Measuring exposure with new fangled cap

[Drew Bedo]

I haven't read all the responses, so I'm sorry if this is redundent.

What about using a focal plane probe? Sinar-six and sinar Booster-1 (for minolta meter) come to mind. The current model is a sinar probe with Broncolor meter.

This would be in-camera metering on your LF camera.

[swmcl]

Hi guys,

I have been testing... but I will also test using the technique of Jim and Andrew.

I will let you know what I find.

Cheers,

Steve

[swmcl]

OK ...

My observations are recorded in the attached pdf.

The conclusions ....

Almost every meter will read the same scene and give the same reading. So too the lenses. They will all pass a very similar amount of light for a given aperture.

So ... the real variable in this setup is the brightness of the ground glass. Mine is a stock piece that came with the Chinese camera. This means that it will not be especially bright.

What I have found is that if I shoot into the sun with a new-fangled white cap on the lens I can take a reading (with the lumisphere retracted) from the centre of the ground glass and extrapolate this reading to a final shutter and aperture combination such that it produces a Zone 1 or Zone 2 exposure on the film. In my case, I need to shoot at 15 stops higher shutter speed than the one suggested from the reading into the sun to get a Zone 1 exposure through a white cap.

Cheers,

Steve