How does one track action with a fast telephoto prime lens?

With my normal-range prime lenses, I tend to shoot with both eyes open — what I see in the viewfinder has a high correspondence to what I see with my other eye. With my 70mm (105mm in 35mm-equivalent terms), it's a little trickier, but not so much that I really ever have to think about it.

With the Pentax DA★ 200mm f/2.8, though, it's a different story, for two reasons. First, at 300mm-equivalent, the field of view is so radically smaller than my unaided vision that it's just confusing to operate with two eyes. And second, the depth of field is so small that if I move away from my target, there's good odds I'm just looking at blur.

If this were a zoom lens, I might consider tracking the scene at a wider focal length and then zooming in. But that's not an option.

Clearly, people use these lenses for sports and wildlife photography all the time. What's the trick? I was at a not-so-fast-moving kung fu demonstration, and kept losing people. I can't imagine catching a bird in flight; do people just point at a flock and hope something is in the field of view? Is this just a matter of really learning to know the lens, or is there something I can do?

Answer

Based on the last two answers I may be missing the point of the question here, but instead of worrying about aperture, your question more directly relates to how do I track action.

Tracking abilities I would split into 3 categories.

1. The Camera


2. The Lens


3. You

Part 1: The Camera

Some cameras just wont do tracking particularly well. You really need one that can do continuous auto-focus (not all do). This is the AI Servo mode if you're in Canon land, or on Nikon there is a C/S/M setting that does this (you want C for Continuous). I'm afraid I can't comment on Pentax, but refer to your manual. So set your camera to continuously focus.

The next thing to check is to ensure it is using all available AF points. Again, this varies by camera, but you may have a diamond of 7 or 9, or be lucky enough to have more - 19, 51, 61.....depending on make and model of camera. Just make sure all of them are enabled.

Also, think about the metering mode you choose. for things against the ground, or landscapes, you may want evaluative or full metering, but for a bird or aircraft in the sky, choose centre-weighted or spot metering.

Finally, choose your shooting mode appropriately. For action shots you will want shutter priority mode. I think Pentax use the mnemonic "Tv", as do Canon. Nikon and others just use "S". Then set a shutter speed appropriate to your action. Fast moving = 1/1000th or more. Slow subjects = 1/250th maybe? The benefit of your fast lens will be felt as you can keep the ISO low whilst still getting correctly exposed shots.

Part 2: The Lens

I'm not sure this pertains to you as its about image stabilisation, and I think the Pentax uses in body stabilisation. But in the Canon/Nikon world long lenses with IS/VR modes also have a stabiliser "mode". If you have this, ensure the mode is set correctly for your shooting type. Mode 1 is generally for overall use, handholding, normal shooting. Mode 2 usually only tries to correct vertically, so is useful for panning. Perhaps in the body of the Pentax you can select the mode too??

Also, the AF of the lens must be sufficiently fast to keep up with the constant refocussing by the camera body. But the lens you suggest has an SDM motor which seems to be well liked and fast.

Part 3: You

Practice your panning. Practice following targets across the ground and sky. It doesn't have to be in the dead centre of the frame but there's nothing worse than a raft of photos of your favourite car, plane, bird, etc with it's back end cut off! You may find a change of stance helps, or to hold the lens differently, or use a Monopod. Also, I would not tend to keep both eyes open as when you are tracking action, it only serves to distract you. Concentrate on whats in the viewfinder as thats what the camera sees.

I hope that helps?