Need help with "simple" lens repair - 35-70mm f/2.8

[glenn_c1]

<p>Hello all,</p>

<p>I have a 35-70mm f/2.8 AF-D lens that has a couple of minor scratches on the front element. I've procured a replacement element from Nikon, actually an inexpensive protective front glass, and a lens spanner, but I'm having difficulty removing the threaded rings that hold the glass in place. It looks as though they should simply unscrew. One complication is that there are two rings and it's not completely obvious which needs to be removed first - one perhaps acts as a lock ring for the other, but it's not clear which.</p>

<p>If anybody is familiar with the process I'd appreciate any help. Are these rings often particularly tight? I assume they are normally right-hand threaded?</p>

<p>Thanks in advance.</p>

 

[photo5]

<p>Why not bring your lens in to your local camera repair technician? That way you're bound to not damage the other elements with your inexperience, and have a good lens for years from now. If you don't have a local repair tech in your area, I can recommend a good one here in Washington State. I bought a near mint Nikon 50mm f1.2 AIS lens last year, and when I had it overhauled, the tech found some damage inside, resulting from an inexperienced technician in the past. It was disappointing.</p>

[glenn_c1]

<p>I could, but I prefer to repair things myself when possible. The key I guess is to know what not to attempt. This seems like it should be pretty basic, since it's merely a front protective element.</p>

 

[peter]

<p>I think I would take it to a techo too. This sounds like a fast and cheap fix for an experienced technician with the right tools and skills. A lens spanner helps but may not be the end of the story. e.g.Lenses need collimating don't they - to ensure thay are mounted squarely in their mount? Do you have a collimator?<br>

But if you really want to remove the lens yourself, one common trick for unscrewing threaded rings is to go to the hardware store and find a rubber hose of the same diameter. The end of this is used as a "gripper" by pressing against the ring and rotating. As its a hose and therefore hollow it "should" not scratch or damage anything. A spanner for this job can slip - with nasty cosmetic, if not optical consequences. <br /><br />Sorry for my gratuitous comments, but while I am a lens fidler too, I have not tacked this one so cannot answer your specific questions. Cheers and good luck</p>

[vick_ko]

<p>Hmmm. Nikon was notorious for sealing items with thread locker. That lockring might well be glued in. See if you can find out for sure, and then find out which thread locker solvent to use.<br>

Case in point - the screws that held the bayonet ring on, at the rear of Nikon SLR AIS lenses were typically glued in. Royal pain in the rear to remove.</p>

<p>...Vick</p>

[photo5]

<p>Yes, unless the front element is loose, it could be part of an element group, requiring them to be split to replace the front one. Of to a technician with you! Let me know if you need a referral to a good one I've known for 20+ years.</p>

[lex_jenkins]

<p>I've reworked a couple of my older manual focus Nikkors. The screws and lock rings weren't set with thread locking compound. No idea about later AF Nikkors, never disassembled one.</p>

<p>Looking at my copy of the 35-70/2.8D AF Nikkor, my guess would be that both locking rings are normally threaded. The inner ring appears to be a security lock for the outer locking ring, rather like a double lock washed to minimize the risk of loosening due to vibration. It would be counter-intuitive for one to be reverse threaded from the other, since it would defeat the purpose.</p>

<p>If you're comfortable with DIY repairs, you might try a careful, selective application of heat. I'd use the tip of a fine soldering iron to the inner ring, just enough to create some heat differential between the rings. The mass of the two rings and surrounding barrel will even out the heat pretty quickly, so work patiently and slowly. If there is any thread locking compound (I'm not seeing any traces on my lens), this will soften it a bit. If not, the heat differential may help loosen things up. I used that trick to loosen the dreaded green grease that decades later hardened into epoxy on Agfa folders.</p>

<p>Sorry I can't offer more specifics, but so far all of my lens overhauls have been to manual lenses - Nikkors, Canon FD, Olympus OM, Agfa Isolette folders. Of them all, only a handful of Zuikos appeared to have used thread locking compound, or perhaps were simply screwed really tightly and defied extrication.</p>