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How to setup AI Servo (1 Viewer)
- Thread starter Saphire
- Start date
pete schofield
Well-known member
Hi Christine not sure what are you expecting to happen?
AI servo is usually used to track a moving object, i.e. bird flying.
The camera lens will continually try to focus on the moving object.
I take it that yours doesn't, what lens are you using?
Pete
AI servo is usually used to track a moving object, i.e. bird flying.
The camera lens will continually try to focus on the moving object.
I take it that yours doesn't, what lens are you using?
Pete
Saphire
Christine
Hi Pete.
I thought that if I set up for a bird in flight, I have nothing to focus on except infinity, then wait for bird to come into one of the focus points while half pressing shutter button. I have even tried it on a blank area and waited for a car to pass, none of the focus points pick up am I missing something. The manual is not very clear on how to use this function. My lens is the sigma 170-500, for birds in flight I usually have it on around 300 to 450.
I thought that if I set up for a bird in flight, I have nothing to focus on except infinity, then wait for bird to come into one of the focus points while half pressing shutter button. I have even tried it on a blank area and waited for a car to pass, none of the focus points pick up am I missing something. The manual is not very clear on how to use this function. My lens is the sigma 170-500, for birds in flight I usually have it on around 300 to 450.
paul goode
Well-known member
Saphire said:
Hi Christine
Slightly confused by your question. Are you holding the camera stationary and waiting for something to fly into the viewfinder or are you picking up on a bird flying towards you and panning as it passes you?
A1 servo will only work on the latter. You have to be 'on' the bird and panning, then half press the shutter to get a focus lock at which point the AF can continually adjust the focus as the bird flies past.
I would imagine that in the first case the AF has no chance of achieving a focus lock in the time it takes a bird or car to zip through the focus point.
The lens you are using is not an issue in this. It will work fine.
Regards
Paul
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paul goode
Well-known member
Just noticed from your 1st message that you have all the focus points switched on. This will make life difficult. Probably better to only have the central point on. This should make it easier for the camera to know what you are trying to focus on.
Regards
Paul
Regards
Paul
robski
Well-known member
For the more technically minded I bump into this on Canon AI Servo - A bit dated but I am sure the general principles apply.
http://photonotes.org/other/ai-servo.html
Robert
http://photonotes.org/other/ai-servo.html
Robert
paul goode
Well-known member
Saphire said:
Hi Christine,
Just looked at the attachment. Not light reading is it.
To get to the bottom line A1 servo could be working and you may not realise.
It sort of works in the background. If you get onto a bird a fair way from you and half press the shutter the bird should come into focus in the viewfinder. As the bird gets nearer still holding the shutter half down the AF should be continually updating to keep the bird in focus. At the point of taking the picture you should have a nicely focussed bird.
Thats the theory. In reality I wonder if you have any examples you could attach because I assume your pictures are blurred and you are assuming the A1 servo isn't working.
Trying to photograph a moving subject brings in a whole raft of other factors such as camera shake, shutter speed, and if you have all the AF points on which one locked onto something. Unfortunately anyone of these (probably plus plenty of others) can cause the picture to be blurred.
One thing is certain with flight shots regardless of the equipment used - it takes lots of practice. Panning alone is a skill that takes time to learn (and i'm a long long way from mastering it.)
Regards
Paul
Saphire
Christine
Paul. I think I may have been causing confusion and not explaining myself, its difficult to express in words what I am thinking. It looks like I have AI servo and AI Focus working correctly as I have no problems taking birds in flight as like you say its constantly following the focus. I was always with the understanding that it was something special and it is no more special then using the camera as normal. I wish when they wrote manuals, they put things in plain English so dumbo's like myself could understand.
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paul goode
Well-known member
Saphire said:
Hi Christine,
Good that we have got to the bottom of it. In future adopt the male attitude - only read the manual when you've broken the camera!
Regards
Paul
Tannin
Common; sedentary.
