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View Full Version : AI Focus vs Servo vs One Shot


Rainyday
25th of December 2011 (Sun), 18:36
Could someone explain to me the advantages of setting the camera in Servo? I"m looking for specific examples because I seem to find situations where I'm not sure what to pick.

I was watching a squirrel the other day. He would be still for about 10 seconds, then hop away a bit, then stay still then hop a bit...then he'd dash like mad up a tree!

Or a horse grazing quietly, slowly ambling through the green grass. One shot or servo?

Thanks!

tracknut
25th of December 2011 (Sun), 19:19
AI Servo for anything that can move. Horses, squirrels, etc. It instructs the camera to continually attempt to focus on the subject.

One Shot for anything where you want to focus once and have no reason to focus again. Houses, trees, anvils, etc.

AI Focus, never.

Dave

Mike R
25th of December 2011 (Sun), 19:49
AI Servo for anything that can move. Horses, squirrels, etc. It instructs the camera to continually attempt to focus on the subject.

One Shot for anything where you want to focus once and have no reason to focus again. Houses, trees, anvils, etc.

AI Focus, never.

Dave
+1
AI Focus may seem like a good option but it just cannot get it right.

gjl711
25th of December 2011 (Sun), 20:06
I agree, one shot if it's standing still or moves rarely. Servo for moving subjects, and AI Focus never. AI focus is suppose to switch between One Shot and Servo based on some set of conditions but never seems to get it right.

snyderman
25th of December 2011 (Sun), 20:09
AI Servo for anything that can move. Horses, squirrels, etc. It instructs the camera to continually attempt to focus on the subject.

One Shot for anything where you want to focus once and have no reason to focus again. Houses, trees, anvils, etc.

AI Focus, never.

Dave

+1 on Dave's comments. Plus, nobody can figure out a practical use for AI Focus mode.

dave

thedcmule2
25th of December 2011 (Sun), 21:39
Huh?

What about a performer on stage that moves around and stops moving and repeats?

Wouldn't AI Focus be good for that?

gjl711
25th of December 2011 (Sun), 21:42
Huh?

What about a performer on stage that moves around and stops moving and repeats?

Wouldn't AI Focus be good for that?It's suppose to but never seems to work right. Keep it in servo and all will be fine.

thedcmule2
25th of December 2011 (Sun), 21:47
Will do, how do you go about manual focusing on a moving performer though? Do you use single shot or continuous high speed?

I'm trying to decide whether to do autofocus or manual focus next show.

Jill-of-all-Trades
25th of December 2011 (Sun), 21:52
AI Servo for anything that can move. Horses, squirrels, etc. It instructs the camera to continually attempt to focus on the subject.

One Shot for anything where you want to focus once and have no reason to focus again. Houses, trees, anvils, etc.

AI Focus, never.

Dave

:) Unless it has ACME stamped on it, then it's most likely gonna drop at any moment.

ImCBParker
25th of December 2011 (Sun), 21:57
I shoot a ton of shows and the only way I shoot is single shot, single point, auto focus . Occasionally servo. People move to much to constantly adjusting manual focus. Would not even attempt it for a whole show. Though I see you have the 50 1.4, which I also have as a backup, and in certain lighting conditions it tends to hunt and I have lost shots as a result. Still would not shoot a whole show manually focusing. Just know your lens limitations.

thedcmule2
25th of December 2011 (Sun), 22:01
I shoot a ton of shows and the only way I shoot is single shot, single point, auto focus . Occasionally servo. People move to much to constantly adjusting manual focus. Would not even attempt it for a whole show. Though I see you have the 50 1.4, which I also have as a backup, and in certain lighting conditions it tends to hunt and I have lost shots as a result. Still would not shoot a whole show manually focusing. Just know your lens limitations.So for a 50mm 1.4 knowing itll hunt what should I do? I used AI Servo on a 50mm 1.2L and it still misses a ton, though that couldve been because I chose apertures wider than 2.0. I need to learn from you guys how to "aid" a lens into focusing well.

Also is there a reason to use or not use hi-speed or low-speed continuos?

Niccas9
25th of December 2011 (Sun), 22:05
Not to highjack this thread, but it seems thedcmule is saying that the particular lens has a lot to do with the accuracy of the autofocus. I have been playing around with Servo and seem to have trouble getting my shots in focus, but my lenses are definitely considered low-end.

ImCBParker
25th of December 2011 (Sun), 22:12
With the 50 1.4, go to single shot vs. servo. I find i get better result in darker situations with single shot, That has helped me at least.

If it continues to hunt, it may simply be too dark and at that point put the camera away and enjoy the show. I find most of the time the lens hunts like that, it is usually really dark and most of the shots will be unsalvageable.

