AI Servo vs. AI Focus - what's the key difference?

Started Jan 28, 2013 | Discussions
StevenLyall Forum Member • Posts: 90
AI Servo vs. AI Focus - what's the key difference?

As I read the manuals - and grossly simplify them, 'One Shot' is for stationary subjects, 'AI Servo' is for moving subjects, and 'AI Focus' is for stationary subjects that might move.

I also read that both 'AI Focus' and 'AI Servo' initially focuses on a single point and then tracks the subject.

If I have read it correctly, then I am not seeing the compelling reasons to pick 'AI Focus' or 'AI Servo', but I realize that there must be some, si I was hoping for some help to understand this better.

Many thanks if anyone can offer some insight.

Steven

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schmegg Veteran Member • Posts: 5,768
Re: AI Servo vs. AI Focus - what's the key difference?
2

StevenLyall wrote:

As I read the manuals - and grossly simplify them, 'One Shot' is for stationary subjects, 'AI Servo' is for moving subjects, and 'AI Focus' is for stationary subjects that might move.

I also read that both 'AI Focus' and 'AI Servo' initially focuses on a single point and then tracks the subject.

If I have read it correctly, then I am not seeing the compelling reasons to pick 'AI Focus' or 'AI Servo', but I realize that there must be some, si I was hoping for some help to understand this better.

Many thanks if anyone can offer some insight.

Steven

The main difference with most bodies is that AI-Servo works quite well where-as AI-Focus does not. Hehe.

I haven't tried AI-Focus on my 5D3, but on all the other bodies I've ever tried it on it's been too unreliable to consider using (IMHO).

Not sure if it's improved on the latest bodies (1Dx, 5D3 and 6D), but I'm so used to working without it that it matters little to me.

The main idea with AI-Focus is that it starts in One-Shot, so you get focus confirmation (which you don't get in AI-Servo), and then it monitors the subject and, if it detects the subject is moving, it switches to AI-Servo and tracks. That's the theory, the practice is sometimes that it doesn't switch to tracking quick enough (or something) and you end up with more out-of-focus shots than you would by using the other modes.

Also, you can customise a button that allows you to switch from One-Shot to AI-Servo (the button must be held down though). You might find this handy perhaps. It'll be a custom control function.

OP StevenLyall Forum Member • Posts: 90
Re: AI Servo vs. AI Focus - what's the key difference?

Again, very helpful.

I've rented a 5D3 for a few days, and it's making me really think about all the features, although to be honest, I've wondered about this for my 40D too.

Very happy with the 5D3 trial, though 

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John-G Veteran Member • Posts: 4,931
Re: AI Servo vs. AI Focus - what's the key difference?
1

The easiest way to remember is: AI Servo works, AI Focus does not.  I have never found a body in which AI Focus worked reliably. Best advice is to simply avoid it and stick to One Shot and AI Servo - they both work as advertised.

Picturenaut
Picturenaut Regular Member • Posts: 331
Re: AI Servo vs. AI Focus - what's the key difference?
1

schmegg wrote:

The main difference with most bodies is that AI-Servo works quite well where-as AI-Focus does not. Hehe.

You nailed it Schmegg, I experienced same  with all Canon bodies I used - including a 5D3. AF-Servo is my default setting, it works with most subjects well, including the challenge of hand-held macro shooting (which wasn't possible in the old days without good AF systems with AF-Servo).

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Picturenaut

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