Hyperfocal/DoF question....again

Sorry about these questions
This time its about the hyperfocal distance

I got an app for my iphone which has calculated the hyperfocal distance to be 1m 35cm

I was using my 5Dmkii, 24-70mm f/16.0 for this photo

In that case your focal length was probably set to about 25mm on your lens. The hyperfocal distance just says that if you focused at it then everything from 1/2 that distance to infinity will be "acceptably" sharp. Given your image though, you would have been better just to focus at 250m since I don't think there was too much that was 1m from you .

e-k

I think you may be misunderstanding what hyperfocal distance is. Very briefly, if you focus at the hyperfocal distance, everything from half that distance out to infinity is "acceptably" within focus. What's acceptable is of course subjective, and it also depends on things like how far your viewer is from the final product. Anyway, in your example, where your hyperfocal distance is 1.35 meters, if you focused on an object 1.35 meters away, then everything from about .67 meters out to infinity should be in focus. In your case, there's obviously nothing that close, so you could have shot at a much wider aperture and still kept your entire scene in focus.

Your app is incorrect or you entered the information incorrectly. Unless you want that object in the lower left corner sharp, you don't need hyperfocal for this shot. Just focus on that central boat.

Bearmann wrote in post #16325403
Your app is incorrect or you entered the information incorrectly. Unless you want that object in the lower left corner sharp, you don't need hyperfocal for this shot. Just focus on that central boat.

I've used two apps for this and entered the exif info on this image, apart from the subject distance because it was on manual focus, which I can't enter.....it's way too big of a distance to enter, unless the hyperfocal distance is calculated with the autofocus, I don't know, but don't believe that to be correct....it can be calculated with manual focus as well

E-K wrote in post #16323944
In that case your focal length was probably set to about 25mm on your lens. The hyperfocal distance just says that if you focused at it then everything from 1/2 that distance to infinity will be "acceptably" sharp. Given your image though, you would have been better just to focus at 250m since I don't think there was too much that was 1m from you .

e-k

Oh, so it's 1.35m from me? Oh I get it now

RichSoansPhotos wrote in post #16326266
I've used two apps for this and entered the exif info on this image, apart from the subject distance because it was on manual focus, which I can't enter.....it's way too big of a distance to enter, unless the hyperfocal distance is calculated with the autofocus, I don't know, but don't believe that to be correct....it can be calculated with manual focus as well

No, the hyperfocal distance is just based on the focal length, format (choice of COC criterion), and aperture.

e-k

RichSoansPhotos wrote in post #16326270
Oh, so it's 1.35m from me? Oh I get it now

Yes, it isn't that the depth of field is 1.35m if that is what you were thinking .

e-k

E-K wrote in post #16326484
Yes, it isn't that the depth of field is 1.35m if that is what you were thinking .

e-k

OK, I get it, thanks

It seemed like your number was too close, but after checking a calculator, you are right on target. Sorry for the misinformation above. However, hyperfocal is not required for this image. Even using a stricter CoC of 0.015, and focusing at 250m at 24mm, you will have sharpness from 2.4m to infinity.

Bearmann wrote in post #16326546
It seemed like your number was too close, but after checking a calculator, you are right on target. Sorry for the misinformation above. However, hyperfocal is not required for this image. Even using a stricter CoC of 0.015, and focusing at 250m at 24mm, you will have sharpness from 2.4m to infinity.

OK, thanks again for the input

In general, you're going to use hyperfocal distance calculations with the aperture as the unknown. Forgive me if I'm beating a dead horse, but I want to make sure its application is fairly clear. This would be my normal process if I shooting something where I want to shoot at the hyperfocal distance.

1) First, I compose the shot. This is especially important with a zoom lens, as I will need to know the focal length I plan on using.

2) I now evaluate the scene I've composed and find the closest object that I want to be in focus. Let's say in this example, I had my focal length set to 50mm and the closest object I want in focus is 5 meters away.

3) Now, I go to my hyperfocal distance calculator and enter a 50mm focal length and 10 meters for the distance. Why 10 meters and not 5? That's because focusing at the hyperfocal distance (10 meters in this case) keeps everything half that distance (i.e. 5 meters) out to infinity in focus.

4) OK, I'm too lazy to pull up a hyperfocal distance calculator online, but lets say it tells me I need an aperture of f/9.0.

5) Now, I set my aperture to f/9.0 and focus on something that's about 10 meters away. Unfortunately, focus rings on most modern lenses aren't very accurate, so I wouldn't recommend using the distance markings on the lens to focus at 10 meters. Now, as a technique, since I'm probably just guesstimating 10 meters, I may add an extra 1/3 to 2/3 stop, depending on how far off I think my estimation is.

And that's it. . .well, press the shutter button of course. Hopefully that makes sense.

I've just realised that what someone told me is true, that if you decreased the focal length of a zoom lens, you also increase the DoF, can someone tell why this occurs?

It occurs because of the position of focal length in the equations.

Bear in mind that like all such comparisons, the other factors must be held constant.

Depth of field has four factors: focal length, aperture, focus distance, and circle of confusion diameter.

The focal length equations are:

If you decrease the focal length without moving the camera, you are widening the field of view. As a result your collected light will, well, be "wider" but this will also affect the "apparent focus" of various things in the scene.

I'm not an image scientist and haven't really delved into all the stuff, so I'll quit before I get myself into trouble!