That being said, if you want to try, position yourself where a light shines just right on the performer's face. Be cognizant of framing, but you should be able to make it work if there is even a small amount of light hitting the artists face. If there is no light and you continue to struggle, see the last point. There are lots of shows I get asked to shoot hat just cannot be shot without flash. You just have to know when to gve up and enjoy the show.

ImCBParker
25th of December 2011 (Sun), 22:14
Niccas, lots of lenses have issues in really dark environments. I have had the same thing happen with my 1.2L and the 1.4. Ditto on zooms. All depends on the particular light(or lack there of) of a venue. The key is to know when to give up unless you know the band and can arrange for flash use for a couple songs.

wisv1k
25th of December 2011 (Sun), 22:20
I have been playing with back button focus separate from the shutter in servo all the time. It seems to be working for me quite nicely. It seems to be the best of all worlds.

BrandonSi
25th of December 2011 (Sun), 23:07
back button + AI Focus works for me (5D2), but I press the focus button repeatedly when shooting so I'm always focusing / refocusing. If I am shooting sports or something moving, I'll go with servo.

I think the general consensus (as you can probably tell) is that one-shot is for still, servo for moving and AIF for nothing. :)

dannequin
25th of December 2011 (Sun), 23:39
Good points brought up in this thread, I never really thought much of those settings until I started changing the subjects that I shot... Shooting multiple things I adjust my autofocusing to what needs to be shot, I may shoot a still subject/posed subject on One Shot because they won't move, but then when I shoot live music I use AI Servo because the artist is constantly in motion, and shooting on One Shot would cause blurring.

AI Focus, I've never really played with to be honest...

Veemac
25th of December 2011 (Sun), 23:52
Using AI Focus is like using green box mode or Auto AF point selection - you're telling the camera that it's smarter than you and should just go ahead and make the decisions without your input - which rarely turns out well. AI Focus sounds good in theory, but doesn't work right in real life. If it moves, use AI Servo; if it doesn't, use One Shot. Don't let the camera try to decide whether it's moving or not.

thedcmule2
26th of December 2011 (Mon), 01:32
Ive read almost everywhere through researching a few minutes ago AI focus doesnt work as advertised, and its best to pick servo or one-shot by yourself.

What do you guys mean by "back-button"? Are you talking about the AF-ON button in the back that forces auto-focus the same way pressing the shutter half-way down does? I just experimented with that while shooting and I had great results. Splitting the functions works so much better for me than having it all on the shutter button whichs feels limited til focus hits.

Also - what do you guys think about all this in respect to single shot, high speed and low speed continuous? How do these tie in for better photography?

Definitely one of the best threads ive encountered all week.

FlyingPhotog
26th of December 2011 (Mon), 01:49
I'm probably in low continuous 95% of the time (7fps) and only use high continuous (10fps) when I want to divide a moment into even smaller slices.

Low continuous still allows me to get off the shutter quickly enough to only shoot one frame but it's still fast enough to capture most sequences when / if I want to.

I reserve high continuous for things like crossing jets at airshows.

Tony-S
26th of December 2011 (Mon), 11:43
They should drop AI Focus and start using eye-control focus again. It's fabulous on my EOS 3.

wisv1k
26th of December 2011 (Mon), 12:43
What do you guys mean by "back-button"? Are you talking about the AF-ON button in the back that forces auto-focus the same way pressing the shutter half-way down does? I just experimented with that while shooting and I had great results. Splitting the functions works so much better for me than having it all on the shutter button whichs feels limited til focus hits.


Exactly. You can hold the focus button is servo and hit the shutter button whenever you want to take the shot. This also allows for easy focus & recompose like in one-shot.

chauncey
26th of December 2011 (Mon), 15:57
I use Servo for most of my stuff for PP purposes...those micro movements/expressions can be swapped out to vastly improve an image.

thedcmule2
26th of December 2011 (Mon), 17:44
I use Servo for most of my stuff for PP purposes...those micro movements/expressions can be swapped out to vastly improve an image.So you use AI Servo when shooting portraits of people instead of one-shot mode? I would think if the person youre shooting moves forward or back an inch the focus wont be on the eyes anymore? Same is the issue in manual I guess.

chauncey
26th of December 2011 (Mon), 17:49
depends on how you have set-up the AF mode

thedcmule2
26th of December 2011 (Mon), 17:59
Are you talking about AF face detection by any chance? Give me a clue here :P or maybe high speed continuous?

chauncey
26th of December 2011 (Mon), 18:22
I'm referring to the myriad of AF options in section III of your custom functions.

tonylong
26th of December 2011 (Mon), 21:27
Ive read almost everywhere through researching a few minutes ago AI focus doesnt work as advertised, and its best to pick servo or one-shot by yourself.

