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50mm objective vs 56mm: light gathering (1 Viewer)
- Thread starter Foss
- Start date
56 divided by 50 equals 1.12 so 12 % greater diameter.
But 1.12 squared equals 1.2544 so 25% greater area.
So, a quarter more light if all the aperture used.
But 56mm and 50mm objectives are often vignetted so smaller than stated, and pupil size is often less than exit pupil.
It is likely that 15x56 and 12x50 binoculars will use all the aperture at night.
But 8x56 and 7x50 will not, especially for older observers.
Common 10x50 binoculars are often really 46mm aperture.
Also, the real magnification is often different to that stated on the binocular.
B.
But 1.12 squared equals 1.2544 so 25% greater area.
So, a quarter more light if all the aperture used.
But 56mm and 50mm objectives are often vignetted so smaller than stated, and pupil size is often less than exit pupil.
It is likely that 15x56 and 12x50 binoculars will use all the aperture at night.
But 8x56 and 7x50 will not, especially for older observers.
Common 10x50 binoculars are often really 46mm aperture.
Also, the real magnification is often different to that stated on the binocular.
B.
lilcrazy2
Well-known member
When I read this, I thought back about playing in dart leagues for the last 30 years, and the fact that I am usually the scorekeeper. I was always amazed at how many of the adult players struggled with multiplication and basic addition and subtraction. Guess your fact explains it.
tenex
reality-based
So you get a 25% improvement there which is really rather modest considering how we perceive brightness... but then again, many 56mm models have mirrorless AK prisms too and slightly higher transmission, which all starts to add up. And a 50mm isn't exactly svelte anyway, so why not go for 56?
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