Originally posted by Serge Hi
I believe the F50/1.7 to be a better choice for the money. First of all, this FA50/1.4 looks a bit overpriced, normally it goes for $200. The second thing is that there's a popular belief that PENTAX-F lenses slightly edge their FA-cousins in terms of IQ (namely sharpness, as it follows from photodo ratings). On the other hand the F50/1.7 has 6-blades aperture that might result in hexagonal highlights in out-of-focus areas. Whatever you decide you won't be disappointed. Both are great lenses.
I totally agree with Serge, I would not even consider leaving the house without a F50/1.7 it is a very fast and sharp lens. I have never experienced hexagonal highlights with over 3,000 clicks with this lens.
I was quite surprised when auctioning two of my spares last month on eBay one went for $227.50 US and the next went for $171.00, the most wonderful part was I bought these lens's at Tag (garage, estate) sales with SF1 bodies for less than $25 US each in pristine condition.
So you may want to look in the direction of tag sales, it is a bit of work but well worth the effort.
Also I have heard one can do very well at pawn shops.
Wendy