I've been lacking a real wide-angle for some time both for my cameras in general and m4/3 in particular. These have always proved difficult and I have had real problems in finding one that I like. In particular they tend to suffer from CA, fringing, distortion and soft corners. My latest try at this elusive lens is the Olympus M.ZUIKO DIGITAL ED 9-18mm 1:4.0-5.6 for my m4/3 cameras, and while not perfect is the best so far.
THE GOOD NEWS
Its very small and light.
It takes filters, which means that it doesn't have a huge front element exposed.
Its a very sharp lens. Even wide open and in the corners.
Colour rendition is excellent.
Its very easy to use and adjust.
Though small and plastic it feels very well made.
Its cheaper than the Panasonic 7-14 alternative.
It works equally well on both my Panasonic GH1 and Olympus E-P2
THE NOT SO GOOD NEWS
Even though its one of the best I've used it still suffers from a fair amount of CA and fringing.
There's a noticeable amount of distortion.
Not very pleasant bokeh.
£500 is not cheap.
As can be seen from the sample pictures I tend to use wide angles like this in a certain way. Focusing on a strong foreground subject and using the wide angle to establish a context and location for the subject. A wide close up lens if you like.
Though I've only had the lens for a day, I do like it. As I said, overall its the best I've used.
Previous tries have included:-
Sigma 12-24mm - On full frame and APS-C. Excellent for CA, fringing and distortion but pretty soft overall, particularly in the corners. Big bulky and heavy. Exposed lens element.
Canon 10-22mm - On APS-C. Very bad CA and fringing. Very soft corners, wide open its almost unusable.
Voigtlander 15mm on full frame Leica. Vignetting in corners and a magenta colour shift. Not the sharpest.
Zeiss 18mm - On full frame. Very expensive and surprising considering its pedigree, it was slightly soft.
Panasonic 7-14mm for m4/3. Very sharp but lots of CA and fringing. Also felt very fragile with exposed lens element.
All of these have eventually found their way to ebay.
I was considering going for the Panasonic 7-14mm again, but after looking at pictures that I had taken with my previous copy was concerned about paying close to £1000 for a lens that gave me concerns with its fringing in particular. I was also always very wary about carrying it around. It did feel very "flimsy" which was great from a size/weight perspective but always worried me in terms of possibly damaging the front element. That element also got pretty dusty as it wasn't possible to use any kind of protection filter on it.
The Olympus 9-18mm is great for size and weight and the ability to use a simple 52mm filter on the front of it is reassuring. I decided to try it after finding some raw samples on the internet, which I thought were very sharp. My copy confirms this. I think its just as sharp as the Panasonic, maybe even slightly sharper. It lacks the extra 2mm of the Lumix but thats not a problem for me. 9mm on m4/3 is wide enough for me. Both lenses focus to 0.25m which is good. The Panasonic is F4 throughout, whereas the Olympus has a bigger zoom range and ends up at f/5.6. However I really do see this a 9mm lens with some extra focal lengths added on rather than as a zoom lens.
So even though its early days I'm pretty positive about the lens. As discussed above I am pretty demanding of super wide angles. My expectation that they should perform as well as other focal lengths has always led to disappointment. In terms of clarity and across the frame consistency this Olympus has proved a pleasant surprise. I suspect that this one might be staying around a bit longer than the others.