I disable the shutter release button for focus and us the AF button and I almost always use a tripod with remote and mirror up. My question is:
If I press my AF and then recompose the shot and then release the AF button will the camera still stay focused on the spot I want? The manual says the button has to stay pressed. For me that defeats the idea of a cable release that allows you to take your hands off the camera completely. I am a bit confused. Mike
Well, let's take this in 2 steps. When you use the AF button it will focus on whatever you've selected. When you release the AF button the focus does not change from what it was last set on.
Now, when you recompose the focus position still doesn't change but you've introduced the possibility that the point you focused on is not in the same plane as it was when you focused. So for a critical focus situation, like with people or macro, you may need to adjust the focus a little.
The AF button only needs to stay pressed if you are in continuous autofocus mode. And then that's only if you need the AF to be changing.
Ah Yes! I have it now. I usually only use AF when I am shooting landscapes so the object moving out of the plane of focus is not usually a problem. For close ups I almost always use manual focus. Thanks for the information. It is now clear to me
You're doing the right thing Mike. People who use a half-press on the shutter release often can't understand why the focus jumped when they re-framed and made the shot. The reasons usually are: (1) The camera was in continuous focus mode, and, just as it was supposed to, the focus changed as they moved the camera to re-frame. (2) The camera was in single focus mode, but they let up slightly on the shutter button, usually inadvertently and without noticing, and when they mashed the button to make the shot the camera focused a second time.
The beauty of using AF-ON as your only focusing method is that you can leave the camera in continuous focus mode. If you're shooting a static subject, you focus, let up on AF-ON, re-frame, and make the shot (paying attention to what Neil said about the plane of focus). If you're shooting a moving target, say a bird in flight, you keep AF-ON down so that focus shifts as the bird flies, and trip the shutter at the appropriate moment.
It's only with the onset of auto focusing cameras that focus has become confused with shutter release. In manual focus days everybody understood that focusing was one operation, releasing the shutter was another. It still is.
Antero I grew up in a small northern Ontario railway town. Many of my boyhood friends were Finns. It is a region very much like Finland and that attracted then in large numbers. In fact, there are more Finns in Thunder Bay tha any other place outside of Helsinki. One of my early friends was named Reijo so I took it as an online name. Some of my best memories come from those times, especially the saturday night sauna Mike
Your nickname “Reijo” is a very common first name in Finland. Any Finnish roots or a mere coincidence?
As to your question, someone on this forum published a wonderful advice to set the camera to continuous autofocus (AF-C) and set focusing to the AF-ON button only. That way you can alternate among AF-C, AF-S and manual focus/focus lock by 1) keeping the AF-ON depressed, 2) pressing it in single shots or 3) not pressing it all. I told about my own experience in this thread: