I already tested the Sigma 30mm f1.4 EX HSM two years ago on a Canon EOS 40D. And precisely because a successor will soon be available for all (?) mounts and because the choice of products drastically changed, I would like to share my thoughts on the lens with you. It still is a highly interesting piece of glass, currently sold at an unbeatable price.
As I demonstrated with my comparison with the DP2 Merrill a short while ago, there definitely are sharper standard focal lengths under the sun (more on the DP2m can be found here and here). Sigma’s new 35mm f1.4 Art and 30mm f1.4 Art seem to be sharper, too, judging by the sample images. Depending on whether one puts the focus on technically perfect picture quality, or on unique look and image character, the image performance of the 30mm f1.4 EX will be deemed a bug or a feature. Sharpness in the middle of the image is good from widest aperture onwards, even though slightly weaker on the SD1 than on cameras with bayer sensors, due to its foveon sensor. The 30 EX is no canny mathematician, but rather a playful painter. And this can be observed very well when considering the edge resolution and bokeh.
Let’s take the following picture as an example: hard afternoon light in direct sun, with a busy background and widest aperture (f/1.4). A horror scenario par excellence for any fast standard focal length. The EX, which is rumoured to be lacking sharpness when it comes to widest aperture (especially on the edges) amongst perfectionists, smoothly passes the test in my opinion .
I am certain that the 30mm of the DP2m as well as the two new Sigmas, the 35 and 30 f1.4 Art, could capture the cat much sharper, but whether the photo (especially the bokeh) would be more harmonious and beautiful as a result I am not so sure about. That is precisely what I mean by “playful painter”. Sharper lenses tend to transfer this sharpness onto the bokeh, which then might be perceived as harsh.
At the time I purchased the Sigma 30mm f1.4 EX HSM for the 40D and then again for the SD1, there was no other standard focal length available within this price range with comparable aperture. Currently, one can choose from various f1.4 30s/35s, irrespective of the mount. Really one is spoilt for choice. So which one to choose? If the price is immaterial, one can choose between Canon/Nikon/Sony and Sigma’s 35mm f1.4 (Pentax does not offer any comparable lens, which makes Sigma the only eligible choice), but the choice should be an easy one considering the price difference to 1st-party-lenses and the much praised picture quality of the Sigma. Among the smaller, lighter and cheaper APS-C optics, one the other hand, one can choose from 1st party manufacturers, which are, however, perceptibly slower with f1.8, and the “old” and “new” 30mm f1.4 by Sigma. The new one promises better image performance across the whole frame, a new finish and the compatibility with Sigma’s USB-dock, which allows for fine tuning the auto focus and other aspects of the lens. The older one is cheaper by half (500€ vs. 250€), less beautiful (although that’s a matter of taste), but still very well built and possesses a unique image character (which can be seen as a positive or a negative thing). So, which one to purchase? It’s not for me to decide, the choice is yours, dear reader .