Inspection of the front looks like a little piece of ND plastic is missing from the photoresistor opening. No problem, plenty of graded ND available in old control strips.
With a little trial-and-error, I found a piece of film with a density to exactly match the response a newer flash, known to produce acceptable exposures. Linearity is good without having to adjust the internal trimmers; 3ft, 6ft, & 12ft flash distances demonstrate the appropriate 2 stop drop.
Last edited by ic-racer; 09-16-2013 at 07:07 PM. Click to view previous post history.
No, I saw that and am trying to roll it around in this ole noggin.
In novicespeak, does it work well now throughout the range? I guess it's the 2 stop comp you mention that is confusing me?
edit: okay I get it, the distance falloff is what you're saying…correct?
Double the distance between a flash and the meter and it should read 2 stops less for each doubling of the distance. That is the test for linearity of the response; no need for any calibrated light source, you just need an accurate way to measure distance and a repeatable flash.
So, yes it works perfectly.
Again, that was just the linearity test. The cheap-and-dirty calibration involved flashing a known to be good SB-28 Nikon flash, set to non-TTL auto, at various f-stops and reading the reflected value with Vivitar meter set to 'reflected light.' White wall, black wall, gray wall, it does not matter. Distance does not matter either. When the meter read the same f-stop as the flash was set for, it was considered 'calibrated.'
Realize that these inexpensive digital units just are accurate to a single f-stop. This Vivitar branded unit was also sold as Polaris or Shepherd FM800 and Novatron used to market one also:
Last edited by ic-racer; 09-16-2013 at 08:15 PM. Click to view previous post history.