Dave posted a nice explanation on hyperfocal distance, what it is and how to set it in the dpreview forums.
This is something that dad tried to explain to me when he first gave me his Pentax 35mm and at the time I sort of got it, but I was also still confused about lense lengths, and what the difference between apeteur priority and shutter priority, or why I’d care 🙂 I’m proud to say that now I do get it and while I don’t use it much, I do “get” it.
In addition to the purpose of the dpreview post (moving the focus point back from infinity as to not “waste” focus in an image, I submit the far more interesting application of this is not having to focus anymore! As it was explained to me, knowing a) the approximate distance you want in focus and b) the f-stop you’ll be shooting at, it’s possible to set your focus ring so that that distance will always be in focus. This lets you run around with your old manual (or high end digital) and simply snap away, without worrying about focusing or what will be in focus, because you already know. Great for crowds or occasions where you want to be quick on the draw. Also it’s information to know about, and I’m glad I saw it here to remind me about it.
Actually, I guess I don’t. I was under the impression that this only worked for fixed length lenses, and I guess in a way I was right, at least, the markings are only on the (only) fixed length lense I have. The charting program shows that it works fine for zoom lenses, you just need a chart (or palm pilot app as I link below 🙂
Other interesting links on the subject:
- Depth of field calculator for the palm pilot and other charts (DOF, circle of confusion…) and whatnots that could be quite useful to keep in your bag of tricks.
- Depth of field caculator done in java.