Canonet 28 Battery Question

Clocker · Mar 23, 2012

Do I absolutely need to have the battery in a Canonet 28 to use it?

A relative gave me one to lighten his packing load before he moved to another state.

It has some nice aperture settings and if the shutter speed is not controlled singly by the camera's battery, I for the most part, want only want to use it in natural light without a flash; the auto settings seem kind of weak.

I think this would be a much stronger camera if it could be used only in a mechanical fashion without necessity of a battery alone.

It has an old film roll in it right now that it's former owner used, that is why I am not messing about with it too much and not completely familiar with it yet, but I did replace the battery a short time ago.

Clocker · Mar 23, 2012

The shutter fires, but nothing moves on the exposure indicator in the viewfinder.

I would just like to know if this camera can be used manually, or is it in need of repair since the exposure indicator does not move?

What exactly does the battery do in this camera?

Is it to synchronize flash to the shutter and power the exposure indicator; does it control the shutter speed?

Is is it for all of those controls or more?

Murray Kelly · Mar 24, 2012

The Canonet-28 needs a mercury battery to function properly. Without it the shutter speed is fixed at 1/30th and all you can do is set the aperture. Mercury cells are unobtainium nowadays.

With the cell it measures the light and on 'auto' it will choose a suitable (to it) speed and aperture.

If you put an alkaline or silver cell in there with some sort of ring to keep it central in the battery holder make sure it is not in back to front. The wrong way round will show no deflection of the needle, although no harm is done. Alkaline and silver cells (LR44/SR44) will under expose the film as their voltage is 1.55V and the original mercury was 1.35V. You can try a zinc-air cell like a hearing aid battery which is in between at 1.45V. They last a month or so and the results are better. There are adapters which cost more than the camera. They incorporate a Schottky diode to drop the voltage that tiny bit.

To save drain on the cell always switch the camera off 'auto' between shoots as this disconnects the volts from the cad sulfide light sensitive resistor.

I have recalibrated a Canonet-28 for a silver cell but it's not for the un-adventurous. I don't know your skills with tiny resistors and a soldering iron.

When working they are great little cameras. Good luck.

Jojje · Mar 24, 2012

I used a Canonet 28 (bought cheaply without a manual) in 1990's with a SR44 battery and soon discovered serious under exposure. Well - I thought - the meter has seen better days and compensated using a setting "ASA 25" for ASA 400 film if my memory serves me right. Worked well enough for negative films.
So this puzzle is settled then. The thing might still work properly - there was nothing wrong with the picture quality.

Clocker · Mar 25, 2012

Thanks for the answers and some very nice and useful technical information.

Getting at the electronic innards at this time in my life seems too much trouble. There was a time in the past I built my own radio equipment, fixed TVs etc.

When friends and aquaintances found out I could do these things they always wanted free repairs. I learned to hate fixing electronics because of this. That was many years ago and I have forgotten much of it.

Currently it has an alkaline cell in it, I did not even think of the voltage issue when I asked a merchant for a replacement for this cell, I was just told that that particular cell replaced the earlier type, bought it and placed it in the camera.

I like the simple solution that Jojje mentions.

Murray Kelly · Mar 26, 2012

Well, I got my soldering experience as a ham so we're not too distant there. Have a read of this
http://www.kyphoto.com/classics/siloxidemodify.html
The author leads you thru the mathematical process but I confess I cut a corner or two.
I ended up with 300R in series and 22K in parallel. Worked fine. If I had to do it again I'd try harder for chip resistors.
There is no guarantee your meter would be identical but the odds are it's the same.

Clocker · May 16, 2012

The meter is working now.

I just opened the bottom end of the camera and super-glued the negative contact back onto the plastic part of the battery holder and it now conducts.

I also obtained an adapter that allows me to use 357 type batteries and the meter is working fine.

Looks like I am going to have to replace all the foam light seals as well.

