It does not have to stay on f1.8, you can change it to other apertures as required you know! The f1.8 gives you the opportunity for narrow depth of field, for example only the nearest eye in focus.

Never was a truer word spoke by mortal man Mike............ I use a 50mm on a 1.6 crop as my 'goto' lens and it is a superb portrait lens and the fact that its the 1.2 means you can also get the narrow DOF and subject isolation in much larger areas.:)

How about f1.4 lenses? I recently acquired the Zuiko 50mm f1.4 for OM-system, reported to be an excellent lens. Do they give an unusably small DoF when wide open?

Unusable? Depends what effect you are after! Run a series of test shots with the camera on a tripod so you know what to expect at different apertures. Don't forget that changing camera/subject distance has quite a marked effect at close quarters.

Take a look at
http://www.dofmaster.com/dofjs.html
a 50mm lens on 35mm film at f/1.4 and a subject distance of 4ft (not an unreasonable assumption for a portrait shot), gives a DoF between 3.92ft. and 4.08ft. As Mike says, it depends what effect you're after. Just bear in mind it gets very very shallow at these apertures and distances which consequently may not give the results you were after.

Thanks for the info, I'll have a play around. I guess f1.4 is a last resort, it's far more common for me to shoot between 2.8 and 11.

I recommend a Canon FL 55mm f1.2.;)

Or for a longer FL portrait lens the Canon FD 85mm f1.2 L....Even wide open its sharp with virtually no CA or abberations...Near perfect IMO. In fact I'd go as far as to say its that good at f1.2 as my Carl Zeiss 85mm f1.4 Distagon T* is at f2 or even f2.8!;)