Getting focus right on moving subjects - Help please!

[EspressoJunkie]

I stumbled upon some street dancers in Belfast today and thought I'd get a few pics.

This is the first time I've tried photographing moving subjects, and I found it harder than I thought, esp when It came to keeping the person in focus. The light wasn't great and my 50mm really seemed to hunt to focus.

Any advice would be appreciated, because I'd really like to go back and get some good shots of these guys.

I've put a few of the pics below so you can get an idea of the issues I had.

Thanks


belfast 1 by dubbleyu, on Flickr


belfast 2by dubbleyu, on Flickr


belfast 3by dubbleyu, on Flickr

 

[paulyoung666]

what focus points were you using and what focus mode ? , i would suggest the single centre point and AI Servo to be the best , what sort of f stop were you using as well , and what shutter speed and iso ? , lots of questions

 

[EspressoJunkie]

The aperature was 1.8, shutter speed on the first was 1/1600, and 1/640 on the last two. Iso was 800. I was trying to get as much light as possible, hence the low aperature. I was in servo, and i was using all focus points (not sure of the name for that!).

Im much more used to shooting landscapes etc (things that dont move while you fiddle with the camera!), so this was very different. Def something Ill try again though.

 

[tdodd]

In AI Servo mode, with all points enabled, the camera assumes the centre point to be where your subject is initially. If it thinks your subject has moved away from the centre and it can see the "subject" with another AF point then it will hand the job over to the new AF point. You must start off with the centre point aimed at what you want to focus on.

The problem you have in these examples is that your subjects are wearing plain, dark colours, impossible for the AF to lock onto. There is no contrast. You need to aim at the logos on their tops or similar, where the camera can see some detail. However, I think the logo is too small for the camera to maintain a track of it if it moves off the centre AF point. The logo will fall into the gap between points and the camera will lose sight of the subject. You will need to start again by refocusing with the centre point over a contrasty area.

You might have had more luck with a single focus point aimed at the face, or with greater skill keeping the centre point on a logo or other contrasty element of the subject. Alternatively, while the subjects may have been moving, it does not look like they would have been changing distance much at all, leaving the AF little to do. You might have had more success in One Shot mode. It's a tough call. Short answer - if what you are doing is not working then try another approach.

 

[Adey]

I think stopping down a bit to increase DOF would of helped, it would let less light in, but i would of took the extra DOF even if it meant 1/300 at ISO 400, or even 1/640 and bump ISO to 800.

Maybe manual focus could of been use here too? Canon AF is a clever bit of kit, but your eyes and brain can do a job when they need to. Or even do focus bracketing, you've got 6.7 fps at your disposal.

Ade