
Normally meters of this kind that I have used are such that the EV figures (the reds 315) correspond to the white/black stripes, such that if the needle points to a particular stripe you can follow the strip up to the corresponding EV number; which EV number you get for a particular needle reading will depend on the DIN you have set on the meter, and every EV number correspond to specific speed/aperture combinations; this is the normal.
These scales look a little bit odd, but should as Bill says, work by correlating the DIN on your film to a stripe which the needle points to, and than read the EV number, or the speed/fstop at the red triangle.
A little bit confused by Fabrizio's EV 15 list. Hasselblads Zeiss lenses all have the EV scale and according to all these lenses EV 15 corresponds to the following list:
EV 15:
15/f:45
30/f:32
60/f:22
125/f:16
250/f:11
500/f:8
If the meter works properly and you point it to a normal contrast view you should get something like 1/125@f/11 or 1/125@f/16 on a sunny day, with DIN 21, as Fabrizio indicates. But that would be EV 14 or EV 15.
/Bertil