Bird In Flight Lost Focus Question

Hello
Was out today trying to get some pictures of hawks and eagles.
I had a good opportunity to get some images of a couple of hawks that were almost directly overhead.
The hawks were a little bit off in the distance but, they were a good size bird and I had them in view through the viewfinder.
As I was panning with the birds and starting to take pictures, one of them went out of view but, I could still see the other one in the viewfinder.

As I started to take pictures of the in view bird, things went completely out of focus in the viewfinder.
I tried to get the camera to refocus but couldn't do it in time before the birds were to far off in the distance.

I was a bit ticked off at the lost opportunity and would like to know what the cause of this might be.
This has also happened to me before when I was taking pictures of a small plane in flight.

I'm guessing the issue may be with my technique as I'm fairly new at BIF but, I'm wondering if it may be an equipment limitation as well.

In both cases, I was using a Canon 40D with the new version Canon 100-400.
Camera is set up for back button focus and was in AI Servo mode.
All auto focus points were being used as the birds were high enough in the sky that nothing could pull focus off them.
Lens was at 400mm.
Shooting in manual mode.

I can understand the camera having a hard time to refocus into an empty sky but, what would cause the camera to loose focus in this situation?
Would it be because of limited tracking ability of the 40D?
The 40D does not have the ability for zone or group focus point selection.
It's either all, or individual focus points.

I would be surprised if it was a lens issue as the lens was bought brand new late last year.
It works perfectly fine in all other situations.

I'm hoping to get out to the same location next weekend as it seems to be a good area for these particular kind of birds and I would like to avoid or at least, limit this issue from happening again.

You are doing the right thing by using all your available AF points (automatic AF point selection) because you can't predict the path the birds will make. Unfortunately if your AF point falls OUTSIDE of the bird (because it was too slow or you were too erratic with movements), it will lose focus and you will need to zoom out, then focus on a far subject to reacquire focus.

I mostly shoot aviation photography but here's what I do.

I assign two buttons for back button focusing

AF ON= single point CENTER af focus, set to One shot. Turn confirmation beep on.

* = automatic af point (all points), set to AI servo mode.

What I do is focus on a distant subject so the viewfinder isn't blurry. I do this BEFORE even taking the shot. Then I center the bird in frame and hit the AF On, when I hear the beep I've gotten focus, then i simply hold * to track in AI servo and snap away.

Additionally on the 100-400mm I set the focus mode to "3M-infinity" for distant subjects as it will improve the speed of AF system. What could be happening is your AF is too slow keep up because have it set to FULL and it simply can't keep.

If it ever does lose focus and everything goes blurry, you have to reset by zooming the lens out, then pick a static far distance object and recompose so the viewfinder isn't blurry. Alternatively you can use the internal zoom ring and move it close to infinity.

5dsraviation wrote in post #18607515
You are doing the right thing by using all your available AF points (automatic AF point selection) because you can't predict the path the birds will make. Unfortunately if your AF point falls OUTSIDE of the bird (because it was too slow or you were too erratic with movements), it will lose focus and you will need to zoom out, then focus on a far subject to reacquire focus.

I mostly shoot aviation photography but here's what I do.

I assign two buttons for back button focusing

AF ON= single point CENTER af focus, set to One shot. Turn confirmation beep on.

* = automatic af point (all points), set to AI servo mode.

What I do is focus on a distant subject so the viewfinder isn't blurry. I do this BEFORE even taking the shot. Then I center the bird in frame and hit the AF On, when I hear the beep I've gotten focus, then i simply hold * to track in AI servo and snap away.

Additionally on the 100-400mm I set the focus mode to "3M-infinity" for distant subjects as it will improve the speed of AF system. What could be happening is your AF is too slow keep up because have it set to FULL and it simply can't keep.

If it ever does lose focus and everything goes blurry, you have to reset by zooming the lens out, then pick a static far distance object and recompose so the viewfinder isn't blurry. Alternatively you can use the internal zoom ring and move it close to infinity.

Thanks for the reply.
I've realized now that the out of focus issue was caused by me.
I rushed to get the pictures and didn't do a couple of things properly prior to taking the pictures.
Next time I will be better prepared.

The out of focus thing happened at the start of the picture taking session and of course, it was the only time for the rest of the day, the birds came really close to me.
They must've known I wasn't prepared!

Interesting how you have your camera set up.
I'll have to check to see if the 40D can be set up like that.

I should use a custom function I guess to cut down on missed settings.

In your last sentence, I assume you mean the focus ring and not the zoom ring?

I shoot a lot of birds in flight with the 100-400 II and from your description it sounds like the birds simply moved from the range of focus. The camera can track them if you can. If the focus system suddenly sees empty sky, it will begin to hunt, looking for something to lock focus.