Canon's manual for the 20D - and I presume the 350D as well - is magnificently unclear about focusing modes. I assume that the person responsible has now been promoted into a high-powered position in the public service, or is possibly drafting taxation law. (He would be a natural.)
But the big thing with flight shots is to turn all the focus points on - it is very difficult, perhaps impossible to get the bird exactly on the centre focus point (or any other focus point) and keep it there as it flies over. With a long lens and a fast moving bird (any bird in flight, pretty much, except for one of the hovering kestrels/kites) you are flat out just keeping the birds in frame.
So do that: keep the bird in frame, and let the camera worry about a focus point. My 20D (and your 350D too, I'm sure) will do a remarkably good job of selecting a focus point if you just tell it to pick its own points and go for it - even against detailed backgrounds, quite often. If the camera can't focus on the bird reliably, you probably need to get closer, or else the light is poor. In either case, flight shots are not a realistic proposition.
Oh, and I find it helps to fire in salvos: set the camera to auto-repeat and bang off three or four shots at a time, release the shutter for a moment, then squeeze again (a half press for a moment first if you have an image stabilising lens) and go for another set. It's only electrons: shoot as many as you like.
But the big thing with flight shots is to turn all the focus points on - it is very difficult, perhaps impossible to get the bird exactly on the centre focus point (or any other focus point) and keep it there as it flies over. With a long lens and a fast moving bird (any bird in flight, pretty much, except for one of the hovering kestrels/kites) you are flat out just keeping the birds in frame.
So do that: keep the bird in frame, and let the camera worry about a focus point. My 20D (and your 350D too, I'm sure) will do a remarkably good job of selecting a focus point if you just tell it to pick its own points and go for it - even against detailed backgrounds, quite often. If the camera can't focus on the bird reliably, you probably need to get closer, or else the light is poor. In either case, flight shots are not a realistic proposition.
Oh, and I find it helps to fire in salvos: set the camera to auto-repeat and bang off three or four shots at a time, release the shutter for a moment, then squeeze again (a half press for a moment first if you have an image stabilising lens) and go for another set. It's only electrons: shoot as many as you like.
paul goode
Well-known member
Tannin said:
robski
Well-known member
With my limited experience with flight shots I've found the light and uncluttered backgrounds is the biggest factor in getting good flight shots. i.e on bright days with a clear blue sky.
least success with trees in the background and limited success with ripples on water as a background.
So I only bother shotting against a blue sky, I have not yet made my mind up wether all or a single focus points works best yet.
I also found fully pressing the shutter in AI servo mode gets a higher in focus rate of shots as the camera only fires when it has an object focused.
Robert
least success with trees in the background and limited success with ripples on water as a background.
So I only bother shotting against a blue sky, I have not yet made my mind up wether all or a single focus points works best yet.
I also found fully pressing the shutter in AI servo mode gets a higher in focus rate of shots as the camera only fires when it has an object focused.
Robert
Personally I have found that for flight shots when the background is plain (such as a blue sky) it's best to shoot with all focus points on. In theory the camera will then focus on the bird rather than focusing on the background. If the background is 'busy' it's probably best to select the central focus point and try and track the bird, if not there's a good chance the background will confuse the auto focus - you'll end up with a blurred bird and a pin sharp background.
Here are two flight shots taken with a 350D, one against sky, the other against a dark (busy) background.
http://www.birdforum.net/pp_gallery/showphoto.php/photo/70230/sort/1/cat/500/page/2
http://www.birdforum.net/pp_gallery/showphoto.php/photo/66899/sort/1/cat/500/page/2
Here are two flight shots taken with a 350D, one against sky, the other against a dark (busy) background.
http://www.birdforum.net/pp_gallery/showphoto.php/photo/70230/sort/1/cat/500/page/2
http://www.birdforum.net/pp_gallery/showphoto.php/photo/66899/sort/1/cat/500/page/2
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