non-ai to ai

P

Park Edwards

Veteran
how hard is it to convert one? i'm thinking of getting a non-ai just cause they're so cheap and then converting it. anyone here able to do it?
 
i have. since the coupling doesn't work with the d90 anyway i just filed the ring down all around, very easy. just remove it (two or three small screws),file it down 2mm, put it back, et voila it fits the d90. it's probably not hard to create a proper coupling either but i haven't tried it.

remember that non ai lenses have older optics, especially the coating but often also by design, so they're not quite as good.

/matt
 
thanks, what did you use to file it down? and in movie mode, i'm not quite sure the optics are even going to matter.

is there a significant difference between 1.8 and 2.0? there's an 85mm f1.8 nai for 190 and an 85mm f2 ai for 125. is it worth going for the 1.8 for that little extra bit of light? Im trying to keep my lens the same and i have a 50mm 1.4 and going for a 28 f2 later.
 
optics always matter. you don't need perfect overall sharpness in video mode of course since you don't need to resolve as many lines, but things like ghosting, flare, coma, vignetting and so on are just as evident. i never use my 35/2 ai-s for that reason. a lousy lens even though it looks good on paper. i guess i need the f/1.4. the amount of light doesn't matter much, but the optical quality between them varies a lot.

i used a small metal file and did it by hand.

/matt
 
the 85/2 is a fantastic lens, i can't see any need for a 1.8 (that's just 1/3 stop) even though i haven't tried it. it's the 35/2 that's sub par but this is not a rule. sometimes the slower lenses are better.

/matt
 
I filed it down all around, the part you're supposed to leave is just for indexing that doesn't work with the d90 anyway. Look at an ai lens and you'll see how much. Maybe 2 mm or so. It's not supposed to reach the small auto aperture contact on the body, the one you engage at f/22.
 
thanks man...i just went ahead with the 85mm f2 ai and just avoided this whole converting process. 1/3 stop loss, not a big deal. Plus it was $75.00 cheaper to go that route.
 
congrats. that's my favorite lens, along with the 24/2 which is also pretty fantastic. it's hard to find a good manual lens that's still wide angle in dx.
 
yeah, i'm watching a 28/2 now on ebay, it's a vivitar, probably not optically up to par with nikkor, but heard it's a pretty decent lens. just gotta win it now.
 
I 've been looking up on non-ai lens compatibility with the d90 and have been getting mixed signals. I've personally mounted a non-ai 50mm/1.4 on the d90 (thought it was a conversion) and everything worked.
Nikonians.org seems to agree. http://www.nikonians.org/nikon/slr-lens.html
And others have mounted non-ai to the d90 http://forums.anandtech.com/messageview.aspx?catid=65&threadid=2251702&enterthread=y&STARTPAGE=2

But majority of people seem to think mounting non-ai lenses will break the camera.
And I still have not gotten a complete explanation why it will not work (pictures would help).

DIY AI modification link
http://www.zi.ku.dk/personal/lhhansen/photo/repair/aimod/aimod.htm

Ai conversion by John White
http://www.aiconversions.com/compatibilitytable.htm

SO is the d90 like the d40 and d60 or like the d80 and d70.

Can someone clarify??
 
non ai lenses have an aperture ring that extends down over the mount flange, and that will mess with or possibly break the small button/lever which tells the camera that an af lens is set to auto. simple as that. there are no other issues. a converted lens doesn't have this problem so it's not surprising that your modded one worked.

file off a few millimeters from the ring and it works fine. no manual lenses, ai or not, work fully with the d90 since the camera doesn't recognize them and won't meter or use any auto functions, so it doesn't matter if you don't create the correct coupling.

/matt
 
i don't know what will happen, i never tried it. you notice right away when you try that it's not a good idea. there are two things that try to occupy the same physical space and using force to solve it isn't likely to be good, at least not in the long run.

/matt
 
the guys who say it works probably have modified lenses without knowing it, or their particular lens is a bit different which isn't unlikely since the mount has been around since forever and has seen many generations of lenses. spend $10 on a lens and try for yourself, much easier than trying to figure it out online.

/matt
 
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