What I want is a single central focus point. Then I can point to an object and tell the camera "focus here" and be in control myself. The camera is currently in some too smart focus mode where it decides where to focus. So I am focusing on a wildflower and the camera thinks that the right thing is to focus on the ground behind it. Or I am focusing on a large flat circuit board, and the camera thinks that the right thing is to focus on some wires that stick up toward the camera. Smart is good, except when it isn't smart.
I had my Canon 5D set up to just have the focus point locked to the center and was quite happy. A quick fix for now is that I have learned that I can tap the screen on the place I would like it to focus and it does so pretty well. I'll have to use this and gain more experience with it. It may solve all of my problems. I will note that touching the screen and trying to drag does nothing useful. A quick "tap" or touch does the trick.
Someday I'll dig deep into all the various focus modes. Here is a forum discussion that has many suggestions:
We have focus modes -- they tell the camera when to focus.
We have focus area selection -- this tells the camera where to focus.
I have already bought into "back button focus", so my camera does not focus when I partially push the shutter button (which is the normal default). My camera focuses once when I press the AF-ON button on the back of the camera. For someone like me who rarely shoots action and does almost exclusively landscape or macro photography, this is perfect. It does (sadly) bypass all of the amazing servo autofocus modes the camera provides.
Canon apparently calls area selection, the "AF Method" You get 7 (8) area modes to choose from:
OK, OK -- I hear you already, "great, but how do I select which one". It is simple, when you know how -- like so many things.
Press the button at the top right of the back of the camera -- just right of the * button. It has a funny box with + in the middle of it to mark it. When you do this, a menu appears at the bottom of the screen -- for about 4 seconds.
While the menu is up, press the M-Fn button up near the shutter button to cycle between modes.
Selecting 1 point AF seems to give me what I want. I have to remember that it is the * button that I reconfigured for back button focus, not the AF-on button.
However, when you carefully read the descriptions, you find out that "spot" is actually smaller than "1 point". Go figure on that.
I found this comment (by a fellow who shoots concerts) interesting:
I can trust the face/eye detection the majority of the time, but I also use back button focus with face/eye detect on one button and manual point selection on another, so I get the best of both options. So, when the eye/face detect does get it wrong which happens about 10% of the time, I can fall back to the point selection instead without missing a beat.
Maybe I can (and should) configure the AF-on button to do the exact same thing as the * button. Maybe. Or I can investigate doing as per the above and have different buttons for different focus methods.
When I do use the AF-ON button the camera will hunt around, sprinkle green boxes on some object it likes (but I usually don't) and focus there.
Tom's Digital Photography Info / tom@mmto.org