Mamiya Prism Finder question

[lifein2x3]

I've noticed with the metered prism for my RB67 that if I shield the eyepiece with my hand, the needle for the meter will give a different result than if I just put my eye up to the rubber piece. I don't know if my wearing glasses (i.e., I can't mash my face up to the eyepiece to make a light-tight seal) has anything to do with it, but I've noticed that some of my shots have been grossly overexposed. With TTL metering, that shouldn't be the case.

Any suggestions, or has anyone else noticed this to be a problem?

 

[Sirius Glass]

Any prism light meter will be effected by the light coming in the eye piece. If you move your head back the light meter will increase the reading.

That said. The CdS light meter that I had for my C330 was so inaccurate that I used a separate light meter instead.

Steve

 

[lifein2x3]

Any prism light meter will be effected by the light coming in the eye piece. If you move your head back the light meter will increase the reading.

That said. The CdS light meter that I had for my C330 was so inaccurate that I used a separate light meter instead.

Steve

So the results I'm getting by cupping my hand around my eye are more likely to be accurate?

 

[Sirius Glass]

If it makes a difference, yes.

Steve

 

[Dave Miller]

Which form of metering are you using, spot or average? The latter may be more inaccurate where the contrast is high, whilst the spot setting is more selective for shadow metering. Initially I cross checked mine with my hand-held spot meter to find out what the discrepancy is so that I could make any allowance necessary.

 

[lifein2x3]

Dave: my understanding was that it only did average metering. This is the finder I'm using:

Looks like I'll have to start double-checking it again against my handheld meter.

 

[max_ebb]

If the problem was from light getting in the eye piece and causing the the meter to show a higher EV, the result would be under exposed film, not over exposed.

 

[lifein2x3]

If the problem was from light getting in the eye piece and causing the the meter to show a higher EV, the result would be under exposed film, not over exposed.

Which makes me wonder if that's not taken into account. With negative film, it's not as much of a problem, but I shoot a lot of Velvia.

 

[Dave Miller]

Dave: my understanding was that it only did average metering. This is the finder I'm using:



Looks like I'll have to start double-checking it again against my handheld meter.

Sorry to mislead you, it's the newer version that has the spot facility.

 

[lifein2x3]

Sorry to mislead you, it's the newer version that has the spot facility.

Ah, okay. That's what I thought, I just didn't know if I'd missed something.

I have a handheld spot meter, so I suppose I'll have to check the batteries in it and break it out next time.

 

[Dave Miller]

What ever you use, i think it best to stick with one meter, unless you are lucky enough to find two that match; and I never have.

 

[Sirius Glass]

What ever you use, i think it best to stick with one meter, unless you are lucky enough to find two that match; and I never have.

YMMV

My Nikon N-75 matches my Sekonic-L98 matches my Hasselblad PME.

What am I doing wrong? :confused:

Steve

 

[lifein2x3]

What ever you use, i think it best to stick with one meter, unless you are lucky enough to find two that match; and I never have.

I'll have to do some testing, but as long as they're within half a stop, I'm okay with that.