5d3 + flash 580 ex behavior

[steliosk]

Hi all
i just bought 5D mark 3, after playing with it a bit, i was satisfied enough BUT here is the snag i hit which is major.

Does anybody of you guys work with a speedlight flash? because the flash changes EVERYTHING.

lets be more specific.

AV program (without flash in the camera)
f/2.8
auto iso 100-25600
min shutter = 1/250

when i put the flash
everything is pretty much screwed!

iso locks to 400 for some reason
the shutter speed disobey the minimum shutter speed (although i can control it through flash control up to 1/60 or 1/200).

i want
auto iso 100-25600
min speed = 1/250
and flash to ttl in order to lit a bit my subjects in front..

any idaes? don't tell me i have to play manually, that scenario is out of the question.. I do weddings.. i can't play with settings during the cemerony, i need something more solid and automated.

 

[steliosk]

the flash is 580 ex II if that helps

 

[Loswr]

The 5DIII has an Xsync of 1/200 s, so unless you use high speed sync you cannot set the shutter faster than 1/200 s. When you attach a flash, Auto ISO is fixed at ISO 400 (count your blessings - older bodies fixed Auto ISO at 400 if you put the camera in M mode!), if you want different you have to manually set the ISO. Note that in Av mode, the camera's meter is setting background exposure, and the subject exposure is set based on the E-TTL II pre-flash.

I highly recommend you read Syl Arena's Speedliter's Handbook.

 

[steliosk]

thanks Neuro,
the major problem is the iso lock to 400
i can't get rid of it in any mode either AV or M

and the worse thing, even when i don't use the flash in e-ttl

somehow the camera locks the iso 400 if a flash unit is connected over it.. doesn't matter the other settings..
if you want to take wide angle shots based in high iso the subject is lit in front from the flashgun and the background goes black with that stupid iso400.

A continuous led light insted of flash probably would save a lot of trouble but even then you'll have to play with the amount of light, (tune up for portraits and tele shooting, tune down when using wide angle)

pffff i got stressed