canon 814 light meter question, don't have mercury batteries

[prograin]

I have a canon 814 that has a light meter that works on two 1.3v mercury batteries which I don't have. Since they don't sell mercury batteries anymore I am using two 1.5v photo batteries. They have the same shape as the mercury batteries but the light meter seems to be detecting more light than what is actually there. I shot some kodachrome 40 on auto and it came back underexposed. I heard that since the two photo batteries have more voltage than the mercury batteries the meter detects more light, so you have to adjust manually, is that so? and second, does anyone know where I can get some 1.3v mercury batteries?

[BolexPlusx]

I don't know what cell this camera takes, but if it takes PX-13 or PX-625 cell you can get a zinc-air substitute that is very close in voltage (1.3V vs 1.27V) These cells have a very limited lifetime (a couple of weeks once you activate them by removing the seal) but the upside is they're pretty cheap and you can find them in most drug stores in the hearing aid section in packages of 5 or more.

The longer life alternative is the MR-9 adapter that allows you to use silver-oxide cells and get the correct voltage, but this is much more expensive.

I ran an experiment with one of my cameras which is designed for two mercury cells in series and found that I registered 1.5 stops higher on the internal light meter when I raised it to the alkaline battery voltage. Opening up the automatic exposure adjustment by an equivalent amount seems to have corrected the exposure (looks good on the screen)

[Hanthx]

Prograin

I shot a ton of film with the 814 and found the similar problem. If you use the 1.5 volt batteries, open up the aperature 1/2 to 1 full stop manually and you should have no problem.

I always thought that there was some amount of light loss to the viewfinder from the lens but that doesn't seem to be the case. Canon calculated for the light loss to the viewfinder so the batteries are the problem. The very first films I shot with the 814 were underexposed about a stop (the same as yours) so...until you find the 1.3 volt batteries, throw it in manual and open it up.

The results afterwards will look great.


Scott

<font color="#a62a2a" size="1">[ December 08, 2002 02:41 AM: Message edited by: Hanthx ]</font>

[Actor]

This site has an article which addresses the problem.

http://home.pacbell.net/mnyberg/super8mm/super8_20.html

I've never had a camera with this problem so I can't say whether it works.

[Frank Houiellebecq]

You can buy replacement batteries PX625 Mercury from euro batteries

[eric_ohman]

If have a chinon 45 and it uses v14px 2.7V batteries. Since v14 isn't available I use two lr9, 1.5v each.

Is it always the same with light meters that they detect more light if they get more V?

The camera has an autoexposure shift. Do you think I shall set it to +1 f-stop or just keep it normal?