Finally sorted my focus issues (Back Button Focusing!)

jamin100

jamin100

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Ben
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Hey,

Ive been having issues until now, nailing focus that i'm happy with. My shots would look ok, but i'd regularly miss focus. This, I think was down to two things. first I was using very low apertures, 1.8 - 3.2 AND because I was using AF-S.

Now, at first using a higher higher aperture and AF-C work for the most part, but taking photos of my children mucking around would still result in me missing focus more times than not.

UNTIL i tried back button focusing!
Now all you pros have probably used this at some point but I'd never heard of it until a few weeks ago but now i'm sold on it!

Basically, in a nutshell I now use the AE-L button on the back of my D90 to focus with rather than half pressing the shutter. It sounds weird and awkward and took me about half a day to get used to but honestly its helped my focus issues dramatically!

Here's the origional post I found about setting up a D90

I don’t know how many folks are using this technique. It was mentioned in the tips thread but I have the feeling it got lost. Plus there are a number of folks new to DSLRs who are jumping on the bandwagon with the D90 that will absorb any good idea.

In the olden days we would set the shutter speed dial, twist the aperture ring, and focus using the lens focusing ring. In the D90 (as with most digital cameras today) both the exposure and focusing locks are tied to the shutter release button. This was also true of my D70s. One of the things I learned very early on from an old Nikonians podcast was to disconnect these two functions.

So on my D90…
I set Auto Focus to AF-C (AF-Continuous) by pushing the AF button on top of the camera (next to the screen) while turning the main command dial button.
Next I set f4: Assign AE-L/AF-L button to AF-ON.
Lastly I set c1: Shutter-Release button AE-L to ON.
So I use my thumb to press the AE-L/AF-L button.

As long as I hold down the button the camera will focus. The minute I lift my thumb it stops. Way cool. It’s like having AF-S and AF-C combo. The other thing this does (with the last step) is to lock the exposure when I press the shutter release part way.

Note there is a drawback for those that want the audio confirmation when the subject is in focus (aka the beep), when you set Auto Focus to AF-C you won’t hear any beeps (instead you can watch the green dot inside the viewfinder for confirmation). Now I should mention what I do with my focus points.

Most often when I can take my time composing, and because the center focus point is the most accurate sensor on the D90, I tend to use AF-area mode single point. I do set the Focus Point Wrap Around to wrap so I don’t have to change directions too often with the Multi-selector if I’m selecting a different point. You can also press the OK button to bring the focus point back to the center. Sometimes I lock the focus point in the center by using the AF Selector Lock switch.

The big advantage to this setup is I can focus on one thing, expose correctly by pointing somewhere else in the scene and compose the view where I want it. When I first used this set up it took about a day to get into the groove but now it’s “just the way it is.” So don't try this without a solid day of practice. About halfway through the day you'll probably be sold on this method. ​

Original thread: http://www.flickr.com/groups/nikon_d90/discuss/72157615929083150/

Here's some shots taken tonight where I think I would have normally missed my focus with my old method.


BrImages-10.jpg by BenR167, on Flickr


BrImages-10.jpg by BenR167, on Flickr
 
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Good post. A lot of experienced photographers use this method.
Thanks for bringing it to the attention of all.
 
So this is like holding the button part way for focus and then composing, but it does for exposure as well?

So in the garden photo, rather than metering on the child, you metered on the grass or something, this set the exposures and then the AF-C means when you point at the child it refocuses, but keeps the exposure settings static?

So the halfway down button locks the exposure, you then use the AE-L button to start the autofocus (or do you need to hold it down?), line up the picture and go?
 
I use back button focus in the AF-S and AF-A modes, prefering to seperate the actions of focus/exposure/taking the picture.

Actually making the decision when to focus.

The D7000 does I find have a 'hair-trigger' and leaving it all to the shutter button has resulted in a number of failed shots.

D in W
 
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Sorry I must be incredibly thick, I cannot see how this is a benefit? So you moved the focus button to one of the back buttons (like some of the Canon bodies have in addition to the normal half shutter depress) and it has improved your focusing? I do not understand.
 
