Av with external flash

[jamlid]

Hi all, new to the forum here - Been a lurker for a while but decided to sign up!

Gear in use is a Canon 400D with kit lens and an Opteka 600DG flash.

I've just been playing around with it in my room and noticed that when using Aperature Priority mode, it will use the same shutter speed of around 3 seconds at ISO100 f4 even if I'm using my external flash mounted or with no flash!

This causes all the pictures to blur tons and is ridiculous. How can I solve this?

I took two identical shots, except one was using Av at f4, the other was Manual at f4 and 1/90th exposure.

The flash was set to ETTL for these.


Am I doing something wrong?

Thanks! This is a great forum!

 

[purpleclouds]

Shoot in P, or manual! Pop it to desired aperture, and a decent shutter speed and let the flash work the rest out...it should calculate how much power is needed automatically!

For wedding work I use f5.6 to f8 and around 1/125 and leave it at that, unless it is a particular shot I am doing which requires otherwise

 

[oldgit]

Nope you are doing nothing wrong. In Av the camera works out the exposure for the available ambient light. If this turns out to be 1/5th then thats what you get. The flash fires as the shutter opens, then for the rest of the time the sensor records whatever else happens, including camera motion. Hence it's blurry.

With flash you need to use Tv or M and faf to get the right exposure

 

[jamlid]

Thanks for the explanations guys