3 Ways to get Better Control of Autofocus
In this post, Steve Berardi from PhotoNaturalist talks about three ways to get better control of autofocus.
Sometimes autofocus can be really annoying. For some shots it’ll focus on the right part of your subject, but then the very next shot it may choose to focus on something far and away into the background.
Sure, you could avoid this problem by always using manual focus, but autofocus is great when you need to focus quickly or when you’re photographing a landscape and you need to focus on a certain spot in the scene.
Well, autofocus doesn’t have to be annoying anymore, because here are three ways to get better control of it:
#1 – Press your shutter button half-way to activate autofocus and then recompose
Set your autofocus point to the center spot, then point this spot where you want to focus and press your shutter button half-way (don’t press it completely yet) to initiate autofocus. Then, while still holding down the button half-way, recompose your shot and press the button completely down to snap the photo.
#2 – Switch to manual focus after autofocusing
Use autofocus as you normally do, but once it focuses on the right spot, just switch off autofocus on your lens to manual focus. Your lens will keep the current focus when you do this. This method works well when your camera is on a tripod and you’re taking multiple exposures from the same spot, like when photographing a landscape.
#3 – Use back-button autofocusing
Normally, your camera will autofocus when you press the shutter button, but with back-button autofocusing, you have to press a button on the back of the camera instead, giving you complete control of when autofocus is initiated.
With back-button autofocusing, you can just set the autofocus point to the center spot, then point that where you want to focus, and finally press the back button to automatically focus on that point. Now for all the shots you take from that position, that focus will be maintained (the camera won’t randomly focus into the background anymore).
You can do the same thing without this back-button autofocusing by switching to manual focus after the camera focuses properly, but using the back button saves time and this way you don’t have to constantly switch back and forth between manual and autofocus (which can inadvertently move the camera sometimes).
Back-button focusing is especially helpful for photographing moving subjects, like birds in flight or other wildlife: just switch on the continuous focusing mode, set the autofocus point to the center spot, and hold down that back button. Now you don’t have to worry about accidentally hitting the shutter button while you’re tracking the subject in your viewfinder.
How to enable back-button autofocusing: Unfortunately, this feature is called something different on each camera, so you’ll probably have to do some digging around in your camera’s manual and “custom functions” to find it. If it’s not labelled clearly on your camera, try changing the settings of the different buttons on the back of your camera (like the AE lock button).
About the Author: Steve Berardi is a naturalist, photographer, and computer scientist. You can usually find him hiking in the beautiful mountains and deserts of Southern California. Read more of his articles on nature photography at the PhotoNaturalist and follow him on Twitter.
41 Responses to “3 Ways to get Better Control of Autofocus” - Add Yours
January 29th, 2010 at 1:19 am
I can personally attest to the value of #3. I discovered my back-button autofocusing feature by accident recently, and it’s been amazing. Now the half-pressed shutter takes a light meter reading, which is actually much more helpful to me. Personally, this would be my #1 recommendation, although you will have to let your brain reprogram itself, too.
January 29th, 2010 at 1:27 am
I almost always use #1. It is definitely habit now – I don’t know if that is because of my mistrust of auto-focus or what. I definitely prefer it though.
January 29th, 2010 at 1:43 am
I use technique #2 regularly for studio still life and product shots. Definitely cuts the number of “opps, camera changed focus on me” shots.
January 29th, 2010 at 1:43 am
#1, with a very shallow depth of field can be troublesome
January 29th, 2010 at 1:51 am
I’m a big fan of this feature too, being very useful in concert shootings. However, I cannot manage to learn which the back-button is when using the grip of my Canon 40D (which is the same model the 50D uses) because it lacks of the AF-ON button (which it happens to be the back-button for focusing when in landscape orientation). Does anyone know? :-/
January 29th, 2010 at 1:57 am
#3: On my Fuji it is indeed called AE-Lock.
And now I know what it is for. Thank you!
January 29th, 2010 at 2:28 am
Nice article, and good tips.
