« on: January 15, 2013, 04:32:42 PM »
no i haven't but i think a pitch black room with no lights on in the middle of the night is pretty much the same thing as far as lighting conditions go.
From what I read the distance of the object lit by the af assist seems to have a significant impact on the focusing ability, next to the lens used... and your "pitch black" setup might sound like a worst case scenario, but not that's necessarily true because in real life the camera has to deal with varying combinations of af and real light.
good point. I was focusing on something about 5 ft in front me. I was able to see the AF beam through the camera because it was so dark and the red really stood out.... and yes, when I say pitch black, I mean pitch black. no street lights shining in through a window... nothing. pitch BLACK.
so anyways, i tested again with as much distance as I could in the same room... the longest dimension of the room is about 30 feet so I just pointed at the wall 30 ft away, even though i couldn't see a damn thing, waited for focus, and shot.... AF worked fine, like I was in a well lit room. the wall was far enough away that I sure as hell couldn't see the AF beam on it. Focus was fine.
I have other thoughts on variables that might be tripping people up:
1) what lenses are we having issues with? I used both the 24-70 2.8 II and the 70-200 2.8 IS II... both at 2.8 when I did my "testing". Maybe f/4 lenses are having a harder time seeing the AF beam in low light.
2) Also, would the color/pattern of what you are focusing on in low light contribute to the camera having a hard time. For example, if the subject was RED in color, or even had something with red tones in it, maybe there wasn't enough contrast between the subject and the AF beam from the 600.
3) Maybe the problem is in the speed lights and not the 5D mk3. Low batteries maybe? maybe without fresh batteries, the AF assist beam isn't bright enough. or maybe some of the new 600 ex-rt units (remember those are new too) have issues
I'm just trying to find a way to re-create the issue that people are having. There's obviously enough of a problem (or two) with this combo that a lot of people are noticing a significantly slower focus speed. I for one cannot re-create the problem. I swear, it's just about as fast as if i was focusing in broad daylight.
Can any of the other people who have the issue reply with the lenses they've used, the subject/color they're shooting, and try it with different speed lights with fresh batteries?
I use the 70-200 f/2.8L IS II and it is the lens I have the most issues with. I have shot 20+ weddings with that lenes two 5D3s and 3 600ex flashes. I have been in a lot of different lighting conditions. What I don't like is that the AF assist beam makes focus worse in most cases. When it is very dark or even black then the AF assist helps and I don't have as many issues. I have found that there are surfaces that absorb more light that make the af assist almost useless. For example if the bride and groom are dancing then I focus on lighter areas like her dress or faces. If I miss and focus on a black tux then there is not hope for the AF assist it is just absorbed by the tux. My problem is that when it is dark but not very dark the lens and camera focus better without the AF assist. I have done it a 100 times where I have attempted focus and the AF assist beam will blink 3 full times before I can get a focus lock. When I turn off the AF assist beam the camera focuses instantly on the same thing in the same light. These lighting conditions are frustrating because it can range to light enough for no AF assist to pitch black and needing the AF assist in seconds and I am stuck messing with my settings and turning on the AF assist for 10-15 seconds. In that time I may have missed something important. Instead I would like to keep it on all of the time instead of switching it on and off. If I leave it on all of the time I am stuck with the frustrating 2-3 AF assist blinks while the camera locks focus. I have found a way around that where I have set the camera up to release priority instead of focus priority so it will allow me to take the picture before the red confirmation blink. 90% of the times those shots are in focus but there is always a chance it isn't and I am afraid that I may miss something important especially at a wedding if I rely on it to be focused before it says it is.