What does the filter coefficient read?
It doesn't say on the colored filters :/
Tiffen 8 Yellow 2 (Wratten #8 I suppose) would be a factor 2, so that's a one stop difference. The ZI does that "properly" while the Sekonic says 1/2 a stop.
Tiffen Orange 21 is factor 3 according to Wikipedia, so what's that.. 1 1/2 stop difference? The Sekonic reads that and the ZI too, sort of.
Hansa G53 - have not found any info on that yet. It's 1 1/2 on the Sekonic and two on the ZI. It might be 1 1/2 on the ZI too, I'm not extremely scientific when it comes to testing.
The red though is a Milo 25a, which is a filter factor 5. Where between 2 and 3 stops that would fall is beyond me, but the ZI says two, while the Sekonic says 3. That's a one stop difference between the two...
These are all reflective readings of the same white-ish background.
I don't really care about the different readings from different meters when it's about half a stop, I just didn't know colour would matter the way it seems to.
My confusement remains, when it put the red filter on my M3, should I add two or three stops?