I use it but the only downside is you can't focus when using a wireless remote. Easy enough to switch menu items for this though.
 
tirc83 said:
I use it but the only downside is you can't focus when using a wireless remote.
Click to expand...

Dunno what wireless remote you use but mine does (RF602's)
 
clicktor said:
Sorry I must be incredibly thick, I cannot see how this is a benefit? So you moved the focus button to one of the back buttons (like some of the Canon bodies have in addition to the normal half shutter depress) and it has improved your focusing? I do not understand.
Click to expand...

For me, when I was using the shutter release button to shoot i'd take a photo and then remove my finger from the button to then proceed with the next. For that second where my finger was released the camera was not focusing on the subject.

Now, I can keep my finger on the AE-L button and shoot with the shutter release button when I want and the camera will always try to focus on the subject.
 
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Dale_d3100 said:
So this is like holding the button part way for focus and then composing, but it does for exposure as well?

So in the garden photo, rather than metering on the child, you metered on the grass or something, this set the exposures and then the AF-C means when you point at the child it refocuses, but keeps the exposure settings static?

So the halfway down button locks the exposure, you then use the AE-L button to start the autofocus (or do you need to hold it down?), line up the picture and go?
Click to expand...

Basically yes.
 
jamin100 said:
For me, when I was using the shutter release button to shoot i'd take a photo and then remove my finger from the button to then proceed with the next. For that second where my finger was released the camera was not focusing on the subject.

Now, I can keep my finger on the AE-L button and shoot with the shutter release button when I want and the camera will always try to focus on the subject.
Click to expand...

So as long as you keep the AE-L button down it will continually focus even if you move to a different subject or the subject moves? which AF area mode do you use? Isn't this quite similar to 3D tracking?
 
terryt said:
So as long as you keep the AE-L button down it will continually focus even if you move to a different subject or the subject moves?
Click to expand...

Yes thats right, as long as I hold the AE-L button the camera is always focusing, as soon as I stop pressing it then the focus is locked and wont budge. Its good for setting the focus recomposing and then shooting.

terryt said:
which AF area mode do you use?
Click to expand...

AF-C

terryt said:
Isn't this quite similar to 3D tracking?
Click to expand...

Does 3D tracking use multiple focus points?
I can use just the center so im always getting the best focus from my cheaper lens's
 
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Just had a quick play, it does't work for me as I usually focus and then recompose, using AF-C refocuses when your recompose. TBH, you can just set AF-C without using the AE-L button and it will continually focus with the shutter pressed halfway, and use the AE-L button for exposure lock.

I guess its down to personal preference and shooting style :cool:
 
terryt said:
Just had a quick play, it does't work for me as I usually focus and then recompose, using AF-C refocuses when your recompose. TBH, you can just set AF-C without using the AE-L button and it will continually focus with the shutter pressed halfway, and use the AE-L button for exposure lock.

I guess its down to personal preference and shooting style :cool:
Click to expand...

Once you have focused, take your finger off the AE-L button so it stops focusing. Then recompose then shoot.

It is just down to personal preference, but it did take me at least half a day to get used to it.
 
terryt said:
Just had a quick play, it does't work for me as I usually focus and then recompose, using AF-C refocuses when your recompose. TBH, you can just set AF-C without using the AE-L button and it will continually focus with the shutter pressed halfway, and use the AE-L button for exposure lock.

I guess its down to personal preference and shooting style :cool:
Click to expand...

That is how I would do it, AF-C and when you take a photo, only release the button back to halfway as this will keep it focusing for the next photo
 
After 30 min of reading and re reading, I get it.

This line is the important bit that makes it work....

As long as I hold down the button the camera will focus. The minute I lift my thumb it stops. Way cool. It’s like having AF-S and AF-C combo. The other thing this does (with the last step) is to lock the exposure when I press the shutter release part way
Click to expand...

So you use both focus methods at the same time without having to change. You can track and focus and take photos (AF-C), release the button and then take photos without changing the focus (AF-S)

The rest of it just makes confusing reading as its not linked to that, or its a by product by doing things backwards.