For #1, if you are shooting with a narrow depth of field, this will be a problem. Select the focus point and use that to focus. More steps involved, but better results.
For #3, using a back button to focus is amazing. I went to it several months ago just to see how I would like it, and fell in love. Now whenever I pick up a camera that doesn’t have the option, or doesn’t have it set, I feel lost.
Before I found the back button to focus, I would use #2 all the time. And for cameras where that isn’t option, it is a very good option… until that amazing, but unexpected, shot pops its head up, and you’re out of focus, and can’t hit the switch fast enough. Thankfully that doesn’t happen all the time, but when it does happen, it’s really annoying!
January 29th, 2010 at 2:54 am
I am soooo looking for tip 3 tonite!
January 29th, 2010 at 3:31 am
#1 may not work on the newer AF systems, because the camera will want to refocus when you recompose (if you are still holding that shutter down halfway)
#2 seems a bit cumbersome if you are doing this between every shot. And if you don’t like a center-composed subject, that is what you would be doing.
#3 is a great option. A possible #4 is to simply use the AE/AF lock button after you have your focal point where you want it (Pretty sure all Nikons have this feature, and I imagine Canon would as well). After you focus, lock it in by holding the AE/AF lock button with your right thumb, recompose, and fire away. As long as you are holding that button down with your thumb, the camera will not refocus on anything no matter how many times you click the shutter. The benefit to this is you don’t have to change any camera settings and you don’t have to reposition your hands at all. With practice, it becomes second nature. I don’t even realize I’m doing it, even though I use it for nearly every single picture during weddings, engagements, etc. As an added benefit, if you are using a metering mode (A, P, or S), you can also lock in a meter value from a neutral object if by chance your subject is all white or bright, or all black or very dark.
January 29th, 2010 at 3:38 am
If you have a camera with a DMF (Direct Manual Focus) mode then #2 is really easy. In DMF, half pressing the shutter gives you the usual autofocus process, after which the camera automatically disengages the focus gear and lets you fine tune before taking the shot (thus avoiding you having to find the AF/MF switch with your hand). I often find this to be the most useful focus mode on my camera.
January 29th, 2010 at 4:11 am
#4. On Canon’s there is an option to set the back button to AF Lock but you lose AE lock (on my 5D at least). That’s a good option for quickly disabling AF if you prefer shutter AF as apposed to Back Button AF.
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Focus and recompose works fine on crop sensors with cheap glass. Once you get into fast glass and especially fast glass on full frame you’ll find that you are shifting your focal plane too much.
The best option is selecting your focal point with your final composition in mind. Hopefully you have a camera with full cross type sensors like the 40D and 50D. (And hopefully Canon will release the next 5D will full cross-type!)
The back button AF works well because it lets you control when the AF turns on. I used to use it to get my focus and then shoot multiple frames when doing portraits. But, since I got my 5D I’ve stopped. I usually have my 580exII on camera (bounced with a black foamy) so I can make use of the AF assist since the 5D’s AF sucks in low light.
If you lean forward or backward, or the subject moves, you will get out of focus shots if you are shooting shallow. And, if you are shooting kids with this technique it’s likely that they will move out of the focal plane between hitting the back button and the shutter.
There are places for every technique, but I’ve found that using the shutter button only and selecting specific focus points provides the best focused shots.
January 29th, 2010 at 4:33 am
#1 – As Scott mentioned, using the center point for focus lock, then recomposing can yield unexpected results. The distance to your desired focus area will not be accurate (think about triangle geometry). The problem is magnified with closer subjects and larger apertures (smaller DOF). A better solution is to select an autofocus point that nearest to the desired focus area and lock with that one. Then recompose slightly to fine-tune your frame.
January 29th, 2010 at 6:15 am
back-button focusing on my canon cameras a year ago has completely changed my life. thanks for sharing with others.
January 29th, 2010 at 7:10 am
@David – There is a Custom Function to switch the AF On and * buttons. That will allow you to use Back Button focus with a grip on the 40D.
January 29th, 2010 at 8:52 am
How does method #1 work with an image stabilizer? Wouldn’t the image stabilizer be trying to compensate for the movement?
