Let’s talk scopes

[GeauxLSU]

Hmmm...I have no idea. Only what I can or can't see! Lol

LOL, I hear you. OK, I found this post (not the article I mentioned) and it addresses what I remember the article addressing.

The exit pupil is the diameter measurement of the circle of light that comes through and out of the eyepiece of the scope and onto your eye. They say that your eye can only dilate to about 7mm so that is the most light that your eye can let in. So any exit pupil of 7mm or more is what you want for low light situations. Now to determine the exit pupil is quite simple. You simply divide the objective lens diameter by the power of magnification. For example a 4x32 scope would have an exit pupil of 8mm, 32 divided by 4. This means your are meeting and slightly exceeding that 7mm. If you are noticing several numbers listed for exit pupil that is because you are looking at a variable power scope which means that it will have several different exit pupil depending on what power of magnification you have it set for. Those numbers probably stand for the exit pupil at lowest power and exit pupil at highest power. Example on a 3x9x40 the lowest power is 3, so 40 divided by 3 is 13.3, the highest power is 9, so 40 divided by 9 is 4.4 therefore your exit pupil range on a 3-9x40 is 13.3-4.4. So during low light any power that allows 7mm OR MORE is what you want to set it at.

That doesn't include tube size and I can't remember how or if that has an effect. But given that math, your eye would limit the light visible in a 40mm variable power scope at roughly 5.7x. In a 50mm scope it would limit it at 7.1x, both obviously well below the 9x upper limit. So, between 5.7x and 7.1x a 50m would have an advantage. Most people I know weld their scope at the maximum setting.
All of that doesn't explain to me why TO MY EYES, a fixed power scope allows more light than a variable at the same power setting, even when the fixed has a SMALLER objective size.

 

[crippen]

Right now I don't think this can be beat. It's a Light Optical Work Japan Optic. That company makes Nightforce, Elite Bushnells, Tango 6's, Razors, EOTech Vudu's etc. The only reason they are even in your price range is because they are direct to consumer. No distributors, no retailers, no reps. You get a pure pass through directly to you. Otherwise this scope is $1000. And take a look at the weight of it. This scope is going on an upcoming Ruger #1 build for me:
https://shop.mavenbuilt.com/collections/stock-optics/products/rs-2

Thats a nice looking rifle you have btw. Keep it classy regardless of your scope choice.

What do you mean by keep it classy? I was going stipple it on my drill press. That’s classy right?

 

[MRH]

On a side note MRH and Bear44 Can one of you two change avatars please

You're not the first to ask. LOL...I suppose it's about time I changed. I'll find another one.

LOL, I hear you. OK, I found this post (not the article I mentioned) and it addresses what I remember the article addressing.

That doesn't include tube size and I can't remember how or if that has an effect. But given that math, your eye would limit the light visible in a 40mm variable power scope at roughly 5.7x. In a 50mm scope it would limit it at 7.1x, both obviously well below the 9x upper limit. So, between 5.7x and 7.1x a 50m would have an advantage. Most people I know weld their scope at the maximum setting.
All of that doesn't explain to me why TO MY EYES, a fixed power scope allows more light than a variable at the same power setting, even when the fixed has a SMALLER objective size.

That's an interesting read. Still, I would think that the quality of the glass also plays into it. Not all 50mm scopes will be the same. I've looked through 2x7x32 scopes that gather light better than some 50mm. BUT, if comparing two scopes of the same model, it seems the 50mm will have the light gathering advantage...I am totally guessing, though.

 

[_Raining]

All of that doesn't explain to me why TO MY EYES, a fixed power scope allows more light than a variable at the same power setting, even when the fixed has a SMALLER objective size.

Fixed power scopes have less lenses so there is less light lost vs a variable power scope.

 

[GeauxLSU]

That's an interesting read. Still, I would think that the quality of the glass also plays into it. Not all 50mm scopes will be the same. I've looked through 2x7x32 scopes that gather light better than some 50mm. BUT, if comparing two scopes of the same model, it seems the 50mm will have the light gathering advantage...I am totally guessing, though.

Absolutely. This is a theoretical "all things being equal" conversation. Above 7.1x, the 50mm can't physically give you an advantage over a 40mm objective. It DOES give you an advantage at say 6x. Again... everything else being equal. Then it's up to the person to decide if that advantage between 5.8x and 7.1x is worth the added cost, weight, scope height/cheek weld, etc..... for their particular needs.

 

[GeauxLSU]

Fixed power scopes have less lenses so there is less light lost vs a variable power scope.

Makes sense. Now I can sleep a little better. Thx.

 

[MRH]

Absolutely. This is a theoretical "all things being equal" conversation. Above 7.1x, the 50mm can't physically give you an advantage over a 40mm objective. It DOES give you an advantage at say 6x. Again... everything else being equal. Then it's up to the person to decide if that advantage between 5.8x and 7.1x is worth the added cost, weight, scope height/cheek weld, etc..... for their particular needs.

For that additional 5 minutes of legal light and better capability to see, it is worth it to me...Even though I don't even own a 50mm at this time. Lol

Everyone else's mileage may vary.

 

[MRH]

On a side note MRH and Bear44 Can one of you two change avatars please

Fixed

 

[Bear44]

On a side note MRH and Bear44 Can one of you two change avatars please

Nope. We are agents of Chaos.

 

[chrislibby88]

Hmmm...I have no idea. Only what I can or can't see! Lol

He is probably referring to “exit pupil” which discribes the area of focused light being projected through the eyepiece lens. An exit pupil larger than the pupil of your eye can’t technically be used because the light is being focused onto an area larger than the pupil, but it gives you a more forgiving eye box and your eye can move around some and still have the full image. An exit pupil smaller than the human pupil is BAD. This is likely what you read about.

Not sure how a scope could pick up more light than is useable to the eye? Unless you are getting blinded by bright light looking through your scope at normal things in daylight??? Lol