Focusing and moving models

I am wondering on how to focus on a constsntly moving models. Do I just put aperture to the highest value? or should I just rely on the autofocus mode of the camera? Thanks.

If you put the aperture to the highest value, you will get increased DOF thereby increasing your chances that your model will be within that DOF while they move around. However, by increasing aperture, you trade off by needing a slower shutter speed to get correct exposure, thereby increasing the chances that your model will be blurry in the photo by virtue of his/her movement. You can offset both these by increasing your ISO values at the trade-off of increased noise and possible color shift and reduced saturation. (more to follow)

Using the autofocus is probably your best bet, assuming that you're using continuous focus and are able to keep the active focus point (or points) properly placed on the model as he/she meanders about. Bear in mind that you may have to adjust the tracking/lock on sensitivity depending on the particular type of movement involved.

With all this said, and going off of just your original post, I would say a somewhat stepped-down aperture (higher value) while maintaining a relatively quick shutter speed and a reasonable ISO with prudent use of continuous AF would be your best bet.

Let me know if that helps...

Thanks for the reply. I've been relying upon my autofocus (I'm using 5D) and I hate it. I got less than 50% hit rate. Maybe I'm to slow. Do most people rely upon their autofocus?

Or should I upgrade to 1 series camera?

You need to be a little more specific about the scenario in question:
Are they inside or outside, walking or faster movement, do you want the whole group in focus at once, what are lighting conditions.

All these scenarios are possible, albeit, some may be more difficult.

tjongkristian wrote in post #6767779
Thanks for the reply. I've been relying upon my autofocus (I'm using 5D) and I hate it. I got less than 50% hit rate. Maybe I'm to slow. Do most people rely upon their autofocus?

Are you using AI servo as your focussing mode? That will give continuous focus and should get a hit rate a lot higher than 50%.

I rely on mine pretty much all the time (400d) and unless i really push it to extremes (think motor racing with cars coming head on), it copes pretty well.

Dont expect miracles though - it is not designed to be the fastest focusing camera. Thats reserved for the 1D series!

If you're thinking that you might be "too slow", it sounds like you're not using AI servo. It's pretty much a losing proposition to even attempt to use one-shot focusing on moving subjects. As I said in my original response, "Using the autofocus is probably your best bet, assuming that you're using continuous focus and are able to keep the active focus point (or points) properly placed on the model as he/she meanders about. Bear in mind that you may have to adjust the tracking/lock on sensitivity depending on the particular type of movement involved."

But please do explain a bit more about your specific lighting/shooting/move​ment situation and maybe I can be more helpful.

I am asked by my friends to shot their dance arts performance. Their will be 2 people on stage. The lighting is adequate for ISO 800. I tried the shot during rehearsal and less 50% is what I got.
@prpledophr: How do I adjust the tracking sensitivity on my 5D?

Thanks.

I know that people will disagree with me on this...but I've photographed quite a few models and have also worked at a few studios and it's totally normal to miss a lot of AF shots when working at shallow DOF and dealing with a moving subject.

If you take a really close look at a lot of long lens shallow DOF photographs you'll notice that a good portion of them aren't exactly razor sharp.

I'm sure that certain cameras are better than others...and there are ways of working and dialing in a system. But there will always be a significant amount of error when using AF and shallow DOF. My advice is just to factor that into the equation...do a little bit of spraying and praying....(Hail Mary's often work well if you're Catholic)

Try and crank up the SS as high as the ISO and f/stop will allow.

tjongkristian wrote in post #6770264
I am asked by my friends to shot their dance arts performance. Their will be 2 people on stage. The lighting is adequate for ISO 800. I tried the shot during rehearsal and less 50% is what I got.
@prpledophr: How do I adjust the tracking sensitivity on my 5D?

Unfortunately, all I have sitting near me at the moment are a 1DmkIIn and a D3... so I can't give you a step-by-step instruction. To be honest, I can't remember from my 20D/30D days how much control those cameras gave you over tracking sensitivity. However, I'd recommend looking in the manual and reading up on the AI Servo section. You're looking for anything that sounds similar to "tracking sensitivity" or "lock-on long/normal/short/off"​. These settings may also be hidden in the custom settings menu. But really, for something like dance arts with only two people on stage, I would venture to say whatever the default setting is will probably work just fine. Just MAKE SURE it's on AI Servo (and use the center focus point if that's the only cross-type sensor you have).

Also, I completely agree with the Gentleman Villan. In sporting events, you're lucky to get 25% of the shots in perfect focus. Very likely, only 10% will be actual keepers. So don't stress it too much, and just shoot a whole lot.

Chauncey's advice is good too. You're not talking about extreme speed and movement here... so 1/500 should be reasonably adequate (or 1/640 or 1/800 if you can pull it off in the lighting conditions). The way you do that is widest aperture and an appropriate ISO. Focus won't matter one single bit if your shutter speed is so slow that everything is blurred anyway. Unless, of course, that's the effect you're going for.

tjongkristian wrote in post #6767785
Or should I upgrade to 1 series camera?

Bit of an expensive gamble on the basis of something that may or may not work

Ok, I will just have to try harder then. Thank you very much guys for the advise, really appreiciate it. Thanks.

@400dabuser: It is just my excuse for my wife to get a really nice christmas present.

I had good luck herewith the center focus point on a face. Tried using other points too, but I could see it hunting & switched back to the center focus point. OTOH, in brighter light shooting cars, I've had few problems using other points.