Skateboard/Sports Photogs: Focus Advice

What would your focus technique be for a shot similar to the one pictured below?


Pre-focus on the rail and shoot at > f8?


This seems like a gamble (especially if you only have one shot), but I'm not sure how else get the skater in focus and keep the background blur-free. If I was to pan with AF tracking, the background would be one big blur. Right?

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Can you elaborate on what you are asking?

If you are talking about obtaining a shallow depth of field then that depends solely on your aperture size and distance from subject to background.

If you are talking about motion blur then that depends solely on your shutter speed.

You can throw it on AI Servo and track the subject and obtain a motion blur free photo by making sure your shutter speed is fast enough. You can also throw it on AI Servo and track the subject and drag the shutter to create blur.

Hope this helps, if not please clarify what you mean.

Have a play with http://www.dofmaster.c​om/dofjs.html

My setup: 60D, 10mm, f/4, subject @2metres (~6ft)
Near limit 0.8metres/2.5'
Far limit ~infinity.

Wide angles are nice for huge depth of field.
Set the focus ring (MANUAL FOCUS) to the approx subject distance and fire away. Use your brain cycles for balancing flash, etc.

more info, f/4 gives you a wide aperture for loads of ambient light and a lot of levels of flash to play with. Also a faster shutter to help reduce motion blur on the subject and anyone in the background skating around outside the glare of the speedlite.

Dark inner thigh, left ear/neck and double shadow from rail on brickwork gives you an indication of where the flash was positioned.

Have fun. Shooting skate stuff is awesome.

Man that was switch? Dang.
When shooting with a flash, I tend to use 1/200s to reduce blur and F/4-8 depending on how much ambient light there is.

I guess what I'm asking is, in a photo like this, how do you make sure that the skater will be in focus.

I ask because if the skater is riding by you (right to left in this case) and you have no time to focus on him while he's doing his thing. If I were to pre-focus (manually) on the rail where I thought he was going to hit it and shot at F8 or above, I wasn't sure if that would guarantee that he would be in focus.

I think the DOF chart that bdp23 posted is what I'm looking for. I haven't dove into it completely, but from browsing, it seems that (for example) if I am shooting with a 15mm Fisheye lens at F8 and my subject is 3ft. from me, then anything from 1.5ft. to 75ft. will be in focus.

Am I reading that correctly? Does the same technique apply if I'm shooting with a long lens (70-200)?

yes, absolutely correct.

there are computer and phone apps to make these calculations and some quick rules of thumb (also google 'hyperfocal distance') and you should spend some time experimenting.

you'll soon understand that wider angle lenses have greater depth of field (distance from closest to furthest elements that will be in focus)

for a canon 60D, f/4, subject @100ft from camera:
10mm near 4.14' far infinity total infinity
70mm near 68' far 189.3' total 121.3'
200mm near 94.6 ft' far 106.1' total 11.5'

(the camera is important because the sensor size effects the depth of field. smaller sensor means greater dof.)

I'm confused. Why can't the OP just manually prefocus 4' past the railing? Why must he focus on an object that is currently there? Just manually focus on the rail, then focus 4' past that... Then you can use your fastest aperture that you've got.

^^ yep, absolutely correct, the OP doesn't have to focus on something already there.

I suggested he manual focus "to the approximate subject distance" (which, with a wide angle will give you a VERY large DoF) and fire away.

In his last post, I think the OP incorrectly assumed he has to focus at the rail:

Beach_Bum wrote in post #12322271
If I were to pre-focus (manually) on the rail where I thought he was going to hit it and shot at F8 or above, I wasn't sure if that would guarantee that he would be in focus.

ewheeler20 is right to ask for clarification, focusing precisely on the rail isn't exactly necessary, but might be required depending on the lens.

Street photographers with rangefinders have traditionally 'zone focused', setting a focal length and knowing the aperture will give them the DoF to ensure their subjects walking down the street will be in focus. They just set it and click the shutter when something interested catches their eye because all the other calculations have been pre-set. They knew before hand that their subjects will usually be just 3'-10'/1-3metres away from them.

The Canon 10-22 has a focusing distance window that you can use, but there may be some lenses (eg the 18-55 kit lens) that don't have this window, so perhaps focusing 'by eye' through the viewfinder at the rail might be a good option.

ewheeler20 wrote in post #12328925
I'm confused. Why can't the OP just manually prefocus 4' past the railing? Why must he focus on an object that is currently there? Just manually focus on the rail, then focus 4' past that... Then you can use your fastest aperture that you've got.

Another quick follow up:
the initial concern was that getting focus was 'a gamble', so the discussion of DoF calculations and hyperfocal distance covered that.

Using something like an 85mm @ f/1.8 would be a gamble, even if you knew 'exactly' where to focus. The skater would only have to be a few inches front or back of the mark, or you'll get the face by the arms and one leg will be out of focus, etc

The 17-55mm @ 17mm f/2.8 would still give you 16' of focusing depth.

Wide angles remove the gamble, even at very fast apertures.

Excellent info guys. I'm going to take some time and really go through it, but I wanted to say thanks for posting!

The other focal issue is that if you use single point focus and know the approximate spot where the skater will hit you can move the point off center to approximate where that will be. That will be most important on the horizontal axis as the vertical axis is less important given the essential equivalence of legs and torso. If you start to track below the bar as he approaches, you should be OK.