This is a bit confusing for now as my knowledge of optics is insufficient
to comprehend the meanings of f, S1, and S2. References 23 and 24 on that
Wikipedia page will help, but I need to read those carefully.
>
>Go here <https://en.wikipedia.org/wiki/Lens_%28optics%29> and scroll
>down about 40% of the page and see the illustration for the "thin lens
>formula" under "Imaging properties".
>
>In the illustration, if we assume that the lens is focused at infinity
>an image would be formed at the focal length f. If you impose an
>extension tube the distance to the image is now S2. So you must use the
>thin lens formula to solve for the image distance S1.
>
>1/S1 = 1/f - 1/S2
>
>If we plug some numbers: f= 50mm, extension = 10mm, S2 = 60mm we get:
>1/f = 0.02
>1/S2 = 0.0167
>S1 = 1/0.0033
>S1 = approx 303mm
>
>
>This will be an approximation since your real lens is not a thin lens of
>negligible thickness and, of course, the object distance S1 is measured
>from the optical center of the lens which is not precisely known to you.
>
Chris
When the going gets weird, the weird turn pro
- Hunter S. Thompson
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