The Bolex H16 RX 5 has a 130 degree shutter opening angle when the variable shutter is all the way open (the lever is all the way up). See below:
The Sekonic L-508 however (and some other Sekonic meter models) assume all cameras have a 180 degree shutter opening angle, a setting that cannot be changed on models like the L-508.
So there is a serious discrepancy here for Bolex users. Below is an utterly confusing excerpt from the L-508 online .pdf manual about how to recalculate for other shutter angles;
Do you understand this? I don't. So I wrote to the US based Sekonic parent company Macgroup and they actually responded, check it out:
Paul:
Instead of this confusing math, we used a Sekonic Cine meter and took a reading with 180 set as the shutter angle until we got an even f/4. Then in the same light adjusted the angle to 130 degrees and took another reading. The second measurement was f.2.8 and 5/10, so your shutter angle adjustment for 130 degrees is one-half stop.
This is a really helpful and easy way to remember the conversion from a light meter that assumes a 180-degree shutter (which is most light meters) to work with the Bolex RX 130-degree shutter. And the one-half stop difference is consistent with the Bolex table which shows the "real" shutter speed vs. the "adapted" shutter speed ... the difference between 1/65 and 1/80 at 24fps is ... one-half stop.
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