Cleaning a Lens - Lubing Focus Helicoid

Anyone have any tips or instructions on this?

Yes, you could search my DIY link directory. There are some links there, here are some:
http://www.flickr.com …0/sets/72157600​384658730/
http://www.flickr.com …r/sets/72157611​844942002/
http://mattdentonphoto​.com …ustar_relubing/​index.html

The lens needs to be disassembled, the old lube removed, then new lube put into the focusing helicoid... which are usually relatively coarse Acme threads. It's usually best to do this without completely separating the helicoid inner and outer barrels. It can be very difficult to put the two halves of a focusing helicoid back together properly, once they're separated.

But a lot of lenses these days use a nylon helicoid and might not use any lubrication at all.

Those that do use lubrication, the type of grease used depends upon whether the parts are metal, what type of metal, or nylon/Delrin. There are also "damping greases" of different weights used to fine tune the feel of the mechanism, or to specially prepare it for use in unusually hot or unusually cold environments.

You might already be aware, any grease used must not "oil off" and you have to be cautious not to over-grease. Be careful that no oil or grease gets onto the aperture blades inside the lens, or the aperture will become sticky and cause exposure problems.

Lens disassembly is different from one lens to the next. Try to track down a service manual for the specific lens you're working on. If at all possible, I'd really want the service instructions in hand before starting to take things apart.

With the electronics in today's lenses, likely there are some specialized test devices used to check the function of various modules. Also, after reassembly a lens will likely need calibration using a collimator and possibly some other specialized optical testing equipment.

Seriously, with a modern Canon lens and no service manuals to refer to, I'd probably just send it to Canon and have them do the work. Older, manual focus/manual aperture lenses - such as the ones at Matt's links - I've worked on without a manual... There are some common assembly methods amoung brands, similar enough from one model to the next that once you learn with a few of them, you can work on others without all the supporting literature... Just keeping very careful notes and taking photos to be sure it's possible reassemble properly.... Still, it's always nice to have at least an exploded view drawing and more detailed servicing instructions, if possible.

Try using kit cleaners from Wal-Mart, I got mine from there.

Good info. Thanks everyone.

The lens in question is a Canon 70-210mm f/3.5-4.5.

It's having a hard time focusing and needs manual help getting from one end to the other at times....

I can't speak to that lens but I once rebuilt a Zuiko 35-70/3.6 because it had lots of ball bearings running around on the inside. As ZoneV commented, getting the helicoids sorted out can be a fiddle because (without a manual) there's no choice but to assemble, test, dismantle, reassemble..) until you've exhausted all the possibilities.

The process is probably easier if you take notes and make photographs as you work your way through the system. I didn't do either so it'was trying....

If it helps, I used vacuum grease as lubricant (reasoning that it wouldn't outgas at all and I'd be spared contamination of the lenses.) In any event, my rebuild worked and the lens was like new.

I wonder what the cost of having this done would be at a store?