Focus first and the expose second sounds odd to me, but you don't have to do it that way using this method. Set the exposure by pointing and holding down the shutter button halfway, then come back to the target and hold down the AEL button for continuous focus (and release if you want when you are happy with the focus). Then push the button down to take photos. You'd need to not release the shutter button fully as you will loose the exposure settings, just release back to half ready for the next photo
 
So this works on the D3100 Dale as well as Ben's D90? (if so, will try and have a play when i get home)
 
Dale_d3100 said:
After 30 min of reading and re reading, I get it.

This line is the important bit that makes it work....



So you use both focus methods at the same time without having to change. You can track and focus and take photos (AF-C), release the button and then take photos without changing the focus (AF-S)

The rest of it just makes confusing reading as its not linked to that, or its a by product by doing things backwards.

Focus first and the expose second sounds odd to me, but you don't have to do it that way using this method. Set the exposure by pointing and holding down the shutter button halfway, then come back to the target and hold down the AEL button for continuous focus (and release if you want when you are happy with the focus). Then push the button down to take photos. You'd need to not release the shutter button fully as you will loose the exposure settings, just release back to half ready for the next photo
Click to expand...

Yup thats it. explained much better than I have.:bonk:
 
I really want to understand, but that flicker thing makes me more confused. I literally have no idea what you guys are talking about and can't see an advantage. :( Someone explain?
 
clicktor said:
I really want to understand, but that flicker thing makes me more confused. I literally have no idea what you guys are talking about and can't see an advantage. :( Someone explain?
Click to expand...

the Canon article I refernced above explains it much better (IMHO)
 
Zarch said:
So this works on the D3100 Dale as well as Ben's D90? (if so, will try and have a play when i get home)
Click to expand...

No idea

Now I understand it I will give it a go.

Then I will need to find a need. lol
 
clicktor said:
I really want to understand, but that flicker thing makes me more confused. I literally have no idea what you guys are talking about and can't see an advantage. :( Someone explain?
Click to expand...

AF-C allows you to continuously focus, you can't freeze the focus

AF-S focuses once and if you want to refocus push again.

This method allows you to combine these

So you can track a subject but if you want to freeze the focus on a point, you can.

I'm yet to find a need for this or can think of a need.
 
I do this as well. in fact, the camera that I have (I bought it from MD on here) came with the option enabled from the start.
 
Why don't you just use 3d tracking for following a target?

I use AF-S and focus on a point I know they will arrive at and then wait if you want 'trap' them (if that is what its called)
 
OK,

I will try and explain this...!!

Hang in there....

The best way to think about this is if you were photographing a race......

Imagine being stood at the finish line and taking pictures on a burst for the whole race.... (i know you cannot do this on most cameras but hang in there....)

So you are at the olympics on the finish line and that Bolt bloke is heading to you at a heafty pace....

If you use the shutter release button to focus and take the shot only the first picture will be in focus and the rest will be out of focus because you would have to stop shooting to refocus (half press) to take the shot again..!

Now using the back focus button you can keep your thumb on it, and hold down the shutter button so as Bolt is legging it at you it will focus in between shots and they should all be in focus.....

This is an extreme example but i think it explains it....!
 
i have had this one from day 1 and love it, i use the AF-ON button and have the AE button for exposure lock.

So i get the exposure i want, press the AE-Lock button that i have set to lock for only 1 frame then i focus using the back button, then i recompose then press the shutter release..!
 
Looks quite handy, will give it a go later, thanks for the info :thumbs:
 
@ Boyfalldown, thankyou for the link to the Canon article explaining it. Yes you are right that does explain it much. much better. :)

However, I would like to comment on the article as below on the benefits if that's ok:

Canon article said:
1: Easier to lock focus

If you are shooting something like a series of portraits of a person, and you want them composed off-center, back-button AF makes it super-easy to take as many pictures as you want. Focus on your subject by pressing the rear button (more on which button later in this article). Once in-focus, take your thumb off the rear button. Re-compose the shot to move your subject off-center. Shoot as many pictures as you like.
If you like to lock focus and re-compose your subjects, you’ll find back-button AF very helpful: Once your focus is set, you can move the camera and take as many shots as you like without AF trying to re-focus on what’s now in the center of your picture.
With focus activation removed from the shutter button, you now can fire any time you like, and remove your index finger from the shutter button after a shot is taken. No matter what, the camera makes no effort to re-focus when you press the shutter button half-way down again.
Click to expand...

