DIY AI conversions

Discussion in 'Nikon' started by tim_taylor|3, May 21, 2004.

  1. Does anyone have any experience in modifying non-AI lenses to an AI
    capability? Some of the more enticing lenses I am after are the pre-
    AI versions and are at great prices. However, they also seem to not
    have the AI kits for them available anymore.

    How hard is it to modify the lens yourself? What tool(s) are
    required? What are the measurements for the cut-out and what is the
    reference point to begin the cut and how long? Do you grind it out
    and if so, what do you do to protect the lens from 'inhaling' the

    Any web site with this info? I have examined the archives here and
    searched the Google with no success.

    thanks in advance for your help!
  2. Here's a link that might help:
  3. John White in Ann Arbor Michigan did mine for $30. I guess you could do it yourself but i
    wouldn't. He machines a little off and then puts an aperture
    sticker on the barrel close to the mount, i don't see the need for the sticker though. Hope
    this helps.
  4. what do you do to protect the lens from 'inhaling' the shavings?
    Simple. You take the aperture ring off before you do anything else. #1 mistake of DIY AI conversions.
    Here's a link to Will Sampson's site:
    I haven't had any work done by Will, but I have seen his stuff. He's the one I would turn to if I needed conversions.
  5. You have to be careful because not every lens can be AI'd well by simply hacking the rear of the aperture ring. Some lenses the aperture ring is too narrow in diameter to reliably engage the AI tab on the camera. One example is the 20/3.5-UD (72mm filter version). This lens requires a bit to be soldered onto the ring where the tab engages. Some AI'd lenses will catch the AI tab at the corner, which is ok on bodies where the tab is metal, but on later bodies where it's plastic it can eventually wear the corner off the tab and then the lens will no longer index.
  6. The label provides a second aperture scale on the aperture ring. Cameras that use aperture direct readout (ADR) use this to display the selected aperture in the viewfinder. The FM, FE, FA, FE2, FM2, FM2n, and FM3a do this, as well as the F3 and F4 (and I assume F5). It's a very useful touch if you have an ADR body. It makes the AI-converted lens function almost exactly like a real AI lens.
  7. I would second Todd's recommendation for William Sampson. He's a regular at yahoogroups and a class act IMO. You can't really DIY unless you have some experience in machining, probably an end-mill I guess. (I used to have my own light metal fabricator and machinist at work and he was brilliant)

    I've seen some real hack jobs on the 2nd hand market. It pays to have a nice AI job if you ever plan to sell.
  8. DIY conversions are up there with DIY dentistry. You can always just buy a cheap FE body(or any other with a flip-up AI tab)and use stop down metering. Factory jobs aside, AI-conversions I've seen haven't been pretty, nor have they enhanced the value of old Nikkors in otherwise nice condition.
  9. DIY dentistry; there was a center column main article on this in the WSJ; several years ago!
  10. I did one AI modification of a 105/2.5 IC Nikkor. Lacking sophisticated milling tools I used a fine cutting 1/4" square file ground smooth on one side. This allows cutting in only one direction. If you do not know how to properly remove the bayonet it’s a perfect opportunity to torque a head or heads of the screws that secure the bayonet. Doing the modification by hand is slow and tedious. I had two additional 105/2.5(s) available to make comparisons with, an AI and an AIS. This assured that I’d cut ring for the proper fit and angle.

    It’s not worth the risk and effort when it can done by someone with the proper tools and considerable experience for just $30.00. I don’t recommend doing your own AI conversions.
  11. I just tried a google search on "AI conversion diy" (the title of this post) and this page came up at the very top of the results...
  12. Well, I actually searched for "DIY AI conversion" (in addition to "AI conversion DIY" with no difference in the top result). The omission of that little "s" seems to make a lot of difference. Sorry for being a little too fast.

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