How to glue the mirror of a EOS 30

supahmario · Joined: 18 Mar 2009 Posts: 615 Location: Berlin, Germany

Hi,

this his the story:
i bougth a nice 3.5/24 S-M-C Takumar (m42 mount) at the bay. when it arrived i checked it on my EOS 30. it worked fine instead of one thing. when i focussed to infinity the mirror didnt work propperly. it hang on the end of the lens. it tried it several times with the hope that it is just a matter of time when it will work propperly. the result was, that the mirror broke away from the frame.

after being very angry about it i remembered the case of grinding off the frame. then i got the idea to cut the frame with a very sharp heated knife. so i did so and the result was great. now the mirror (frame) has enough space to move. and when i lay the mirror in the frame, it is in one line with the edge i processed. so it should work later.

(i used a rubber to fix it while cutting)

the question:
what kind of glue should i use to fix the mirror? the glue that was on the mirror before looked like silicon or something like that. does anybody of you know what kind of glue canon used to fix the mirrors. is someone of you perhaps experienced with that topic? i think it must be a glue that is not agressive to the coating of the mirror.

thank you in anticipation!

ps.: i can hardly recommend to treat the edge of the frame by a hot knife, because there's no need to cover anything to prevent it from plastic splints! the material gets soft and stays on the knife, where i removed it by another knife. but i don't know how and if this works when the mirror is fix in the frame.

pps.: sorry for my english. its some years ago that i learned it in school!

Attila · Expire: 2025-11-18

Farside · Expire: 2013-12-27

themoleman342 · Expire: 2013-01-24

The problem I see with that is the silicone-based glues may lay on fairly thick throwing the focus off since the mirror would now be at a different level, or even worse at a different angle. I wonder how a simple acid-free glue stick (the kind used for photo albums) would hold up. It probably wouldn't be able to take to much punishment. On that same thread of thinking...maybe some rubber cement (probably run into the thickness problem again)? Maybe super-glue makes an acid-free brush on type?

Maybe I am wrong in assuming this, and maybe they do mirrors differently nowadays (sorry I only have rebuilt '70s SLRs) but would an aggressive glue even be a factor? It may very well damage the back of the mirror, which may or may not be silvered, but it wouldn't get through the glass. It is front surfaced so any damage would have to come from above.

Sorry, that probably didn't help any...but just my incoherent babbling on the subject.

~Marc

supahmario · Joined: 18 Mar 2009 Posts: 615 Location: Berlin, Germany

the sickness is no problem, because there are three little hollows where the glue is placed. i also thougt about that it also could be indifferent if the clue is agressive to the backside. but the backside is also silvered and i dont know if there could be a problem when this backside coating isnt intact.

be that as it may...
i was very brave and i tried something....

i used
http://www.uhu-profishop.de/products/de/Montagekleber-Dichtstoffe/UHU-KLEBEN-MONTIEREN-DICHTEN-transparent-Tube-50g.html

...and it works fine. it is transparent, it solvent free and creates flexible connection. and it seems not to attack the mirrors coating. it was very easy to adjust the mirror and after two hours it was strong enough to use it.

Farside · Expire: 2013-12-27

Ah yes, UHU glue. Excellent stuff and fairly benign. If it's only three small spots, just see how long it holds the mirror in place - you might need something a bit stronger, since the mirror flaps up and down.

supahmario · Joined: 18 Mar 2009 Posts: 615 Location: Berlin, Germany

after taking round about 500 shots i can say...

!IT WORKS!
the mirror holds strong!
if it flies away some day i will inform you!

by the way...
i did this operation to another eos 30 (of a friend). and my expierience was, that you have to break loose the mirror and glue it afterwards if you want to get the maximum space between lens backside and mirror, caus there is perhaps 0,5mm space to glue it a bit deeper backwards. for some lenses it also can be enough to operate the mirror frame without loosing the mirror. for the 24er tak it isn't!

so i will report changes.
and if you have questions on this method, don't hesitate to ask me.
i am so proud to be a do-it-yourselfer!

if somebody tried this on an EOS 5D. i would be very interessted in the experiences/differences.

especialy for the sensible and expensive dslr's i would expect, that this should be the better method, caus there are no plastic splints flying around. but i don't know how the modern mirrors react on the heat of the knife or on "removing". perhaps the modern glue is so strong, that the mirror brakes while trying to remove it!?

supahmario.

supahmario · Joined: 18 Mar 2009 Posts: 615 Location: Berlin, Germany

just wanted to report...

1000 shots later it still works. none of my lenses hit the mirror and the mirror itself holds tight.