On Mon, 19 Dec 2005, Jostein wrote:
Stopping down the 50mm to f/2 improves contrast, but introduce more optical errors with small apertures on the 200. This leads me to believe that the best 50mm would be the one that is the sharpest at full opening, whatever that may be...
The 50/1.7 has the reputation for that (as Stan's site says). From memory, the official Pentax Lenses manual claims it has the flatest FOV of all the 50s and is recommended for macro work on extension tubes (and perhaps it mentions reversing, but I can't recall right now).
A used M50/1.7 will set you back, oooh, I don't know... a bag of crisps? The FAs go for 70-odd GBP on ebay.
Give it a try, is all I am saying. Kostas
