580 Targeting Problems in Dark Venues

[sapearl]

Perhaps I'm overlooking a simple control panel feature on the 580ex, but I'm wondering if anybody else runs into this situation during weddings in dark churches or other low light situations.

At the start of each ceremony I'll do processional photos. These are the individual photos of each couple as they march down the aisle to the front of the church. I understand how the 580 needs to "see" the subject before it fires. That is, in poor light it will paint the target with the vertical red LED bars so the camera (5D here) has something on which it can properly autofocus, and then tell the flash to fire.

In really dark churches, it will take the flash a couple of attempts (one or more presses on the shutter button) before it is satisfied and fires. I realize it looks for differences in contrast, etc.

For these shots I've got the camera set to M (about 1/30 sec at f/8) with the flash directed head on, Auto ETTL for the flash. I always end up with a nicely exposed shot - eventually - but sometimes the target couple will have traversed several feet before the flash will fire. This used to me simple with my old MF film rig and 20 Megaton Metz - just manually prefocus, aim and fire. A direct hit every time :lol:

Is this one of those situations where I need a "preflash?" Thanks. - Stu

[PacAce]

No, a preflash is not going to help you here. By preflash, I'm going to assume you mean using FEL.

There's no reason why you can't apply the "manually prefocus" technique with your 5D and 580EX flash. You can use the AF system to prefocus at a spot ahead of time, then set the lens to manual focus (MF). With the lens in MF mode, the camera will fire every time you press the shutter button without it needing to wait to achieve focus. It's assumed that the lens already is in focus.

Or, if you set C.Fn-4 to 1 or 3, you can use the "*" to prefocus and then let go of it. Since your focusing won't be linked to the shutter button, the camera won't try to refocus when you press the shutter button to take the picture.

[René Damkot]

No. This is an AF 'problem'. The *camera* won't fire before AF is achieved. Just do as you always did; Manually prefocus and fire away....
Not sure about the 5D, but the 1D series are known to take an awfull long time to achieve AF with a speedlights AF assist beam. (the red pattern). The 20D is quicker in the same situation... :rolleyes:

[sapearl]

Thank you Leo - this helps my understanding much more, having only used the 580 for about 6 months.

I guess I've grown a little lazy and "auto-focus dependent" in my old age ;) . With my MF equipment the lens was pretty sizable with a large, easy to see and read distance scale. Well, that's not quite the case with the scale on the 24 - 105L and many other Canon lenses. But the solution is easy enough to try out at my next wedding.

With the way things happen so quickly at this point in the wedding, I think I'd be a little more comfortable with your first suggestion, as opposed to the Cf alternative. All in all though, these are excellent suggestions and I appreciate it. - Stu

........There's no reason why you can't apply the "manually prefocus" technique with your 5D and 580EX flash. You can use the AF system to prefocus at a spot ahead of time, then set the lens to manual focus (MF). With the lens in MF mode, the camera will fire every time you press the shutter button without it needing to wait to achieve focus. It's assumed that the lens already is in focus.

Or, if you set C.Fn-4 to 1 or 3, you can use the "*" to prefocus and then let go of it. Since your focusing won't be linked to the shutter button, the camera won't try to refocus when you press the shutter button to take the picture.

[sapearl]

I don't have any experience with the 20D or 1D Rene, but I've always felt the 5D had pretty quick autofocusing.

The main problem is that sometimes I'll be centering on a groomsman wearing a dark suit, in a dim church or hall, with very flat lighting contrast. Basically this is really lousy lighting. I can see the AF assist painting the target repeatedly, but apparently it's not happy with level of contrast, or lack thereof.

Eventually the beams will intersect a contrasting edge of suit or bridesmaid dress and the flash will fire before I get run over by the advancing couple :lol: . - Stu

No. This is an AF 'problem'. The *camera* won't fire before AF is achieved. Just do as you always did; Manually prefocus and fire away....
Not sure about the 5D, but the 1D series are known to take an awfull long time to achieve AF with a speedlights AF assist beam. (the red pattern). The 20D is quicker in the same situation... :rolleyes: