canon 580ex flash

Greywolf123

Is it possible to shut the flash off and still use the 580 for autofocus

ziggy53

Greywolf123 wrote:

Is it possible to shut the flash off and still use the 580 for autofocus

I believe you need the flash on to allow the flash to coordinate the autofocus assist light with the camera.

You can set the flash to manual, power it down to 1/128th, and point the head up or even backwards so that the flash doesn't contribute to the exposure. The assist light will work as you wish. (You could even fire the flash into a blackened hood at 1/128th power without too many problems methinks.)

I am curious why you would want the autofocus assist light with no flash at all?

ziggy53

cmason

The 580 has a setting to turn off the flash entirely, yet still use the focus assist, which on the 430EX and 580EX, use a separate red beam, and not the flash tube itself.

The 580 can turn off the 580 flash so that it can be used as a controller for off camera flashes using Canon's ETTL flash control system. This way, the 580 can provide focus assist, and send settings to other flashes, while not providing flash from the camera direction.

Look in your manual, it is described there.



edit: speling

Greywolf123

ziggy53 wrote:

I believe you need the flash on to allow the flash to coordinate the autofocus assist light with the camera.

You can set the flash to manual, power it down to 1/128th, and point the head up or even backwards so that the flash doesn't contribute to the exposure. The assist light will work as you wish. (You could even fire the flash into a blackened hood at 1/128th power without too many problems methinks.)

I am curious why you would want the autofocus assist light with no flash at all?

ziggy53

I do a lot of work in abandoned buildings with very low light but its really hard to manually focus the camera and with the 580 I can focus in on a subject in a complete darkness.

Has anyone actually done this before because I followed the directions in the manually but it still fires.

Thanks Owen

pathfinder

The ST-E2 IR transmitter works as a focusing aid also. Rather effectively.

I have not tried using a 580ex this way, but I have heard of it.

Mac Swenson

I just got an ST-E2 a week or two ago, mostly for basketball since I dont wan't to/can't shell out hundreds for real strobes. It works great with the 2 580EX's that I have. The only problem i have noticed, is that the flashes have to almost be in front of you,(i think the manual says like 30 degrees to the side at most) or else they wont fire consistantly. But if you have them set up right, it's amazing.

pathfinder

What kind of distances are your 580exs from your shooting position?

It is interesting that basketball is one of the activities that folks complain about the ST-E2 being not very effective.

Many shooters use PWs when shooting in arenas. I know the local college hoops arena is set up to trigger with PWs or a similar device.

Mac Swenson

pathfinder wrote:

What kind of distances are your 580exs from your shooting position?

It is interesting that basketball is one of the activities that folks complain about the ST-E2 being not very effective.

Many shooters use PWs when shooting in arenas. I know the local college hoops arena is set up to trigger with PWs or a similar device.

Most of the time, they are slightly a in front of me, and off near the corner of the base line, I will shoot from various spots on the baseline, and the farthest one of them could be would be about 30 feet. I have had better results by turning the flash so that the IR receiver if pointing slightly backwards towards me, but the head of the flash is pointing out where i need it. I would love to get a set of PW's and some real strobes, but since i mainly do outdoor sports, and my glass tends to be long, I think i will buy some more indoor/super low light glass first.

xris

Greywolf123 wrote:

I do a lot of work in abandoned buildings with very low light but its really hard to manually focus the camera and with the 580 I can focus in on a subject in a complete darkness.

Has anyone actually done this before because I followed the directions in the manually but it still fires.

Thanks Owen

Not sure what camera you're using, but my guess is that if it's in a Full Program mode it removes your control and fires the flash anyway. On the Canon SLRs that means setting to one of the letter modes rather than the 'pretty picture' modes (i.e. use P, T, A etc instead of mountain, flower, head, etc.)

pathfinder

Program Mode in the EOS cameras, with flash, is designed to permit handholding so the shutter speed will not go below 1/60th I believe.

EOS flashes work much better in Av, Tv or Manual mode for most purposes.

1 Series cameras do not have the little mountain, little head, little flower choices, of course.......

Greywolf123

I'm using a Canon 20d and I just want to use the 580 kind of like a ST-E2 just to help me focus in very low light I followed the instructions in the manual but the flash still fires

pathfinder wrote:

Program Mode in the EOS cameras, with flash, is designed to permit handholding so the shutter speed will not go below 1/60th I believe.

EOS flashes work much better in Av, Tv or Manual mode for most purposes.

1 Series cameras do not have the little mountain, little head, little flower choices, of course.......

cmason

Greywolf123 wrote:

I'm using a Canon 20d and I just want to use the 580 kind of like a ST-E2 just to help me focus in very low light I followed the instructions in the manual but the flash still fires

Read the manual..you will note in fine print that is says that with the 580 set on master mode,with flash off, it fires a pre-flash, not the full flash. The pre-flash is what the camera uses to judge the flash requirements for the shot. The shutter opens after the pre-flash, so this flash is not being used to light the scene. Even if you use the ST-E2, the flashes will fire a pre-flash.

Rhuarc

Just a quick question, do the other Canon flahses (ie, the cheaper ones) allow you to do this as well, use the flash as AF Assist? I'm trying to figure out which flash I'll be getting to go with my XTi.

Trasmc

I use a 430EX on a 20D - I'm assuming the 580 works the same way. In order to use the "infrared" beam for AF assist in low light without the flash firing, I set my camera Custom Function 7 (Flash Firing) to 1 (Does not fire). The flash will use the focal assist feature, allowing the camera to focus, and then will not fire when the shutter is depressed.

Have fun!

chet79

Rhuarc wrote:

Just a quick question, do the other Canon flahses (ie, the cheaper ones) allow you to do this as well, use the flash as AF Assist? I'm trying to figure out which flash I'll be getting to go with my XTi.

I too would like to know. I have a 430ex. Also - can the on-board flash be used to focus (but not fire)?

BenA2

chet79 wrote:

I too would like to know. I have a 430ex. Also - can the on-board flash be used to focus (but not fire)?

The ability to use the flash for autofocus, but not to fire for the shot, is set by custom functions and is not a limitation of the flash unit itself. The 20D/30D line on up have the custom function needed to disable the flash, but use the infrared focus assist lamp. The Rebels (XT/XTi) do not.

P.S. This limitation caused me to buy the ST-E2 for natural (low) light focus-assist. Ironically, what really happened is I went back to using flash, because I could use it off-camera, producing much better results.

pathfinder

BenA2 wrote:

The ability to use the flash for autofocus, but not to fire for the shot, is set by custom functions and is not a limitation of the flash unit itself. The 20D/30D line on up have the custom function needed to disable the flash, but use the infrared focus assist lamp. The Rebels (XT/XTi) do not.

P.S. This limitation caused me to buy the ST-E2 for natural (low) light focus-assist. Ironically, what really happened is I went back to using flash, because I could use it off-camera, producing much better results.

I have suggested the ST-E2 for getting the flash off the camera several times, as the lighting is just so much better.

It is worth repeating. Thanks, Ben