Repair of the Nikkor 20mm f/3.5 Ai-S!

[richardHaw]

https://richardhaw.com/2017/11/27/repair-nikkor-20mm-f-3-5-ai-s/

a very simple lens to overhaul. 

[David H. Hartman]

A note on AI v. AIS: the AI has a 100 degree focus throw while the AIS has only a 70 degree throw. I don't think I'd care for the AIS on account of the short focus throw.

Dave Hartman

As usual the specs come from Roland's site. I own the AI and like it for its very low flare and no ghosts.

[richardHaw]

A note on AI v. AIS: the AI has a 100 degree focus throw while the AIS has only a 70 degree throw. I don't think I'd care for the AIS on account of the short focus throw.

Dave Hartman

As usual the specs come from Roland's site. I own the AI and like it for its very low flare and no ghosts.

I would have gotten the Ai if I knew about this  thanks for the tip!

[Roland Vink]

I also use the AI 20/3.5 for the same reason as above, that website is very useful sometimes
Since it is optically the same as the AIS, I imagine the AI is also simple to repair.
It is known for being less than perfectly sharp at infinity, but for landscapes where I usually shoot at f/11, the results are quite acceptable.

[Jack Dahlgren]

A note on AI v. AIS: the AI has a 100 degree focus throw while the AIS has only a 70 degree throw. I don't think I'd care for the AIS on account of the short focus throw.

Dave Hartman

As usual the specs come from Roland's site. I own the AI and like it for its very low flare and no ghosts.

For 20mm the shorter throw of the AIS is not a significant hardship in my opinion.

[richardHaw]

there is one quirk with this lens and that is it's a bit hard to nail the focus perfectly when you rely on the digital rangefinder 
there is a workaround to this

[jpgrahn]

Well, tell us!
Please, please, with sugar on!

I have the lens. It is really small. Big difference to the modern 1.8/20 AF-S G!

[richardHaw]

Well, tell us!
Please, please, with sugar on!

I have the lens. It is really small. Big difference to the modern 1.8/20 AF-S G!

well, in my experience as far as my sample is concerned. critical focus is achieved JUST when the dot becomes solid when you rack it from the left. Some lenses will do it from the other side. I think that this is "backfocus" or "frontfocus" manifestation on manual lenses 

for example, my NOCT will give you the best focus on my Df when you rack it from infinity and JUST when the dot lights up then that will give you a very sharp result wide-open. If you move it just a bit further then it's going to be off by a bit. I hope that I am making sense here...

by the way, I am still looking for your picture with Helga. I will mail it to you as soon as I found it in my iCloud it got screwy after I upgraded!

[jpgrahn]

Don't worry! No rush!
I wish I had had more time to spend in Tokyo checking out camera shops.
All the best

[richardHaw]

https://richardhaw.com/2017/11/27/repair-nikkor-20mm-f-3-5-ai-s/

just rewrote this old article, added lots of new photos, too.