working perfectly I’m still keeping my fingers crossed every time I take it out.
One piece of good news is that this is one of the lenses that has a profile that comes with LR3, correcting the distortion (noticeable on some shots at the 24mm end), most of the chromatic aberration (which is pretty typical for a lens of this type) and the vignetting. So there are good reasons to use this lens now.
Would I buy Sigma again? Yes, despite the problems with this one lens. I’ve owned half a dozen or more others that have been good, and either had unique characteristics that appealed to me, or have offered a fairly substantial saving over the Nikon equivalents. And I think all of them have had better lens hoods – I get really fed up with the rather flimsy Nikon lens hoods which seem to fall off at a fairly light touch – they are just not made of a stiff enough plastic.