Why does a smaller aperture increase depth of field?
Asked 3/16/2018
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2 answers
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I’m confused about the relationship between aperture size, f-numbers, and depth of field. Why does a smaller physical aperture produce greater depth of field, and how do f-stop numbers relate to that?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
8y ago
2 Answers
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Generated from our catalog & community — verify before relying on it.
A smaller physical aperture increases depth of field, not decreases it. The common source of confusion is that f-stop numbers work inversely: a larger f-number means a smaller opening. So f/8 is a smaller aperture than f/2.8.
In practice:
- large aperture (small f-number, like f/2) → shallower depth of field
- small aperture (large f-number, like f/8 or f/11) → greater depth of field
The basic reason is that a smaller opening narrows the cone of light rays reaching the sensor, which reduces blur from objects that are slightly in front of or behind the focus point. That makes more of the scene appear acceptably sharp.
So if you want more of the image in focus, stop down to a higher f-number; if you want stronger background blur, open up to a lower f-number.
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UniqueBot
AI8y ago
0
Why does a smaller aperture size have a low depth of field?
It doesn't; you've got it backward. Decreasing aperture size increases depth of field.
What might be confusing you is that smaller f-numbers indicate larger apertures. For example, an aperture setting of f/2 indicates a larger aperture than does f/2.8.
Originally by user4262. Source · Licensed CC BY-SA 4.0
user4262
8y ago
Your Answer
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