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Best low light scopes?

Discussion in 'Long Gun Accessories and Optics' started by Sniper66, Dec 17, 2014.

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  1. Sniper66

    Sniper66 Member

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    I have a question for you out there who have or have had lots of different scopes. Which scope gathers light the best? On deer hunts in late afternoon, as the sun sinks slow in the western sky, especially on overcast days, visibility becomes a real issue. Shooting coyotes, prairie dogs, and other well camoflaged critters on overcast days are increasingly challenging. Do you find that a 50mm objective lens helps significantly? As my eyes age, I need all the help I can get. I only have one 50mm objective; the rest are 40mm. I am thinking about changing some scopes to increase visibility, but wanted to hear what you all have to say.
     
  2. jmr40

    jmr40 Member

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    The quality of the glass is far more important than the size. Assuming equal quality glass a 50mm lense will allow you to get a tiny bit more light only when the magnification is set on 7X-9X over a scope with a 40mm lense on it. Adjust to lower, or higher magnifications and a 40mm scope will do exactly the same thing.

    The scopes magnification along with its objective size determine how large the cone of light is that comes out the rear of the scope. It does not determine how bright it is. That is determined by the quality of the glass and the coatings. A 50mm scope set on 10x, a 40mm scope set on 8X and a 20mm scope set on 4X all transmit 5mm of light from the rear of the scope. For most people 5-6mm is as much as the human eye can process. Having less than 5mm usually means it is a poor choice in low light. More than about 6mm is just wasted.

    You need to be looking at a scopes light transmission ratings. The very best $1,000+ scopes transmit 95% or more of the light that enters. Most of the mid level scopes selling in the $300-$500 range will be in the low 90's. Most of the sub-$200 scopes will usually range from 85%-90% light transmission. Some of the budget scopes will be 80% or less.
     
  3. matrem

    matrem Member

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    Assuming equal glass quality, "exit pupil" (objective lens diameter divided by power) equal to or greater than your pupil is all our eyes can receive.

    Usually between 5mm and 7mm for most of us.
     
  4. taliv

    taliv Moderator

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    i don't think that's accurate at all. physically, a larger scope collects much more light.

    40mm -> 1256 sq mm area
    50mm -> 1963 sq mm
    56mm -> 2463 sq mm

    so the jump from 40 to 56mm while only 30% more diameter is 96% more area, which means twice as much light is coming in.

    that light has to go somewhere. saying it all goes out onto a 5mm exit pupil is fine, but you're still putting 2x as much light into that 5mm circle which == "brighter"

    comparatively the differences in coatings for glass in the same category is probably only a few percent of light transmission.
     
  5. redneck2

    redneck2 Member

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    I can tell you from extensive hunting experience that a Leupold VX-3 4-14x40 will let you shoot when it's too dark for irons. There may be something that gathers more light and is clearer, but I've never seen it.

    As noted, quality of glass and coatings is key here.
     
  6. Gordon

    Gordon Member

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    yeah Taliv gets it; sure coatings and "glass quality " ect. BUT does anyone think the Germans were stupid optical engineers when they decided on 8x56mm as optimum "night" scopes ? The wide open pupil is one thing but the "light gathering" ability of the larger lens of same quality is all ways greater . In answer to the OP original question; depending on the quality of the lens you can afford a 50mm scope usually will give more detail in dark conditions than a 40mm, not that much but more. A 56mm lens starts to get noticeable tho....
     
  7. urbaneruralite

    urbaneruralite Member

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    It's more about quality of scope and soundness of design than anything else. You only need the 50mm if you go over 9x magnification. I've been really impressed with a Weaver Super Slam recently. If it's in your budget, you might try a Leica.
     
  8. Haxby

    Haxby Member

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    Yes. No question about it.
    For maximum low light performance, you want the best scope you're willing to pay for, and the biggest objective you're willing to put up with.
    Advertised light transmission numbers are just numbers made up for advertising.
    Sniper66, if you have 40mm and 50mm variable scopes of comparable quality, you can verify a lot of this yourself.
     
