Originally posted by Ben-G I've only two: 77&31 lmtd
(...and i'm in doubt between an old fa 50/1.4 and a 43 lmtd)
As someone who has owned the FA50 and now has a 43 I would suggest the 43. The 50 is nice, but really very soft till around f2, so the 1.4, 1.6 and 1.8 apertures are really not that great compared to say using the FA43@1.9.
Consider the following shot (taken with the FA43 wide open at 1.9);
Things worth mentioning about this shot. It's sharp enough at 1.9 to pass off as being acceptable. Because it is being shot wide open the bokeh is round and not hexagonal like you would get if you shot the 50 at f2 (which you might need to stop down to to get acceptable sharpness on par).
What the FA50 cannot achieve is the kind of bokeh quality of rendering that the FA43 achieves, if you look at those wine glasses they are resolving just gloriously and really add to the shot.
The additional 7mm of frame is welcome over the 50mm (imo), you can get more context for solo portraits and/or is much better suited to doing shots of couples than I ever could achieve with 50mm.
IMO 50mm is overrated, I think of the 77 as being perfect for solo shots, 43 for solo shots+context or couples shots and the 31 for an extension of solo + context or larger groups (but that is subjective as I do not own a 31 yet).
The 43 is also metal, significantly smaller than the FA50 (especially when you compare them both with necessary hoods).
My only question is whether you really feel you need the FA43 if you already have the 31. It's arguable that you can pull off similar shots with the 31 to the 43. If you only have the 77 and 31 maybe you should seek a FA135 which is apparently excellent for those times 77 is struggling for reach?