How do you focus?

[trencheel303]

I just twist that focus thingy until it looks right.


Steve.

 

[admirable]

Why use AF-ON?

If you are continually tracking a moving subject (A1 servo) with the shutter button half pressed there is the chance that you could relieve your finger pressure on the button enough to disengage the auto focus without realising.

e.g., if you take a burst of shots and then lift your finger slightly and then take another burst there is the chance you will lift your finger too much hence losing auto focus.

By using the AF-ON button to focus, your constant finger pressure ensures that auto focus is maintained. Exposure is fixed at shutter activation.

 

[JEmerson]

I use a single AF point with no expansion.

I often choose to go with the assist button as the centre poin when held. (great if you need to switch for a second in the middle of action). Then the back button is used for AF-Stop. I do this because I spend more time AF than I would MF. Therefore it makes sense to hold the button for
the least amount of time.

But occasionally I actually switch to traditional back button focus if it suits what I'm shooting better.

 

[bomberman]

If you are continually tracking a moving subject (A1 servo) with the shutter button half pressed there is the chance that you could relieve your finger pressure on the button enough to disengage the auto focus without realising.

e.g., if you take a burst of shots and then lift your finger slightly and then take another burst there is the chance you will lift your finger too much hence losing auto focus.

I don't understand this way of thinking because surely when you press the shutter all the way down again you go through the half-press point anyway

 

[Arkady]

I don't understand this way of thinking because surely when you press the shutter all the way down again you go through the half-press point anyway

The problem there is that if your original target has moved off the original focus-point and is being tracked by the multi-point AF system, the camera may try to re-aquire the subject which may take too much time, thus causing you to miss the shot completely, or worse, re-aquire a different target altogether.

 

[Nifkin]

On my 50D the half pressed shutter sets the AF only, not the exposure meter. Therefore the exposure settings will change as I move the camera around a contrasty scene when I have the shutter button half depressed, whilst the AFstays locked. I have not altered any of the camera's AF settings out of the box to make this happen. I can see the AF-ON button's usefulness for tracking moving subjects, as you don't have to refocus every time you lift your finger from the shutter button. But if I want to use exposure lock when re-composing a picture it's kind of tricky to use the * (AE lock) button and the AF-ON at the same time, so, in that situation I will use a half-depressed shutter button for focussing and the * button for metering in conjunction.

 

[Arkady]

...or shoot in manual mode...

 

[Nifkin]

...or shoot in manual mode...

Yeah there is that, but I'm nowhere near as experienced or as old lol as you, Akela. So, whilst I will shoot in manual when the lighting is consistent, I tend to use Av or Tv (depending on what I want to capture) for when I'm running about the streets. Otherwise there wouldn't be much use for the AE lock button, eh? I don't want to spark a debate about it here, but I think that Av and Tv modes are still valid modes for creative photography if you choose to use them, and use them correctly Anyways, likw I said; I think the AF-ON button is only really useful for when taking action shots where you're tracking a subject and taken a rapid succession of shots.