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I was evaluating the Sony FE 20mm f/1.8 G and saw few videos where it was mentioned that it is excellent for landscape photography. However this lens has normal focal distance of about 0.5 feet for a subject which is fixed then how is it able to focus on things which are far away? My understanding is that all far away mountain landscape should stay out of focus but that doesn't happen.

Can someone please explain how the focal length will play a role here. If it can focus on far away objects then why we say focal distance to be 0.5 feet?

jng224
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Lokesh
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    YOu are confusing focal length with focus distance. They are not the same thing. A lens' focal length is measured when it is focused at infinity. – Michael C Nov 01 '20 at 10:46
  • @MichaelC: My question came while analysing portrait lenses. If i have 85mm, f1.8 lens then subject can be at about 2 feet to be in focus but if my lens is 20mm f1.8 then subject can be 0.5 feet away to be in focus. If i want take 20mm lens to 2 feet distance then it will not be in focus. So my understanding is that a prime lens can have object always at a fixed distance. Is that correct? – Lokesh Nov 01 '20 at 10:53
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    No. The focal length is the distance from the lens to the imaging medium (film or sensor). The focal length is measured when the lens is focusing collimated light (i.e. when the focus distance is infinity). But a prime lens can be focused to converge light that is not collimated (closer than infinity) by moving the lens away from the imaging medium - or in a complex lens with multiple elements moving the equivalent thin lens that those elements add up to further away from the image sensor or film plane. – Michael C Nov 01 '20 at 11:04
  • Thanks. I have edited my question as its more about focal distance. So what i interpret is that any lens can focus on anything, its just about adjusting focal distance, is that correct ? – Lokesh Nov 01 '20 at 11:16

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