Do people with above-average visual acuity benefit from low-magnification optical aids (binoculars & scopes in the 2x range or lower) the same way average or poorer-sighted people do?

Submitted by screwyoushadowban t3_126pp7u in askscience

If someone has, say, 20/10 or 20/9 vision will they benefit from the magnification effects of, say, low-power binoculars or scopes the way average-sighted people do (or even better, with additive or partial multiplicative effects maybe?), or will those tools be of no (or lesser) use to them because their eyes already do what those tools' lenses and prisms do, rendering them redundant? If low-power magnification does benefit them more than the average person, will their better-than-average vision mean they also experience a greater benefit from higher magnification optical tools?

I'm only asking about tools focused on magnification of objects and not, say, corrective lenses for farsightedness/hyperopia that a person with above-average visual acuity might need.

Thanks!

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iimplodethings t1_jedfy1a wrote

I don't know as far as daylight goes, but in low light conditions a big part of the advantage of optics (even low magnification) is just collecting MORE light. A 5" telescope will gather a lot more photons than a 3" telescope (or a 1/4" eyeball pupil) even if they're the same magnification.

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mfb- t1_jedjlbs wrote

Any binocular worth spending money on will give you a magnification of a factor 2 even with 20/10 vision, so better vision without binoculars transfers to better vision with one. With the caveat that using binoculars and glasses together can be tricky, but that's not specific to the ideal vision strength. A really cheap binocular might be worse.

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rootofallworlds t1_jee9vmm wrote

Almost always yes, but there can be exceptions.

For a bright source the level of detail you can see using an optical instrument is limited by whichever is "worse" of two factors. Firstly, the inherent resolution of the instrument because light is a wave and it diffracts around edges. A perfect point light source produces a blurred image at the focal plane, known as the Airy disc. For a telescope the resolution depends on the diameter of the main mirror/lens (the aperture) and the wavelength. (I don't know for microscopes).

Secondly, the visual acuity of the eye multiplied by the magnification in use.

In general when using "low" magnification for a given instrument the second factor is the limit, while with "high" or "too much" magnification the first factor becomes the limit.

2x is low magnification for almost anything, but if you had a telescope with an exceptionally small objective lens it could be limited by diffraction.

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