Canon LTM Canonet 25 battery

Canon M39 M39 screw mount bodies/lenses
I think this should use the P625 mercury, right? There are a couple of ways to go - use a modern alkaline equivalent (P625A, LR9, etc) and reset your asa dial by one stop so that you would set 200asa for a 400asa film. This works, but the alkaline batteries lose their voltage fairly quickly, so the meter will be off in a couple of weeks.

You could have a shottky diode fitted behind the battery compartment and use a modern SR44 with an O-ring. This should give the correct meter reading and silver-oxide batteries do hold their voltage well over time.

Alternatively, you could use a battery adapter that allows the use of the SR44 - there are many of these available from the Cris one at $29.99 to the one I sell to RFF members at £7.50. I think you need to be careful here - the current draw on old canonets can vary dramatically from 20uA to as much as 40mA. The Cris adapter will only handle a maximum of 200uA, which is not enough for most Canonets, it is also around 0.015" too thick for some cameras.

[Start blatant plug] My adapter is capable of carrying 200mA continuous, so is plenty strong enough for any Canonet and all those old light-meters from the 1970's that draw 100 to 150mA. It is also the right thickness (or sometimes 0.005" thicker) so there is no problem with physical size. Finally, it will light the battery test button on a GIII QL17, and not many types will do that. [end blatant plug]

Of course, if the camera needs the PX1a battery (but I think that's only the QL19E and S), you have the same options, but with more problems from the Cris adapter due to current drain. I do one of these too, but they are £10.

Hope that helps.

Regards
John
 
The camera does use the 625 battery and the drain is quite high. I would recommend one of John's adapters.

Regards
Kim

john neal said:
I think this should use the P625 mercury, right?

Regards
John
 
john neal said:
I think this should use the P625 mercury, right? There are a couple of ways to go - use a modern alkaline equivalent (P625A, LR9, etc) and reset your asa dial by one stop so that you would set 200asa for a 400asa film. This works, but the alkaline batteries lose their voltage fairly quickly, so the meter will be off in a couple of weeks.

You could have a shottky diode fitted behind the battery compartment and use a modern SR44 with an O-ring. This should give the correct meter reading and silver-oxide batteries do hold their voltage well over time.

Alternatively, you could use a battery adapter that allows the use of the SR44 - there are many of these available from the Cris one at $29.99 to the one I sell to RFF members at £7.50. I think you need to be careful here - the current draw on old canonets can vary dramatically from 20uA to as much as 40mA. The Cris adapter will only handle a maximum of 200uA, which is not enough for most Canonets, it is also around 0.015" too thick for some cameras.

[Start blatant plug] My adapter is capable of carrying 200mA continuous, so is plenty strong enough for any Canonet and all those old light-meters from the 1970's that draw 100 to 150mA. It is also the right thickness (or sometimes 0.005" thicker) so there is no problem with physical size. Finally, it will light the battery test button on a GIII QL17, and not many types will do that. [end blatant plug]

Of course, if the camera needs the PX1a battery (but I think that's only the QL19E and S), you have the same options, but with more problems from the Cris adapter due to current drain. I do one of these too, but they are £10.

Hope that helps.

Regards
John
Thks for input. After posting the thread, I bought a Duracell 625A which fits the compartment very well, and is moderately priced at about $4.75. I am running the first roll of film thru the camara right now, so I will check the drain after the roll is done. I don't take a lot of pictures, and have reasoned that taking the battery out of the cameras I use Yashikas and Canonet, while time consuming, is the most practical way for me to go right now. I will keep your reply for future action.
Best regards,
bmarkmain
 
John, do you have a web site and/or specs/prices for the adaper? I know a few bods with now defunct 625 kit (OM-1 etc). Some have used the old Rollie/Minox version although not in QL17s

Regards,

Fred
 
Fred said:
John, do you have a web site and/or specs/prices for the adaper? I know a few bods with now defunct 625 kit (OM-1 etc). Some have used the old Rollie/Minox version although not in QL17s

Regards,

Fred

Fred,

I don't have a website at the moment, but do sell adapters to members here at a discounted price of £7.50 each for the P625 and I will shortly be offering a PX1a adapter at £10 each. Both use the readily available SR44 and include UK postage (overseas airmail is extra at £1.50 for up to 5 adapters).

Specs are always a slightly movable feast as I use old battery cases as the basis of the design. The height of adapter plus SR44 usually comes out within 0.005"under to dead on spec for the 625, and within + or - 0.010" on height for the PX1a. Having said that, the diameter will always be right as the case is a 625.

Electrically, I used to supply 3 different types to cater for different uses, but I have now sourced a new diode that should suit all installations up to 200mA, so it will work in high current situations like the Nikon F and old Gossen light meters. This design will always outperform the (expensive) Cris one as his will only handle something like 100uA maximum current due to the surface mount diodes he uses (I know that a QL19E draws 40mA). This also makes his 625 about 0.015" too thick. My design will even light the test bulb on a QL17 GIII and there are not many that will.

The design will only work correctly with a SR44 as the power source and I would advise users to cover the light cell between shots, and remove the battery from the body while in storage to minimise battery drain.

I just got an order from a UK camera dealer, so will be producing a large batch of the 625 model in the next few weeks. I have agreed with him that any orders I get direct from the public will take precedence, and he is happy for me to fill his order as & when I get time.

I will be making a public announcement here shortly when I have taken some pics of the new designs, but feel free to contact me via this email address:- batteries[at]drakes-bottom.co.uk and share it with your friends.

Look forward to hearing from you.

Regards
John
 
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