AF assist beam

[tecboy]

I'm having an autofocus issue in low light. I thought about using AF assist beam, but it may distracts a lot of people in night clubbing. I have bought a fast lens and hopefully it will help. Tip?

 

[Derrel]

If you are using flash at smaller f/stops and close range, like say f/7.1 or f/8, with a wide-angle lens, using ONE, single AF point in poor light, your camera might not be able to establish a reliable focus lock on subjects that are low in contrast, or have smooth surfaces. This depends somewhat on the AF module, but my experience is that using a multi-point AF pattern, where more than one AF point is potentially active, allows a modern, high-tech d-slr the ability to use the on-board computer and multiple, active AF points to almost like, digitally map the subject, and get a focus lock FAST...whereas with one,single,dead-center AF point, in poor light the camera just see-saws back and forth, unable to focus.

Again, flash, small f/stop, and depth of field. With cameras that have face-detection AF, or AF area auto-selection capability, the camera's own hardware and software can actually HELP get focus lock when the light sucks. Buuuut, it does that only if it is allowed to. My biggest tip is to test out your equipment, and know what it does well, and where it has issues. There is a pretty big percentage of forum people who continually preach, "Turn everything OFF, and use >ONE< single AF point, the one that's smack dab in the middle of the screen." I really do not agree with that in a lot of situations, since automatic focus is an automated system that can often work better when MORE DATA, when MORE focus readings, and MORE surfaces are read and analyzed. The thing is though, it takes effort to read the manual and to actually LEARN how your camera's various modes work, and a lot of people want an easy, simple answer, so the advice, "Use center point AF only, and turn off allllll the extra features!" sounds like an instant answer. Well-it's not.There are no instant answers. So, again, my biggest tip for you; read up on how your 70D's focusing system can be configured. Learn what options there are, and actually try some of the high-tech features out to get a feel for them. See what the 70D can do with this new, fast lens, in the situations you encounter.

Again, your camera, your lens, your nightclubs. Some of the newer cameras have much better AF modules than what a lot of people are used to. Some people are unaware of how well face detection AF can actually work, and have never once even tried the auto-area AF selection options most cameras have. Many people have never really taken the time to try, let alone learn, how all of their camera's focusing modes work. Even though focusing is supposed to be automatic, or automated, we have a large contingent that constantly say use one,single,dead-center AF point, and that will solve all your problems. I don't think the answer is to convert a modern, AF d-slr into the 2014 equivalent of a 1969 film SLR that can focus on whatever happens to be smack-dab in the middle of the screen.