Hyper Focal Distance (hfd) Calculators-results vary?

Ive been looking at a few different hfd calculators online and have found slight variances in the numbers they produce. They don't vary too much, for example outsight.com says that the hfd for 20mm@f/11 with a 1.6 crop factor and CoC of 0.02 is 6.4 ft and nikonians.org says it's 5.8 ft. Probably not enough to make a substantial differnce in dof. My real question is why do some of them ask for distance to subject and some do not. If I know the hfd doesn't that become the subject of the image since that is what I'm focusing on? I know that dof calculators require distance to subject to make their calcs but why would a hfd calculator ask to that? Isn't distance to subject what I'm using the calculator to find out. I hope I've presented the question clearly. I may have created my own circle of confusion. Thanks,
Bruce.

Bruce: You have created your own confusion. Hyperfocal distance is NOT the distance to the subject. Hyperfocal distance is the focusing distance you would set on the lens so that everything from half of that distance, to infiniity will be "acceptably" sharp for the given aperture. There are 3 critical variables in the calculation of the Hyperfocal distance: Focal length of the lens, Aperture used, circle of confusion limit. With those 3 you can calculate HF distance. Let's say you have a beautiful landscape in front of you with a wonderful background that is 1/2 mile away and clouds in the sky beyond. Your foreground is a lovely tree branch basking in the light with the lap of the lake waves coming up on it. You'd like to get it all in "acceptable" focus in your image. You are using a 24mm lens with an aperture of f/11. My calculations would indicate that the HF distance is 8.67 feet. That would allow everything from 4.33 feet to infinity to be acceptably sharp.

Hope that helps??

I'm not sure I can do it adequately, but from your questions it sounds as though a little clarification is needed. Subject distance is needed because as you focus further and further from the camera, the DOF for a given aperture increases. And when using hyperfocal techniques, no, you don't always focus on the subject. You might focus elsewhere in the frame, only using the subject distance to make sure your principal subject is within the DOF.

I used to use the heck out of HF scales back in the day when they were a standard feature engraved onto lens barrels. But I find the contemporary calculators---- all of them---- to be a royal PITA. Not the variation between them, but their cumbersome nature.

As a result I've fallen into using the DOF preview button more, along with a detailed examination of the shots on my LCD. Most helpful of all is what I call "focus bracketing." I'll estimate the right spot to focus, then vary that slightly through a series of shots for closer examination and selection later on a larger screen.

I do a whole lot of belly flop photography, actually laying down on the ground with wide angle lenses and including elements of the scene right up to within inches of my lens. My principal subject might be 10 to 100 feet away from me, but using hyperfocal methods, I'm only focusing a foot or two in front of the camera. DOF is critical to pull off such images, but the calculators are beyond cumbersome and next to worthless to me.

I'm attaching a representative belly flop shot. The closest detail is mere inches in front of the lens. I was most concerned about that little clump of bee blossom in the puddle, but as I recall I focused on the near edge of the water to achieve focus from the foreground to the horizon.

Hey Keith and Hank - I think you're agreeing with Bruce. He said

If I know the hfd doesn't that become the subject of the image...

I believe he meant "doesn't the HFD become the subject", which is a little awkward, but correct.

So Bruce, the only reason I can think of that a hyperfocal distance calculator would ask for subject distance is if it's capable of calculating DOF in general. Or was created off of software that was capable of general DOF calculations.

I acknowledge becoming more geezerly by the day, but I can't wrap my mind around calling the focusing point my subject. Semantics don't matter, long as he has his mind around hfd- whether or not he uses the calculators.

APS sized sensors are a lot more forgiving when it comes to the extremes on hyper focal distance but with larger sensors the HDF does not work at the extremes.

Example that you can try yourself. Camera 5D MII 17-40mm @ 17mm f22

Subject 1.5 ft (actual focusing point)

Closest object inside of frame 9 inches (maybe just dirt)

You will find the area at 9 inches not very sharp and I would not call it acceptable.

OK Hank - try this..."If I know the hfd, doesn't that become the focus point of the image"...focus point == subject, subject == focus point, at least I think that's what Bruce is equating. Although, of course, you aren't always focused on the subject.

My comment is a little out of line here and you have gotten some very insightful comments Bruce from very knowledgeable and experienced folks which is great. But I must say, once you get caught up in the "calculations" part of photography I believe you have wondered way off track from the reasons that makes nature photography enjoyable. So my advice would be to not rack your brain too much on hyperbolas and hypotheses. Maybe just take lots of pictures and see what you get. And if you need to make adjustments to what your doing.

You nailed it David. I understand where Keith and Hank are coming from and artistically they are right since the hfd it is usually not what I want the viewer to be drawn to. But technically I think it is the subject, because it's what I'm focusing the camera on. It might be a dirt clod, pine needle, or whatever. Hank, unfortunately my camera doesn't offer dof preview. Thanks everyone, I'm moving towards clarity. :)

Hey Bruce....glad I got it right. Of course, I agree with Hank that it's not the way most people think of it. The point of using the HFD is that you get DOF such that most things are in good enough focus and the subject can be anywhere. I wouldn't say the the point your focusing on, or the distance, would be the subject of the picture. For instance....you may have a tree that you are photographing offset in the scene, but you use the center focus point on something else within the frame to focus. The tree is still your subject - and referring to it that way would avoid confusion.

Lack of DOF preview would frustrate me too, Bruce! Try my "focus bracketing" with reviews on the LCD. I've become really familiar with the magnifying function, and in fact, it's better than DOF preview for my eyes.

You got it Hank. I use live view>magnify>focus for virtually every landscape shot I take. I don't know if it's the best method, but it seems it's the best I have with my current equipment. Focus bracketing...hmm...I've made a mental note.

I haven't used live view Bruce, so I've got a question. When watching on screen, can you see the DOF change as you spin through the aperture scale, or it merely what you see with an auto wide open, as in what a standard image looks like without pressing a DOF preview button?

I ask, because if the DOF doesn't change on screen as you spin through the apertures, you might have to resort to what I do- carefully examining the image after you've taken the shot.

Coming from a position of ignorance about live view.

at this point, that is a major difference between Nikon and Canon/ The Canon allows DOF preview while in 100% on live view. IMO the best feature a camera ever had (for landscape). DOF preview in live view allows the shooter to quantify DOF visually at any aperture. The effect is to allow optimum aperture for every image.

Hank, once I get the shot set up I magnify the image in live view and move around the frame to check the critical areas for sharpness. If I think it can be improved I change the aperture or experiment with the hyper focal distance and go through it again. I used to check it again after taking the shot but I've come to believe that it's redundant. I can't see the dof change in live view just by dialing through different apertures unless I refocus also. As I said, I don't know if it's the best method but that's what I'm doing now. As I gain experience or upgrade equipment this may all change. I can't visualize the dof preview feature. I may have to go to a photo shop to see what I've been missing. But that's scary because I may leave with less $ in the bank. :)
I hear you Brad. To me photography is the perfect blend of technology, art and nature. I do take a lot of pictures and learn a lot by comparing the results, but I think I can improve quicker and enjoy it more by understanding all three of these elements. I'm not a real techie person so it's not likely that I'll get bogged down by overloading on the technical side.
I've really benefitted form the discussion here. Thanks to everyone for your insights.