Super 8 Light meter sensitivity...

[Dcm]

Anyone have a problem with a light meter that seemed TOO sensitive? I recently bought a nice Nizo and loaded it up with new mercury batteries... everything seemed to be working well... I shot a test reel of Plus X with mixed results... everything I shot outside looked fantastic, but indoors, everything was underexposed... not too suprising, of course, I thought I'd been getting good readings indoors (sunlight through windows).

Next I put in a Tri-X cart and indoors, at night, my automatic light meter was giving me a constant reading between 4 and 2.8... under a single 75 watt lightbulb!.... a friend's super 8 camera was of course telling her there wasn't enough light. So I'm wondering if this light meter isn't over sensitive... which will cause me to underexpose everything... thoughts? I must be missing something obvious.

thanks,
dcm

[Santo]

Where could you have gotten mercury batteries? They haven't been made for years and years. My guess is you used 1.5v alkalines which have too much voltage and throws off your readings much like you describe. Switch to either wein cells, or even cheap hearing aid batteries (675) from the drug store work good and last a couple of months in these applications. They closely match the correct voltage of the extinct mercury cells. In old slr cameras they have a shorter lifespan as there is no "off switch" like there is on super 8 cameras to turn off the current draw.

[Dcm]

I'm pretty sure they're mercury... Jim's Camera in Seattle has a decent surplus, and Washington law allows the sale of mercury battery back stock. Naturally they're a bit expensive.

dm

[mattias]

was the lightbulb in the frame? that will throw the meter off immediately, but i guess you knew that...

/matt

[Dcm]

Nope, didn't have the camera aimed at any bulbs. This was a reading off an off white wall. FYI, I looked at the batteries last night... they read "HD625"... which, on some websites I have found to be a Mercury-1.35 volk battery, and on others to be an alkaline 1.5 volt. It should be obvious by now that I know very little about batteries. Maybe I'll try the hearing aid batteries... just to be sure.

Just got a roll of Tri-X back from the lab and... everything is underexposed, as I feared. And yet I distinctly remember getting excellent readings. Dang.

dcm

[francis]

the other problem with the meters in the cameras is the designs.

firstlly, they are composed of two oddly shaped peices of thin sheet metal that slide past each other. over time they can rub next to each other or have points that they get 'stuck'.

there are several types of photocells used in exposure meters in the cameras. some stay consistant over time while others dont.

the best option is to use a sperate handheld meter for the best accuracy

[Patrick]

Taking a light reading from a white wall as you say would cause underexposure for sure.

[Dcm]

Regarding the white wall... me and all of my friends were taking readings off the same wall in the same spot... so while, yes, that would lead to underexposure if we were filming something, we were just comparing the readings. And mine were consistently off...

But... I may have fixed it. I noticed a few days ago that the Tungsten/Daylight Filter knob was not quite switched over to the Tungsten setting... so I pulled it a little further and - tah dah - the light meter opened nearly 2 stops... switching it to the filter opened it almost one more... so beware NIZO owners... if your filter knob is not fully engaged to one or the other settings, the light meter may take incorrect readings...

So... tomorrow I'll get another roll back... we shall see. Thanks all.