Do You 'Back Button' Autofocus?

Been using AF-On for years too, on my 350D and now on my 5D mk2. I found it seems natural, so intuitive when you want to focus and meter from different areas.
 
A question about this, even though I use this for one shot mode, does it auto track when in AI Servo mode? (does that make sense?)
 
scottthehat said:
tried it couldn't get on with it, as vr/os is only activated off the shutter button and i was finding i was getting blurry shots.
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IS is activated whenever you start metering or AF, so this method works fine, with Canons at least.

tiler65 said:
A question about this, even though I use this for one shot mode, does it auto track when in AI Servo mode? (does that make sense?)
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I think I might be missing what you're asking here, but AI servo works the same regardless of what button you use to focus.
 
scottthehat said:
tried it couldn't get on with it, as vr/os is only activated off the shutter button and i was finding i was getting blurry shots.
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Yes, on Nikons the VR is activated by half-pressing the shutter release...but I have no problem with this. I like being able to keep VR depressed whilst selectively pressing the AF-on as required; given that the VR needs time to settle this helps prevent the AF from losing the plot as you compose the shot and choose your moment.
 
Sorry for what to most will seem like a simple question but I saw this thread and thought i'd have a look on my 450D. I found I have 4 options, the first was selected by default and what ive always used.

0: AF/AE lock
1: AE lock/AF
2: AF/AF lock, no AE lock
3: AE/AF, no AE lock


Could someone possibly explain what the difference between each is in simple terms? As you can probably guess I don't have a clue :thumbsdown:


Thanks...
 
a lex said:
Sorry for what to most will seem like a simple question but I saw this thread and thought i'd have a look on my 450D. I found I have 4 options, the first was selected by default and what ive always used.

0: AF/AE lock
1: AE lock/AF
2: AF/AF lock, no AE lock
3: AE/AF, no AE lock


Could someone possibly explain what the difference between each is in simple terms? As you can probably guess I don't have a clue :thumbsdown:


Thanks...
Click to expand...

0: AF and exposure controlled by the shutter button.
1: Exposure locked by shutter button, AF by back button.
2: AF by shutter button, AF locked by back button no exposure lock
3: Exposure started by shutter button, AF by back button, no exposure lock.

With those options I would probably use #3 and manual exposure with spot metering when the lighting was tricky or #3 and auto exposure with matrix metering for casual shooting conditions.

Many of the newer higher range Canon bodies have an additional button at the back which is used for either AF on/AF off as selected this allows the * button to be reserved for exposure lock giving the best of both worlds.
 
DiddyDave said:
^^^ that (needing VR) is one of the few times I don't

DD
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somewhat embarrassingly - on those few occasions I do need it I end up pressing the back button and a shutter half press at the same time, although only one of my lenses has VR so using it is pretty rare
 
boyfalldown said:
somewhat embarrassingly - on those few occasions I do need it I end up pressing the back button and a shutter half press at the same time, although only one of my lenses has VR so using it is pretty rare
Click to expand...

I use VR so rarely I keep advising my mates to save £600+ and buy the non-VR one and a decent monopod instead :D

DD
 
I've looked in the Nikon D300 manual - where does it say that it disables VR functionality?

Also, can someone just help clarify for me what the perceived benefits are of using this approach? I've never tried it but I'm going to now. I just wondered if the benefit was apparent only under certain shooting conditions?
 
Just had a quck go at this on some random indoors tests and can't for the life of me think why I never did it before :shrug: Seems intuitive to use it like this, but I guess the proof will be in the pudding so to speak, and I'll see how I get on over the weekend
 
LJR said:
I've looked in the Nikon D300 manual - where does it say that it disables VR functionality?

Also, can someone just help clarify for me what the perceived benefits are of using this approach? I've never tried it but I'm going to now. I just wondered if the benefit was apparent only under certain shooting conditions?
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it doesn't disable it - but to switch VR on on the Nikon you need a shutter 1/2 press - so using the af-on button just doesn't start VR
 
LJR said:
Also, can someone just help clarify for me what the perceived benefits are of using this approach? I've never tried it but I'm going to now. I just wondered if the benefit was apparent only under certain shooting conditions?
Click to expand...

The bottom line is that you can leave the camera in AI Servo (Continuous) focus mode so that the camera is always ready to deal with action/movement, but you can also cease the AF function at any time, simply by lifting your thumb from the AF button, so you gain the advantage of One-Shot (Single) AF without having to fiddle around changing AF modes. That will give you the freedom to simulate One-Shot (Single) and use focus/recompose, if you wish, while still being ready for action if it all kicks off.

