Sigma has released a pair of prime lenses for micro four/thirds cameras, such as the Olympus PENs. I've been testing the 30mm F2.8 EX DN($199 US) because it fits nicely between my Olympus 17mm f/2.8($219) and the longer 45mm f/1.8 telephoto($399).
The first thing I noticed with the Sigma 30mm is that it's larger than the two Olympus primes. On the E-PL2 body (shown above), it looks great. On the PEN Mini, the Sigma looks a little oversized. Despite its greater diameter, it's still very light (135g / 4.8oz). The metal lens mount is nicely finished. But the lens mechanism inside does move around when not in use. Once you turn the camera on, it engages, eliminating movement until you actually focus. I'm guessing that this is a byproduct of Sigma's new linear focusing system.
On the camera, autofocusing is fast and smooth. You can manually focus on the fly using the large knurled ring at the front of the lens. Focusing action is nicely dampened.
Threads on the front of the lens accept 46mm filters and accessories. A lens hood is not included, but you do get a nice zippered case.
Since the 30mm behaves like a 60mm mild telephoto with the micro four/thirds sensor (crop factor of 2X), you can soften the background when shooting wide open. Overall sharpness of the lens is good. It has decent close-up ability allowing for 1:8.1 magnification at 11.8"
The Sigma 30mm F2.8 EX DNis an affordable prime lens for micro four/thirds users, especially useful for Olympus PENs because it doesn't have image stabilization built into the lens. It performs best when the camera's firmware is up to date. For example, when I mounted it on my E-PL2 with firmware 1.0, the lens became hyperactive constantly adjusting the aperture with changing lighting conditions, even when locked down in Aperture Priority mode. I would upgrade your camera firmware if you plan on using this lens.
On start up, I also noticed that there's a 1-2 second delay before the lens was ready to shoot. It feels like the lens and camera are establishing communication during this delay. Once everything is ready however, the lens focuses quickly, quietly, and accurately.
I do like having the faster f/2.8 aperture at the 30mm focal length. On the 14-42mm, f/3.5-5.6 Olympus zoom that comes with the PEN cameras, the aperture is f/5.0 at 30mm. So this prime delivers a stop and a half more light at the same focal length.
The lens should also look good on the black version on the new Olympus OM-D E-M5 bodythat is due to be released later this month.
Overall, I rate the Sigma 30mm a notch below Olympus prime lenses. But if you want a mild telephoto with a reasonably fast aperture for an affordable price, you'll probably like shooting with this glass. I'm going to keep mine.
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