In my blog piece about the Sigma 50mm f/2 DG DN I Contemporary Lens (Sig50-2), I noted that I had not had a chance to try it out at night. There are several things worth finding out. For instance, are there any ugly aspects to the bokeh at night (flaring, excessive coma etc)? Is f/2 wide enough for my purposes (in other words would the extra light-grasp of, say, an f/1.4 lens be make-or-break)? And so on and so on.

I've been going through some of the pictures I've taken since the evenings drew in over the autumn and winter to address this. I think the pictures speak for themselves. In general terms, what I saw for daylight photography holds up a night. On the Sony A1, the Sig50-2 pictures are sharp with pleasant bokeh and no obvious vices. There is always an argument for the fastest possible lens after dark, but realistically, with modern digital sensors where ISO3200 holds no terrors, f/2 is enough.

Parenthetically, I'll also mention that I also had a chance to (very briefly) shoot the Sig50-2 against the Sony 50mm f/1.2GM and f/1.4GM versions. I'm not going to put any pictures of that up here as it was only to get a first partial impression. One thing to note is that the Sig50-2 has a fractionally narrower field of view than the Sonys, but nothing to worry about. My goodness, all three of these lenses are very sharp all across the frame. With any of these, you can shoot wide open with no reservations. Having grown up in the film era, where you shot wide open accepting that the edges probably weren't going to be great, this is a revolution. At f/2 all of these show exemplary sharpness. At the edges, at f/2, I felt that the f/1.2 lens is fractionally sharper than the Sig50-2, but only looking at the images at 300% on screen. Unsurprisingly, the Sony 50mm f/1.2 GM has the best bokeh at f/2 of all three. The Sony 50mm f/1.4 GM is amazingly sharp too. But to my surprise, I felt that the bokeh on the Sigma lens was just a little softer and more pleasing. That is subjective, of course, and no-one would realistically object to any of the bokeh. These are three amazing lenses.

The Sig50-2 is a much less expensive lens than either of the Sonys (the 1.2 lens is about 3.5 times as expensive and weighs more than twice as much; the 1.4 costs about 2.5 times and weighs one and a half times the Sig50-2). You get what you pay for, but that extra light grasp and background separation come at quite a cost. There are other benefits of having an own brand lens on a high-end Sony camera, but still. For me, the Sig50-2 represents a very good value proposition.

Long story short: the Sig50-2 is an exemplary modern lens.

The pictures below are a few aviation pictures, and a few street photos. The first three are from RAF Northolt (as is the opening picture above); the last four are from the Regent Street and Piccadilly Circus area. One other point while I think of it. At Northolt, I was shooting a lot hand-held: the light from the hangars over the far side of the pan is pretty dim (EV approx 2). So, how as the autofocus in that dim light? Absolutely fine. I’ve just looked again through my pictures, and not one is out of focus. The Sig50-2 does not have any built-in image stabilisation, but on the A1, the camera body IS works well. For instance, the Apache picture below was 1/13 sec. I was shooting down to 1/5 sec that evening with a good rate of sharp pictures. On the street in central London, there is much more light, so it is less of a challenge to the autofocus system, but nevertheless, the A1-Sig50-2 autofocus was extremely reliable.