Need a little help please .

I usually use my auto focus since my eyesight leaves a little to be desired . When taking pics of birds and birds in flight in particular , it seems the auto focus has a mind of it's own . Sometimes I get the bird , sometimes the fore or background . The auto focus occasionally flips out when I try to get one with all sky .
What can I do ,short of failing at manual focus , to actually get the bird in sharp focus . Thanks .

This is where the rebel series of cameras really fall short.

This is where (just mentioning aps-c) the 60D, 70D, 7D and 7D mkii come into play. They have area or zone focus that can better track the focus with a lot more AF points. These are considered more sports and wild live cameras.

All that i can say is make sure that you are using continuous focus, not single shot.
If possible, pre focus where the you think the bird will be. This will make the AF quicker then having to search or travel a long way to get focus lock.
I am not sure with your camera if you just want to use center point focus or all point AF.

Also use an aperture of F/8 or F/11 if the light permits. This will help as you are at the telephoto end of the lens to give you enough DOF.

What AF mode is being used? What lens? Etc...

Wow . I Have no idea what continuos focus is or how to use it . I'll have to play my rookie card and ask for explanations . Thanks .

75 - 300 lens And again I only know the lens was set to auto focus . stabilizer on . The camera was set to the sports mode . Other than that I am still trying to learn . Thanks for the feedback . As you can tell more help is needed and appreciated .

So I'm guessing you haven't read the manual? you should.

Pretty sure you will need to get into one of the more manual modes (Av, TV, M) to have full control over the focus settings. I'm sure the "sports" setting gets you closer, but you will want to really get to know what is offered and how to use it to really improve your accuracy.

And sure the Rebels are not as capable, but they can certainly do the job. As with all photography, just putting yourself in the position to get the shot goes a long way.

JPB the elder wrote in post #17612768
Wow . I Have no idea what continuos focus is or how to use it . I'll have to play my rookie card and ask for explanations . Thanks .

75 - 300 lens And again I only know the lens was set to auto focus . stabilizer on . The camera was set to the sports mode . Other than that I am still trying to learn . Thanks for the feedback . As you can tell more help is needed and appreciated .

You're shooting a 600D, which is a rebel. I don't remember if that has AI Servo mode, or not. Basically, you want to match your focus mode (this is not the same as camera mode, this is specific to autofocus) to what your are shooting. After that, it will be up to practice.

AI Servo will continuously adjust focus on selected point(s) as you track your subject and move between points based on settings. You should determine if your camera supports this.

I am sure more experienced people will chime in.

Yes I have , and continue to read the manual . Repeatedly . Not having a photog background and not really knowing anyone else that ''knows '' photography , I am attempting to learn as I go . This site and folks here have already taught me quite a bit .
So what you are saying is I should be using , and learning those particular settings for what I want to capture ?

JPB the elder wrote in post #17612789
Yes I have , and continue to read the manual . Repeatedly . Not having a photog background and not really knowing anyone else that ''knows '' photography , I am attempting to learn as I go . This site and folks here have already taught me quite a bit .
So what you are saying is I should be using , and learning those particular settings for what I want to capture ?

Start with the basics of Av, Tv and work from there. Learn AF modes, too. Also, understand that wanting to BIF right off the bat is asking a bit much. It takes quite a bit of skill as well as a very good understanding of exposure and mechanics to do BIF well. Just sayin'.

Strontium wrote in post #17612786
You're shooting a 600D, which is a rebel. I don't remember if that has AI Servo mode, or not. Basically, you want to match your focus mode (this is not the same as camera mode, this is specific to autofocus) to what your are shooting. After that, it will be up to practice.

AI Servo will continuously adjust focus on selected point(s) as you track your subject and move between points based on settings. You should determine if your camera supports this.

I am sure more experienced people will chime in.

Yes it does have the Al servo mode . I read through and what I came away with was I need to set it up and use another mode other than sports . Pushing the button halfway while holding on the bird will keep it continually focusing on the bird . What happens when I use the multishot ? Will it hold the same focus point ?

