[johnlam321]

各師兄, 我有問題

body: 450D
flash: Nissin Di622


In P mode, AV+/- = 0 with Di622 flash on, on a tripod, i shot a picture at 18mm, the picture came out with ISO 400, F 5.6, shutter 1/60

then

In AV mode, AV+/- = 0 with Di622 flash on, on a tripod, (same spot, same focus point), shot the picture at 18mm with ISO 400, F 5.6 but the camera use 1" shutter, and the picture is Over.

Why did the camera use a longer shutter when i have the same ISO and F? and the picture is over because of the 1" shutter

Why didn't the camera use 1/60 shutter like in "P" mode before??

[bb1032003]

The different of the P mode and AV mode will depend on your setting of the shutter speed when use flash in the customer function.

The camera meter will just detect the background light when you use AV mode so the shutter speed will be as low as 1 second (because you did not set in the customer function to 'fixed' the shutter speed). The Nissin flash may not be fully compatible with the camera body so the the flash just produce normal output (should be cut down as the shutter speed is so low). You may manually set the flash output to -1EV or even -2 EV to compensate.

See your manual on the customer function setting, and you can try to reduce the flash output as mentioned about before you fixed your shutter speed in the AV mode when you use flash.