Hyperfocal vs. extreme apertures

[Scottes]

This came about in Share from http://photography-on-the.net/forum/viewtopic.php?p=348626 concerning a picture of a covered bridge I took. gtg asked a question, and my answer - and subsequent questions - are below. I decided to move this part of the conversation here.



The 2nd photo really has the concept of DOF well explained. What F-Stop did u use. Jus Curious. :D

I used f/22, but I really have to play with that. Considering hyperfocal distance I should have been able to get the same shot with f/8, and steered clear of corner distortions and such caused by such a small aperture, and remained at an aperture closer to optimal.

But then I read about people, like the "f/64" club I think it's called - who go to extreme apertures in order to get the sharpest picture. But if f/8 and hyperfocal could get the shot and get everything in focus then why go to the smallest aperture?


So, with the lens set to f/8 and the hyperfocal distance I should have been able to get the entire image in focus. Why would I want to go to a smaller aperture?? If everything is in focus, how is it that a smaller aperture would get things their sharpest? Doesn't the smaller aperture bring about the possibility of barrel distortion and other un-wanted effects?


Finally, does anybody know if the "Landscape" mode on a 10D/DRebel/etc actually sets hyperfocal distance, or just sets it to the smallest aperture?

[Jesper]

I have a book about wildlife photographers, with a few pages about the photographer and techniques (s)he uses and some photos. There is one guy in that book who makes photos with homemade lenses, or even simply a piece of cardboard with a tiny hole in it. With something like that (a pinhole camera) the DOF is infinite.

He made close-up photos of insects sitting on trees, but not only the insect is in focus, also the surrounding buildings which are tens or hundreds of meters away.

He estimated that the aperture on those photos was somewhere between f/128 or f/256.

The smaller the aperture, the smaller the hyperfocal distance becomes - so with a very small aperture, everything will be in focus from very close to very far away.

Note that if you use very small apertures, f/16 or smaller, your photos might actually become less sharp because of diffraction. The aperture becomes so small that light "bends" around it instead of going straight through. See http://photonotes.org/cgi-bin/entry.pl?id=Diffraction

Landscape mode on the 10D/300D etc. does not cause the camera to focus on the hyperfocal distance. It just focusses normally, at the spot you point the active AF point to.

Barrel distortion doesn't have anything to do with the aperture.

[Scottes]

Barrel distortion doesn't have anything to do with the aperture.

It was diffraction I was thinking about, I just couldn't think of the word.

But if everything will be in focus using f/8, is there any reason to go to f/22?

[PacAce]

Barrel distortion doesn't have anything to do with the aperture.

It was diffraction I was thinking about, I just couldn't think of the word.

But if everything will be in focus using f/8, is there any reason to go to f/22?

Scott, you probably already know this but hyperfocal distance is dependent not only on the aperture but also the focal length of the lens being used. So, for a given aperture, the hyperfocal distance will vary depending on the lens being used.

But, for the sake of argument, let's say that we're using a 50mm lens. At f/8, the hyperfocal distance is 6.1 meters. So, anything within 3 meters to infinity will be in focus.

Now, at f/32, the hyperfocal distance is 3.1 meters so anything within 1.5 meters to infinity will be in focus.

If you are taking a pictture of your wife who is standing about 5 feet in front of you, you would have to set your aperture to f/32 and manually set the focus point at 3.1 meters to get both your wife and the background mountain range in focus.

If you don't want your wife in the picture and you don't care whether any of the closeby foreground subejcts are in focus or not, then it doesn't matter if you're shooting the mountain scene at f/8 or f/32.