I cannot see a benefit to using back button AF focus in this situation. i.e. Why would you not just focus using half shutter depress then recompose and then fully depress to take the shot? Unless you are in a studio and you have a 100% stationery target when you know the focus will stay the same 100% of the time this is of no benefit imo.

Canon Article said:
2: Easier timing of shots

Similar to point number one above, but yet another benefit of pulling focus away from the shutter button is that critical timing becomes simpler to manage. For example, if you were shooting a speaker at a podium, he or she might periodically look up or make a gesture that would be an ideal instant to capture. If you’ve focused with back-button AF, your index finger is free to shoot at the decisive moment. There are no worries about holding your finger half-way down and waiting, waiting, waiting in that position for your subject to do something interesting.

Even with a very animated subject that may be moving around, you can have your camera’s focus set to AI Servo AF (to track any movement), and just keep your right thumb on the back button to keep focus active, while your index finger can be ready to shoot with no worries about also preserving focus.
Click to expand...

To me, the above is infact a disadvantage if you were to set the AF to the back button. Your finger would have further to press on the shutter all the way down through both clicks in order to fire a shot. Since this advantage is supposed ot be about timing, I'd say that hampers any timing. The only benefit it brings is being able to rest your index finger a little, but again, when is there a time that a "very animated subject" as referred to above, is going to be stationery and be able to have focus locked in place for extended lengths of time. Hardly ever.

canon Article said:
3: Less risk of focus errors with moving subjects

For sports photographers and others taking action pictures, back-button AF lets you stop focus whenever something might interfere with the moving subject you’re tracking — without requiring you to stop shooting. In sports, for instance, it’s common for a referee or another player to come between the camera and an athlete being photographed. With back-button AF, it’s easy to momentarily pull your thumb off the rear button, and you can still keep shooting by pressing the shutter button fully. The camera instantly stops focusing when your thumb comes off the back button. Once the obstruction is out of your way, you can immediately pick-up your primary subject by pressing your thumb on the back button again.
Click to expand...

Subjects coming into the frame and interfering with the focus would only occur when using AI Servo (constant adjusting focus). On Canon bodies we can just use one shot focus. the suggestion to use the back button so you can "momentarily release your thumb from the rear button" is the same as just saying "stop focusing" for the time the object is in the frame. I cannot understand why this is being labelled as a benefit again. There is nothing you cannot do with the normal shutter half depressed method.

Canon Article said:
4: Easier over-riding of AF with full-time manual focus

More than half of Canon’s lenses have a neat feature called full-time manual focus*. Even if the lens’s AF/MF switch is in the AF position, these lenses allow the shooter to instantly adjust focus manually by simply turning the focus ring on the lens. There’s no need to first move the switch to MF.

With back-button AF, this becomes a nearly foolproof feature. Use the autofocus whenever you like by pressing the rear button with your right thumb. Shoot whenever you like by pressing the shutter button. And if you want to touch-up focus, or totally over-ride what the AF is doing, just pull your thumb off the rear button and turn the ring. No matter how many pictures you shoot, pressing the shutter button will not cause the AF to try to kick-in and re-set the focus you just adjusted manually.
Click to expand...

Again this is only a benefit if you want to keep the focus you manually adjusted yourself using FTM to be locked in place for extended periods. No benefit in most real world situations, although I can see how it could destract you having to half depress the shutter constantly whilst fine tuning focus manually using FTM yes. So I will give the Author this one yes, partially.

Canon Article said:
5: Easier macro and close-up focusing

In close-up photography, it’s often necessary to focus manually, because AF tries to make little changes each time you shoot. With back-button AF, you can concentrate on composition, instead of keeping AF locked in place.
Many times, you’ll find that it’s actually easier to get consistently sharp close-up pictures of small objects by pre-focusing, and then moving yourself forward or backward until you see the critical sharp focus appear in your viewfinder. Once again, with back-button AF active, you can use the AF to get within general range (press the rear button with your thumb, then take your thumb off the button), and move a little bit to get things critically sharp. Most important, you can then shoot freely, without AF trying to re-focus each time you touch the shutter button. Finally, touching-up focus with the full-time manual focus feature on certain Canon lenses is simple and quick, and the autofocus never fights you by trying to un-do what you just adjusted.
Click to expand...

