The Zuiko OM 40mm F2 pancake lens is one of my favourite lenses of all time. Apart from being nice and small, the performance from this lens is impressive.
Being 40mm, it is great for street photography, as it is wider than a fifty and sits nicely between the 50mm and a 35mm. Having the bonus of going up to F2; not only does this lens have the bonus of having a shallow depth of field, but it also have lovely bokeh.
There are of course fallouts for using vintage lenses at wide apertures, and there is no perfect lens when it comes down to this sort of thing. However, this lens has character at F2, and I love the results you can get at this aperture.
The secret weapon of this is the short focusing distance. I have measured this lens at focusing around 24/25cm. This is fantastic for F2 close-up shallow depth of field shots.
Adapted to my Fujifilm X-T2, which has an APSC size sensor, this lens is about 60mm full frame equivalent. This is still very usable for street, and is great for street portraits. This lens has great micro contrast, and at F5.6 down to F16 the lens is sharp to the corners.
I have the beschoi OM to FX adaptor, which sticks out around an inch and a half from the body. With some of the larger lenses (24mm F2, 28mm F2), they protrude quite far out of the body, but the small 40mm F2 pancake makes the whole set up feel very natural.
Finally, I always have fun shooting this lens. I find it easy to get creative with, and I know I can trust the results. It is one of the more expensive Zuiko OM lenses, but any street photographer would love to have a versatile small quality lens in their collection. Fantastic on film, and beautiful on digital.