Strontium wrote in post #17612791
Start with the basics of Av, Tv and work from there. Learn AF modes, too. Also, understand that wanting to BIF right off the bat is asking a bit much. It takes quite a bit of skill as well as a very good understanding of exposure and mechanics to do BIF well. Just sayin'.

I seem to be able to locate the BIFs . Now I need to work on the rest . Now y'all have given me some guidance to get there .
Thanks

JPB the elder wrote in post #17612789
Yes I have , and continue to read the manual . Repeatedly . Not having a photog background and not really knowing anyone else that ''knows '' photography , I am attempting to learn as I go . This site and folks here have already taught me quite a bit .
So what you are saying is I should be using , and learning those particular settings for what I want to capture ?

I'd stick with Av and as said above f/8. You would then crank ISO until you can get around 1/1500, or better.

Ai Servo is the focus mode you will want to use. I'm guessing that you won't have a lot of options to set for the focus mode. More advanced cameras have lots of options for focus tracking.

You will adjust exposure compensation depending on the subject and lighting conditions.

I understand that this place is a wealth of knowledge but the more you know the better questions you can ask. Ai Servo should be fully explained in the manual so getting an idea of what your camera is capable of is just where I would suggest you start. As I was getting at above, the focus function of Canon cameras from model to model and generation to generation varies greatly. So the specifics of what I know about the 6D is not going to apply (other than the broad concepts already posted) to your camera.

Chet wrote in post #17612811
You probably want to chose center point focus point, set custom function 4 to 1 and use the "*" to focus. That way your focus can be locked independent of your shutter. The Xti is still a very capable camera, if exposed correctly iso800 can be cleaned pretty well.

I don't shoot birds, but this is the one tip I was going to suggest beyond AI Servo - setting your metering/focus to another button. If you search for something like custom focus buttons or back button focusing, you should be able to find enough information.

I initially set up my camera for this because I was trying to shoot sports, but grew to love it and use it all the time now.

Good luck!

Thanks for all the tips . I will start reading and practicing . Hopefully I will be able to share some better pictures soon . And ask better questions .
Thanks again .

I have that body and it is a very capable body when you are just starting out. You will want to assign custom functions on your T3i and assign the Back Button Focus to the "*" key if you are going to go for Birds In Flight (BIF) shots. You will have some limitations as your body and lens are not the best. Now, don't think you can't get shots, but your ability to get keepers is limited somewhat by your body/lens choice. Your lens is not known for fast focusing, and the focusing system on the camera is somewhat limited. These are both reasons I have since upgraded.
But here is my suggestion, user AI Servo, which will allow you to continue to focus track on the bird as it tracks across your viewfinder. Definitely try to keep the center point on the bird as you track. (Center is usually the most robust on most cameras). Change the focus button to something other than the shutter button. This will allow you to user the * button to focus while not having to maintain a half press to keep it focusing with the shutter. Use Auto ISO, that camera is good to about 1600 ISO, but let it go to 3200 if needed as I would rather have a somewhat noisy image that is in focus than a poorly focuses non noisy image. Also use continuous shutter so you can take multiple shots as the bird is flying. Your shutter will only get 3 or so shots per second, but you have a better chance of getting a shot if you are not relying on just one shot.
And practice, practice, practice. BIF is not easy. I have upgrade both my camera body and my lens and still only get about a 25% keep rate.
Keep coming here and asking for help, there are a ton of great guys and gals here who have helped me tremendously on my journey to get better.
Good luck and hope to see more shots from you soon.

I had a 600D. For birds, I strongly suggest that you use Tv mode, rather than Av.

With the 600D in Av mode and using AutoISO, the camera prioritises a low ISO, and therefore will choose a longer exposure (lower shutter speed) in order to minimise the ISO. Higher end bodies allow you to set a minimum shutter speed in Av mode, which can get over this issue, but the 600D doesn't let you set a minimum shutter speed in Av mode.

Keeping the shutter speed up (above 1/500th of a second, if you can) will give you a much better chance of a keeper of a bird in flight (or any motion, really). Setting the shutter speed to 500 in Tv mode, the camera will open the aperture up (lower f number), and then raise the ISO to get a proper exposure.