Re: Replacement of PX625

["Bingen, Marc" <BMA@trasys.be>]

I found information about the topic on the Canon FD Mailing List
(I suppose it is the same for Minolta, Nikon ...)
I add some extracts hereafter. The remark of Chris Robertson seems
to be the most interesting approach.

Marco

 ------------------------------
Greg Tims (gtims@IX.NETCOM.COM)
Sun, 04 May 1997 09:11:49 -0700

John Y. Liu wrote:
>
> At 11:55 AM 5/2/97 -0400, you wrote:
> >
> >Original (mechanical) F1:
> <snip>
> >Uses the (no longer available) PX625 mercury batteries.
> <snip>
>
> Are there substitutes, e.g. Wein? Or since I hope to get a old F1 >
someday and am currently in Europe should I stock up on mercury
> batteries before returning to the US?


Older Canon cameras (F-1, FTb etc.) used a PX-625 1.35 volt mercury
battery to power the meter. The nice thing about the mercury batteries
was they provided CONSTANT power over their lifespan and then just died;
meter readings remained consistent throughout. Several years ago,
evnironmental legislation in the United States banned mercury batteries
for photographic use (Dentists can still fill your teeth with mercury
based Amalgam but we can't use mercury batteries in cameras; go figure!)
Existing stocks of batteries can be sold until depleted (which they
almost are.) Countries other than the US still have mercury batteries
available to them. Canon recommends a Wein Zinc Air Cell battery as the
direct replacement for the PX-625 mercury battery.


The following are the options for the older Canon cameras using the
mercury batteries:


WEIN AIR CELLS: Wein manufactures "air cell" batteries that directly
replace the old mercury batteries.
Problem: expensive and short life (about once every 1 to 2 months at
about $8.00 a pop.) You can extend battery life by removing the battery
after each use and placing a piece of tape over the two little holes in
the battery - air is the catalyst that makes this battery work and
exposure to air causes slow discharge.


ALKALINE: The PX 625 mercury battery is 1.35v whereas current
alkaline/air cell batteries are 1.5v. You can use the 1.5v battery but
the metering accuracy will be off by approximately 1-stop underexposure.
OPTIONS:


(a) Buy up someone's existing supply of PX625 mercury batteries and hope
you outlive the inventory.


(b) Adjust your film ISO/ASA to compensate for approximately 1-stop
underexposure when using a 1.5 volt battery.


(c) Adjust your exposure to compensate for approximately 1-stop
underexposure when using a 1.5 volt battery (assuming you did not adjust
ISO/ASA addressed in option (b) )


(d) Canon Camera Repair Techs can modify/adjust the camera's meter to
work accurately with the 1.5 volt batteries. Two quotes I had were in
the $60 range for meter modification if that was the only work to be
done on the camera. Both sources said they would do the modification as
a "freebie" during a CLA (cleaning, lubrication and adjustment) which
runs in the neighborhood of about $140. The metering accuracy will
still degrade, however, due to the alkaline's SLOW DEATH syndrome!
("1.5->1.4->1.3->1.1V ... to death" I suppose - Marco)


(e) C.R.I.S. Camera Service (who does Canon F-1 repairs by the way)
developed a product called the MR-9 Adapter. Its a little "sleeve" that
allows use of 1.5v alkaline batteries in cameras requiring 1.35v mercury
batteries. At first glance, it appears expensive ($29.95 plus $1.50
shipping) BUT it is cheaper over the long run than constantly replacing
Wein Air Cell batteries. It is claimed that this product provides
constant voltage over the battery's lifespan similar to the way mercury
PX625 batteries operated. Phone Number for C.R.I.S. Camera is
1-800--216-7579 and their WEB site is at http://www/criscam.com
Disclaimer: I have absolutely NO affilitation with this company.


Hope this helps somewhat.

 --
Greg Tims
Gig Harbor, WA  USA
gtims@ix.netcom.com

 --------------

Chris Robertson (crobertson@STIC.NET)

I have an adapter for using 1.38v zinc air hearing aid batteriy (675) in
the F-1. These batteries are the same thickness but smaller diameter
than the PX625/PX13. The battery fits into the adapter which makes it
the perfect size.


The batteries are cheap and you can find them anywhere. A pack of 6 is
$5.99 at the local drug store! They are labled as 1.4v but are actually
1.38v. The only drawback is you have to wait about 30 minutes after
pulling the tab off the battery to reach operating voltage.


I got the adapter from a guy at a camera show for $10. If anyone is
interested I can try to find his card to contact him.

 --
Chris Robertson
San Antonio, TX