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Canon FTb QL -- Light meter & battery help

Svati Patel , Nov 17, 2006; 10:55 a.m.

I recently found my dad's old Canon FTb QL. When I first found it, the light meter didn't work. I bought a battery at Radio Shack (625A Alkaline I believe) and replaced the old. The light meter still doesn't work. I know the instruction manual says to use a mercury 625. So, I'm not sure if it's the battery or the light meter. Any thoughts? It seems a mercury battery is hard to find.

Svati

Responses

Minh Nguyen , Nov 17, 2006; 11:05 a.m.

The light meter doesn't work, mercury battery 1.35 volt and alkaline battery 1.5 volt are not much different.Either will activate the meter if it work.

Michael Madio , Nov 17, 2006; 11:06 a.m.

The Alkaline battery will make the meter move, but it won't be accurate. Sounds like the meter may be broken, which is a common problem with older cameras.

Michael Axel , Nov 17, 2006; 01:10 p.m.

It could be dirty contacts as well. I know the Canon EF (which I use) has the same batteries, but it also has a built-in voltage regulator so the 1.5v batteries are still accurate. I don't know if the FTb has the circuitry or now. I don't know anyone who makes mercury batteries anymore because of their toxicity, but my EF does fine with the 625 Alkalines. The EF uses two batteries. Is the battery cover seating okay or difficult to screw in? There are probably contacts on the cap and the body side. Clean them with a pencil eraser.

Kenneth Katz , Nov 17, 2006; 01:15 p.m.

Try cleaning the contacts in the battery compartment, they may be corroded. While alkaline battery will produce inaccurate meter readings, there are available alternative (just google "mercury batteries" on Photo.net and you will get a ton of suggestions. I use an alkaline battery as a replacment for a mercury battery, and adjust the ASA setting to compensate for the different results. Not a perfect solution but works for me.

Frank Schifano , Nov 17, 2006; 09:14 p.m.

The meter on my Canon FTb QL with the 1.5 volt battery matches very closely the meter in both my Nikon FM2 and Nikon F3. Both have very good built in meters. You needn't be overly concerned about the voltage difference. If the meter isn't working at all, then something else is clearly wrong. It could be something as simple as dirty battery contacts. If there is evidence of damage from a leaky battery in the compartment, the problem could be worse. You could opt to use the camera without the built in meter. It will function perfectly without a working meter. A good hand held meter can likely be had for the cost of overhauling this camera's metering system and can be used in other applications as well.

Vincenzo Maielli , Nov 30, 2006; 08:31 a.m.

Hi, dear Svati. The Canon FTb QL have an meter switch, near the film rewind lever. Take the switch meter in "ON" position. For replace the outlawed PX 625 battery, use one Weincell MRB625 zync air or the MR9 battery adapter (my preferred solution). The MR9 adapter have a built in micro electronical circuit that reduce the 1,5 voltage of the silver oxyde battery to the 1,35 voltage of the old PX625 mercury oxide battery. Ciao.

Luc Moreau , Mar 18, 2010; 06:30 p.m.

Just got a FTB(n) as well, and the old battery was still in there, apparently it had started to leak a bit. I cleaned the battery compartment using Q-tips and replaced with a new 625A. No joy, needle stayed down. Then I removed the battery again and used a small screwdriver to scratch the electrical contact in the bottom of the compartment. It had some corrosion on it (not immediately visible but enough to isolate the contact from the battery). After that it performs like a charm. I don't think you need to care a lot about the voltage difference, if you shoot negatives (I don't use slide film personally). I'll get my test roll from the lab in a couple of days but the meter readings looked quite appropriate during my shooting test walk.

Christian Muro , Aug 13, 2014; 07:35 a.m.

I recently bought a Canon FTb QL as well, and I recently noticed that the battery was leaking (hence the light meter inaccuracy). The problem is: before I researched the battery type, I removed the battery with my fingers to inspect for corrosion. After researching, I found that there is a possibility that the battery I removed was a Mercury 625. Although I am hoping the previous owner replaced the original battery, should I be concerned about touching a leaking Mercury battery?

Replacement battery options:
1. WeinCell MRB625 (1.35v Zinc Air Battery)
2. MR-9 Battery Adapter + Use of 386 / SR43W Silver Oxide battery (1.55 V)

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