Originally posted by pschlute Take camera off tripod; attach disc; move to subject position and take reading; remove disc; put camera back on tripod.
I would rather use a light meter
LOL!
In fairness, one would probably measure in the incident light BEFORE putting the camera on the tripod.
And a standalone light meter isn't hassle free either because there's no automatic way to transfer the meter's reading to the camera. Moreover, this filter also measures incident white balance which is something that standalone light meters don't do.
The ultimate incident light meter would be tiny, clip to the camera strap with a carabiner or slip into the hot shoe, and then use NFC, bluetooth, or the hotshoe to send the reading to the camera.
But the deeper issue is that with digital, it's so easy to take test exposures, chimp for exposure, study the histogram, etc. that it really reduces the need for incident readings.