It might not need insulating from the body case because it looks like there is a small amount of non-conductive paint at that area, but should I consider putting some kind of insulating material between the case and the negative battery terminal?

I am also trying to figure out where the battery door leaf spring goes.

I can't find a blow-up schematic of the this particular camera, but I did find one of the G-III 17 which shows almost the same leaf spring and it is placed pressing at the hinge of the battery door on within the lower or bottom camera plate.

Does the battery door leaf spring in the Canonet 28 fit in against the hinge in the same manner?

Murray Kelly · May 16, 2012

Sounds good. If the meter goes just run a strip of film thru to check it out.

Jon Goodman is the guy for light seals. Excellent service and instructions for that camera to boot.

The camera was a RRF 'Pass the camera' project and is now permanently in The Nederlands so I cannot comment about the spring. Sorry.

Jeffrey c nelson · Apr 12, 2019

I'm aware this is an old thread but i found an inexpensive battery adapter that fixes this voltage problem.

https://paulbg.com/Nikon_F_meter_batteries.htm

Jeffrey c nelson · Apr 12, 2019

I'm aware this is an old thread but i found an inexpensive battery adapter that fixes this voltage problem.

https://paulbg.com/Nikon_F_meter_batteries.htm

mklw1954 · Apr 18, 2019

Quote: I'm aware this is an old thread but i found an inexpensive battery adapter that fixes this voltage problem.

https://paulbg.com/Nikon_F_meter_batteries.htm

This adapter is good, I use them, but it does nothing to modify the voltage of the battery used. Put a 675 hearing aid battery in this adapter as a good solution to having 1.35/1.4 volts as provided by the old mercury batteries.

Whomever3454 · Sep 10, 2021

Hey I hope I’m not too late to receive a response.
I’ve recently acquired a Canonet 28 in very nice conditions that I honestly bought on a whim but are now trying to see if I’ll actually be able to use it. My only trouble has been the battery, I was advised that I could use a small 1.35v hearing aid alkaline battery to replace the mercury battery that is originally needed. Can anybody advise if this could be a good fit? I was told that it needed to be a specific one but I’ve encountered a few folks that have said this could do just well.
Thanks in advance

Paul Howell · Sep 10, 2021

I use hearing batteries with all my vintage cameras, most current in a Minolta HI Matic 11. The 625 hearing aid battery fits just fine many such my Konica T3, others need a small O ring to take up space or a bit of folded aluminum if the zinc air is a little thinner. I also put a very small piece of Scotts Tape of one of holes so the battery will last longer, and after finished shooting for the day I take the battery out and put the paper tab that comes with the battery over the holes until I need it.

MattKing · Sep 10, 2021

Whomever3454 said:
Hey I hope I’m not too late to receive a response.
I’ve recently acquired a Canonet 28 in very nice conditions that I honestly bought on a whim but are now trying to see if I’ll actually be able to use it. My only trouble has been the battery, I was advised that I could use a small 1.35v hearing aid alkaline battery to replace the mercury battery that is originally needed. Can anybody advise if this could be a good fit? I was told that it needed to be a specific one but I’ve encountered a few folks that have said this could do just well.
Thanks in advance

Welcome to Photrio.
As indicated above, those hearing aid batteries are actually not alkaline batteries, they are zinc air batteries.
In addition to the approach that Paul Howell mentions, you can also buy relatively inexpensive re-usable adapters that are exactly the right size to both fill the battery compartment properly and insert the smaller hearing aid batteries.
Zinc air hearing aid batteries are sold in quantity and relatively inexpensive, but without the sort of extra steps Paul mentions don't last very long once opened.
There are other types of adapters that allow you to use much longer life silver oxide batteries instead, but for those to work they need to incorporate a circuit to modify voltage.
I use the hearing aid batteries and related adapters in some situations, and the relatively more expensive silver oxide batteries and related more expensive adapters in others.

Canonet 28 Battery Question

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