We have all developed our own methods that work for us depending on the equipment that we use. The description above with regard to multiple focus buttons and setting the lens to a certain point before taking shots would never work for me. There are just too many things to do before firing. In most cases, you don't have that kind of time. I use center point only and I use the shutter release for focus and fire.

If an opportunity presents itself, I can be firing within a second or so and I get pretty good results.

From your description above it sounds to me like it is simply a matter of bettering your technique. Shooting birds in flight is not the easiest thing to do. The first time I tried it I had a gull nearly stationary above me in the wind and I couldn't get a clean picture to save me. It took a tremendous amount of practice before I got to the point where I was returning good results.

The other thing that comes to mind here is the 40D. I'm quite sure that Canon has furthered the development of the focus tracking since that camera was introduced. I'm not at all familiar with it but just thinking about the fact that it isn't newer technology may have something to do with your difficulties.

Shot my first air show with that body. I would probably not use all AF points on a 40D. I had that body and it was excellent but zone AF which uses all AF points was not as sophisticated. I did start not using zone AF or all focus points until I got the 7D2. Not sure if all focus points is called zone on the 40D. It is has been too many years.

I'd stick to single point. Also check to see if you can adjust Tracking Sensitivity (TS) with that body. A negative setting will make the camera take longer to start looking to something else to focus if your AF point goes off target. A positive number makes it focus on something else immediately.

I have always set my cameras TS to -2 for birding. You get about a second to get your AF point back on target. It may not seem like much but that can make a big difference.

If I'm shooting something like a marathon and want to take shots of two runners I set TS to +2. Now when I move the AF point from one runner to the other it focuses instantly. There is no delay.

Forgive if the 40D does not have TS. Again it has been too long. I think my 50D had it. 7D for sure. If it does have it the factory setting will be 0. -2 is very useful for birding.

saea501 wrote in post #18607750
I shoot a lot of birds in flight with the 100-400 II and from your description it sounds like the birds simply moved from the range of focus. The camera can track them if you can. If the focus system suddenly sees empty sky, it will begin to hunt, looking for something to lock focus.

I think this is what happened and the lens did go into a hunt mode.
I just have to remember to manually use the focus ring the next time it happens because I'm sure it will happen again until I get a better technique developed.

digital paradise wrote in post #18607831
Shot my first air show with that body. I would probably not use all AF points on a 40D. I had that body and it was excellent but zone AF which uses all AF points was not as sophisticated. I did start not using zone AF or all focus points until I got the 7D2. Not sure if all focus points is called zone on the 40D. It is has been too many years.

I'd stick to single point. Also check to see if you can adjust Tracking Sensitivity (TS) with that body. A negative setting will make the camera take longer to start looking to something else to focus if your AF point goes off target. A positive number makes it focus on something else immediately.

I have always set my cameras TS to -2 for birding. You get about a second to get your AF point back on target. It may not seem like much but that can make a big difference.

If I'm shooting something like a marathon and want to take shots of two runners I set TS to +2. Now when I move the AF point from one runner to the other it focuses instantly. There is no delay.

Forgive if the 40D does not have TS. Again it has been too long. I think my 50D had it. 7D for sure. If it does have it the factory setting will be 0. -2 is very useful for birding.

I don't think the 40D has the TS option.
I just did a quick check in the manual and I don't see it listed in the index.

I'm curious about one of your suggestions.
It's the one about using only a single auto focus point when tracking a bird(s).
In my situation at the time, there was nothing to pull focus off the birds as they were up high in the sky.
Wouldn't only using a single auto focus point make it harder to keep the moving bird in focus where as using all 9 focus points would increase the chances of keeping the bird in focus?
As long as the bird stays within the area covered by all 9 active auto focus points.

Thanks for the tip about TS values.
If a Canon 7D Mark lll ever comes out, and if it's a worthy upgrade from the Mark ll version, I hope to get one and your TS tip will come in to play with that I would think.

canongear wrote in post #18608181
I think this is what happened and the lens did go into a hunt mode.
I just have to remember to manually use the focus ring the next time it happens because I'm sure it will happen again until I get a better technique developed.

I don't think the 40D has the TS option.
I just did a quick check in the manual and I don't see it listed in the index.

I'm curious about one of your suggestions.
It's the one about using only a single auto focus point when tracking a bird(s).
In my situation at the time, there was nothing to pull focus off the birds as they were up high in the sky.
Wouldn't only using a single auto focus point make it harder to keep the moving bird in focus where as using all 9 focus points would increase the chances of keeping the bird in focus?
As long as the bird stays within the area covered by all 9 active auto focus points.

