Here's a small note to myself. You can read it if you like.
Today I learned a little bit more about my Sekonic light meter. The Sekonic light meter is supposed to tell me what speed/aperture setting is appropriate for a given ambient light. This is used by photographers to get the correct setting, espcially when you are dealing with films and not digital images. This gets a bit more interesting when you want to get the correct setting for flash photography.
In tonight's test run, at 1/60s shutter speed, the Sekonic was telling me to set the aperture at f1.0. I thought that was quite unusual. Surely I have been doing flash photography at the more usual aperture settings of between f5.6 and f11. Then I remembered that my camera flash was set to to TTL mode, meaning that the flash intensity was automatically adjusted by the camera. It was the same on my SB900 flash, which was automatically adjusting the flash intensity in the auto mode. In fact, in the TTL mode, I don't really need the Sekonic light meter to assist me. I can set the camera speed and aperture at liberty and the camera will automatically adjust the flash intensity. (Note: max sync speed is 1/250sec for flash).
To test this, I changed the flash mode to Manual. Sure enough, the light meter told me to set the aperture at f11 (whereas it was f1.0 before), as the flash was firing at full intensity in the manual mode. The picture came out correctly exposed.