Lets say it's a sunny, clear sky day. Sunny 16 rule kind of day. If I meter in reflecting mode, facing north and get a reading of 1/100 @ f16 with filmspeed of 100; Should I be able to turn around and face south and meter again in incident mode and get the same reading?

I'm using a Sekonic L 508c (it really dosen't have a 1/100 sec speed setting, but 125 is close enough). Would I be more accurate to meter off a grey card instead of north sky? It seems like I should be able to turn around and face south and get the same reading in incident mode.

I've tried this but the sky wasen't exactly clear. (some high thin white clouds were present). I don't remember the results, but I remember they weren't the same.

dee