Nikkor 28mm f2.8 AI-s infinity problems

About two years ago when I purchased my FE, I wanted a quality wide angle lens to go with it. I snagged a good looking 28mm f2.8 AI-s off eBay but was too inexperienced with manual focus to realize that the focus in the split prism was off by a good bit. I do not have focus issues with my other Nikkor lenses. Because I realized the problem too late I let the lens sit for awhile, not really sure how to proceed. Recently I decided to replace it but because of my budget I purchased the less coveted AI version. I am now second guessing that decision and am wondering if anyone could provide a tutorial on how to possibly do some surgery to adjust the infinity focus. I have read enough of how sharp the lens is and would love to salvage it if possible.

Also, there are also a lot of photographers saying that the 28mm AI-s is superb for close up photography but sharpness suffers in landscape photos. Is this true? I tend to lean more toward landscape with a wide angle lens so would it be best to just keep the AI and forget the AI-s? Thank you for any information.

Bryan

Richard Haw has a guide to repairing this lens at Repair: Nikkor 28mm f/2.8 Ai-S. He mentions adjusting infinity focus.

Even should you decide to sell the lens, it will be worth more if the infinity focus is correct.

Check the basics first. Like the seating of the bayonet mount - easily removed - and the positioning of the focusing collar.

It only takes a fraction of a millimetre error to throw infinity focus right off.

Does the lens show any sign of being dismantled? And how far off is infinity focus? A mile out and it may mean that the helicoid has been amateurishly taken apart and badly re-assembled.

Check the basics first. Like the seating of the bayonet mount - easily removed - and the positioning of the focusing collar.

 

It only takes a fraction of a millimetre error to throw infinity focus right off.

 

Does the lens show any sign of being dismantled? And how far off is infinity focus? A mile out and it may mean that the helicoid has been amateurishly taken apart and badly re-assembled.

At least at outward appearance, the lens does not seem to have been dismantled. Now, I may have exaggerated just a bit about how far off the focus is. When trying to focus on a 4-inch wide piece of siding trim about 2-2.5 football fields away and using the split prism, the outer edge of the piece in the bottom prism may be almost touching the inner edge in the top part of the prism. In other words, maybe off by about 6 inches at that distance.

I may have exaggerated just a bit about how far off the focus is. When trying to focus on a 4-inch wide piece of siding trim about 2-2.5 football fields away and using the split prism, the outer edge of the piece in the bottom prism may be almost touching the inner edge in the top part of the prism. In other words, maybe off by about 6 inches at that distance.

You've twice mentioned now that the lens is not able to focus on distant objects as far as your viewfinder indicates. But how do the photos turn out? When the subject is very far away and the focus ring is turned as far to the right as it will go, is the resulting picture sharp?

Might sound a bit daft, but have you got a DSLR you could try this lens with?

If you use zoomed LV on something actually at infinity, eg. a far, far off mountain....then,

A) Can you get it in focus?

or...

B) Won't turn 'far enough', but is getting there.

If it's A), where does the focus indicator show?

It sounds like a very minute error. A bit of dirt or hardened grease on the infinity end-stop, or the corresponding focus collar stop, could easily cause such an error. Same goes for the seating of the bayonet mount, or some warping or distortion thereof.

I'd look into removing the bayonet mount and cleaning underneath it first. Then next the focus collar. But as others have said; a split-image screen isn't a good guide to lens focus accuracy.

Seating a makeshift GG on the film runners and inspecting the image with a good magnifier is about the only way to verify infinity focus. Other than a DSLR with Live View.