Focus Problem!

I am new to Bird Photography. My focus keeps going in and out. Was trying to shoot a bird in a tree and it was a nightmare. I'm using AI servo and spot focus. Any suggestions?

What lens? Do you use the back buttons to focus?

Small targets in low contrast situations can be tricky with AI Servo. Some bodys work better than others, my 1d mk3 was considerably better at AF in low light than my 7d mk1. Keep range as close as possible. I have added macro tubes on occasion to shorten mfd even more. Try to keep af point on eye.

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Canon 70 - 200 f4. Wasn't using back button.

Often what happens when trying to shoot birds in trees is that the lens shifts focus to something else around or behind the bird as you move slightly. Ie a leaf or twig grabs the focus and the bird moves out of focus.

This is why many bird photographers use back button focus for this type of shooting. You attain focus once, then release the back button. When you press the shutter, the camera doesn’t try to acquire focus again.

Spot focus is also problematic sometimes if there isn’t enough subject contrast. Try using single point and see if that helps.

Gregsiem wrote in post #18962720
Often what happens when trying to shoot birds in trees is that the lens shifts focus to something else around or behind the bird as you move slightly. Ie a leaf or twig grabs the focus and the bird moves out of focus.

This is why many bird photographers use back button focus for this type of shooting. You attain focus once, then release the back button. When you press the shutter, the camera doesn’t try to acquire focus again.

Spot focus is also problematic sometimes if there isn’t enough subject contrast. Try using single point and see if that helps.

This. Back button focus eliminates shutter stutter where you inadvertently refocus in the process of activating the shutter.

Thanks, I'll give it a try!

Atrawick wrote in post #18962446
I am new to Bird Photography. My focus keeps going in and out. Was trying to shoot a bird in a tree and it was a nightmare. I'm using AI servo and spot focus. Any suggestions?

I agree with the other respondent that the camera is probably picking up twigs and branches or other stuff in front of, behind or near the bird as it moves around and the AF automatically assumes that this other object is the subject. For that reason, I turn off automatic focus "hunting" and use manual focus to follow the subject and then let the camera autofocus just before tripping the shutter.

Even when out in the open, the AF hunting will throw the focus way off at times when a moving bird leaves the AF point and the camera tries to focus on the background and, if that's far away, or has nothing to focus on, it can put the focus so far off that it won't find the subject when you get back on it. This happens a lot on water birds as the reflection off the water is essentially at infinity to the AF system and that's where it shifts the focus and can't come back. Big waste of time while the bird is moving out of sight.