How do you focus?

Wilky76

Wilky76

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I much perfer to use the AF-ON button to focus, than the half press way, it took me a while to get use to it but now comes second nature to me.

The AF-ON way work better if you shoot any moving action in varible light as it doesn't lock the exposure until that shutter button pressed.

Much better way in my book.
 
I find that feature of the D300 works very well for me too, once I discovered it!
 
I have recently started using the M mode and find that this is the best way to 'lock' the exposure.
Takes a bit of practice to get it right and I am still making plenty of errors but I am definitely getting some better results.
 
Does that only work without image stabilisation?

I have to press half way for the IS to kick in .......... I think.

John
 
Viking said:
Does that only work without image stabilisation?

I have to press half way for the IS to kick in .......... I think.

John
Click to expand...
IS should be active just by looking through the view-finder. I can't see it making any difference but I may be wrong.

How do you use the AF-ON button exactly? And what's 'locking up the exposure'?
 
Sorry guys but "locking the exposure","AF-ON" ever thought of sticking the thing in ,manual mode as we used to do in the film days to get our shots of those pesky backlit Dinosaurs
 
I use a rangefinder patch or a loupe on ground glass :thumbs:

I use the * button on my 5d though and then tweak with manual focus if I need to
 
I either do it all the normal way or if I'm waiting for the right moment in terms of focus I'll use the * button to lock the exposure and then AF when the time's right.
 
Kryptix said:
IS should be active just by looking through the view-finder.
Click to expand...

The IS lenses I've used all require a half press of the shutter button to activate the IS system.

To answer the OP's question I still use the half press method but I've not had the 40D long, however changing to the AF-On method is one of things I plan on trying out.
 
I use the AF-ON button, much better results for continuous focus in motorsport...

However a word of warning to fellow Nikon users, if you have a VR lens and for some reason VR is switched on, the AF-ON button does NOT activate VR - you still need to half press the shutter release to get it spinning up...
 
Kryptix said:
IS should be active just by looking through the view-finder. I can't see it making any difference but I may be wrong.

How do you use the AF-ON button exactly? And what's 'locking up the exposure'?
Click to expand...

AF-ON is nikon.

But for Canon there is a custom function that allows you change how the * button works

How does IS know you are looking through the viewfinder? You have to press a button to activate it...
 
RichardtheSane said:
AF-ON is nikon.

But for Canon there is a custom function that allows you change how the * button works

How does IS know you are looking through the viewfinder? You have to press a button to activate it...
Click to expand...

AF on, is a button on the newer Canons as well. I use the * to focus on my 5d and 400d. Massive benefits for me over using the shutter release to focus.
 
Ah yes, I remember looking at the new grip for my 40D and seeing that. Thanks for pointing that out.
 
RichardtheSane said:
How does IS know you are looking through the viewfinder? You have to press a button to activate it...
Click to expand...
If the camera is on, IS is working... Surely? Without touching anything, if I look through the view finder it's very still. If I switch IS off it all goes mental.
 
Kryptix said:
If the camera is on, IS is working... Surely? Without touching anything, if I look through the view finder it's very still. If I switch IS off it all goes mental.
Click to expand...

Nope, if that was the case the IS would be drawing power from the battery constantly, as IS is quite power hungry your batteries wouldnt last long.

You can hear the IS spin up when you press the shutter half way.
 
Yeah, my bad -- just tried it. Always wondered what that whirling sound was!

I guess I must have been holding it extra still and thought IS was on.
 
Never really gave it a go until I read this thread - works brilliantly doesn't it?

CaptainPenguin said:
Sorry guys but "locking the exposure","AF-ON" ever thought of sticking the thing in ,manual mode as we used to do in the film days to get our shots of those pesky backlit Dinosaurs
Click to expand...

I shoot in manual most of the time – a leftover from my medium-format and 5x4 days - but have recently started using AV and even P and the half-press is pretty reliable. Manual is great until the light changes and then you have to faff around, not good in a hurry. Great for landscape though
 
I changed a few weeks ago to using the back button to activate AF on my 40Ds. I've now switched the AF-ON and * buttons over so that AF can be activated on the grip when shooting vertically. Now I've got used to it, I'm finding much better than having AF activated by the shutter release button. I can manual focus without flicking the switch or the focus changing when activating the shutter. Also, I can disengage AF when something comes between me and the subject so the lens doesn't start hunting.
 
I'm sorry guys I think I'm being a bit dense here.

What problem with using a half pressed shutter is solved by the AF-ON button?