Furthermore, you might be shooting something that is not moving around at all - perhaps a perched bird - but you don't have a focus point that is well positioned for the composition you want. With back button focus you can get your camera focused/recomposed and then wait for the moment the bird looks in the right direction or makes the right pose etc.. You are then free to release the shutter without that pesky AF screwing things up. Obviously you could switch to manual focus, but what a palaver, and where would you be if the bird then decided to take off and you wanted to track it?

Another example - you are shooting BIF (birds in flight) with a camera with unsophisticated AF - e.g. a Canon 50D - and using a single AF point to track it. If your aim falls off the target for just a brief moment the camera will flounder, probably switching to the background if there is contrast there. You may lose the bird completely. By using back button focusing, if your reactions are quick enough, you can suspend AF until you get back on target, and then resume focusing again. Meanwhile you can maintain a half press on the shutter so that your IS continues to operate and you are ready to take the shot.

Another example - you are second shooter at a wedding, standing at the far end of the aisle. You have the B&G and vic at the far end, pretty stationery while the service is conducted. Again you have that poor spread of AF points so you need to focus/recompose. You can then fire off several shots, while they are stood in position, and the AF won't operate each time you take a shot. However, with the camera in AI-Servo mode you will be ready for the moment they come up (down?) the aisle to track them and keep tracking them. It's all done on one button. No faffing about switching between focus modes from One-Shot to manual to AI-Servo and risking getting it wrong.

Basically, back button focusing gives you the tools of AI-Servo, One-Shot and manual focusing all without changing any of the camera settings. If you want AI-Servo AF then press and hold. If you want One-Shot AF then press and release. If you want manual then don't press. Simples.
 
Hey Tim - thanks for the clarifications. It seems though to perform the same function as AE/AF-L which is the button right alongside my AF-On. I suspect I'm just being incredibly dense (won't be the first time). I'm going to play around with it - given I do shoot quite a bit of motorsport from time to time I can definitely relate to the quick switching between Continuous and Single AF servo!
 
tdodd said:
The bottom line is that you can leave the camera in AI Servo (Continuous) focus mode so that the camera is always ready to deal with action/movement, but you can also cease the AF function at any time, simply by lifting your thumb from the AF button, so you gain the advantage of One-Shot (Single) AF without having to fiddle around changing AF modes. That will give you the freedom to simulate One-Shot (Single) and use focus/recompose, if you wish, while still being ready for action if it all kicks off.

Furthermore, you might be shooting something that is not moving around at all - perhaps a perched bird - but you don't have a focus point that is well positioned for the composition you want. With back button focus you can get your camera focused/recomposed and then wait for the moment the bird looks in the right direction or makes the right pose etc.. You are then free to release the shutter without that pesky AF screwing things up. Obviously you could switch to manual focus, but what a palaver, and where would you be if the bird then decided to take off and you wanted to track it?

Another example - you are shooting BIF (birds in flight) with a camera with unsophisticated AF - e.g. a Canon 50D - and using a single AF point to track it. If your aim falls off the target for just a brief moment the camera will flounder, probably switching to the background if there is contrast there. You may lose the bird completely. By using back button focusing, if your reactions are quick enough, you can suspend AF until you get back on target, and then resume focusing again. Meanwhile you can maintain a half press on the shutter so that your IS continues to operate and you are ready to take the shot.

Another example - you are second shooter at a wedding, standing at the far end of the aisle. You have the B&G and vic at the far end, pretty stationery while the service is conducted. Again you have that poor spread of AF points so you need to focus/recompose. You can then fire off several shots, while they are stood in position, and the AF won't operate each time you take a shot. However, with the camera in AI-Servo mode you will be ready for the moment they come up (down?) the aisle to track them and keep tracking them. It's all done on one button. No faffing about switching between focus modes from One-Shot to manual to AI-Servo and risking getting it wrong.

Basically, back button focusing gives you the tools of AI-Servo, One-Shot and manual focusing all without changing any of the camera settings. If you want AI-Servo AF then press and hold. If you want One-Shot AF then press and release. If you want manual then don't press. Simples.
Click to expand...

:thumbs: Thanks for taking the time to pen this as this answers all my questions and more. Gonna give it a go but on the face of it, it seems like a no brainer to have your camera set up like this. (My 2P).
 
Biggest camera revelation ever to me when I discovered it some 4 years ago. The only time when I feel it isn't necessary would be in manual exposure mode, or if you are an exposure compensation god. Much less necessary now due to the rather ridiculous (and very useful) amount of AF points on the D300. Essential on anything with 11 points or less I'd say due to the reframing you'd have to do.
 
