View Full Version : How do you focus?
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.
Paddysnapper
20-05-2009, 06:48
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
Does that only work without image stabilisation?
I have to press half way for the IS to kick in .......... I think.
John
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'?
dreameruk
21-05-2009, 12:33
yep the af on for me aswell,
focus with back button recompose the shot and fire :)
CaptainPenguin
21-05-2009, 12:40
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
raathistle
21-05-2009, 13:18
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.
sepulchre
21-05-2009, 13:23
IS should be active just by looking through the view-finder.
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.
desantnik
21-05-2009, 13:32
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...
RichardtheSane
21-05-2009, 13:41
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'?
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...
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...
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.
RichardtheSane
21-05-2009, 13:57
Ah yes, I remember looking at the new grip for my 40D and seeing that. Thanks for pointing that out.
How does IS know you are looking through the viewfinder? You have to press a button to activate it...
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.
Steve Smith
21-05-2009, 14:22
I just twist that focus thingy until it looks right.
Steve.
sepulchre
21-05-2009, 14:34
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.
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.
specialman
21-05-2009, 14:52
Never really gave it a go until I read this thread - works brilliantly doesn't it?
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 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
foodpoison
21-05-2009, 14:57
I just twist that focus thingy until it looks right.
Steve.
Steve your dry humour always puts a smile on my face :p
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.
hyakuhei
21-05-2009, 15:16
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
dreameruk
21-05-2009, 15:29
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.
snap this is the way mine is set up :thumbs:
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
:plusone:
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
I fail to see why as well.:shrug:
reddeathdrinker
21-05-2009, 16:44
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
snap this is the way mine is set up :thumbs:
:plusone:
Because the half-pressed shutter button locks the exposure as well, whereas the AF-ON button doesn't...
Because the half-pressed shutter button locks the exposure as well, whereas the AF-ON button doesn't.
soooo...if you shoot everything manually as I do mainly, apart from focus, the AF-On button isn't really a huge advantage then?
soooo...if you shoot everything manually as I do mainly, apart from focus, the AF-On button isn't really a huge advantage then?
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.
Because the half-pressed shutter button locks the exposure as well
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.
Trixster
21-06-2009, 10:43
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.
hyakuhei
21-06-2009, 11:04
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.
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.
snap this is the way mine is set up :thumbs:
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.
billybob99
21-06-2009, 11:16
Usually badly
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.
I don't think that a half press will lock the exposure on Canon or Nikon unless you've fiddled with the custom settings.
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.
Blue Eagle
21-06-2009, 16:45
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.
Same with the 450D, i dont get why you would use the button unless you wanted to stop it focusing for a moment.
str1nger
22-03-2010, 01:38
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 :)
seltechpc
22-03-2010, 09:28
Same with the 450D, i dont get why you would use the button unless you wanted to stop it focusing for a moment.
This article may throw some light on the matter. It takes a little while to get used to but soon becomes instinctive.
http://thediscerningphotographer.com/2010/01/11/back-button-autofocus/
Paul
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
trencheel303
22-03-2010, 20:52
I just twist that focus thingy until it looks right.
Steve.
:clap: :thumbs: :lol:
admirable
22-03-2010, 21:28
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.
:D
JEmerson
22-03-2010, 21:57
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
04-04-2010, 10:49
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
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.
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.
...or shoot in manual mode...
...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 :thumbs: 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.
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