I have a problem using the 540EZ Speedlite with the EOS1V in ONE-SHOT AF mode (but the same problem is with the EOS300 too): the AF infra-red auxiliary light starts each time that I press the shutter speed button, independently from the contrast of the subject.

I think that this light should starts only if the AF procedure needs its help and I don’t understand why it lights every time (disturbing the subject).

The problem persists if, instead of the 540EZ, I use the 550EX (born to be used with EOS3/EOS1V); therefore it can’t be a problem of incompatibility between the 540EZ and the EOS1V camera body.

Is there someone that can give me an answer? (Take note that I perfectly know that using the AI SERVO AF mode the above mentioned auxiliary light is inoperative)

Thank you in advance

Corrado Puccinelli (puccinelli@inwind.it)

-- Corrado Puccinelli (puccinelli@inwind.it), February 03, 2001

Answers

Are you sure subject contrast detemins when the AF assist light comes on?

My guess is that the ambient light level would determin when the light comes on. You wouldn't want the camera first to try to AF, then if it couldn't, try again with the AF assist light. Better to use it when you don't need it than not use it when you do.

Just a guess, I could be wrong.

-- Bob Atkins (bobatkins@hotmail.com), February 04, 2001.

Excuse my ignorance (I don't have a 1v...) but isn't there at least 1 custom function that deals with the parameters of the AF assist light? Or is this function strictly enable/disable. I thought maybe it might be disable/enable if needed/enable all the time. I could be right out to lunch on this one. David Bindle

-- David Bindle (david.bindle@usask.ca), February 05, 2001.