This is my first time learning to use a light meter.

Measuring ambient seems to be working and straight forward. However measuring the flash seems to be broken. I have it set to wait for a flash. When I triggered the flash with my camera, a reading came out. So it seems to have picked up the flash.

So I would get a reading of F/5.6 for example, with ISO3200 and 1/30 shutter speed. It would even tell me that flash is 60% of the light contribution. Seems to make sense but the weird thing is, when I adjust the power of the flash, it doesn't change the readings at all. What am I missing here? I would adjust the power of the flash up and down by 3-4 stops and still nothing.

Everything is in manual mode. My camera was in manual mode, flash is manual power.

I'm using a Sekonic SEL758DR

  • \$\begingroup\$ Are you keeping an eye on the tenths? Since you have a pretty balanced flash/ambient ratio, adjusting down to zero (turning the flash off and just doing an ambient reading) will only bring you down a stop and a bit at most. And going up is similarly limited by the contribution of the ambient until the flash becomes by far the dominant source. (And then it depends on what you're metering; retracting the dome or using the spot means you need to be a lot more careful.) \$\endgroup\$
    – user28116
    Aug 4, 2014 at 14:08

1 Answer 1


I guess I would try a test environment where the flash is contributing 100% (or nearly) of the light instead of 60%. Also, another simple experiment of setting the flash correctly based on guide number and distance (fstop = GN / distance) and taking a test shot, then significantly increasing the power and trying another test shot at the same fstop should result in an overexposed photograph, If it doesn't, perhaps your flash isn't setting the power the way you thing it should. Your meter should result in the same report. Adding ambient light to the equation is just confusing the issue, so try it without any contribution, and use your camera as an indication of the power output of the flash. It's possible that your flash may be telling you that you are adjusting the power, but it itself may be reading the light in the scene and shortening the flash duration to make a "good" exposure. What flash is it?


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