I have several questions regarding OCF.
Let's say I use a Metz 48 AF-1, it has a GN of 158. So does that mean on full power it will always be 158, and when I reduce it's power to 1/2 it will be halved to 79?
Also in P-TTL or TTL mode, you have absolutely no way of knowing which GN it is in because it automatically sets the flash based off camera settings for you, correct? So to calculate everything, you need to set flash to manual only?
So let's say I set my GN to 79 to conserve battery power, I would have to do 79 divided by how many feet my subject is away to get the needed f-stop?
So my subject is 15 feet away, I would do 79 / 15 = 5.26. With the number 5.26, I would use a f-stop of f/5.6 since it's closest?
Not sure if this correct, but I believe it is. I'm confused here, help me out! Thanks.
EDIT: What if there are more than one flash? Would I only have to calculate whichever one has the highest GN?
Last edited by LeDave; 02-18-2010 at 04:51 AM.