The Lightmeter FAQ
Underneath. Unscrew with a coin.
What kind of battery does it use?
See here about that
How does it work?
Mechanically, it is a wonder of design. The film speed selector has "bumps" on it, which hit a lever, which causes the entire meter to swivel.
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INFO
> K-3 Manual (pdf)
> K-3 Videos
> FAQ
> Tech Info
> Lightmeter Info
> Lens Mount
> Disassembly
>> Front
>> Inside
> Assembly
>> Inside
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ACCESSORIES
TimeFlow
Intervalometer
Lightmeter
Battery
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OTHER NCS
WEBSITES
intervalometers.com
> Arri
> Bolex
> Eyemo/Filmo
> Film Resources