If I'm not mistaken to find the guide number use this GN= F STOP X DISTANCE in feet AT ASA Ex: Asa = 100 distance = 10 ft f-stop reading = f16 then gn = 160
- Guide Numbers Jake Primgaard
- Terrence L. Markley
If I'm not mistaken to find the guide number use this GN= F STOP X DISTANCE in feet AT ASA Ex: Asa = 100 distance = 10 ft f-stop reading = f16 then gn = 160