Repairing a Konica C35??

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Jamie123

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I recently bought a Konca C35 on an auction site and there are a couple of things wrong with it. I could've sent it back but I really didn't pay much for it so it wasn't really worth even paying the return shipping.

What bothers me most is that the rangefinder is way off. Is there any way to open the camera and adjusting the rangefinder?

Also, the lens seems to be slightly crooked. I don't know how to describe it exactly but the bayonnet ring is not completely parallel with the focusing ring.

Last but not least, does anyone know what batteries that are available can be used?
 
Jamie: I'm not sure what you mean by the "bayonnet ring"; perhaps you are referring to the filter ring or threads? If so, then no, it is not completely parallel to the focusing ring. If you look at the camera from above and move the focusing ring, you will see it is not always parallel to the camera body. That is normal.

Regarding the focusing, how do you know it is "way off"? I assume you have run some film through and the results were not in focus. Or are you just looking at the distance markings on the lens barrel?

If the RF really is off, then my guess is that there is an adjustment screw somewhere under the top plate, so you'd have to remove the top plate. Be careful, of course, to not break the connection to the hot shoe. I've never had a C35 apart; mine have had spot-on focusing; the lens is very sharp.

There are some helpful disassembly notes on this page

As far as battery goes, it takes a mercury PX675, which are no longer available. You can use a Wein zinc-air substitute, which are somewhat expensive. Also available are zinc-air hearing aid batteries, which are smaller, so need some sort of spacer to seat the battery properly. The other option is to have the meter circuit modified to use silver-oxide batteries. Mercury cells put out 1.35v, zinc air are 1.4 volt, and silver-oxide are 1.55v. This is why you can substitue zinc-air without circuit modification (close enough), but silver oxide you can't do a direct substitution because it will give you about 2-3 stops exposure error. Alkalines are the same as silver-oxide but the problem is worse because alkalines drop voltage more slowly than high-drain silver oxides. So metering can change over time even though the meter is still active, leading you to believe there's something wrong with the camera.
 
In real terms there is no difference in the voltage of a mercury battery, a wein cell or a hearing aid battery. They are share the same chemical reaction. 😉

A Wein cell is a zinc air battery the same as the hearing aid batteries. The only practical difference is that it has fewer holes and so will not produce the same current. It also has a slightly different electrolyte to stop it drying out as quickly. Both these changes mean that that for camera use, you are likely to exhaust the battery before it dries out (about 6 months). The life of the zinc air can be prolonged to almost the same period by blocking off all but one of the holes with nail varnish. 😉

All 3 batteries rely on the oxidation of one of the components. With the zinc air cells, the oxygen is provided by air getting into the case through the hole(s). In a mercury battery, the chemical construction is the same but with the addition of mercuric oxide to act as the oxidising agent. It was this that caused their manufacture to be banned.

Kim

Trius said:
As far as battery goes, it takes a mercury PX675, which are no longer available. You can use a Wein zinc-air substitute, which are somewhat expensive. Also available are zinc-air hearing aid batteries, which are smaller, so need some sort of spacer to seat the battery properly. The other option is to have the meter circuit modified to use silver-oxide batteries. Mercury cells put out 1.35v, zinc air are 1.4 volt, and silver-oxide are 1.55v. This is why you can substitue zinc-air without circuit modification (close enough), but silver oxide you can't do a direct substitution because it will give you about 2-3 stops exposure error. Alkalines are the same as silver-oxide but the problem is worse because alkalines drop voltage more slowly than high-drain silver oxides. So metering can change over time even though the meter is still active, leading you to believe there's something wrong with the camera.
Click to expand...
 
Kim

Does that mean you can vary the voltage of the hearing aid 1.4v cells by keeping some of the hole sealed? Say down to 1.35v 🙂
 
Kim: I did not know about the slight difference in electrolyte in the Wein cell; thanks. But as for the "only" practical difference being that and fewer holes, I was referring to the Wein 625 (or 675) replacement as different in form factor, i.e. it is manufactured to the same dimensions as the original mercury units, and hence are physically just "drop-in" replacements.

Zuik: I think the covering of the holes doesn't drop voltages, only depletion of electrolyte due to drying. Kim?
 
Trius said:
Jamie: I'm not sure what you mean by the "bayonnet ring"; perhaps you are referring to the filter ring or threads? If so, then no, it is not completely parallel to the focusing ring. If you look at the camera from above and move the focusing ring, you will see it is not always parallel to the camera body. That is normal.
Click to expand...

Yes, that's what I meant. I knew "bayonnet ring" wasn't the right expression but I couldn't think of a better one 🙂


Trius said:
Regarding the focusing, how do you know it is "way off"? I assume you have run some film through and the results were not in focus. Or are you just looking at the distance markings on the lens barrel?

If the RF really is off, then my guess is that there is an adjustment screw somewhere under the top plate, so you'd have to remove the top plate. Be careful, of course, to not break the connection to the hot shoe. I've never had a C35 apart; mine have had spot-on focusing; the lens is very sharp.
Click to expand...

Yes, I only looked at the distance markings. Since I don't have a battery yet I didn't bother testing it with a roll of film. However, I can hardly get anything in focus. When the lens is at its closest distance setting (1m / 3.5ft) the rf shows objects to be in focus at about 3m distance.

Thanks for the link! I'm still reading through the page. I haven't quite figured out yet how to remove the advance lever and the shutterrelease but I guess with some experimenting I'll figure it out.
 
Update: Following the link that Trius gave me I figured out how to ajust the rangefinder and it was actually quite easy and didn't require me removing the topplate. Unfotunately, while trying to figure out how to open it, I unscrewed the pc-sync and accidentally broke off the contact. It's not a real problem because I wasn't going to use it anyways but I wouldn't mind opening the topplate so I can remove the little piece that's moving around inside now.
 
Isn't the RF adjustment in the screw under another screw in the back of the camera? I lost a screw in the top plate of my C35 as well, it's somewhere inside I would guess but never found it since.
 
Kat, the adjustment was indeed a screw under another screw right below the viewfinder.

Kim, thanks for the offer but I think I'm ok for now. The shipping to Switzerland would probably be way too high anyway. Besides, I'd still have to figure out how to remove this top plate and I can't for the life of me find out how to do it.
 
thank you greyhoundman! With your description I was finally able to open it so that I can screw the PC plug back on! Now all I have to do is buy a battery and I'll be off shooting with my (first!) rf camera! 🙂
 
Instead of opening a new thread I'm asking this here: Can anyone tell me how long a PX675 usually lasts in a Konica C35? The guy that sold me the C35 on an auction site is sending me a spare one he had around.
 
I'd also like to ask, does anyone have parts for sale? I'm looking for a battery cover in decent shape, and a black film rewind system. There is something wrong with my s3's rewind, the fork is loose so that while I turn that lever around, the film spool doesn't go with it so the exposed film doesn't go back into the canister. I'm thinking the two konica models are quite similar, so maybe I can transplant one from a black C35...
 
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