January 29th, 2010 at 9:45 am
Interesting ideas BUT
The author should specify the brand/type of camera(s) he is talking about, yes?
Not all camera manufacturers need nor have the back button feature.
DPS – you should have caught this before publishing.
January 29th, 2010 at 9:56 am
I’m on a Canon Rebel Xsi and I can’t figure out where to find back-button autofocusing. I found a section in the manual called “AE Lock”….Is it also known as “AE Lock?”
January 29th, 2010 at 4:45 pm
I use #1 almost exclusively and #2 for those times where #1 doesn’t work for me. I’ve only used my AF button on the back when I’m trying to use live view. I’ve found #1 to be of great value especially when I’m striving for very shallow depth of field shots. I used #1 for the following shot to only focus on the ice:
http://www.jljfoto.com/Other/Todays-Images/5762973_WM3MW#751486886_SD6iZ
January 29th, 2010 at 7:11 pm
I liked the article. It was simple to go # 2 but i didn’t think that way, now onwards i’ll try it. I usually use #1 but for my studio & programmes i use #3, it helps me to keep control on the moving or for more stedy shots.
January 29th, 2010 at 7:50 pm
#3
Couple back focusing with AI Servo. You can easily track moving targets.
January 29th, 2010 at 11:45 pm
After reading this I configured my 40D to use back button focus and it’s really a cool feature. Something I discovered is enabling this custom function allows you to focus with either the back button or the shutter release button — very cool.
@val y – Steve shoots with Canon gear though the techniques discussed should work with most DSLRs.
January 30th, 2010 at 1:32 am
@Zach – The back AF button on the late model Canon cameras works for AF out of the box. The custom function works to take AF OFF the shutter, keeping it on AF On only, so that you can focus with the back button alone which allows you to essentially have on demand auto focus since you can now click the shutter without engaging it.
January 30th, 2010 at 2:33 am
#3 on a Nikon D40:
* Go to “Custom Setting Menu” (It’s the little pencil.)
* Select option #12 (AE-L/AF-L).
* Set this option to “AF-ON”.
Your camera will now autofocus only when you press the “AE-L/AF-L” button (which is under your right thumb when shooting).
January 30th, 2010 at 5:26 am
@Scott – thanks for pointing this out. I just downloaded the 40D manual from the Canon Web Site and now realized by setting the custom function I switched the purpose of the AF-ON and * buttons. I’ll have to change that back so things function as they normally would.
January 30th, 2010 at 5:35 am
Not sure why I have ignored this feature. I’ve been battling focus changes when trying to shoot the same subject, such as a plant with leaves at different depths. I will definitely give this a try today and probably utilize every time in the future.
January 30th, 2010 at 9:03 am
I’m on a Canon Rebel Xsi…here’s how Canon describes how to find it.
http://www.usa.canon.com/dlc/controller?act=GetArticleAct&articleID=2286&productID=190&articleTypeID=5
January 30th, 2010 at 2:05 pm
I’m honestly limited by #1 and #2. Can’t wait to get some practice with #3. Love this place.
January 31st, 2010 at 1:08 am
Maybe start noting : “DSLR Only” tips.
January 31st, 2010 at 5:24 am
Photography
Your topic is very nice. Coming for digital camera change the photo effect.
January 31st, 2010 at 6:03 am
Thanks, Scott, that made the trick ;-)
January 31st, 2010 at 11:38 am
Interesting article. Learned something new with #3 and will definitely have to learn that technique.
I agree with commenters who say #1 will change your focal plane and using fast glass will cause out of focus on the details that you want sharp. I used this technique when I first started shooting with digital point and shoots. Didn’t work so well when I went DSLR.
Thanks Steve for this very informative article.
February 1st, 2010 at 3:53 am
Hey, sorry for this late response.. I was out camping in the desert the last couple of days, so I’m just now getting back to a computer. Anyway, thanks for your comments!
@scott / jeff – thanks for pointing out that you need to focus “with your final composition in mind.” I should have mentioned this in the post.
