minimum shutter speed with flash

[sulla]

Dear all!

Just a quick question: I set my 5D3 to a minimum shutter speed of 1/125, autoISO, and this works for non-flash photography in Av and P mode.
Putting a speedlite on it, the camera overrides this and drops the shutter spped slower (1/60 or slower). (I know this is how it is ment to be, according to the manual. I find this a strange behaviour, though.)

Question: Is there a way to enforce a minimum shutter speed with a flash on in P or Av mode?

Thanx, Sulla

 

[candc]

go into the menu section for flash and change the sync speed. i think it is 1/200 min for the 5diii. if you need faster than that then set the flash mode to "hss" (high speed sync) you can then shoot at faster shutter speeds

 

[Ian_of_glos]

When you are using AV mode, by default the camera assumes that you want the background to be correctly exposed as well as your subject. If you are using ETTL then this will calculate the correct flash power so your subject is exposed correctly. The 5D mk3 then leaves the shutter open after the flash is fired until the background is correctly exposed. Personally I find this behaviour rather annoying because the shutter can remain open for a very long time, but the 5D mk 3 does allow you to set a faster shutter speed by changing the "flash sync speed in AV mode" setting. You can choose either the camera's sync speed (1/200) or a shutter speed between 1/60 and 1/200. Please note that if you use either of these options then it prevents you from using High Speed Sync on your flash - because you are not allowing the camera to use a shutter speed that is faster than 1/200. If you are using AV mode then you can only use high speed sync if you set "flash sync speed in AV mode" to auto.
Using Manual rather than AV will give you a lot more control over your exposure and you can set a shutter speed that exposes the background the way you want it to look. You can still use ETTL to expose your subject correctly.

 

[JonAustin]

When you are using AV mode, by default the camera assumes that you want the background to be correctly exposed as well as your subject. If you are using ETTL then this will calculate the correct flash power so your subject is exposed correctly. The 5D mk3 then leaves the shutter open after the flash is fired until the background is correctly exposed. Personally I find this behaviour rather annoying because the shutter can remain open for a very long time, but the 5D mk 3 does allow you to set a faster shutter speed by changing the "flash sync speed in AV mode" setting. You can choose either the camera's sync speed (1/200) or a shutter speed between 1/60 and 1/200. Please note that if you use either of these options then it prevents you from using High Speed Sync on your flash - because you are not allowing the camera to use a shutter speed that is faster than 1/200. If you are using AV mode then you can only use high speed sync if you set "flash sync speed in AV mode" to auto.
Using Manual rather than AV will give you a lot more control over your exposure and you can set a shutter speed that exposes the background the way you want it to look. You can still use ETTL to expose your subject correctly.

+1

When not using flash, I find myself shooting in Av mode most of the time. But if I want to expose a dark background in Av mode with flash, I'd better be using a tripod.

I have found it's just easier to shoot in Manual mode when using flash most of the time, because you set all the variables as you want them, rather than leaving those decisions to the camera's program. The exception is when I'm shooting in bright light with flash (i.e., to prevent shadows under hats, in eye sockets, under noses); in those situations, I'll use HSS in Av mode.