Another 580ex question!

[Duncan.F]

Hi all,
When I have my flash set to ETTL and full auto on the camera I get 1/60 and F4. If I put it into AV mode at 2.8 in the same conditions I get a much slower shutter speed say 1/10. Why is that?!

Ta,

Duncan

 

[david1701]

because full auto won't drop the shutter below 1/60 and likes the DoF at f4

Av lets you pick aperture and usually keeps the shutter above 1/60 for the same reason, a camera custom function controls that - I don't know which on a 5d

 

[trevorbray]

I expect it's because the camera is evaluating the light without flash. Go into custom settings and change the setting for flash sync in AV mode from Auto to 1/200th. From here I then put the flash in Manual. Set it 1/2 power and go from there. Incidentally if you have an iPhone I reccommend downloading an App called Photocalc. It'll help you work out how much flash power to use.
Hope this helps. Although I'm sure someone on here will give more specific help. For me flash isn't my strong point.

 

[Duncan.F]

Hi,
Thanks for the info! Yes much better with 1/200, but why 1/2 power if you are on ETTL. Doesn't the clever gizmo software adjust out power to suit?

Dunc

 

[trevorbray]

Duncan. I usually have my flash in manual mode. Sorry for any confusion.

 

[Duncan.F]

Duncan. I usually have my flash in manual mode. Sorry for any confusion.

No, I didn't read your post carefully enough! [along with every manual I have ever owned]. Yes I understand now but I am only at the beginning of understanding what a clever bit of kit it is!

Cheers,

Dunc

 

[david1701]

Hi,
Thanks for the info! Yes much better with 1/200, but why 1/2 power if you are on ETTL. Doesn't the clever gizmo software adjust out power to suit?

Dunc

with ettl you need to dial in the right amount of exp compensation for a scene (largely black -ve, largely white +ve)

I have a mate who uses flash in manual all the time, I like ttl on camera as I move about a lot and manual for ocf as its just easier