Contax 139Q Blackout Fix?

[cz23]

I talked to Nippon about a 139Q issue and they suggested the body is probably not worth repairing. So I thought I'd ask here about a DIY fix.

What happens is that sporadically the VF blacks out after pressing the shutter. Press the shutter, the shot appears to be taken OK, but the VF remains dark.

If I jiggle the lens in the mount it frees up and is good for shooting again. As far as I can tell this does not happen when a lens is not mounted.

Appreciate any thoughts on this. Thanks.

John

 

[KoNickon]

So the mirror remains in the up position? And the shutter closes properly? Maybe not worth troubling yourself with further, if jiggling the lens in the mount cures the problem.

But you shouldn't be able to jiggle the lens -- there should be no play at all in the lens mount. Have you made sure the screws on the mount are tight?

Sorry if these are obvious things that you've already tried. Just want to make sure the basics are covered.

 

[p.giannakis]

What lens are you using? Have you tried any other lens to see if it still occurs?

 

[cz23]

KoNickon, thank you.

Isn't the mirror being stuck the only thing that could cause blackout? It's odd because when I jiggle the lens and it frees up, I don't hear mirror slap. I hear only a faint sound, more like the "snick" of an M.

As far as the "jiggle," there really isn't significant play in the lens. Just the act of trying to rotate it does the trick.

John

 

[cz23]

What lens are you using? Have you tried any other lens to see if it still occurs?

I'm using the Planar 50 1.7, which is the only lens I have for it.

 

[splitimageview]

Could be the lens, could be the camera. See if you can try a different lens. The stop down mechanism in the lens might be gummed up, preventing the mirror from returning to normal viewing position.

 

[sevo]

Is it a real blackout? If so, there is a issue with the mirror lockdown. If the lens is merely stopping down on its own, it will be the aperture coupling - and might be lens side. Does it happen with different lenses?

 

[cz23]

Is it a real blackout? If so, there is a issue with the mirror lockdown. If the lens is merely stopping down on its own, it will be the aperture coupling - and might be lens side. Does it happen with different lenses?

Thanks. I don't have another lens but will try to locate one. Yes, I think it's an actual blackout. However, like I said, I don't hear mirror slap when I move the lens and it frees up.

John

 

[Jake Mongey]

Heres what i would recommend before anything else, remove bottom plate clean and lube then tighten screws on lens mount and see if you can lubricate the mirror box parts. I dont know what the contax is like but a bit of lube goes miles in any cmaera

 

[FrankS]

My Hasselblad does that after every exposure. 😉

 

[FrankS]

Seriously though, try firing the camera without a lens attached and watch what happens. Report back.

 

[splitimageview]

Take the lens off, stop it down to f/16, move the stop down lever so the lens is wide open (against the spring tension), and then let go. Does the lens stop down instantly or is it sluggish?

If it's sluggish, the problem is the lens. If it stops down instantly, the problem is in the camera.

 

[cz23]

Frank, it works fine without a lens.

splitimageview, it stops down instantly.

Jake, I'll give that a try tonight.

Thanks again, everyone.

John

 

[msarkki]

If it works without the lens you might be experiencing mirror slippage. Glue that holds the mirror on its holder gives up and mirror slides down on its holder over time. Finally it slides so badly that it hits back of the lens. It can go up but will not come down until lens is detached. Mirror should not be extending over edge of the holder. This issue is not uncommon with contaxes and yashicas.
Easy fix is heating the mirror holder a bit from backside to soften the glue, carefully pushing/sliding mirror back on its holder and securing it with a tiny drop of e.g. Super glue on to mirror/holder front edge.
Proper fix is to take mirror out and glueing it back.

 

[cz23]

If it works without the lens you might be experiencing mirror slippage. Glue that holds the mirror on its holder gives up and mirror slides down on its holder over time. Finally it slides so badly that it hits back of the lens. It can go up but will not come down until lens is detached. Mirror should not be extending over edge of the holder. This issue is not uncommon with contaxes and yashicas.
Easy fix is heating the mirror holder a bit from backside to soften the glue, carefully pushing/sliding mirror back on its holder and securing it with a tiny drop of e.g. Super glue on to mirror/holder front edge.
Proper fix is to take mirror out and glueing it back.

Thanks, I'll look at that carefully tonight. The mirror is set back a bit from the mirror stop edge, and there is no give at all when pressure is applied to the front of the mirror.

The strange thing to me is that if I jiggle the lens to clear the blackout, there is no mirror slap. If the mirror was stuck up, you'd think its release would be obvious.

John

 

[FrankS]

Nothing comes into the viewing path but the mirror to cause a blackout.
Sticky aperture blades would greatly dim the viewfinder if set at f11 or 16, but not a total blackout.

 

[cz23]

Nothing comes into the viewing path but the mirror to cause a blackout.
Sticky aperture blades would greatly dim the viewfinder if set at f11 or 16, but not a total blackout.

Yeah, I agree the mirror has to be sticking sometimes. Playing a little more, I see any tap on the camera releases it. I'll try some of the suggestions here.

John

 

[msarkki]

Thanks, I'll look at that carefully tonight. The mirror is set back a bit from the mirror stop edge, and there is no give at all when pressure is applied to the front of the mirror.

The strange thing to me is that if I jiggle the lens to clear the blackout, there is no mirror slap. If the mirror was stuck up, you'd think its release would be obvious.

John

Yes, evenwhile the mirror has slipped, it does not really give at all unless you apply some heat to it.
When you release the lens, you will practically gradually free some space so the mirror does not get released from its topmost position, thus the "slap" could be pretty minor. If you can post or send private message of a picture of the mirror up against the prism (e.g. shutter open in "B") I think it could be seen whether mirror has slipped or not.

Tolerances are really small, I had a 139's little sister, Yashica FX-D, which worked fine with Yashica 42-75 lens but not with Zeiss 35-70 lens. It seemed that Zeiss lens protruded just that little amount more towards the mirror chamber that it revealed a slightly slipped mirror. And if I recall correctly mirror is hinged in such a way that it can be pushed back a bit when it is raising up. Thus it will go up but will not freely return back to correct position.

I think the other options are either a mechanical failure on mirror mechanism or a sticky mirror damper foam on mirror box ceiling. However these should cause issues regardless the lens is attached or not. Thus I would still bet my money on a slipped mirror.

 

[cz23]

Just a quick update on this issue. Last night I lubricated the mirror hinge mechanism and worked it quite a bit. Ken Hansen once told me to use sewing machine oil on a sluggish Rolleiflex aperture dial, so I had some of that. It seems to have helped a lot. Enough so that I loaded a roll of film and will see how it goes.

The mirror in upper position does look like it sticks out too far. So if lubrication does not fix the problem, I'll try msarkki's suggestion to heat and re-seat the mirror. From watching a few Youtube videos, it appears the upward mirror movement has much more force that the downward movement. That makes sense and would explain the catch on the way down.

Thanks again for your support.

John

 

[radi(c)al_cam]

May be a silly question, but anyways: May it have to do with the mirror damper? I mean, since the mid-1960s these mirror dampers were made from some sort of foam plastic that is by now usually completely deteriorated and acts like a glue…

edit: I see, msarkki is also suggesting to check the damper.