Issues with Autofocus

[GorgeWalker]

Hi Guys,

Thanks so much for all your help on my previous thread.

I had posted an update and mentioned some issues grabbing a focus point. The scenario was a bird in a heavily branch tree. Was placing one of the focus dots, the middle one (is that what they are?) but it just wouldn't focus on the bird in question.

Real downer - as it was a stunning bird (Scarlet Robin I think) that was metres from me!

Details as follows:

Camera - Nikon d3500
Lens - AF-P DX NIKKOR 70-300mm f/4.5-6.3G ED VR

Exif:
155mm
1/125 sec shutter speed
f/7.1 aperture
ISO 800

How do I get better at telling the camera what I need in focus? Any tricks?

143710

[ricktas]

Nikon let you choose how many focus points you have (via the menu), also there are several other auto-focus features, like 3D tracking that you will need to learn about. For bird photography it is worth changing your menu so that you have a single focus 'dot' and use that.

Another thing to know is that auto-focus works by finding the contrasting edge between two items and it uses that to 'lock on'. This is why when you aim the camera at a clear blue sky the autofocus will 'hunt' as it cannot find something to lock onto.

More practice and some reading of the usermanual and understanding of how auto-focus works and what options you have to make the autofocus work for you based on the subject, will help you here. Eg the 3D tracking I mentioned above is great to photograph items that move randomly as once you lock onto your subject the camera will track that subject and keep it in focus (think of something like a tennis player moving around a court, side to side and front to back). I know that is not relevant to your bird in a bush, but once you know how your autofocus works and what mode is best when, then you will be on your way.

[ameerat42]

^Pretty well says it all. Especially for bird photography (but not only that), you aim to focus on the bird's eye.
You set a reasonable f-stop for the lens you're using to allow for a fairly useful DOF (depth of field). That will
not be the same for different focal lengths, so say f/8 on a 50mm lens will give you more DOF than f/8 on a
lens of 300mm, etc... ("etc" means read, study, practise...)

- - - Updated - - -

PS: by way of a "trick", you can (generally) retain the focus setting by lightly but not fully pressing the shutter button.
This will allow you to recompose the shot as desired.

To reiterate, find the AF pattern that gives you a single, central focus point.

[GorgeWalker]

^Pretty well says it all. Especially for bird photography (but not only that), you aim to focus on the bird's eye.
You set a reasonable f-stop for the lens you're using to allow for a fairly useful DOF (depth of field). That will
not be the same for different focal lengths, so say f/8 on a 50mm lens will give you more DOF than f/8 on a
lens of 300mm, etc... ("etc" means read, study, practise...)

- - - Updated - - -

PS: by way of a "trick", you can (generally) retain the focus setting by lightly but not fully pressing the shutter button.
This will allow you to recompose the shot as desired.

To reiterate, find the AF pattern that gives you a single, central focus point.

So. I've set my Nikon to have a single point of focus as per Ricktas recommendation.

Now, I focus on the eye on the bird than hold the shutter button or lock the focus with the lock button to frame the picture using the rule of thirds (as per the reading/learning material on this page)?

[ricktas]

So. I've set my Nikon to have a single point of focus as per Ricktas recommendation.

Now, I focus on the eye on the bird than hold the shutter button or lock the focus with the lock button to frame the picture using the rule of thirds (as per the reading/learning material on this page)?

Yes. So now time to practice it

[ameerat42]

[In theory] Yes (central spot assumed). [/In theory] :cool:

- - - Updated - - -

Checked the Exif and found that the AF was set as:
"Metering Mode Matrix"

[GorgeWalker]

[In theory] Yes (central spot assumed). [/In theory] :cool:

- - - Updated - - -

Checked the Exif and found that the AF was set as:
"Metering Mode Matrix"

What should this mean to me? I know earlier it was seemingly set to focus on multiple areas of the frame? That what you mean?

[ameerat42]

Yes. That's right.

[ricktas]

What should this mean to me? I know earlier it was seemingly set to focus on multiple areas of the frame? That what you mean?

It means set the focus spot that is active to the centre one. The one that is in the very middle of the image when you look through the viewfinder. You can set which one is active, choosing the centre one offers the best accuracy as lenses are sharpest in the centre.

[Toddyh]

I'm not familiar with 3D tracking but is it a replacement for AF-C (continuous autofocus)?
Normally I would have suggested to the OP becoming familiar with the differences between AF-S and AF-C.