Sharpness, Resolution, Contrast ?

Hi all,

What does one look for when trying to assess the above ?

Regards, Colin

That's a very, very difficult question to answer. All lenses have a balance of properties, and it may well be that one is enhanced at the expense of others. So, if you want reportage shots on Tri-X film that look contrasty and gritty you want high sharpness and high contrast (SMC Pentax-M 50mm f1.4 perhaps) but fine resolution may not be as important.

You haven't mentioned the drawing of a lens, that is, its ability to render straight lines as straight lines, and many modern zooms let that slide but go for high sharpness.

If you are interested in this vast subject, I would suggest some books on lenses - there are plenty to choose from, and they will help to guide you through this morass of information.