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When some people take photos of the landscape, why do they not use like a low f-stop like f/32, because wouldn't you want everyone in focus because it's a landscape?

But quite a lot of people use f-numbers like f/16 and f/11, so it wouldn't all be in focus? I wanted to know why? How come people prefer this?

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First people want to have (when making photos of landscape) almost all in focus. But they do not use F22-32 because on such aperture diffraction degradate the quality of images.

Second, when shooting landscape the trick is to use so named hyperfocal point. For example with 50mm lens, fullframe camera, F9, if you focus on 9.33 meters from the camera you will have everything from 4.83 meters to infinity in focus. You can check for other values here.

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    \$\begingroup\$ The values will depend of your threshold of what you consider in focus, and that may depend on the pixel size (resolution) of the sensor. The calculator seems to take that into account.. \$\endgroup\$
    – Carsten S
    Dec 2, 2023 at 11:46
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    \$\begingroup\$ It also depends upon the intended display size and intended viewing distance. The Depth of field will change on the same image displayed at the same size as the viewing distance is changed. The DoF also changes if viewed from the same distance at different display sizes of the same photo. \$\endgroup\$
    – Michael C
    Dec 6, 2023 at 7:02
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The resolving power (ability to image closely spaced points) is dependent on the f-number setting.

This has been well studied and is called the Rayleigh Criterion.

Below is the Lines resolved at various f-number settings, by Sr. Rayleigh (Nobel Prize Physics Astronomer Royal).

f/2 = 696 lines per millimeter (l/m)
f/5.6 = 249 l/mm 
f/8 = 174 l/mm 
f/11 = 127 l/mm 
f/22 = 63 l/mm 
f/32 = 44 l/mm 
f/45 = 31 l/mm 
f/64 = 22 l/mm

Note: A setting of f/8 is higher than pictorially useful films.

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  • \$\begingroup\$ No, the f numbers are relative numbers (focal length divided by the (effective) aperture). They don't say anything about the diffraction limit. The diffraction limit is dependent on the absolute (effective) aperture. \$\endgroup\$ Dec 3, 2023 at 18:55
  • \$\begingroup\$ @Peter Mortensen -- How much error is induced if you use effective aperture vs. aperture as engraved on the lens barrel? \$\endgroup\$ Dec 5, 2023 at 15:08
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You might want a fast shutter because the wind is blowing or something is moving in the landscape.

Some landscapes are more effective with a shallower depth of field to accent a particular feature. Perhaps you do not consider this a landscape.

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Depth field doesn't matter that much at infinity focus

Depth of field increases with focal distance. Punching into an online hyperfocal distance calculator: a 50mm lens will be in adequate focus for everything from 7m to infinity if focused at 15.5m. Rarely if ever is a landscape photographer going to want that much sharp foreground framing a subject that's mostly at roughly infinity focus. Differences in focus help model the space of an object so you can tell the difference between the two.

Additionally, stopping down more than f/5.6 or f/8 tends to reduce sharpness by diffraction so it's just not worth the tradeoff for most subjects. This leads to the usual aphorism of "f/8 and be there". The optimal aperture for a daylight-lit static subject is going to be in the range from about f/5.6 to f/11.

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Why do you assume that something in the scene wouldn't be in focus at f/11? Why wouldn't it be? It will appear in focus if it's within the depth of field respective to the distance that is focused upon. Things outside the depth of field won't appear in focus – but (especially when photographing distant scenes) there may simply not be anything in the scene that is outside the depth of field, even at f/11.

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    \$\begingroup\$ While this is true it doesn't explicitly say why f/11 is better than f/32. I know you know why :) \$\endgroup\$
    – Philip Kendall
    Nov 30, 2023 at 16:22
  • \$\begingroup\$ Yes, fair enough, the "real" answer is about avoiding diffraction. But I think it's also important for people to realise that you can also focus on something at infinity with a wide aperture, and that depth of field when focusing on far distances is quite large even with apertures like f/11. \$\endgroup\$
    – osullic
    Dec 1, 2023 at 12:05
  • \$\begingroup\$ I did link to our canonical hyperfocal distance question :) \$\endgroup\$
    – Philip Kendall
    Dec 1, 2023 at 12:18

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