LJR said:
Also, can someone just help clarify for me what the perceived benefits are of using this approach? I've never tried it but I'm going to now. I just wondered if the benefit was apparent only under certain shooting conditions?
Click to expand...

It separates focusing from shooting, a bit like the old days (when I started) where you focused the lens manually with your left hand, and fired the shutter with your right.

Allows you to focus and recompose, focus on subject, lift thumb, recompose, fire.

I take a lot of bird pictures, sometimes they are amongst branches, once I have the bird focussed I release the button, I know that a slight movement in the camera will not cause focus to switch to a foreground / background object.

It gives you a greater control over focusing, it only focuses when you tell it to.

It is strange to start with, but worth sticking with.
 
tdodd said:
Furthermore, you might be shooting something that is not moving around at all - perhaps a perched bird - but you don't have a focus point that is well positioned for the composition you want. With back button focus you can get your camera focused/recomposed and then wait for the moment the bird looks in the right direction or makes the right pose etc.. You are then free to release the shutter without that pesky AF screwing things up. Obviously you could switch to manual focus, but what a palaver, and where would you be if the bird then decided to take off and you wanted to track it?

Another example - you are shooting BIF (birds in flight) with a camera with unsophisticated AF - e.g. a Canon 50D - and using a single AF point to track it. If your aim falls off the target for just a brief moment the camera will flounder, probably switching to the background if there is contrast there. You may lose the bird completely. By using back button focusing, if your reactions are quick enough, you can suspend AF until you get back on target, and then resume focusing again. Meanwhile you can maintain a half press on the shutter so that your IS continues to operate and you are ready to take the shot.
Click to expand...

Spot on, and once you get used to it you will get a lot more keepers :thumbs:
 
Interesting stuff. Can't wait to get out and mess with this now :)
 
This looks interesting, will give it a go later.

I'm fairly new to all this so good to get into the habit early, I think it will be a great help when on Safari next month!
 
i've yet to master this, only having my left arm/hand to manipulate all these buttons, but i enjoy the challange.
tripod i do use occasionally where this function should help drastically.

thanks.
 
I have now set back button focus on my 450D, along with AI Servo mode

I know that I no longer get a focus confirmation with AI server but how do I know what focus point it is using. Would I be better of setting focus to just the centre point.
 
I don't know the specs of the 450D but you may find that centre point is a bit more sensitive/accurate, if you have a lens of f/2.8 or faster. Indeed, it might be better regardless of the lens. I'd say use the focus point that allows you to create the best composition with the least amount of recomposing. If an outer point is used, but is struggling, try the centre point. Often the centre point will be the best choice anyway.

One things Canon users should note (and it may affect other brands too) - in conditions of poor light/contrast you may find that AI Servo struggles to find focus properly, whereas proper One Shot mode has a better chance to lock on. In those situations you would be wise to switch to "proper" One Shot AF. If AI Servo cannot get a lock on a stationery subject it probably won't help you in trying to track a moving one, so really you will have lost nothing. You can still carry on using the back button to perform focusing
 
tdodd said:
The bottom line is that you can leave the camera in AI Servo (Continuous) focus mode so that the camera is always ready to deal with action/movement, but you can also cease the AF function at any time, simply by lifting your thumb from the AF button, so you gain the advantage of One-Shot (Single) AF without having to fiddle around changing AF modes. That will give you the freedom to simulate One-Shot (Single) and use focus/recompose, if you wish, while still being ready for action if it all kicks off.

Furthermore, you might be shooting something that is not moving around at all - perhaps a perched bird - but you don't have a focus point that is well positioned for the composition you want. With back button focus you can get your camera focused/recomposed and then wait for the moment the bird looks in the right direction or makes the right pose etc.. You are then free to release the shutter without that pesky AF screwing things up. Obviously you could switch to manual focus, but what a palaver, and where would you be if the bird then decided to take off and you wanted to track it?

Another example - you are shooting BIF (birds in flight) with a camera with unsophisticated AF - e.g. a Canon 50D - and using a single AF point to track it. If your aim falls off the target for just a brief moment the camera will flounder, probably switching to the background if there is contrast there. You may lose the bird completely. By using back button focusing, if your reactions are quick enough, you can suspend AF until you get back on target, and then resume focusing again. Meanwhile you can maintain a half press on the shutter so that your IS continues to operate and you are ready to take the shot.

