The guy who said there is no such thing as a dumb question, never read this!

My 2pence worth.
The 70-200 2.8 (IS) has two AF focussing modes on the side of the lens 1.4m to inf and 2.5m to inf. I know you said that your subject is 25m away so this would'nt affect your shooting I supose.
Is your in camera multi AF points set to single or multi focusing?

Thanks all, I have my answer, I think, and appreciate all the help. The Canon 30D can not take a shot in auto focus single shot mode unless it can actually find something to focus on. I imagine as I learn the 580EX there is a way to shoot out some light for auto focus and then it will take the shot. Thanks.
Joe

Joe now hits the unsubscribe button before he begins chasing his own tail.

joegolf68 wrote in post #2316263
Thanks all, I have my answer, I think, and appreciate all the help. The Canon 30D can not take a shot in auto focus single shot mode unless it can actually find something to focus on. I imagine as I learn the 580EX there is a way to shoot out some light for auto focus and then it will take the shot. Thanks.
Joe

Joe now hits the unsubscribe button before he begins chasing his own tail.

Just use the Infrared Assist beam on the flash unit. Geez.

cdi-ink.com wrote in post #2316408
Just use the Infrared Assist beam on the flash unit. Geez.

Great JOB! not reading the OP.

canonphotog wrote in post #2316460
Great JOB! not reading the OP.

The original post was resolved. Now he's saying he can never AF in the dark. Which is not true.

joegolf68 wrote in post #2313877
With the 70-200 I was 25 feet away. It was with room light pointed at a black cat.

I know you probably have a handle on this by now, but even in bright daylight I find it difficult to take a photo of our black cat unless I can focus on his eyes. Being black seems to confuse both our 20D and Pro1.

momentz wrote in post #2318189
I know you probably have a handle on this by now, but even in bright daylight I find it difficult to take a photo of our black cat unless I can focus on his eyes. Being black seems to confuse both our 20D and Pro1.

I have the same problem with photographing Black cats.. First of all I dont have a Black cat and secondly I dont think it would be fair on the cat if I went out and bought one just for photos.

I think Canon should issue a Black cat disclaimer.

so Joe have you got your Sh** together yet!!?? and yup the camera's got to see something with contrast to focus, if you ever get a shot of something black back in the black shadows...show me!!!

joegolf68 wrote in post #2313877
With the 70-200 I was 25 feet away. ... If I am in a totally dark room, with a Speedlite attached, I figured I could still take a picture.

I know the "Can I take a pic when AF fails" question has been answered, but here are some ancillary thoughts.

The 580EX has a stated AF Assist effective range of 0.6-10m (2-32 ft). At 25ft you might have been near the limits of the effective range, especially with a dark non-reflective target (black cat).

The 24-70 may have been able to lock focus where the 70-200 failed because the shorter focal length allowed more of the image in the focus sensor area and therefore better or more numerous contrast edges which makes for a better target for resolving focus.

rippanics wrote in post #2320179
so Joe have you got your Sh** together yet!!?? and yup the camera's got to see something with contrast to focus, if you ever get a shot of something black back in the black shadows...show me!!!

Unreal! Hi Mike! Did you see I gave your name and site to one of the members here? I hope that was ok? I will PM and email also! Aloha Mike.