auto-focus on moving child?

[kaileen_galhouse]

I am often in a position of trying to photograph a child crawling towards me -

I am down on the ground, totally at their eye level, and they are moving

towards me, smiling at me, and it's a great shot...except I can't focus

correctly with autofocus unless they happen to pause for a moment. I use

natural light only at this point, often inside depending on weather, so I am

shooting wide open with my 50mm/1.4 lens. An inch of movement makes a

difference. Is that the problem - do I have to be using a smaller aperture? Or

can I adjust my autofocus (I have never changed the settings from whatever the

default is, but I have heard there are options like "dynamic"?) so that it can

more easily focus on the baby moving towards me? Just so I am clear, I am

changing the focus area with every shot, so that part is fine - but what about

the autofocus settings?

[mark u]

"Follow focus", "dynamic focus", "continuous focus" and "AI Servo" are all terms used by various manufacturers. Trying to use that feature at close range with an aperture as wide as f/1.4 can be very challenging for the camera - but system capabilities vary according to the body you are using. For advice on what is useable for your camera, it will help to know which body you are using.

[james_lai]

That would be a tough challenge for even the fastest AF systems, especially at close distances. With my kids, I found that they often like to repeat their movements, so I would focus manually at a point the baby will crawl through and shoot when the baby hits that spot. I would also try to stop down a bit to give yourself more leeway.

[mark pav]

Also, the 50mm lenses I'm familiar with are driven by a motor in the camera, rather than one in the lens. As such, they don't focus as quickly as the bigger internally-driven lenses.

[amy_c1]

hi kaileen,

 

your photos are gorgeous and i really like your web site. i read another post from you recently about networking in the VA area - although i no longer live in d.c. i would love to chat/email - i am a beginner and am looking to learn about techniques, etc. from your photos i can tell that i can definately learn a lot from you! let me know if you're up to it.

 

about your question, i have had the same issue recently. i am also using a 50mm lens pretty much wide open. i am going to try the dynamic focus feature and maybe stopping down if i can (although it is hard using natural light). i was also going to try a longer lens to give me a bit more time before the little guys get so close to the camera.

 

let us know what works :)

amy

[geoffs1]

Mark Pav, "Also, the 50mm lenses I'm familiar with are driven by a motor in the camera, rather than one in the lens. As such, they don't focus as quickly as the bigger internally-driven lenses."

 

Ideally, the continuous-AF modes reduce the need for ultra-fast AF a bit. The lens only needs to focus in small increments as the subject moves, not shift from the previous focus point to the new one in one shot.

 

Even in an ideal world (and AF speed notwithstanding), dynamic closeups with a shallow DOF will always be a challenge just because keeping the focus point on the place you want sharp may turn out to be nearly impossible.

 

This may be a situation for manual or pre-focusing, although they also have their drawbacks...

 

Cheers,

 

Geoff S.

[kaileen_galhouse]

Thanks for everyone's responses. I am using a D80 if that helps. Stopping down is very difficult with using only natural light. I have never tried manually focusing but I'm sure that's a challenge as well. Sounds like there may not be a good answer!

 

Amy, email me!

[geoffs1]

Kaileen Galhouse, "I have never tried manually focusing but I'm sure that's a challenge as well."

 

And it's made particularly difficult by the focusing screens in most DSLRs that omit all of the manual-focusing aids...

 

Cheers,

 

Geoff S.

[Jochen_S]

My own continous AF has a compareably lousy hit rate at portrait distance, but at least does the job on groups playing soccer, when I also stop down for some DOF. Maybe putting your flash on AF assist beam only could help a bit.

[kirk_teetzel]

pick a spot, set the lens to manual focus and set the focus at that spot. When the child crawls to that spot, fire the shutter.

[ester]

I was just trying the same thing Kaileen and couldnt manage it, and I have to try with a two year old running right at me. I agree that it would probably yeild the best photos but its just soo hard. I know al servo cant manage it but will also try manual focus so thanks for posting this thread.

[craig_shearman1]

What ISO are you using? You should be able to kick it up and get a smaller aperture.