I was out walking locally this morning and I decided to take my Nikon 20mm f/4 Ai with me. This lens is quite well known for being a good performer and prices remain quite high on the used market. Whilst I have never owned any other 20mm lens I don't feel any lack of confidence when using this lens. It takes some care to get the best out of it and it does not like the sun to glance on the front but the images are absolutely no disgrace. I suppose I should be lusting after the new 20mm f/1.8 but I don't miss not having AF for what I do and have never fallen out with my f/4 so why change? I may add the f/1.8 one day though
I share a few photos from today but any 20mm f/4 information or other examples appreciated. Also how much different is it to the later f/3.5 lens with regards to its results?
These were taken on the D750.
Edit to sum up my findings:
Well worth using live view and magnification - it is hard to tell when this lens has reached peak focus and if it is off, the results suffer quite badly.
Infinity focus is optimum just shy of the stop - using the hard stop works, but not optimum.
All stops are useable but fall-off and edge sharpness go by f/8 (f/8-16 best performance).
Contrast is a bit lower than modern lenses but not in a bad way - it has good colour.
My rating is 7 out of 10.