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Your eye vs. optimal mm scopes?
- Thread starter bgast
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marksman1941
Well-Known Member
- Joined
- May 20, 2013
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Generally it's about low light transmission where there's less ambient light hitting the objective lens.
Assuming the same glass quality in each scope, at full daylight you may not see a difference in clarity between a 1" tube with a 40mm objective and a 34mm tube with a 56mm objective.
At dusk when it's last shooting light, the 34/56 scope will give you a few more minutes of being able to see your crosshairs and your target clearly.
Assuming the same glass quality in each scope, at full daylight you may not see a difference in clarity between a 1" tube with a 40mm objective and a 34mm tube with a 56mm objective.
At dusk when it's last shooting light, the 34/56 scope will give you a few more minutes of being able to see your crosshairs and your target clearly.
Hugnot
Well-Known Member
Unit is - lux.
3 or 4 for night with no moon
about 50,000 for direct sunlight
The eye pupil will dilate or contract. About 7mm max to about 3 minimum. Objective lens divided by power gives exit pupil. So 56mm/20 = 2.8 mm.
Other stuff being - from Wikipedia
"The Rayleigh criterion shows that the minimum angular spread that can be resolved by an image forming system is limited by diffraction to the ratio of the wavelength of the waves to the aperture width. For this reason, high resolution imaging systems such as astronomical telescopes, long distance telephoto camera lenses and radio telescopes have large apertures."
Small aperture width, more diffraction & image degradation. Light from a tiny little exit pupil of 2mm or smaller will easily fit into any eye pupil.
Diffraction - bending of light waves caused by the aperture becoming a secondary source (propagating) of light waves - light spreading, less intensity. making an increased dull fuzzy image or sometimes an image consisting of concentric rings.
And
Optical science guys use the term - "numerical aperture" or NA to describe a lens. A lens with a bigger NA has a bigger angle of acceptance, like a cone with a larger diameter as related to cone height or length. This results in more light being gathered in the pointy end of the cone providing better resolution.
Glass quality & coatings matter. Some 40 mm objective lens scopes are noticeably brighter than other 50mm objective lens scopes - both set at the same power.
Scopes with fat tubes like 30mm & 34mm will have internal lenses having larger NA's.
A nice 34/56 scope would be as good as it gets.
Whatever -never ever look at the sun directly with or without an optic.
3 or 4 for night with no moon
about 50,000 for direct sunlight
The eye pupil will dilate or contract. About 7mm max to about 3 minimum. Objective lens divided by power gives exit pupil. So 56mm/20 = 2.8 mm.
Other stuff being - from Wikipedia
"The Rayleigh criterion shows that the minimum angular spread that can be resolved by an image forming system is limited by diffraction to the ratio of the wavelength of the waves to the aperture width. For this reason, high resolution imaging systems such as astronomical telescopes, long distance telephoto camera lenses and radio telescopes have large apertures."
Small aperture width, more diffraction & image degradation. Light from a tiny little exit pupil of 2mm or smaller will easily fit into any eye pupil.
Diffraction - bending of light waves caused by the aperture becoming a secondary source (propagating) of light waves - light spreading, less intensity. making an increased dull fuzzy image or sometimes an image consisting of concentric rings.
And
Optical science guys use the term - "numerical aperture" or NA to describe a lens. A lens with a bigger NA has a bigger angle of acceptance, like a cone with a larger diameter as related to cone height or length. This results in more light being gathered in the pointy end of the cone providing better resolution.
Glass quality & coatings matter. Some 40 mm objective lens scopes are noticeably brighter than other 50mm objective lens scopes - both set at the same power.
Scopes with fat tubes like 30mm & 34mm will have internal lenses having larger NA's.
A nice 34/56 scope would be as good as it gets.
Whatever -never ever look at the sun directly with or without an optic.
Rich Coyle
Well-Known Member
bgast,
I Confess, I didn't read a single post. Nevertheless, there is real world value having an exit pupil larger than your pupil. You dpn't have to be perfectly in line with the center of the scope to use it.
I Confess, I didn't read a single post. Nevertheless, there is real world value having an exit pupil larger than your pupil. You dpn't have to be perfectly in line with the center of the scope to use it.
Hugnot
Well-Known Member
Big diameter exit pupil - scope "eye box" is real big & parallax adjust & focus adjusted for range, will allow limited side to side or up/down movement without reticle moving on target & sharp image. A 3-16X42 when set at 3X would have a real big exit pupil of 14 mm allowing much lateral eye movement & bigger field of view & brightness & bigger eye relief upon peering thru scope with a 7mm diameter human eye pupil.
Don't have to get into academic stuff to make things work good.
Don't have to get into academic stuff to make things work good.