I've never used AI Focus enough to have an opinion of how well or not-well it works. But, yeah, the "concensus" is that it doesn't work so well.

Now, how many of those opinions are based on experience and how many are based on "I read this on the Web"? Well, I don't know:)! Occasionally someone pops up and says that they use it with good results, like someone has done in this thread!

What do you guys mean by "back-button"? Are you talking about the AF-ON button in the back that forces auto-focus the same way pressing the shutter half-way down does? I just experimented with that while shooting and I had great results. Splitting the functions works so much better for me than having it all on the shutter button whichs feels limited til focus hits.

While it's true that the default function of the AF-ON button is to activate the AF (along with the shutter button half-pressed) the people on here who talk about "rear button AF" are typically referring to the fact that they have used a Custom Function to actually switch the focusing activation from the shutter button to the rear button, meaning that half-pressing the shutter button will not start the AF, only pushing the rear button.

And, there is a reason why I say "rear button" and not the AF-ON button. In your Custom Functions there are two that you can use for this operation:

One C.Fn "turns off" AF on the shutter so that you are only using the AF-ON button (by default). I'm not sure about the 60D, but on my 1D3 that is C.Fn IV-1. Look in your manual for descriptions of what each possible setting does -- I have mine set to 3: the shutter does AE Lock (as well as snaps the pic) and the rear button does Metering and AF.

The other C.Fn that can be helpful is, in my 1D3, C.Fn IV-2, right after the first one.

This C.Fn switches the function of the AF-ON button and the AE Lock (*) button. This is a nice function to have because for older DSLRs which don't have an AF-ON button, but do have a * button, the only way to get rear button focus is to switch to the AE Lock/* button. Again, the shutter button can be used to do AE Lock if you program it that way.

So, I have three DSLRs, two of them older models without the AF-ON button, so I have programmed my 1D3 to switch the AF-ON and the * button functions, so all three of my bodies use the * button for rear button AF.

Also - what do you guys think about all this in respect to single shot, high speed and low speed continuous? How do these tie in for better photography?

Definitely one of the best threads ive encountered all week.

I often use a short burst in "iffy" conditions (lower lighting and hand-holding) or when shooting a sport, moving wildlife, or a rapidly moving event.

For the moving stuff I'm in AI Servo. But with my main "walkaround" body I'm more typically in One Shot AF, although, like I said, I'm always ready to fire a short burst, 2-3 shots, when I want to give myself a better chance of a keeper. Often, though, funnily enough, the first of the burst is as good as the rest!

As to High Speed/Low Speed Continuous, well, on my 1D3, which can go to 10 fps, I set my High Speed to 6 fps and have gotten thousands of sports/wildlife shots without regret -- I did't get the camera for the 10 fps. But yeah, there are some scenarios when I could imagine wanting to switch over. In fact, a logical thing might be to set the Low Speed to 6fps and the High Speed to 10 fps, I dunno, 'cause for what I've shot the 6 has worked!

BaghdadFred
27th of December 2011 (Tue), 00:47
I get the whole AI Servo mode or one shot usage but what about the best AF Point selection setting for action shots?

When using Auto Select 19-Point AF you can see the focus points changing in AI SERVO mode. However I often use Single Point AF but that doesn't move with the subject. Either mode seems to basically work however just having sufficient shutter speed seems to help the most.

I've photographed probably about a dozen or so 5k runs here and I feel like I've never gotten it totally right. We did a 5k on the 24th and it was one of my worst shoots in a long time. Thankfully there was another shooter backing me up that day. Ended up with a ton of shots that had back focus issues and there was a lot that were just soft or OOF. I believe I was running AI SERVO and 19PT AF that day.

FlyingPhotog
27th of December 2011 (Tue), 00:51
I would never trust the camera to "know" where I want the focus point to fall.

If you don't want to focus "center mass," then move the focus point yourself to where you want it. Shoulder height. Head height. On the runner's feet. Whatever.

Control your image creation and don't let it control you! ;)

tonylong
27th of December 2011 (Tue), 01:10
I admit that when doing sports/action shooting I stick with Center focus AI Servo. I've never gotten confident in using auto points in AI Servo shooting. My shortcoming, I shoot that stuff with a 1d3 which should deliver good results, it's just that like I said I haven't developed the confidence...

BaghdadFred
27th of December 2011 (Tue), 01:31
I would never trust the camera to "know" where I want the focus point to fall.

If you don't want to focus "center mass," then move the focus point yourself to where you want it. Shoulder height. Head height. On the runner's feet. Whatever.

Control your image creation and don't let it control you! ;)

So your suggestion would be to use Single Point AF and shoot center mass or the face? I am wondering if it would be better to also bump up 2-3 f stops and thus increasing the DOF and possibly reduce the focus problems.

