Just wander if there is any translate.

All I want to know in other wards at what point (iso) i should use light on camera.

At the point where the disadvantages of on-camera light outweigh the disadvantages of image noise from that particular ISO.

I routinely take my 5D to 1600 and 3200; rarely 6400, and almost never 12,800 if I can help it.

Just wander if there is any translate.

6db is one stop. Doubling the ISO setting is like increasing gain +6db. ISO 100 is most similar to (but the same as) 0db gain.


All I want to know in other wards at what point (iso) i should use light on camera.

It's a subjective choice influenced by composition, white balance, spectral balance of the light, and picture profile settings. But I don't see what that has to do with your first question.