AF Assist Beam - help needed

[Chris F]

In preparation for a LOW light shoot I was looking at a few options. amongst others I looked at the AF Assist Beam function of the 7D and the 5D Canon cameras, specifically working with the 580EX II Speedlight.

The owners manuals of the 7D and 5D is most helpfull and in both cases the settings are under C.Fn III, but under diffirent sub groups. The beam was set to ON.

The Speedlight's manual was not as "nice", but still clear to follow. The default setting is for this beam to be ON, checked on two Speedlights.


I experienced the following:
- the 5D worked as expected, while testing at home. At the venue I could not get the AF Assist Beam to fire ...

- the 7D would not work, no matter what settings I tried. Then briefly the on-camera beam on the 7D fire 2 or 3 times, but I could not get it to fire again. At the venue the Speedlights beam fired 3 or 4 times, then no more ...



There is only one way to set up the cameras. But with the Speedlight it can be done ON the flash, or from the camera when the flash is mounted. I tried both options, still no joy.

When using the flash I work in MANUAL mode, but I tried the other modes as well just to see if this will make any difference.

Four different L lenses were used during the tests


Both bodies were bought late 2011, it still has the firmware that it was shipped with.



QUESTION:

Am I missing something, or is there some trade secret to getting this to work consistantly ?

I will appreciate your assistance to get this resolved.

[Anonymous]

For the beam to work AF must be set to one shot or AI Focus. It wont fire if youre using AI Servo.

[Chris F]

Thanks William !

Both cameras are on AI Servo 99% of the time ....


stopped typing, and tested both ... William you were SPOT ON !

[Chris F]

William so this begs the question - what to do in low light with moving objects ?

[Gavin van Dam]

William so this begs the question - what to do in low light with moving objects ?

Ask them to keep still

Jokes aside, this thread helped me as well, couldn't figure out why my focus assist beams when intermitent on Saturday night. I had my camera set in AI Servo

[Chris F]

Gavin glad to see I am not the only one ...


actually the biggest "issue" was that I would take (well try to) a few pics of the venue, dancing etc, then some of the guests would pop in at the make shift photo booth. In the booth I had a constant light source, so every couple of pics I had to change all the settings on the camera ....

TIP - DONT trust your eyes !! When you have been shooting in a dark venue and then walk into a "dimly lit" area you THINK there is enough light, but far from it !

not complaining - this was the biggest learning curve in a while ! (fortunately it was a favour and not a paid shoot)



This experience makes me even more scared of the 2 month old tog with a 500D wanting to do a wedding ....

[Anonymous]

Glad I could be of some assistance.