-Rob
 
OneTen said:
I changed a few weeks ago to using the back button to activate AF on my 40Ds. I've now switched the AF-ON and * buttons over so that AF can be activated on the grip when shooting vertically. Now I've got used to it, I'm finding much better than having AF activated by the shutter release button. I can manual focus without flicking the switch or the focus changing when activating the shutter. Also, I can disengage AF when something comes between me and the subject so the lens doesn't start hunting.
Click to expand...


snap this is the way mine is set up :thumbs:
 
hyakuhei said:
I'm sorry guys I think I'm being a bit dense here.

What problem with using a half pressed shutter is solved by the AF-ON button?

-Rob
Click to expand...

I fail to see why as well.:shrug:
 
Yv said:
soooo...if you shoot everything manually as I do mainly, apart from focus, the AF-On button isn't really a huge advantage then?
Click to expand...

You still need a half press of the shutter to activate the meter though if you use it. I find having metering and focusing separate helps at times. Also as OneTen said; you can manual focus without having to switch AF off.

You also effectively get AI servo and one shot focussing without having to switch between them, as you can release the focus anytime you want and still shoot.

Edit: Half of that had nothing to do with what you said :D sorry.
 
reddeathdrinker said:
Because the half-pressed shutter button locks the exposure as well
Click to expand...

I don't know about the D300, but that's not the case on my D50. I can half press the shutter button and the camera meters according to where I point it, continuously adjusting the exposure accordingly.

The same thing happens with the few other DSLRs I've tried too.
 
I'm happily using the * to focus on my 450d. It seems a lot more logical and intuitive than having the shutter button do both focus and meter, especially when you may well want to focus and recompose etc.
 
I don't think that a half press will lock the exposure on Canon or Nikon unless you've fiddled with the custom settings.

My D300 is set up to focus priority shutter - that means that it won't take a photo without an AF confirm. I've recently switched to using the AF-ON button for focusing and I find that it provides a useful separation of concerns. Another useful thing about my setup is that its now incredibly unlikely that I can accidentally snap some shots by knocking the shutter release.
 
OneTen said:
I changed a few weeks ago to using the back button to activate AF on my 40Ds. I've now switched the AF-ON and * buttons over so that AF can be activated on the grip when shooting vertically. Now I've got used to it, I'm finding much better than having AF activated by the shutter release button. I can manual focus without flicking the switch or the focus changing when activating the shutter. Also, I can disengage AF when something comes between me and the subject so the lens doesn't start hunting.
Click to expand...

dreameruk said:
snap this is the way mine is set up :thumbs:
Click to expand...

Its the way i have it set up as well and i have moved the focus select to the Dial so that i can use my thumb to change it with the grip, find that quicker than pushing the focus select button and then the top dial. Its seems quicker as i change focus points more than i change apertures.
 
Half press shutter button to gain focus and keep it pressed to lock it, exposure varies as I recompose.
Back button set to lock just exposure until I press it again.
That way I can choose to lock just focus, just exposure or both.
 
hyakuhei said:
I don't think that a half press will lock the exposure on Canon or Nikon unless you've fiddled with the custom settings.
Click to expand...

I don't think it does either and it's easily checked. When I half press to focus on the sky then swing round to point at the carpet, the focus remains locked but the meter resets exposure.

I just don't "get" AF-ON. It seems to introduce an action for thumb and forefinger where a half-press does the same action with the forefinger.
 
I've had a good look at this and come to the conclusion that on a Nikon at least, the button only serves two functons. In fact, the D300 manual could not be more clear "pressing the AF button has the same effect as pressing the shutter release button half way".

The AF-ON button is useful in only two circumstances:

1. If the MD-D10 battery pack is used, the AF-ON button can be configured to the same functions as the AE-L/AF-L button i.e. exposure lock etc.
2. In LV (live view) when set to tripod mode, focus cannot be set with the shutter release button at all. It can only be set with AF-ON.

Outside these modes it is virtually superfluous. Unless of course, people feel more comfortable using it, then that's their choice.
 
Jim B said:
I don't know about the D300, but that's not the case on my D50. I can half press the shutter button and the camera meters according to where I point it, continuously adjusting the exposure accordingly.

The same thing happens with the few other DSLRs I've tried too.
Click to expand...

Same with the 450D, i dont get why you would use the button unless you wanted to stop it focusing for a moment.
 
OK,

so how do i re-program the AF-ON button and the * button?

I want to have a go and see what all the fuss is about :)
 
Take a look at this series of videos presented by one of Canon's Engineers, each video lasts about 35 minutes and gives a real insight to Autofocus.


http://www.video.bhphotovideo.com/

when arriving at this page type "Canon Autofocus" into the search box, you will then see 3 videos about this subject.

I watched all 3 last night and decided I am still better off using manual focus as I have always done, less faffing around.

John
 
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