Canon F1 battery mod

[Joel_L]

I have a collection of older film cameras I randomly pic up for an outing. Several of them used the mercury batteries of the day. For a while, I had just been using the air hearing aid batteries. These worked OK but do self drain/wear out with time once the seal is removed. They also seem more prone to leaking if you forget about them. There are adapter$ but I never bought them. Years ago I had modified a couple Olympus cameras I have so thought now it was the F1s turn.

The F1 was actually quite easy to do, remove the battery cover and the bottom plate comes off, remove 3 small screws and a sub plate comes off and theres the the only wire you care about. I removed the whole battery holder assembly but the job could also be done with everything in place.

I used a BAT83 Diode to do the voltage drop.

Unsolder the red wire from the battery tab and solder the anode ( non band end ) to the red wire, and solder the cathode ( band end ) to the battery tab. That's pretty much it. It all tucks inside neatly.

A word of caution, the red wire does not have much slack, don't want it to disappear into the body. It seems you also can not pull on it much. When I first finished the mod the meter was way off. When I investigated, I was seeing full battery voltage at the meter. In the end, I added some wire to give some slack and then it worked fine. My service manual does not show how this is wired inside, so I'm not sure what the cause of the issue was, only that loosening things up made it work.

When all was done and working, the F1s meter seems to be with 1/3 stop of an FE2 I compared it to.

I will get out and put a roll of film through it but I expect it will be fine. Now I just use Silver batteries and an O-ring.

 

[Joel_L]

Oops, after posting, I see there is a place for camera mods. I can't see a way to move or delete this, so if a Moderator would move this....

Thanks

 

[flavio81]

Oops, after posting, I see there is a place for camera mods. I can't see a way to move or delete this, so if a Moderator would move this....

Thanks

Instead of commiting the horrid sacrilege of implanting a mundane diode in the sacred internals of the Canon F-1, the most beautiful, best made japanese camera from the 70s, you could just put the o-ring and a #675 hearing-aid zinc-air battery, which gives the correct voltage at all loading conditions, lasts for months, and is cheaper than silver-oxide batteries. May Kwanon (the buddhist goddess of mercy from which Canon got its name) have mercy on your poor misguided soul that sold itself for a bunch of silver... oxide.

Years ago I had modified a couple Olympus cameras I have so thought now it was the F1s turn.

Comparing the lowly OM cameras to the holy F-1!! Another sacrilege!! Repent!!

Just joking; looks like a neat installation. But I do think the zinc-air cells are the best replacement.

 

[Chan Tran]

I don't like the diode for dropping voltage. The voltage is constant only if the battery voltage is constant and neither silver oxide or alkaline battery voltage is as constant as the mercury battery voltage thru its useful life.

 

[M-88]

I wish there was that much free space in OM-1. I tried to mod it, but couldn't fit the diode.

 

[Joel_L]

There is, both OM-1s I have I did inside the camera.

I wish there was that much free space in OM-1. I tried to mod it, but couldn't fit the diode.

 

[Joel_L]

From the cameras I have converted, I have not had an exposure issue, really does seem to work well. May want to select the Diode based on what the actual meter circuit draws ( range ), I like the mod.

I don't like the diode for dropping voltage. The voltage is constant only if the battery voltage is constant and neither silver oxide or alkaline battery voltage is as constant as the mercury battery voltage thru its useful life.

 

[Joel_L]

I have not been happy with the Zinc Air batteries. I used to use them but they self drain and always seemed to be dead when I wanted to use the camera. When you pop a new one in, sometimes they take too long to come up to voltage and be able to supply the current. The internal mods are reversible.

Just joking; looks like a neat installation. But I do think the zinc-air cells are the best replacement.

 

[M-88]

There is, both OM-1s I have I did inside the camera.

Perhaps your resistors were small in size. Or maybe I'm happy with performance of zinc-air battery. I don't really know.

 

[flatulent1]

Nice mod. I had this done to a few FTb over the years, but for my F1 I splurged and bought the CRIS adapter.
(It's not a good idea for me to play with hot tools, I don't have the proper use of one eye and often can't see what I'm doing.)

 

[benjiboy]

I bought two MR9 adaptors http://www.smallbattery.company.org.uk/sbc_mr9_adapter.htm for my two F1n's and they work perfectly even with transparency film.


mr

 

[cooltouch]

I don't like the diode for dropping voltage. The voltage is constant only if the battery voltage is constant and neither silver oxide or alkaline battery voltage is as constant as the mercury battery voltage thru its useful life.

Even though the 675 hearing aid battery may have a relatively short life, it's discharge profile is virtually identical to that of the old mercury cells. At least one comparison chart I've seen shows that it is actually a bit better than the old mercury batteries. This is the best reason I can think of to use 675s instead of going the diode route. Personally, I don't care about the short life of the hearing aid batteries -- not when I can buy a card of 48 of them at Costco for under $10. These days, unless I'm shooting my F-1 on a frequent basis -- which usually doesn't happen -- I just pop a fresh one in before heading out with the old classic. I usually cut out a section of the bubble card the batteries are stored in -- a section with maybe 8 cells -- and toss it into my camera bag so I'll always have a fresh battery whenever I might need one.