Battery for Canon 7s

[Fausto]

I recently picked up a 7s with a 50/1.2 lens. This baby is quite heavy, and I haven't heard such good things about about the lens but it's lovely & I'm really looking forward to trying it out.

So does anybody know which battery I should use for the meter?

 

[John Shriver]

If you have a real mercuric oxide PX13 or 625 battery, use that. Otherwise, any of the mercury battery substitutes, such as a 675 zinc-air hearing aid cell (plus O-ring), a Wein cell, or the C.R.I.S. adapter for silver-oxide batteries.

The one thing not to use is the carbon-zinc 625 batteries. Just won't be accurate at all.

There is much information on the whole mercury battery substitution problem out there on the web.

 

[venchka]

The 50/1.2 lens is one of a kind. Use it. Enjoy it. If you love it, keep it. If you hate it, sell it to me.

 

[jlw]

So does anybody know which battery I should use for the meter?

If you really plan to use the meter, save yourself some headaches and buy the MR-9 adapter from C.R.I.S. This will let you use a currently-available silver oxide battery.

Incidentally, in case anybody is thinking of it, don't get the idea you can "adjust" the camera to use an alkaline battery. Per the factory service manual, the Canon 7s metering system has NO "pots" for electrical adjustment. If the meter's sensitivity is too high, the manual advises painting small dots of paint inside the diffuser; if its sensitivity is too low, you're supposed to chip a slightly larger hole into the mask using a needle! I'd say the cost of the adapter is worth it to avoid this procedure!

 

[Fausto]

Phooey. Looks like I'm going to have to get an adapter for the old Gossen Super Pilot as well. Maybe I should just break down & buy a digisix.

Do the adapters have to be replaced in time?

Thanks for the advice, by the way.

 

[colyn]

The C.R.I.S. MR-9 adapter is a waste of money. It's based on the Germanium diode which will allow more current to flow through as a result of higher (summertime heat) ambient temperature and current flow heating it up.

Go to http://www.colyngoodson.com/manuals.html and click on the battery adapter link and download it. If you don't want to make the adapter yourself you then will need to buy the Wein cell 625 zinc air battery to get proper voltage

 

[venchka]

I use a pair of Wein zinc-air batteries in my ancient Gossen Luna Pro. They work fine. The voltage exactly matches my mercury cell 625 batteries. The Wein cells have been in my Luna Pro since last October. They are still going strong. I have no reason to doubt that they will also work in the Canon 7s.

 

[jlw]

The C.R.I.S. MR-9 adapter is a waste of money. It's based on the Germanium diode which will allow more current to flow through as a result of higher (summertime heat) ambient temperature and current flow heating it up.

Erm... all that aside, the MR-9 does work fine in a Canon 7s.

But hey, if it's a question of principle, by all means download the 11 pages of instructions, order the kit of parts from the guy in the Netherlands who wrote the instructions, block out an afternoon of your time, and go to it.

 

[DrLeoB]

Wien cell from Ritz Camera, about 5 bucks, works great in my 7s... exposures are dead on...

 

[outfitter]

I use a pair of Wein zinc-air batteries in my ancient Gossen Luna Pro. They work fine. The voltage exactly matches my mercury cell 625 batteries. The Wein cells have been in my Luna Pro since last October. They are still going strong. I have no reason to doubt that they will also work in the Canon 7s.

I have run my Luna Pro for years on a pair of 675 zinc-air hearing aid batteries (same as Wein with a few more holes) - cost about $0.75 each. You can use o-rings (#9 I think) plus a washer for a spacer if you need to - instead can cut a small section of tubing to hold the two together (haven't tried this yet). Amost all my 1.3v battery needs have been met by these means.

Michael