Sometimes prospective buyers can become seriously confused with all the new lenses replacing older lenses. It doesn't make it any easier that sometimes the only apparent difference (apart from a face-lift) is the change in nomenclature. The Sigma 30mm f/1.4 is such a case. The first lens was officially called the Sigma 30mm f/1.4 EX DC HSM, while the new one is the Sigma 30mm f/1.4 DC HSM A1. So, does it mean anything the new one is no longer an "EX" lens? What's that A1 there? To cut to the chase, is this a better lens, should you opt for the older instead? I'll try to address all of these concerns today. First of all, let's clarify that both of these lenses are meant for cropped sensors (DX).
The old (left) and the new (right) Sigma 30mm f/1.4:
To better identify to which lens I'm referring to below, I will use green font to refer only (or mostly) to the old lens and red to refer only (or mostly) to the new one.
+ small, light, very fast "normal" DX lens. Reasonably priced.
+ Very good center performance. Better corner performance (does it really matter?)
+ Decent autofocus speed and accuracy. Compatible with Sigma USB Dock.
- So-so corner performance, stopping down doesn't help much (again, who cares for corner performance @ f/1.4?)
- Distortion characteristics could have been better.
- Quite a bit of CA, and it affects daylight bokeh somewhat.
|In casual low-light photography, when you can't be bothered with flashes and/or tripods, any difference in corner performance becomes negligible. Does it matter which lens was used for this one? I don't think so.|
- a general-purpose low-light lens.
- a travel lens? You lose focal length flexibility, but you gain the ability to shoot without flash even in very low light
- corner-to-corner consistency makes this a better (stopped-down) landscape lens.
- portraiture. Too short, distorts, wasn't crazy about the bokeh.
- very tight spaces. 30mm in DX is not as wide as you would think.
- Beginners be warned: f/1.4 requires discipline. Make sure you understand the limitations in depth of field.
The Sigma 30mm f/1.4 lens is a very good choice for the Nikon DX shooter who is looking for a well-balanced all-around solution. Notice I didn't make a separation between the old and the new version yet - both of them are great walk-around lenses. The basic difference is the corner performance. If that's important to you, the new one is the lens to pick. Keep in mind, however, that the difference isn't always visible and you're gonna hit other limitations - the camera's and, more importantly, your own - before you see lens limitations. If, on the other hand, you care more about the center, then the new one has nothing... new to offer there. It's not any better than the old one. One other major difference is the price. At $499 the new Sigma is not exactly cheap. Compare it with the excellent Nikkor 35mm f/1.8 DX which costs less than half the price; is an extra 2/3 of a stop worth it? For some maybe, for most probably not. Ultimately, you can't go wrong with either of these Sigmas (or, since I mentioned it, with the Nikkor 35mm f/1.8). Just keep in mind that real-life photography is a very different thing than examining diagrams. With real photos that you plan to share with your friends online or print and hang on your wall, corner performance @ f/1.4 becomes a very unimportant thing.