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scopes, 50 vs 44,40..etc
- Thread starter NHSHOOTER
- Start date
The amount of light any optic transmits is based on 3 things. The scopes objective size, magnification, and lense quality.
If you divide the scopes objective size by the magnification you will determine the size of the cone of light coming through the lense to your eye. A 20mm lense set on 4X will let exactly the same amount of light through as a 40mm lense set on 8X or a 50mm lense set on 10X. The diameter of that light beam will be 5mm in diameter. Going up to a larger lense will be more helpful in low light at higher magnifications. You want a scope that will let in about 5 or 6mm of light at the magnifications you plan to use.
Using a larger objective on lower powers will let in a larger beam of light, but most human eyes will only open up to 5 or 6mm. Having a 50mm lense set on 5X will let in about 10mm of light, a 40mm scope set on 4X will let in exactly the same, but the human eye simply cannot use any more than 5 or 6, so it is wasted.
But this only determines the size of the cone of light coming through the scope. The lense quality will determine how bright it is. Really good scopes in the $1,000 and up price range will let through 95+% of the light. Most of your mid-level scopes will be in the low to mid 90% range and many of the cheaper budget scopes will be in the 85%-90% range.
Bigger glass costs a lot more money to get the same quality. In the same price range a smaller 40mm lense will likely be better in low light than a 50mm lense costing about the same.
For my money 40mm is as big as I want. A 50mm lense will only be an advantage when set on 8X or 9X. Any lower, or higher magnifications and it will offer no useable advantage. When you look at higher costs, heavier scopes, and more difficulty in mounting the slight advantage just isn't worth the benefits.
In Europe, where hunting at night is commonly practiced the 50-56mm lenses are common. A scope with a 32-40mm lense will allow you to see anything during legal shooting times in the USA.
If you divide the scopes objective size by the magnification you will determine the size of the cone of light coming through the lense to your eye. A 20mm lense set on 4X will let exactly the same amount of light through as a 40mm lense set on 8X or a 50mm lense set on 10X. The diameter of that light beam will be 5mm in diameter. Going up to a larger lense will be more helpful in low light at higher magnifications. You want a scope that will let in about 5 or 6mm of light at the magnifications you plan to use.
Using a larger objective on lower powers will let in a larger beam of light, but most human eyes will only open up to 5 or 6mm. Having a 50mm lense set on 5X will let in about 10mm of light, a 40mm scope set on 4X will let in exactly the same, but the human eye simply cannot use any more than 5 or 6, so it is wasted.
But this only determines the size of the cone of light coming through the scope. The lense quality will determine how bright it is. Really good scopes in the $1,000 and up price range will let through 95+% of the light. Most of your mid-level scopes will be in the low to mid 90% range and many of the cheaper budget scopes will be in the 85%-90% range.
Bigger glass costs a lot more money to get the same quality. In the same price range a smaller 40mm lense will likely be better in low light than a 50mm lense costing about the same.
For my money 40mm is as big as I want. A 50mm lense will only be an advantage when set on 8X or 9X. Any lower, or higher magnifications and it will offer no useable advantage. When you look at higher costs, heavier scopes, and more difficulty in mounting the slight advantage just isn't worth the benefits.
In Europe, where hunting at night is commonly practiced the 50-56mm lenses are common. A scope with a 32-40mm lense will allow you to see anything during legal shooting times in the USA.
Objective size does not affect field of view. Manufacturers list field of view specs.
Yep....where hunting at night is commonly practiced the 50-56mm lenses are common.
mxsailor803
New member
I've got a rifle set up for night hogs that I use a Leupold VXII 4-16X50 and as far as quality goes, the lesser priced scopes may work ok. I use to use BSA, Bushnell Banners, and newer Redfields. I've still got a couple newer Reds and they are decent at gathering light. All of those are around 40mm. My dad has a VXII with a 40mm and compared to my 50mm, differences are very minimum. I can go a little more magnification in low light but not enough for it to be justifiable. Go with a quality scope around a 40-42mm range and you should be good to go.
boltomatic
New member
Yes, for the same price range and manufacturer.
Its not the only factor, but yes, a larger front lens means more light.
That said, a 50mm lens on a $150 scope is not going to outperform a 30mm lens on a $1000 scope, but if you are comparing scopes from the same manufacturer in the same price range, then its safe to assume a larger front lens will pull in more light.
I'm not sure about field of view, I think that only has to do with zoom level.
Its not the only factor, but yes, a larger front lens means more light.
That said, a 50mm lens on a $150 scope is not going to outperform a 30mm lens on a $1000 scope, but if you are comparing scopes from the same manufacturer in the same price range, then its safe to assume a larger front lens will pull in more light.
I'm not sure about field of view, I think that only has to do with zoom level.