@clubped – I’m not sure how all image stabilization systems work, but with Canon, I know that if I compose, hold the shutter down halfway and then recompose, the IS will try to compensate, BUT: if you hold your final composition for a second or two, the IS will figure out what you’re doing and stabilize around your new composition.
@val – I use Canon, and have used back button autofocusing a lot on their SLRs. I’m sure there’s some cameras out there that don’t have or need this feature, but to list them all would have taken up an extraordinary amount of time and space.
-Steve
February 1st, 2010 at 3:37 pm
I couldn’t see the advantage of #3 over #1. If you use back-button autofocusing you have the focus point in the middle, press the button then recompose and take a picture. When you recompose, you basically change the focal plane and suffer the same drawback as that of #1. Please someone explain to me on this? Does #3 function the same as “AF lock” button? Thanks for sharing this good info, Steve.
February 2nd, 2010 at 6:13 pm
Good and informative article. Useful ways to get better control of autofocus. Keep blogging and thanks.
February 12th, 2010 at 6:00 am
Great tip on the back button option!! I had never used it before but this really helps when I have to auto focus quickly- Thanks!
February 13th, 2010 at 4:32 am
Option #3, “Back Button”, is especially useful for aerial photography. This technique was suggested to me as I prepared for aerial trip at Denali. (5DII) Worked beautifully as light changed constantly while focus did not.. Each “half press” of the button yielded curren exposure setting. Also used exposure bracketing for best exposure. In fast changing situation, “Back button” focus allowed me to concentrate on composing. See website for examples.
May 13th, 2010 at 4:09 pm
So to clarify…if I’m using the “back button” on my Canon 40D for focusing I should:
- Put the part of my subject that i want in sharp focus in the center of the frame
- Press the button on the back (AF-ON) (I guess in theory this locks that particular focus right?)
- Then as long as my subject is the same distance away I can recompose – (meaning I can now have the subject off to the left within my frame) and the camera will have kept the focus on my subject who is now off to the left within the frame?
Thanks,
Heather
May 14th, 2010 at 12:52 am
Heather, not so much. Read this:
http://visual-vacations.com/Photography/focus-recompose_sucks.htm
Then, I would suggest setting up the joystick on the back of the camera to control focus point selection. Using that you can select the focus point that makes sense for your composition and have a very minimal amount of recomposing needed.
The back-button AF works well when the camera and subject doesn’t move and you want to take repetitive shots without having to focus and recompose in between.
However, if you’re dealing with shallow DOF then both focus/recompose and back-button focus may lead to OOF shots. There could be minimal movement between clicks that aren’t adjusted for with re-focusing and as in the article I linked states, recomposing changes the distance, even if only slightly.
If you’re shooting with plenty of DOF then it matters much less, so part of this depends on what kind of glass you have and what aperture you typically shoot at.
May 15th, 2010 at 8:44 am
Scott,
Thank you so much for taking the time to reply. The article really helped me gain a better understanding! I think my problem lately with achieving focus has been that I’ve been shooting a lot with a shallow DOF so when I’m recomposing the angles are different and like you’ve mentioned the distance changes. Thanks again! Heather
July 7th, 2010 at 3:50 pm
If shooting a small child who is likely to “wiggle”, would the recommendation be to have the Canon 40D in AI Servo mode and continue to depress the back button AF and shoot? Also if I know I want the child on say the left side of the frame would it be appropriate to have the far left point selected, then use the back button AF to maintain focus?
July 9th, 2010 at 7:38 am
From a vantage point along the coast, I focus on a coconut tree (around 500 metres away) across the lagoon. My ancestor rests under that tree. So I wait for sunset to take multiple shots of that tree till it is almost completely dark. The sun happens to set just beside that tree, so you can imagine the drama AND the camera thirsting to focus elsewhere as the sharp contrasts change. No. 2 IS FOR ME! I’ll try the back-button alternative sometime. But it would be tedious in dark twilight. I think. Thanks Steve.
Tiberman – Mauritius
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