Canon 40D AF assist lamp question

[rhodeislandguy]

As I understand it, the 40D uses the on board flash as an AF assist lamp. (In contrast to the Nikon 80D, for example, which has a separate lamp.) Can the Canon's flash be set to "off" while still being able to use the AF-assist lamp? I'm considering buying this camera in part to take photos in museums which typically do not allow flash, but often have low lighting levels that may require the use of an AF-assist lamp. Can any Canon owners help me out with the answer to this?
Thanks!

[griptape]

Unfortunately, no, you can't use the af lamp without raising the flash, and you can't "turn off" the flash when it's up. Your only option is to open the flash, get your focus, close the flash, and take the picture. It's a royal screw up in design that should have been addressed 3 generations ago, but hasn't.

[rhodeislandguy]

Unfortunately, no, you can't use the af lamp without raising the flash, and you can't "turn off" the flash when it's up. Your only option is to open the flash, get your focus, close the flash, and take the picture. It's a royal screw up in design that should have been addressed 3 generations ago, but hasn't.


Bummer! Guess I'll have another look at the Sony a700!

[nqjudo]

You most certainly can turn off the built in flash when it is up. Refer to page 103 of the manual. By setting flash fire to 'disable' in the flash control menu, you can use the flash AF assist without the flash firing for the shot. This also works for external speedlites.

[griptape]

You most certainly can turn off the built in flash when it is up. Refer to page 103 of the manual. By setting flash fire to 'disable' in the flash control menu, you can use the flash AF assist without the flash firing for the shot. This also works for external speedlites.

My mistake. This isn't possible with cameras prior to the 40D is it? I've been very misinformed if it is.

[D Thompson]

My mistake. This isn't possible with cameras prior to the 40D is it? I've been very misinformed if it is.
Yes, it's possible with the 20D. Custom function #07 set to 1 (flash does not fire).

[griptape]

A dedicated flash assist not attached to the flash would still be nice, but I'm glad to know it's not as big of a screw up as I had the impression it was. Maybe I should ask people if they've read their owner's manual before taking their experiences as truth.

[GaryS]

The problem still exists however. If you are in a place where flash is not allowed, you cannot use the pop-up flash assist, because the assist works by using the flash.....

A speedlite's assist works with a red lamp, which is usually fine in a museum...

[fractalgfx]

You can also get IR assistance with an external flash.

[coldrain]

You most certainly do NOT have to use AF assist light in any museum. AF assist is for when it is DARK, not for lower light situations....

I have even used the Sigma 18-50 f2.8 EX DC on my EOS 350D in various museums, not a combination that will want to focus well in the dark. And I have not had ANY problems what so ever.
And they were not the most well lit museums either!
What will be of use in a museum (muccccch more in fact than AF assist) is IS.
So... on a 40D a Canon EF-S 17-55 f2.8 IS USM or the new very improved kit lens EF-S 18-55 f3.5-5.6 IS USM will be very welcome in museums.


In fact, you will get in trouble in museums with Nikon AF assist light... the light is very visible. So... do not worry about this in connection with the Canon EOS 40D. It will perform fine in museums.

If you buy good lenses you will even never need AF assist in the dark (night)... tele lenses may start to hunt a lot, but tele lenses can not be helped by AF assist light anyway.

Example for you from a very dark museum in Athens, where the objects were lit with not very bright light at all (to protect the ancient treasures from light influences of course), taken with my EOS 350D with Sigma 18-50 EX DC, at ISO 800, 40mm, 1/50th sec, f4.0:

[nqjudo]

Hey Coldrain. Was that shot taken at the National Archaeological Museum of Athens? I was there just before the closure for the pre-Olympic renovations and they were absolutely strict about no pictures, flash or not.

[coldrain]

I have been in 3 archaeological museums in Athens. I think the national one, was fine about photographing, just not with flash.
This one is a different museum, about the cycladic islands.. I forgot its name. And there (non-flash) photography was also allowed. A 3rd with lots of iconic art, did not allow any photography. Which I can understand, ALWAYS you find idiots that flash "by accident" anyway.

I did ask about if I could though. And they probably did recognize it was a DSLR, and not a compact camera... so they did trust me not to flash.

[Chatt69chgr]

I am a neophyte digital camera user having recently purchased a 40D. I ran into this problem with the flash at a museum. I had no idea how to turn it off and also didn't realize that the on board flash worked with the AF Assist in low light levels. I read the replies above but am still confused. It appears to me that if the camera is in autofocus mode and you are shooting in sufficiently low light levels then the flash will pop up and be actuated to provide AF Assist. If I understand the replies above, use of a sufficiently "fast" lens will allow the camera to gather sufficient light even in "dim" conditions to AF without the flash firing to provide AF Assist. But, if I want to guarantee that the flash will not fire, then I need to follow the procedure in the 40D manual to disable the flash. I assume that, in this case, I would need to shoot using manual focus. Is this correct? Also, there was discussion on using the external speedlight. I have the 580EXII. Does it have some method of accomplishing the AF function without firing the flash---something about a red light? I am asking because I would like to be able absolutely guarantee that the flash would not fire if I was in a museum where they didn't allow flash. I would hate to be escorted out for breaking museum rules. Thanks.

[24Peter]

To turn off the in-camera focus assist, go into the menu "C.FnIII AF-assist beam firing" - set to either "disable" or "only external flash emits".
To insure the pop up flash doesn't fire, use a mode other than full auto (green rectangle) or other than one of the other special modes. (In P, Av, Tv, or M the flash won't fire unless you manually pop it up.)

[Chatt69chgr]

Thank you for the reply 24Peter. I'll certainly give your suggestions a try.

[Rhys]

I use the STE-2 for non-flash focussing. The problem is that it's a clunky great big thing that should have been built into the camera on the pentaprism where the Canon logo is situated.