Focus on moving subject

[borisnikon]

When I try to shoot pictures of moving subjects, especially flying birds, I can't get a good focus. When I use manual focus the subject goes to fast to do anything and my auto focus can't cope. It is only a cheapish 70-300mm lens but I don't have money to get a better one. Is there anything else I can do?

 

[Robin Usagani]

turn on all of your focus points and use continuous focus.

 

[borisnikon]

As it isn't the best lens the focus just isn't fast enough.

 

[Big Mike]

What camera are you using? (*edit....I'm betting it's a Nikon)

Most cameras have 3 basic focusing modes.
Still subject mode (Single Shot on Canon, AF-S on Nikon)
Moving subject mode (AI Servo on Canon, AF-C on Nikon)

There is usually a hybrid mode as well. On Canon, it's AI Focus, on some Nikons it's AF-A.
The Hybrid mode tries to achieve focus and lock on, like still subject mode, but if it things your subject is moving, it will try to track your subject.

For shooting BIF (birds in flight), you'll probably need moving subject mode or the hybrid mode. Try a Google search for focus+BIF.

 

[borisnikon]

I use a nikon d3100 not the best I know. So if I just go to one of the menus I should be able to change the mode. Thanks

 

[borisnikon]

I have just looked on my camera and on auto modes you can only have the af-a but on the manual modes you can do all of them.
If I us af-a the focusing is still a bit slow but that is my lens I guess there is nothing I could do about it.

 

[MTVision]

I have just looked on my camera and on auto modes you can only have the af-a but on the manual modes you can do all of them.
If I us af-a the focusing is still a bit slow but that is my lens I guess there is nothing I could do about it.

Af-a is an automatic mode and will switch from af-s to af-c depending on the subject. It will switch to af-s if the camera thinks the subject is stationary or af-c if camera thinks subject is moving.

 

[MTVision]

Also Program mode (P on dial) is basically an automatic setting and you should be able to change the AF mode

 

[borisnikon]

Ok, will try that thank you

 

[KmH]

You may want to note that the complete D3100 user's manual is not included with the camera as a hard copy.

It is only included as one of the files on the disc that comes with the camera.

 

[Overread14 2]

For birds in flight there are a few schools of thought on the best method - each is somewhat subjective to experience and situation:

1) af-c (ai-servo in canon talk) avoid the hybrid modes as they can often get things wrong, and since you are shooting a moving subject anyway being in continuous AF mode is the one you want. Next up is linking in the AF points; for a bird in flight you've basically two choices for AF

a) Single point AF - for a lower end camera body this typically means being limited to the middle point; whilst higher level bodies will have more advanced outer points to free up creativity a little more. This mode allows you to point the camera at the subject and tell the camera what you want in focus - keeping that single AF point on the subject is key however so you have to be good at tracking and panning the flight of the subject itself (you want to aim for the head if you can - bodies are good but on birds the wings flipping in and out might well throw the focus in some shots).

b) All points (or for advanced cameras a localised grouping) this mode is good for if you are shooting a bird against the sky or a similarly flat scene where there will be no points of focus closer to you than the bird itself. If shooting in a more complex situation where objects might well move between you and the bird then this is not an ideal mode since the AF might well lock into them instead of the bird itself. AF is basically dumb and only looks for the nearest point of contrast difference that it can detect and lock onto.

2) Manual focusing - good for panning birds in flight if they are moving almost parallel to the camera (ie not flying away or toward yourself) since their amount of motion change is going to be small; so you can manually lock on the focus and then make small changes as needed; this mode is subjective however in that not all DSLRs have good viewfinders so some can find it much harder than others; DSLRs also lack MF aids that older film SLRs used to have for manual focusing aids - so can be more tricky as a modern method.

 

[borisnikon]

Thanks for the help, now I should get some good shots