How does aperture affect infinity focus and sharpness in landscape photography?
Asked 5/12/2015
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I use a fast manual-focus lens for low-light landscapes and often focus near or at infinity. How does aperture change the result in that situation?
Specifically:
- If focus is set to infinity, does aperture still affect depth of field and sharpness?
- Is everything from the minimum focus distance to infinity sharp when focused at infinity?
- For tripod-mounted landscapes, is it generally better to use a wider aperture with shorter shutter speed and higher ISO, or a smaller aperture with longer shutter speed and lower ISO?
- Will long exposures make the image softer, or is lens sharpness at different apertures the bigger factor?
Assume a typical landscape scene where overall sharpness matters.
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
11y ago
2 Answers
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If you need to have as much as possible including infinity sharp, it's better to focus at the hyperfocal distance instead of infinity. Then everything from half the hyperfocal distance to infinity is acceptably sharp. There are websites and smartphone apps to calculate that distance.
I'm not sure what you mean by "It is my understanding that with manual focus set to infinity, everything from min. focussing distance should be in focus.". What do you mean by minimum focussing distance?
Lens aperture is a factor when focussing at infinity, or focusing at the hyperfocal distance, or focusing at any distance: smaller aperture results in larger depth-of-field, and larger aperture results in smaller depth-of-field. That is always true, regardless of focusing distance. Note that the hyperfocal distance changes when you change the aperture: since the depth-of-field is smaller when using a larger aperture, the hyperfocal distance needs to be larger (closer to infinity) in order to have sharpness up to infinity.
Originally by user32390. Source · Licensed CC BY-SA 4.0
user32390
11y ago
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Generated from our catalog & community — verify before relying on it.
Yes—aperture still matters even when focusing at infinity. A smaller aperture increases depth of field; a wider aperture reduces it. Focusing at infinity does not make everything from minimum focus distance to infinity sharp. If you want the greatest front-to-back sharpness, focus at the hyperfocal distance rather than simply setting the lens to infinity.
For distant-only scenes, use the aperture where your lens is sharpest, often around f/5.6–f/8 (sometimes f/4, depending on the lens). Wide open settings like f/2.8 may be softer from lens aberrations, while very small apertures like f/11–f/22 can lose sharpness from diffraction.
On a tripod, the usual landscape priority is low ISO and an aperture chosen for sharpness/depth of field, letting shutter speed be as long as needed. A long exposure by itself does not soften the image if the camera is stable; softness is more likely from poor focus, lens performance wide open, diffraction, or subject movement.
For best results, magnified manual focus is often more reliable than just turning the ring to the infinity mark.
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