Thanks for the tip about TS values.
If a Canon 7D Mark lll ever comes out, and if it's a worthy upgrade from the Mark ll version, I hope to get one and your TS tip will come in to play with that I would think.

I didn't use all AF points with the 40D so I really can't comment on how well it worked. Yes single point is more challenging but the centre point is usually more accurate. If you lose focus stop shooting until you re-aquire. If you can't pull focus in if they are high in the sky how far away are they?

I'm on a 50D, which was really the last of the xxD bodies fitted with the really limited AF system, although I think it's a little different to the one in the 40D. You cannot adjust the tracking sensitivity on these bodies, but there is one useful option in the AF custom menu. That is the AF Drive when AF not possible. I highly recommend that you set this to off, and that is how I would leave it. What his does is to stop the AF system from driving if the image is so out of focus that the AF system cannot find any valid target. So if you drop a small subject off the AF points, or something passes very close in front of the subject, the AF will not drive to the opposite end of the travel and try doing a lock from that location.

I find it really useful since I got my 150-600, since that can make a subject at the other end of the focus range completely invisible. Generally if you are tracking something the distance won't change that fast that this setting will be a problem. I don't even have any issues if I need to swap from a close to a far subject with the 150-600, since it has FTM and I can just turn the focus ring manually to the other end of the travel id required, and often I can do it just as fast as the AF motor. It's a little less easy on my 28-300 without FTM, as you do need to switch to MF to make that change, or just point the camera at something it can focus on, then move it down/up so that the distance will track with the lens in AI Servo. I don't really have too many problems when using my standard zoom, a 20-40 ƒ/2.8, since it is hard to get anything that far out of focu that the AF cant't get a signal.

Personally as well as the AF drive being off I normally run the camera with AI Servo and BBAF separated from the shutter, but with * and AF-on swapped, so my grip buttons still work. The only time this gets changed is if I'm using a remote switch, since you have to have AF on the shutter button for a remote switch. My remote switch though is customised and does have two buttons though. So I can still focus with the thumb.

Alan

digital paradise wrote in post #18608218
I didn't use all AF points with the 40D so I really can't comment on how well it worked. Yes single point is more challenging but the centre point is usually more accurate. If you lose focus stop shooting until you re-aquire. If you can't pull focus in if they are high in the sky how far away are they?

Just a rough guess but, I would say they were 60-80 yards away, maybe a bit more.
They didn't fill the frame which didn't help matters any.

BigAl007 wrote in post #18608827
I'm on a 50D, which was really the last of the xxD bodies fitted with the really limited AF system, although I think it's a little different to the one in the 40D. You cannot adjust the tracking sensitivity on these bodies, but there is one useful option in the AF custom menu. That is the AF Drive when AF not possible. I highly recommend that you set this to off, and that is how I would leave it. What his does is to stop the AF system from driving if the image is so out of focus that the AF system cannot find any valid target. So if you drop a small subject off the AF points, or something passes very close in front of the subject, the AF will not drive to the opposite end of the travel and try doing a lock from that location.

I find it really useful since I got my 150-600, since that can make a subject at the other end of the focus range completely invisible. Generally if you are tracking something the distance won't change that fast that this setting will be a problem. I don't even have any issues if I need to swap from a close to a far subject with the 150-600, since it has FTM and I can just turn the focus ring manually to the other end of the travel id required, and often I can do it just as fast as the AF motor. It's a little less easy on my 28-300 without FTM, as you do need to switch to MF to make that change, or just point the camera at something it can focus on, then move it down/up so that the distance will track with the lens in AI Servo. I don't really have too many problems when using my standard zoom, a 20-40 ƒ/2.8, since it is hard to get anything that far out of focu that the AF cant't get a signal.

Personally as well as the AF drive being off I normally run the camera with AI Servo and BBAF separated from the shutter, but with * and AF-on swapped, so my grip buttons still work. The only time this gets changed is if I'm using a remote switch, since you have to have AF on the shutter button for a remote switch. My remote switch though is customised and does have two buttons though. So I can still focus with the thumb.

Alan

Thanks very much for that tip and explanation.
I'm definitely going to try that.

canongear wrote in post #18608839
Just a rough guess but, I would say they were 60-80 yards away, maybe a bit more.
They didn't fill the frame which didn't help matters any.

That is a long way to crop to fill the frame in PP. Single point can be tough at those distances. Also those distances atmospheric disturbance is not always helping you either. I tend to avoid shooting at those distances because even if it is in focus I can't get much out of it and I like push crops a lot.

That is why I post a lot of SIF shots (seagulls in flight) to get some practice in until I find more interesting birds. We have a couple of local ponds infested with them.