I removed the microscopic set screw (and promptly dropped it on the carpet--note to self, unscrew screws over a tray with a magnet). I've taken the lens out of the shell and I can see two brass projections on opposite sides on the inside of the shell that go up and down in wide slots. When I turn the focusing ring, I can visually see quite a lot of play--the brass projections move laterally when they should only go up and down, correct?
Now I assume I need to remove the lens mount and aperture ring again.
What does the wide slotted screw near the front element supposed to do? Is it to calibrate infinity or something?
fftttt! yeah, those pesky tiny set screw. You need that, mostly, the optical group is held in by the barrel you just twisted off, that set screw keeps it tight so THAT doesn't loosen and move the optical group around OR out. Use a magnet on the carpet and see if that will pick it up, sometimes it works.
Ya don't have to to pull off the aperture ring if you don't want, the mount might need to come off so you can line up the aperture stop down lever with the slot on the optical unit when you Put It Back Together (which you Will, yes?).
The wide slotted takes off the front groups of elements in the Front Optical Block. Once you get the whole Optical Unit out you can see how the rear group can be removed. The helicoid barrel is next.
This is what I ended up doing. The screwdriver I had was about 5/64", I think 3/64" or even 1/32" might be the right size(?). I don't know that I have guts, I'm probably just stupid. At least I'm not trying to grind the rear element to install a Dandelion Chip.
Originally Posted by Newt_on_Swings
Yes, I promise I will put it back together! Not just so I can use it (it's my second-most used lens), but out of respect, too. I'm trying to find the screw, I hope I'm not SOL. My coworkers are helping me look.
Originally Posted by RidingWaves
I'm taking care with the optical group. When it's removed, there's no way to attach caps, and there's not really any protection for the front or rear elements.
Just set it on its side and make sure it doesn't roll off the workbench. If you can't find the set screw don't worry, you can take one off another lens or you can even do without, just make sure you don't loosen that barrel when you unscrew a filter or hood.
Oh, I didn't even think of that. I have a beat-up 200mm f/4 AIS of the same vintage that I never use. Sure enough, it has the same set screw, at least it looks the same. I actually called the Nikon USA Parts Dept today but I was on hold for about 20 minutes before I gave up.
Anyway, to get back to the focusing issue, I can't see any way to the adjust the the |_| -shaped focusing grooves or the brass protrusions. If the grooves are a tiny bit too wide and there is play, does this mean the grooves or brass "keys" are simply worn out?
I was going to set up a flickr account and take some close-up photos of the various interior components in case anyone is interested, but as it turns out, 108 proof Kentucky bourbon and black coffee on the side doesn't really mix with macro photography. Plus my D200's battery was dead when I tried to turn it on--I can't remember the last time I used it (it's my only digital camera, unless you count my iPhone, which I don't).
I might be becoming what Sover Wong refers to as the dreaded "cowboy".
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I contacted Roger Cicala, the proprietor and author of the wonderful lensrentals.com blog. He told me he might be considering publishing a tear-down of the 50mm f/1.2 AIS.
By the way Mr. Waves, I enjoyed viewing your blog. I wonder how I never came across it before?
Thanks, just for the true geeks.
Its the same size, so you can use that set screw.
Drinking and operating a screwdriver can be hazardous to your gear. Use caution. I speak from experience...
I've made the effort and checked my copy of a 50mm Ais, and On Mine, when you remove the optical block you can peer inside of the barrel and see the two brass 'keys'. Those have no adjustment, and if that brass wears too much and gives slop it looks as if *To Me* that those were meant to be replaced with factory original parts as part of a Nikon CLA. This is different than most MF lenses.
The reason you were on hold for 20 min is probably because nobody is bothering to answer the phone. Nikon stopped selling parts months ago to anybody.
The plan *I would do* is to add a bit of heavy Lens Helicoid Grease on both surfaces of each brass key, that may take some of slop out. Of course, this was after I was satisfied that all 4 of those screws were nice and tight. Or send it to Nikon USA.
*slaps forehead* I remember this. There were riots in the streets and petitions everywhere. At the time I didn't grasp the implications. They should really play an audio message if you try to call the parts department instead of just blasting ads at your face.
Originally Posted by RidingWaves
Thank you thank you thank you Christiaan for taking the time to help an unexperienced novice in need, I hope I haven't been too much of a nuisance. Your diagnosis jives with what I can see. It's too bad there's no way to adjust these things or to add a spacer or something. I will try as you said and add a small amount of grease.
Yeah, where that really hit was us geeks who like to fix rather than sending Every lens in. Sometimes you have to though, I'm pretty certain Nikon would fix the lens, they are still making this model so spares are available.
IMO this shows the minute differences between Ais and the older series. The older ones were made to have more adjustment, either during assembly or as parts wore. The Ais IMO were made to be easier and more modular in assembly and to have components swapped out as they wore, which is fine as long as Nikon still supports and works on them. What sucks is trying to find parts now. Mind you, it takes some serious hard and long term use for ANY Ais lens to show the amount of wear that I'm talking about.
BTW try ebay, some smaller shops put nikon parts on there and if you call them you can sometimes find the part. I'll see if I have the parts list for your lens and see if I can find the secret code to use...
Ooo secret catalog codes... Also your site is really nice, great photographs