Hi, just got what I thought was a pretty sweet fuji 6x8 rangefinder on ebay. Loaded a roll of film and was making some test shots – noticed some dust on the lens and gave it quick burst of air from my blower bulb and to my horror the little ring with the fujinon 65mm, ebc etc lettering on it flew off.
My question is can I just use superglue or something similar to glue it back on? started googling this and noticed some folks saying don't use superglue, the gasses could harm the lens...anyone have any advice? seems sort of overkill to send it in to a repair shop for something that seems so on the surface.
Do not use any glue that fixes the ring as not to be removable, as underneath it is that cone to be taken off.
Aside of that, properly done cyanacrylate ("super glue") would not harm the lens.
BUT yes under circumstamces it can: I once hat to use cyanacrylate on my workbench, and while I was cementing something the tube with glue was leaking quite a drop. I wiped off that drop but erroneously not discarded the tissue but dropped in on my workbench next to a tele lens standing upright. The next day the whole lens was covered with fingermark stains from that glue vapour. (This effect is used in forensics to make fingerprints visible.) With some solvent I got rid of all stains but I admit I was shocked.
(As some of you might know meanwhile from my posts, there are two substances I try to avoid as far as possible: silicone oil and cyanacrylate glue.)
Don't use superglue. Just don't risk it. Even if it doesn't fog the glass it can fog plastics.
I'd use Elmer's glue, white glue. Water-based, easily rubbed away if it gets where it shouldn't be, easily removed when needed. Very light film on the back surface. A small paint brush would be a good applicator. Wipe a cotton swab around the inner edge of the ring before dropping in place to push the glue back from that edge and avoid it squishing out. It'd be best to remove the old glue squiggle from both pieces, but you risk chips going into the lens body so maybe best not to worry.
Don't panic, your camera isn't broken, that's a bit of cosmetic trim which is supposed to be removable when the lens gets serviced. You want future repair techs to be able to peel that part off without damage. An adhesive like Cemedine Super X (available from Japanese sellers on eBay) might be ideal, as it sets up slowly, cleans up with naphtha, and remains pliable.
RE: a contact cement.
Nope, Uh-Uh don't do it. Used as you suggest, it's permanent. But use a minor amount one one surface will do the job just fine & still be removable.
The traditional camera technicians(US) glue for this would be Pliobond on one surface only.