Focus Method explanation needed please

rickp

I keep reading about Hyper Focal Distance and having everything in focus after certain distances.

Can someone explain to me how this works or how to do it. I'm heading to yellowstone next month and I want to make sure my landscape shots are in focus and I maximize clarity. I'm not sure that using the AF points on my 7D will work the best if taking a picture of a mountain range 15 miles away from across a lake.

I've also installed a hyper focal distance calculator in my ipod touch but I'm not sure I get how to use it.

Also, i'm reading Bryan Peterson's book "Understanding Exposure" and he makes reference to the Distance Scale focusing method, is that the same as using the hyper focal distance method?

Thank you.
R.

craig_d

Distance scale focusing requires a distance scale printed on your lens with DOF indications for different apertures. You estimate by eye the distance from you to your subject, turn the focus ring on the lens until it says that distance is in focus, then compose and shoot. If your lens has no distance scale, then you're out of luck.

Hyperfocal distance focusing is simply focusing to the hyperfocal distance for your current combination of focal length and aperture.

Hyperfocal distance is nothing more than a calculation of the distance you need to focus to if you want as much of your field of view to be in focus as possible. The idea is that you want to determine a focus distance at which infinity will fall just inside the far limit of DOF. This focus distance is called the hyperfocal distance and it varies with both focal length and aperture (and also with sensor/film format and desired print size, but these subtleties are often ignored). You can then assume that the near limit of DOF is roughly half the hyperfocal distance. The end result is that you have everything in focus from half the hyperfocal distance to infinity.

The next question is, do you really need this? Often, no. If the nearest thing in your frame is a few miles away, then it's almost certainly beyond your hyperfocal distance anyway unless your camera is mounted on a large telescope, so just set your focus to infinity.

HaveCameraWillTravel

RE: Hyperfocal distance
Until I read about Hyperfocal distance recently, I never even considered it.
And then, I thought "Have I been shooting all these years and don't know how to focus a camera manually?"

I did know that if you focus at a specific distance, the DOF would determine how far in front and in back of that distance would be in acceptable focus, and that wide apertures and long focal lengths dramatically decrease DOF. But, having been spoiled with AF, it was (and still is) easier to just focus on infinity and set the DOF for a clear foreground. Or focus on the foreground (if I wanted the background soft) and set my DOF for the amount of blur.

I think the easiest way to do the hyperfocal distance thing is to pick the closest foreground object you need in acceptable focus (near limit of DOF), double that distance, then set the aperture so your camera's hyperfocal distance matches that, and focus on the HF distance. (Changing the focal length would obviously change the composition.) But it's a real pain having to break out a programmable calculator and enter the data in.

One can fill a table with data taken from an online HF distance calculator and put it in a small notebook that fits in the gadget bag. It's faster to look up your distance than to calculate it in most cases. Find your focal distance, then find the f-stop that gives you the HF distance you need to focus on, given what you're shooting, set lens to manual, focus and fire away.

Here's a link to a decent hyperfocal distance calculator:
http://www.dofmaster.com/dofjs.html

Hope this is helpful. Most times, as the other poster said, you don't really need to use this technique unless you need to max out your DOF.