Disabling 580EX Flash (To use AF assist only)

[jcw122]

OK, I was wondering...

Is it possible to somehow not use the flash, but use teh AF assist beam in the 580EX? I'm looking to get a new lens soon, and my selection may not have amazing AF, and I wanted to use it in low-light, so I was hoping the AF assist beam could help me out.

Thanks.

[begovics]

Try to set it as master, and then disable the master flash. It will only pre-flash and AF assistant will work normally.

[Echo63]

Try to set it as master, and then disable the master flash. It will only pre-flash and AF assistant will work normally.


it still pre flashes doing that though

i tried to do this yesterday with my 580EX and a borrowed 400d in the nocturnal house of the perth zoo. (read that as no flash or bright lights)

i just set the flash to manual, 1/128 power and covered the head with gaffer tape (3 layers stopped the light coming through)

when i did this the 400d (with 50f1.8, 1600ISO) acted funny, in AV it flashed 1/4000 - f22 so i just shot in manual - f1.8 and whatever shutter speed i needed (it varied between 1/15 and 1 second) and used a monopod braced against the guide railing to take the photos

[begovics]

I don't know if the option with 'master' will screw up camera measurement with Av or Tv mode, but with option 'off' it will do it for sure. NEVEC (http://photography-on-the.net/forum/showthread.php?t=107588). Someone in 'Small Flash and Studio Lighting' will be able to help more here.

[jcw122]

Oh crap, thanks begovics, I didn't realize this wasn't in the proper section.

[Jim G]

custom function 7 on the 20D is flash firing - set it to "off" (1) if there's a similar one on your camera. the 580EX will not fire but the AF assist will. No preflash.

[Jim G]

Hmm. Okay, I was just looking through dpreview's site and no such custom function is listed for the 350D.. Maybe there's another way to do it.

[jcw122]

Hmm. Okay, I was just looking through dpreview's site and no such custom function is listed for the 350D.. Maybe there's another way to do it.

Darnet, that's too bad, I'd play with the Custom Funcs right now myself, but my rechargable batteries for the 580EX are all dead (these things go SO fast even when not in use)

[Jim G]

Darnet, that's too bad, I'd play with the Custom Funcs right now myself, but my rechargable batteries for the 580EX are all dead (these things go SO fast even when not in use)

I just had a look through the 580EX custom functions as well and I can't see anything in there that would help you... Good luck with that. Might be a good excuse to upgrade ;)

[Curtis N]

Set the flash in manual mode at 1/128 power and point it straight up or backwards. It won't create enough light to affect much.

[jcw122]

All right thanks guys, at least a higher Canon DSLR has the feature to turn the flash off, so the feature exists, just not with my camera lol.

[René Damkot]

Setting flash to manual will not allow you to use Av, Tv or P though. Setting flash to 'master-master flash off' will. You will still get a preflash though. And NEVEC. Only way around it is turning your flash on, focus, turn the flash off, shoot. Alternatively, get an ST-E2.

[Jim M]

Is it too dark to just use manual focus? Hang around inside until you regain your visual purple and you might be able to see well enough to differentiate sharp from fuzzy.

[Curtis N]

Rene', I understand your point about NEVEC, but I don't understand this statement.Setting flash to manual will not allow you to use Av, Tv or P though.In P mode it will throw the shutter speed to 1/60 so that might not be a viable option, but Av or Tv should work, as long as you account for NEVEC.

[René Damkot]

If you set Manual on the flash, Av will max out the shutterspeed (1/200; 1/250 or 1/8000s depending on camera model and whether HSS is used)
Tv will flash a 'closed all the way' aperture at you, P will do both.
If the flash is set to 'M', so must the camera. Pretty annoying and stupid behaviour from Canon.

[Curtis N]

annoying and stupid behaviour from Canon.Ah yes. I had forgotten about how that works, since I use that combination of settings so rarely. And I agree with your sentiments.

[jcw122]

Is it too dark to just use manual focus? Hang around inside until you regain your visual purple and you might be able to see well enough to differentiate sharp from fuzzy.

I already have a Split Focus Screen in my 350D for old school manual focusing, it's very helpful, but it's difficult to use in low light, for me at least.

I'm not even totally sure the AF assist beam will help considering my expected working distance, I wanted it for small bands (like HS rock bands) photography at small shows.

[begovics]

custom function 7 on the 20D is flash firing - set it to "off" (1) if there's a similar one on your camera. the 580EX will not fire but the AF assist will. No preflash.

And no NEVEC. Just tested.

[eelliott]

To get AF Assist without flash, set CF03=1 on the 580EX. This works on my XTi and I think it should work on any Canon body which is incapable of TTL.

CF03=1 forces the 580EX to TTL mode (rather than E-TTL II mode) which causes the flash not to fire when mounted on an E-TTL II body. But the AF Assist light works.

I've only tested in Av mode.

Only slightly off topic:

o I haven't found a solution for the 430EX (which was one of my reasons for buying the 580EX). The 430EX does not support TTL mode, so that is not an option. My other idea was to set it to Slave mode (thinking that it wouldn't fire without a Master to command it), but the flash fires anyway. The only other 430EX approach that I've seen around the web is to insulate some of the hot shoe contacts. I included this off-topic stuff in case a searcher is debating between the 430EX and 580EX. Another option is the ST-E2, which, while more compact and less expensive than the 580EX, did not appeal to me because of its reduced capabilities. For $139 more ([$369 - 2 x $15 rebate] - $200), the 580EX includes the flash and additional wireless range (as I recall).

o My old 430EZ works similarly (AF Assist without flash) because it only supports TTL. But the thought of carrying around a large extra flash whose only purpose is AF Assist didn't appeal to me.