Chris

@MichaelClark Well it would work using the HFD.

@MichaelClark This composition wouldn't work if I changed it to 20/20 vision. I would have to back up wich would change my composition.

If I stop down to f/16 I get a DOF of infinite. It says total = infinite. That means everything from 1.24m to infinity should be acceptably sharp for a 30" monitor.

The numbers would be enough for a waterfall that is really close with some rocks in front if it.

HFD is 4.22m

this is what I get from the cambridge one, using f/8.0 ( I couldn't put 7.1)

How can I know use the calculator to my advantage?

I want my picture to be sharp enough for a 30" screen

I focused on the rock that's 3m away

Let's say I zoomed in to 15mm and my aperture is f/7.1

let's start with a maximum DOF

Could I counter that 'illusion' by using a smaller aperture? Let's say I focused on a rock that's 3m away at f/7.1 but the background is too blurry, should I stop down to f/11 or even more or readjust my focus?

There is only one point in focus and the human eye won't see it if the picture is not blown up all the way. This is why all the landscape pictures look tack sharp but when zooming in I can see where they put the focus on.

WHich is why you said DOF is an illusion right?

Only if I open up my aperture so that the DOF becomes shallower, the human eye will see a difference.

This means, I could as well focus on something that is 3 m away and the viewer would still perceive the subject that's 10m away as sharp.

But that can't be true, which is also what you've been saying the whole time. If I focus on something that's 10m away because I want the viewer to be drawn to this subject, the picture will still have an overall good sharpness and for the viewer will be no noticeable difference between the subject that is 10 m away and the near limit.

THey just tell me that everything from the near limit on is acceptably sharp

I am willing to learn but I don't understand what they are good for

What are those calculators good for exactly? I've read that many say they are useless.

that's what those pictures illustrate

Total DOF : infinite

And I don't understand that concept. I understand all the technical aspects, such as the light rays being parallel etc. but when using those calculators It confuses me. It doesn't correspond to what I see in the picture.

But as I said, I can change the values and the calculator always says DOF of infinity.

Then the illustration is a little bit misleading. There should be a DOF of x m/inches/feet and then infinity.

@MichaelClark So if I put f/7.1 @10mm the hyperfocal distance is 0.75m. The pictures illustrate it as if everything beyond 0.37 (0.75 HFD) is within infinity, thus acceptably sharp. If I focus at 1m, everything beyond 0.43m should be within infinity. If I put 50m everything beyond 0.73m is within infinity.

@MichaelClark I've been testing different focal lengths with the same composition and I can't help it but I don't really see a noticeable difference between the hyperfocal distance and any focus distance further away. I took the camera off the tripod and focused on something at the end of the hallway which is at least 10 m and then put it back on the tripod. The shot was just as sharp/unsharp in the foreground as the shot taken with the hyperfocal distance.

@Michael Clark The calculators all say 'infinity' and I understand that this means everything will be acceptably sharp.

What is my real DOF then?

after a certain distance the nearest acceptable sharpness doesn't change

I should go to bed. I'm getting so worked up over this. For instance, put a focal length of 10mm and an aperture of f/11 or whatever you want and then put different focus distances from 1 to whatever you want. The nearest acceptable sharpness does not change as well as the DOF. I could just focus on anything, even if it's 1000 meters away, the pictures should be equally sharp. What am I missing here?f

So that mean with a wide angle lens, if I focus at something beyond the hyper focal distance, I'll always get a DOF of infinity even at a narrower aperture?

@MichaelClark I've been testing different focus distances and when focusing further away than the hyperfocal distance, the foreground is always sharper. How can this be?

I really appreciate your help @MichaelClark! I'm just really frustrated so if I may sound rude it's not intended. I'm sorry!

Also, what exactly does near limit of acceptable sharpness mean? Is it the distance from my camera or the distance in front of the subject?

By the way, almost every landscape tutorial says I should use at least an aperture of f/11. I just tried taking the same picture again just with an aperture of 7.1 and the background and foreground are visible blurrier, even when looking at it from a distance. When stopping down to f/16 it gets blurrier as well due to diffraction.

*than

I like taking pictures near the ground because it gives a nice effect with a wide angle lens when the stones are in the first third of your picture, then the water, then the distant objects.

This is interesting because when I went to the beach lately I focused at roughly 20m with an aperture of f/11 @15mm and everything is sharp from front to back. If I put these values in the calculator it gives me a hyperfocal distance of 1.05m which is roughly what I used to focus on the vacuum today and I've found this to be the sharpest of the three pictures I posted today.

without sacrificing sharpness in the background

so I want to get the foreground, which includes a small lake with stones, in focus

I'm going on a hike tomorrow where I want to try taking a picture of a waterfall

according to the markings

the closest should be 0.24m

What if the nearest thing is just 30 cm away and the farthest 20m, where am I going to focus on then? Is there an equation I can average my focus point?

So I have to resize my images manually to all common native display sizes?

@MichaelClark I thought any OS will resize the image to fit the screen. If I want a picture to be suitable for multiple display sizes and resolutions, how can I achieve that without cropping several copies?

@MarkRansom So should I just focus manually on something I want to be in sharp focus and use the DOF calculator to check if my far background would be within infinity?

Anyways, I was going to say that if I use the numbers of the calculator my picture won't be as sharp as when using AF. Now it gets even more confusing for me as when using AF my lens focuses at different distance depending on whether I use live view or the viewfinder.