Lens confusion (again)

My wife would like a new portrait lens with quickshift. She says she is happy with what she sees through the viewfinder of her K5 with her 50mm Pentax-A she just wants to have auto focus and WR. Now after reading recent posts about focal length I'm confused

So my question is this, what lens should I buy her considering

* She likes the K5 & Pentax-A 50mm distance from subject / fov
* She wants quickshift
* She wants WR
* I would like it to be FF compatible if it can but this isn't too important!

Thanks for the advice!

PS: I need to buy her a lens before my new Pentax DA* 300mm gets here (or before she finds out anyway lol)!

The only one really is the DA* 55mm f1.4

Agree with Mike, it's perfect for the job, and the same as the traditional portrait lens used on film. That is, 55mm on APS-C is almost exactly an 85mm-equivalent.

Thanks guys

I think that there is one for sale in the Clasifieds.