After reviewing my last set i know now I really should have had a higher shutter speed and possibly smaller aperture for wider DOF and just really cranked the ISO up to compensate. Noise I can deal with easily enough in PP, OOF just ruins the shot.

FlyingPhotog
27th of December 2011 (Tue), 01:39
It depends on your shooting angle and what you're trying to achieve.

Isolating a runner from either head on or from the side will require shallow DOF. A desire to show "speed" will require a slow-ish shutter speed which generally means a small aperture.

Use of ND filters can let you shoot slow and still maintain shallow DOF.

I've not shot runners but to my mind, focusing center mass should be fine for head on shots but wanting to key in on specific features (say, panning with the feet or faces) would probably mean choosing a focus point that will hit your intended spot in the frame yet still allow you to fill the frame and not have to grossly crop in post.

BaghdadFred
27th of December 2011 (Tue), 02:39
Just simply trying to stop time, be in focus and get a good expression out of the runner. Sound easy enough but when you dealing with early morning light and moving objects shot wide open at 200MM its not the easiest thing to always lock a focus on and it come out good and sharp.

Here is another shot from our Thanksgiving Day run which came out better than the Christmas Eve set but is still quite soft IMO.
http://baghdadfred.smugmug.com/CeremoniesandEvents/MWR-Events/2011-11-24-MWR-UIII-Turkey/i-v6ZSKKq/0/XL/20111124-IMG5116-XL.jpg

PixelMagic
27th of December 2011 (Tue), 04:07
Focusing on the runners' faces or bodies MAY not provide enough contrast for the AF to work reliably. If the runners are wearing bibs focus on the numbers since they are usually black and white and set an aperture that will give you enough depth of field.

I use Single Point with AF Expansion (left/right assist points) enabled to increase the AF reliability.



So your suggestion would be to use Single Point AF and shoot center mass or the face? I am wondering if it would be better to also bump up 2-3 f stops and thus increasing the DOF and possibly reduce the focus problems.

After reviewing my last set i know now I really should have had a higher shutter speed and possibly smaller aperture for wider DOF and just really cranked the ISO up to compensate. Noise I can deal with easily enough in PP, OOF just ruins the shot.

PixelMagic
27th of December 2011 (Tue), 04:19
The guy on the left is in focus; isn't that what you wanted?

Take a look at this thread: http://photography-on-the.net/forum/showthread.php?t=1044790&highlight=copenhagen+marathon
From the EXIF he using around F/5.6 most of the time.

Just simply trying to stop time, be in focus and get a good expression out of the runner. Sound easy enough but when you dealing with early morning light and moving objects shot wide open at 200MM its not the easiest thing to always lock a focus on and it come out good and sharp.

Here is another shot from our Thanksgiving Day run which came out better than the Christmas Eve set but is still quite soft IMO.
http://baghdadfred.smugmug.com/CeremoniesandEvents/MWR-Events/2011-11-24-MWR-UIII-Turkey/i-v6ZSKKq/0/XL/20111124-IMG5116-XL.jpg

BaghdadFred
27th of December 2011 (Tue), 06:34
The guy on the left is in focus; isn't that what you wanted?

Take a look at this thread: http://photography-on-the.net/forum/showthread.php?t=1044790&highlight=copenhagen+marathon
From the EXIF he using around F/5.6 most of the time.

On the thread above the photographer had WAY more available light than I normally do which makes a big difference. I downloaded one shot and noticed he was at F/4.5 1/1600sec at ISO 400. My photos would be almost black in those settings.

I guess the question I am trying to answer is if operating at a higher f-stop will provide a better chance of catching things in focus since f/2.8 has quite a short DOF.

tonylong
27th of December 2011 (Tue), 11:18
Fred, with the above photo, are you saying that the runner on the left looks out of focus when you see it more enlarged? I'm asking 'cause at the small size it doesn't look bad...

BaghdadFred
27th of December 2011 (Tue), 12:58
Here is my shots from Christmas eve run. Most of my keeper shots were done at 70MM at f/2.8 @ 1/400. Very few keepers shot at 200MM. In any case we have yet ANOTHER 5k scheduled for New Years Eve. So i get to test out my settings again.

http://baghdadfred.smugmug.com/CeremoniesandEvents/MWR-Events/2011-12-24-CHRISTMAS-EVE-FUN/i-wWTJhW7/0/XL/20111224-IMG7168-XL.jpg

FlyingPhotog
27th of December 2011 (Tue), 12:59
Go Air Force! :lol:

scroller52
28th of December 2011 (Wed), 15:04
i actually only use ai-focus 99% of the time via back-button and i'm satisfied with the results.