Trying to take photo of baby moore hen, what do I need to change?

[WalkingintheAir25]

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[Big Mike]

I personally don't like any version of auto area mode (auto point selection on a Canon). You are basically asking the camera to decide what it things your subject is, and to focus on it.
I much prefer using single point selection so that I can tell the camera exactly where to focus.

What focus mode are you using? If you are using AF-S (still subject mode) you might be locking the focus (holding down the shutter/AF button) while your subject moves out of position. If the subject is moving, you may want to use AF-C, so that the lens continuously tries to focus.

Keep in mind that when using a smaller aperture (lower F number) and especially at such a long focal length, your DOF (range of acceptable focus) is going to be very thin. So if you miss the focus, even only a little, your subject will be out of focus.

If want a deeper DOF, to get multiple subjects in focus for example, then you need to use a smaller aperture (higher F number). This will force you to use a slower shutter speed or higher ISO though.

Shooting with a long telephoto lens is a somewhat specific skill. It's generally harder to do well, than shooting with a 'regular' lens. You need to be more careful with your focus, you need to hold the camera & lens more still....the list goes on. So keep practising.

Lastly, I suppose it could be possible that your lens (or camera) is in need of focus calibration. For example, if you know for sure that you were focused on the bird in the first one, but the grass came out sharper....then your lens might be back focusing. But before diving into that problem, try to rule out user error.

 

[robbins.photo]

On my D5200 for most wildlife photography I prefer to set the autofocus settings to single point autofocus in combination with AFS-C and then select my point of focus myself, if at all possible it's best to select one of the eyes as your focus point when you can.