fotoman150 wrote:
I don't want to use autofocus points! I just want to focus on the center and recompose. I was shooting a wedding a week ago and I was using the Mark III for the second time. I focused on the bride during the ceremony with the groom slightly out of focus in the distance and every time I try to recompose the camera would refocus on the center autofocus point.
I had to switch to my old camera because I couldn't deal with the Settings during the ceremony. What are the proper settings for auto focus that will allow me to focus just on the centerpoint and recompose and shoot. I can't find any straight answers online anywhere and no luck in the search function here. I even bought a book on the instructions and there is only talk about using the different focusing points
I don't want to use autofocus points! I just want... (
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It sounds as if you've selected Single Point AF and manually selected the center AF point (using the joystick or other controls).
There are two ways (at least!) to do focus and recompose technique:
1. Use "One Shot" focus mode. That's designed for stationary subjects only. As soon as focus is achieved, AF stops and locks, and the camera gives you Focus Confirmation (green LCD in the viewfinder, an audible "beep" if you have it enabled... which I do because it alerts me when I'm in this focus mode... some cameras also can give confirmation by briefly flashing red either the active AF point or the entire display in the viewfinder, which can be enabled or not on many models that have it.) The "problem" with One Shot is that if the subject or you or both move... if the focus distance changes at all for any reason... the camera can't respond. It's focus remains locked for some short period of time or until you release the button and reapply pressure on it.
2. Use "AI Servo" focus mode AND Back Button Focusing. This mode is designed for continuous focusing and tracking of moving subjects. It never stops and locks, until you stop pressing the button. Without Back Button Focusing it's impossible to use focus and recompose technique because the AF will refocus on the background or whatever, as soon as the AF point is moved off the subject when you recompose. With BBF, you
disable AF control at the shutter release button, so that it's only controlled by the AF On button under your thumb (optionally can swap the function of AF On and */AE Lock buttons, if preferred). Then you can start and stop AF any time you wish, using your thumb. Takes a little practice, but soon becomes second nature. This allows leaving the camera in AI Servo all the time, ready to use with either stationary or moving subjects.
AI Servo with BBF is a sports/wildlife photographer technique, but can be used for almost anything with reasonably high degree of precision.
For really critical focus, such as close portraits with shallow depth of field effects that need to be extra precise, you still might want to switch to One Shot and select a single AF point that's exactly where you want the camera to focus.
Note: There are settings that a.) give the joystick direct access to AF point selection (normal/default you have to press the AF selection button in the upper RH corner of the camera first) and b.) set up the joystick so that pressing ("clicking") it causes the AF to immediately return to a pre-determined point (most people set this as the center point). If these are set up on your camera, bumping the joystick can cause the AF point to switch.
Note: DO NOT use AI Focus... a third possibility besides One Shot and AI Servo. AI Focus actually not a focus mode at all. It's sort of "point n shoot" automation where the camera is supposed to decide for you whether or not the subject is moving, then switch to AI Servo or One Shot, whichever the camera "thinks" is appropriate. In my experience, this sometimes works well... other times it doesn't or causes a slight delay or fails to respond correctly if a stationary subject starts moving... or a moving one stops. I avoid it, if for no other reason, because it gives up a lot of your control over AF.
Note: Many zoom lenses today are "varifocal" designs that don't maintain focus when zoomed. This is done to allow more compact, lower cost designs... more complex "parfocal" designs that maintain focus are less necessary with today's high performance AF systems. HOWEVER, varifocal zooms can cause problems if using One Shot: If you focus, then zoom the lens to a different focal length, the image will no longer be focused correctly.... unless you remember to release the button fully, then reapply causing the lens to re-focus. Instead using AI Servo with BBF solves this possible problem too... Continuously updated focus when running AI Servo will instantly correct any loss of focus caused by a varifocal design lens being zoomed. You might test any zooms you're using, to see if they are varifocal or parfocal designs. It's easy to tell with a couple test shots. Just focus on something normally and take a shot... then zoom the lens without any effort to re-focus (turn off AF, if necessary) and take a second shot. Check to see if both are in focus, or if it shifted after zooming.