The OM Zuiko Auto-W 24mm Olympus is the most compact wide-angle lens that you can buy for a good price. It is only 180 grams and has a length of only 31 mm. The filter thread is 49 mm. By the way: the minimum focus distance is only 25 centimeters.
I received an excellent copy of this lens from the company "OM Laboratory" of the best German OM -specialists Frederick Gordon in Frankfurt / Main.
Although it is so small it is still one of the best performers among the old manual wide angle lenses. Even at full aperture, it is very sharp and reaches its best image quality when it stops down to f/5.6. The bokeh is fantastic and it has an undetectable edge drop. Distortion is virtually non-existent.
Compared with the also very good Tokina 24mm no difference in sharpness and image quality can be observed. The Olympus Zuiko-W has the great advantage that the lenses used are specially sealed. This lens is not so much sensitive against light.
The following two pictures show the same subject photographed each other with the lens. There are no significant differences observed. The first picture was taken with the OM 24mm f/2.8, the second with the Tokina 24mm f/2.8.
I can fully recommend the OM 24mm f/2.8. It is particularly suitable for adaptation to the Sony NEX cameras and other system cameras.
Here are a couple of sample photos from the last few days: