DIY Meopta Flexaret cleaning.. Didn't go so well ;p

Degenetron · Oct 1, 2008

Ok, so i've had this old TLR sitting on my shelf for ages and today i thought i'd see if i could 'fix' it.
The focusing knob was stuck and that was my first item on the agenda. After a while i managed to get it open and see what the problem with the focusing was, it was simply completely stuck due to old grease and dust..
"well, problem solved", i think and start cleaning it. After im done with the screw mechanism for the focus i decided to give the mirror a good once over too.. that was a problem.
This was no ordinary mirror at all. Its a piece of glass thats coated with some very fragile reflective material on the "business side" (the one that reflects). It promptly got a cyan/magenta coloured haze and i rubbed straight through the coating.
I'm thinking i could just have a regular mirror cut to size and that will sort the issue, but there is probably some reason for the mirror to be made this way, no?
So would any of you know what kinda purpose this mirror had (if any)?

ic-racer · Oct 1, 2008

Some suggestions were in this thread: (there was a url link here which no longer exists)

Anscojohn · Oct 1, 2008

It's a front surface mirror. And, iirc, the Flexaret's were real tricky b.st.rds to work on.

Degenetron · Oct 1, 2008

Thanks ic-racer. I'm wondering how much of a problem it would be with a regular mirror though.. According to the internet () there will be a double reflexion with a regular one.. but how bad will it be? anyone tried?

Also, if i do order the right one, will it also be "uncleanable"?

Degenetron · Oct 1, 2008

Well, getting the front off was pretty simple Anscojohn. A Few tiny screws that may not be so simple to get back on though, but im sure i'll manage Also i guess i might not get the focusing to correspond 100% with the distance scale, but i know *aproximately* how it was angled when i losened it so it shouldn't be too far off. I'm not touching the fine mechanics of the shutter etc.

wclavey · Oct 1, 2008

If you use a rear surface mirror, in addition to the double image, won't the focus be off by 2x the thickness of the mirror glass because the image will have to pass through the glass 2 times to get to the reflective surface (or perhaps a fraction more than that, because the light will pass through the glass at an angle)?

Degenetron · Oct 1, 2008

wclavey said:
If you use a rear surface mirror, in addition to the double image, won't the focus be off by 2x the thickness of the mirror glass because the image will have to pass through the glass 2 times to get to the reflective surface (or perhaps a fraction more than that, because the light will pass through the glass at an angle)?

I can safely say: "no idea"

Dhar · Oct 1, 2008

Recoating?

You could also completely clean the mirror off (as in, remove the coating, too), and then send it out to get recoated. Aluminum recoating doesn't seem too expensive...a quick google found these guys: http://www.alcoat.net/

Not sure how they'd react to a small, rectangular mirror, but shop around -- you should be able to find front-surface coating for not a lot of money.

-g.

Degenetron · Oct 1, 2008

Thanks for the info and options guys Hope is not lost it seems. I guess i'll get a regular mirror cut tomorrow, just cause it's the fastest and simplest solution(idea). Then probably acknowledge that it was a waste of money and explore the other options

Trask · Oct 1, 2008

Well, the previous poster is correct -- a regular mirror will just introduce a significant focussing error. Go ahead and do it, if you wish, but you know in advance it ain't gonna work. Believe me, the Meopta engineers and every other camera maker would have loved to use a standard mirror, but there's a very good reason they don't.

Good luck, by the way. I've often thought that if someone else is smart enough to put it together, so am I. Experience has sometimes shown otherwise!

Degenetron · Oct 1, 2008

Hehehe Trask. Yeah, that thought has tricked me into many a project This time it seems it was valid though. As for the mirror. Thanks for confirming. I'll drop the initial quick fix then.

Chris Nielsen · Oct 1, 2008

Hi, I used to work for a glass shop and they had the ability to do a surface silver on a piece of glass. There must be places around your neck of the woods that can do the same - essentially any place that can silver a regular mirror can also do surface silver.

DWThomas · Oct 1, 2008

I replaced the mirror in a Flexaret circa 1975 by buying an oversized front surface mirror from Edmund Scientific and cutting it (yes, a bit scary). Today I'm not even sure Edmund is still around. There's possibly some equivalent source.

DaveT

k_jupiter · Oct 1, 2008

DWThomas said:
I replaced the mirror in a Flexaret circa 1975 by buying an oversized front surface mirror from Edmund Scientific and cutting it (yes, a bit scary). Today I'm not even sure Edmund is still around. There's possibly some equivalent source.

DaveT

And make sure you measure the thickness o the mirror. Any other front surface mirror will be off by the difference in the thicknesses of the two mirrors. The back silvered mirror will be off by the thickness of the glass x 2.836. The image also won't line up in the viewfinder.

tim in san jose

Steve Smith · Oct 1, 2008

If the original is a front surface mirror and you only have a rear surface mirror to replace it with, I would try to glue the new mirror directly on top of the old one. That way, the reflecting surfaces of the two mirrors would be almost in the same place. You may need to shim the focussing screen just a little bit higher (perhaps the thickness of a piece of paper or two) but this should be easier than trying to lower the screen which you would need to do if you completely replaced the screen.

Steve.

DWThomas · Oct 1, 2008

k_jupiter said:
And make sure you measure the thickness o the mirror. Any other front surface mirror will be off by the difference in the thicknesses of the two mirrors. The back silvered mirror will be off by the thickness of the glass x 2.836. The image also won't line up in the viewfinder.

tim in san jose

It's been so long my recollections are a bit hazy, but I think (within reason) you can compensate for thickness by recalibrating. Use a ground glass in the film plane and adjust the position of the viewing lens (I recall it is threaded in with a setscrew to lock the setting) to match the focus. I think that's what I did.

I'd say with the refraction through the glass and multiple surfaces, the back silvered idea potentially introduces an assortment of complexities best avoided.

DaveT

bnstein · Oct 1, 2008

Edmund scientific is still in business at http://scientificsonline.com and will sell you a 51x51mm front surface mirror for about $5. There are also recipes on the net for DIY silvering. I have an old flexaret that Ive been meaning to get to to look at the mirror as the view is dark, but will leave it on the back burner for the moment!

Uncle Goose · Oct 2, 2008

Ahh, the good old Flexaret! First of all, what type of Flexaret do you have?? If you really want a mirror you can always contact Cupog (search ebay, he's there) and ask if he has a spare mirror lying around. But be sure to know what type you have (if you don't know, post a photograph here, I can tell which one it is by sight).

As for repairs, I only do the shutter and mirror cleaning on the Type II till IVa, I don't mess with the transport either, to many springs and other little bits. The rest of the Flexarets are hard to repair and need a skilled person to do it.

And Oh, I just thought about it, I still have a spare mirror from a busted Type VII, so if your mirror is 55x65mm then I have a replacement for you.

weasel · Oct 2, 2008

Another potential source of mirrors are from old polaroid sx70 cameras. I paid $2 for one at a yard sale, and cut the mirror to fit a rollei with a de-silvered mirror.
I would think that anytime you muck about with the mirror the focus will need to be adjusted.

pgomena · Oct 2, 2008

You can make many adjustments to a camera with a butter knife and save $20 at the camera repair shop.
Camera repair shops charge $40 to fix cameras adjusted with a butter knife.

Front surface mirrors are not difficult to find. Looks like you have some good sources mentioned above. Good luck!

Peter Gomena

Degenetron · Oct 2, 2008

Oh, wow. Lots of good advice here I checked with edmund scientific, but their mirrors seem to be a bit too small for my needs. My mirror is aproximately 46x57x1.6mm (only had a tape measure at hand). A couple of other places i checked had larger mirrors, but they were also thicker. I'll shop around a bit and see if i can find something to cut down or maybe better, drop a few lines to this cupog guy.

EDIT: oh, and i almost forgot.. It would be nice to have it identified uncle goose. I don't have my digi here atm though, but from looking at cupog's ebay store it looks identical to the type IIa, with one exception. the one pictured there doesn't seem to have a self timer lever mine has. It is situated on the right hand side (when facing the lenses) of the lower lens.

Uncle Goose · Oct 3, 2008

Degenetron said:
EDIT: oh, and i almost forgot.. It would be nice to have it identified uncle goose. I don't have my digi here atm though, but from looking at cupog's ebay store it looks identical to the type IIa, with one exception. the one pictured there doesn't seem to have a self timer lever mine has. It is situated on the right hand side (when facing the lenses) of the lower lens.

The Shutter arrangement on the IIa varies because it was made for over 25 years. Some early examples have prontors while later examples have Metax shutters.

Too bad the mirror I have lying around is too big for a IIa. But be sure to post a picture of it when you have your digicam around.

Degenetron · Oct 3, 2008

The shutter speed dial says Prontor SV, so i assume it's a prontor then I'll go pick up my digi later though, and post a pic. I got your email btw, Uncle Goose. However i didn't pay too much attention to the sender name, this-is-a-notification-do-not-reply@apug.org, and replied. This is what i meant to say:

Thank you so much for the offer. Unfortunately, my mirror is 46x57mm
(atleast close to that). After reading through the numerous replies to
the post i see there are quite a few options though, so i should be
able to sort it. But again, thanks

Degenetron · Oct 3, 2008

Ok, got the pic. it's just of the shutter and lens housing as i decided it needed more cleaning and haven't assembled it yet, but the rest is identical to the IIa.

EDIT: Nothing like using a flash to make seemingly clean things look filthy

bnstein · Oct 3, 2008

the other possibility for the mirror is DIY: the amateur telescope guys do it all the time. It looks like a fiddle, but if there is no other alternatives .....See eg Dead Link Removed

DIY Meopta Flexaret cleaning.. Didn't go so well ;p

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