This again is a debate on whether it is confortable for people to half depress the shutter to hold focus for extended periods of time. For me it's a non issue. For others I guess that's fine.




Am I miss understanding any of the above with my comments?
 
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if you use the half shutter to focus, if you then recompose the camera will autofocus again when you take the shot, meaning the subject will be out of focus.

The only way around that is to change the AF point or use back button focusing. Changing AF point can be a pain for moving subjects like in street.
 
redddraggon said:
if you use the half shutter to focus, if you then recompose the camera will autofocus again when you take the shot, meaning the subject will be out of focus.

The only way around that is to change the AF point or use back button focusing. Changing AF point can be a pain for moving subjects like in street.
Click to expand...

Hang on a sec....define recompose?
I'm saying, say I focus on a subjects eyes by half pressing shutter button, then keeping it half pressed, I move the camera slightly to adjust for a full body shot and then fully depress the shutter to take the shot. Yes, this can lead to less accurate focusing so is a trade off. (i.e. using center focus point for more accurate focusing) I cannot understand how the back button helps in this situation assuming that central focus point is always being used.

You are saying that to recompose is to refocus entirely? I take recompose to mean reframe the picture, not fully meter and focus again.
 
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clicktor said:
@ Boyfalldown, thankyou for the link to the Canon article explaining it. Yes you are right that does explain it much. much better. :)

However, I would like to comment on the article as below on the benefits if that's ok:
Click to expand...

rather than comment on your individual questions I wonder if it would be easier to think of the AF-On button as an easier way of using the Focus Lock button there is on many bodies. The real advantage to me is that I can easily stop focus when I need to - like pressing the Focus Lock button, so when I want to recompose for example rather then having the focus still working when I press the shutter.

I know that doesn't make a whole heap of sense. Sorry. May I suggest the best thing to do with this is try it and see if it works for you. I think it takes about 100 shots to get used to this, but after those 100 I've never wanted to go back.

The only real disadvantage I've found is on occasion I may pass my camera to someone else, who is expecting to focus from a half press of the shutter and can't work out why no focus that way
 
redddraggon said:
if you use the half shutter to focus, if you then recompose the camera will autofocus again when you take the shot, meaning the subject will be out of focus.

The only way around that is to change the AF point or use back button focusing. Changing AF point can be a pain for moving subjects like in street.
Click to expand...

I just re-read what you wrote. OK, I think the thing we disagree on is this...

"if you then recompose the camera will autofocus again when you take the shot"

To that I'd say, no it wouldn't. Why would it? If you took your finger fully off the shutter and then refocused yes of course it would, but why would you do that? That takes away any reason that you focused elsewhere in the first place?

confused
 
clicktor said:
I just re-read what you wrote. OK, I think the thing we disagree on is this...

"if you then recompose the camera will autofocus again when you take the shot"

To that I'd say, no it wouldn't. Why would it? If you took your finger fully off the shutter and then refocused yes of course it would, but why would you do that? That takes away any reason that you focused elsewhere in the first place?

confused
Click to expand...

assuming you were in AF-C mode then it would, but in AF-S mode it wouldn't unless, as you say you took your finger right off the button. TBH I think the advantages limited in AF-S mode
 
Another way of doing it which lots of people do is they have learnt where the auto/manual focus switch is and flick this locking the focus. Then you can do what you want with the camera in terms of composition and take the photo
 
clicktor said:
I just re-read what you wrote. OK, I think the thing we disagree on is this...

"if you then recompose the camera will autofocus again when you take the shot"

To that I'd say, no it wouldn't. Why would it? If you took your finger fully off the shutter and then refocused yes of course it would, but why would you do that? That takes away any reason that you focused elsewhere in the first place?

confused
Click to expand...

I use AF-C
 
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