m43photo has issued a review of the features of the Sigma 30mm f2.8 prime lens for Micro 4/3 cameras.
(Click Here) to read the review on m43photo.blogspot.com
A quick summary of the pluses and minuses are:
- Simple lens design (no extreme wide angle, super fast aperture, small size) allows decent results in inexpensive lens.
- Price - currently $199 on Amazon
- Bokeh at f2.8 (close to subject) looks okay to me. At 60mm equivalent, it could be useful for environmental portraits and the like.
- Autofocus is fast
- Size - not large, but certainly not a pancake lens (see above)
- It rattles when it's not powered up
- Time delay on powering up the camera
- No hood supplied with it (this is true of the Lumix 20mm as well)
The focal length reminds me of the effective focal length of a 50mm normal lens on the Leica M8, which has a crop factor of 1.33, making the 50mm have the field of view of a 65mm lens (this 30mm has the field of view of a 60mm full frame lens). I have never been pleased with a 50mm lens on the M8. So, I don't think this is the focal length for me on Micro 4/3. I prefer a little longer lens for portraits (like the 45mm f2.8 Pana-Leica Macro Elmarit), and a little shorter one for general use (the Pana-Leica Summilux 25mm f1.4 is a super lens, as is the Panasonic Lumix 20mm f1.7). For reference, the Lumix 20mm is about $300 now.
If I were shopping for an inexpensive prime lens, I would give this lens a try. By the way, $199 is not that cheap, when you compare it to say a Nikon AF-D 50mm f1.8, which is faster, offers great image quality, and goes for $135 on Amazon (I've seen it for under $100). Of course, Nikon gets the economy of scale from selling many more units.
As it is, there are better alternatives in the "normal" focal length for Micro 4/3, and 30mm is not really in that range, anyway.
I generally don't pass judgment on lenses I haven't tried, and realize it's not totally fair or well-informed. However, based solely on specifications, let alone what the post above adds to that, I am sure this is not a lens for me.
That said, I'm sure some skillful photographers will make absolutely beautiful images with it.
In fact, you can look at some images in a flickr group dedicated to this lens (seems to include other mounts as well, but all Sigma 30mm f2.8 lenses).
(Click Here) to go to the flickr group page.