Another example - you are second shooter at a wedding, standing at the far end of the aisle. You have the B&G and vic at the far end, pretty stationery while the service is conducted. Again you have that poor spread of AF points so you need to focus/recompose. You can then fire off several shots, while they are stood in position, and the AF won't operate each time you take a shot. However, with the camera in AI-Servo mode you will be ready for the moment they come up (down?) the aisle to track them and keep tracking them. It's all done on one button. No faffing about switching between focus modes from One-Shot to manual to AI-Servo and risking getting it wrong.

Basically, back button focusing gives you the tools of AI-Servo, One-Shot and manual focusing all without changing any of the camera settings. If you want AI-Servo AF then press and hold. If you want One-Shot AF then press and release. If you want manual then don't press. Simples.
Click to expand...


Aah, now it makes sense. I'll give this a go on my 5D later however I can't see it giving me much advantage for shooting landscapes though it makes sense for most other scenarios. :)
 
LJR said:
Interesting stuff. Can't wait to get out and mess with this now :)
Click to expand...


Im just learning to do this too.
On the D300 change custom settings
A1 - release
A5 - AF-ON Only.

Set to continuous focus on front switch.

Now you have..

Single focus by pushing the AF button once
Continuous focus by holding the AF button down
Manual focus by turning the focus ring.
 
I found out about this a couple of weeks ago inthe d300 owners thread, & find it a great improvment in using the camera, however I did mess up some times but kept at it & now really got the hang of it ..brilliant
 
Thanks Munchycarrot (very cool name!)

Also I just had some feedback from 'Mike' at Nikon regarding the relationship between the AF-On and the lens's VR. I'll quote it here.

Use of the "AF-ON" button will disable VR in the camera.

The reason for this is basically to allow you to lock focus and then reengage VR.

You MUST separate focus from the shutter and have AF only activated with the "AF-ON" button. This is performed by a custom setting which varies in each camera.

Why would you do this?

If you are in a situation where you want to lock focus and then have VR active as you are shooting, it is great.

For sports or action, or times where you may choose to manually focus, it still allows you to have VR but not have the focus racking.

So for example, when shooting sports where I am fixed on a single athlete who will stay in position, I don't have AF activated by the shutter release (custom setting above), only via AF-ON. I press AF-ON and when it achieves the focus I want, I release it. My focus is now LOCKED on that plane. When I press the shutter release halfway the focus will NOT change. However, upon pressing the shutter release halfway, VR is now active and will be active when I press the shutter-release fully and take the shot.

So now my focus does not vary and I can concentrate on being steady and VR will also come into play.

I know that is a lot to digest, but it's a very good technique and used on the sidelines and in nature shooting.

Feel free to ask more on this.

Thanks,

Michael
mrubin@nikon.net
Click to expand...
 
I've had a Canon 350D for about 4 years and a 450D for about 4 months and I never knew about this function!

The idea is just brilliant and should definitely inprove my BIF shots because the AF just jumps around normally if you lose track of a bird.

Just shows there's always something new to learn!
 
You guys are certainly giving this a good case for me to give it a retry :)

First time out (way back) I didn't get on with it at all, but that may have been me not setting the camera up properly in all fairness. I hate to admt user error but I guess it happens to the best of us :D

Will see how I get on with it today if I get chance.
 
ryanyboy said:
You guys are certainly giving this a good case for me to give it a retry :)

First time out (way back) I didn't get on with it at all, but that may have been me not setting the camera up properly in all fairness. I hate to admt user error but I guess it happens to the best of us :D

Will see how I get on with it today if I get chance.
Click to expand...


The RTFM factor is something that applies to us all...It was a total revelation to me, but now it's second nature.

Manuals are the most boring things ever:bang:
 
I have never used back button focus, and never really understood why, what or how it works. Thanks to this thread, I now understand and so will absolutely learn to use it!! Thanks :clap:
 
Thanks tdod, that's the best explanation I have seen on the subject.

Send it to Canon to put in their manuals.
 
Here are a couple of examples I shot last night, where back button focusing was pretty much essential. I needed to be in AI-Servo mode to follow the action, but I also needed to be able to suspend focusing if an obstruction appeared, and yet still be in a position to release the shutter. If focusing had been locked to the shutter button it would have been a disaster.

(This was my first time shooting basketball, or any indoor sport, so it was a voyage of discovery for me. These were shot with a 7D at 1/250, f/2.8, 6400 ISO.)

20100115_201954_2163_LR.jpg
20100115_205313_2274_LR.jpg
 
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