OK you made me go out and do a quick test.
These are jpegs direct from the camera @ f2.8, on a tripod that I did not move between shots.
Hope it helps. Sorry I do not have a 15 (yet
)!
FA35
DA40
A50 1.7
For me there appears to be a greater difference between the field of view between 50 and 40 than between the 35 and 40.
I guess it makes sense since one is 10mm vs 5mm, (duh)
IQ wise the 35 and 40 are pretty close for me as well.
If the 40 wasn't such a pretty little thing I probably would have sold it by now, but I just can't bear to part with it since the size is so convenient.