20mm f2.8 AI-S, my first super-wide angle manual lens

[Zang]

Exactly, corners are bearable at f/4 and fully acceptable from f/5.6. The other real issue with this lens is, apart from the wavy distortion, the sensitivity to flare (unlike the 20/3.5 AI). Otherwise it is a joy to use because of its ideal size. Manual focussing (on a matte screen) is difficult in dark places, but with the Z cameras that's no longer an issue.

Right... At the price of just $85, I'll forgive her for all her shortcoming

The lens initially had dirt and oil inside, but after being rebuilt, it looks like it hasn’t seen much use at all.

[Zang]

Looks like a very good sample...

Thanks Akira, indeed it does.

The overhaul was satisfying as I witnessed just how much dirt and oil was removed. Every part was dipped in solvent, thoroughly washed with soap and wiped with alcohol.

[Sören Hese]

The 20mm f2.8 AIS - I used two different copies - never really sharpened up in the extreme corners on DSLR FX systems. I really enjoyed using the lens since build quality is wonderful but my use boils down to specific uses f.e. tilted on an A6000 with a converter or when shooting extreme near far combinations. Imo its just not sharp enough on modern F-mount sensors even closed down to f8 or f11  (havnt tested much with the Z8 but my guess: same problem).  However, I will keep mine - its nice to have sometimes and its so small . Best wishes! Sören

[Gil Aegerter]

I've never had the f2.8 AIS, though I have the AF version, which seems to be OK, though I haven't shot a lot with it. I've had the f3.5 AI and UD and the f4 in AI and K version. The f3.5 AI is the one that has stayed with me -- I sometimes will take it and a 55-200mm for my D5500 and call that good for travel.