  9. taliv

    taliv Moderator

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    one very subjective way to tell for yourself is to hold the scope with objective towards a light in your house. hold a sheet of paper behind the ocular. you'll see a little circle of light.

    repeat with various scopes at various magnification settings and see for yourself which spot looks brighter
     
  10. hq

    hq Member

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    As some people already have mentioned, a combination of appropriate exit pupil and maximum lens size is the basic combination. Glass quality and coating is another factor and there are huge differences between brands and product lines.

    First of all, in most european countries hunting isn't restricted by sunset or dawn so higher-end european manufacturers have made low light performance a priority. The obvious choice for hunting at dusk, dawn and moonlight has been Zeiss Diavari 3-12x56 or Diatal 8x56, both offering exit pupil of 7mm at 8x magnification. They have dominated magazine tests at least since the 80's and while they still are great scopes for low light hunting, Swarovski has managed to equal or even beat them with their Z6i 2.5-15x56. They are the top choices if low light performance is a must and even though some manufacturers like Schmidt & Bender have come close, they still have an advantage. A few years ago one of the more reputable magazine tests surprised me, because even Nightforce got its butt soundly kicked by Swarovski and Zeiss. Leupold, Bushnell Elite, Burris and many other quality scopes were so far behind that it wasn't even funny anymore.

    If you don't have $2k or so to burn, there are a couple of manufacturers with strong bias towards low light performance but without Zeiss/Swaro price tag, namely Meopta and IOR/Valdada. I've used Meopta Meopro 4-12x50 for a few years now and while it doesn't compare to Diavari, I've made quite a few clean shots with it in nothing but moonlight. In low light it's very noticeably better than 4.5-14x50 VX3 and has one of the best BFTB ratios of mid-priced scopes. I've also used Valdada 4-14x56, which is even better, except for its $1000+ street price. Still great value.

    There's one low light scope that I really, really would like to have. It's the discontinued Zeiss Conquest 3-12x56. Optically it's very close (if not identical) to older Classic Diavari, it was priced at less than $800 and even though illuminated reticle wasn't available, it was the low light scope bargain of all time. I had a chance to compare it to a Victory Diavari, side by side, when sun was setting and it took a conscious effort to find a meaningful difference between the two. Massive value. I'd hazard a guess that a major factor for it to be discontinued was that it (almost) could rival scopes twice its price in low light performance.
     
  11. Cypress

    Cypress Member

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    I hunt hogs at night without the use of night vision or lights. Moonlight only. I have played with several scopes so far and the best bang for the buck I've found is the bushnell 4200. Mine is a 2.5-10x40 firefly reticle. I don't charge the reticle but it's nice and thick and really helps on black pigs. I can see well enough to hunt a week on each side of a full moon with this scope.
     
  12. Lloyd Smale

    Lloyd Smale Member

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    spend your money on glass quality not glass size
     
  13. taliv

    taliv Moderator

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    please don't misunderstand my comments. i am not saying there won't be a big difference in a $60 scope and a $2000 scope in terms of light transmission. there probably will. and to make matters worse, when comparing cheap scopes, the quality tends to get much worse as the magnification and lens size go up.

    i'm definitely not suggesting you go buy the biggest cheapest scope you can find. :)
     
  14. hq

    hq Member

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    If you can have one but not the other, yes, but in reality you want both. I have a few 38-42mm Zeiss scopes and while the glass quality is great, their low light performance is lacking because small(ish) objective has a limited light gathering capability.
     
  15. Sniper66

    Sniper66 Member

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    I knew I would get some good info from my fellow shooters out there. I am reminded that my brother uses a Picar (German) 8X56mm on his favorite squirrel rifle. I'll look through it as I continued to research this. At this point in my life, I may spend my money on optic upgrades rather than more rifles.
     
  16. OpticsPlanet

    OpticsPlanet Member

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  17. Haxby

    Haxby Member

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    Something to consider.
    To see the difference a bigger objective makes in low light, you will have to do the comparison in low light. You will also have to spend enough time in low light for your pupils to dilate and your eyes to adjust. A one hour period starting from a little before sundown works, if you are in shadows and looking at something in shadows. Going from a lighted room to the dark back yard won't let you see the difference.
     
  18. Lloyd Smale

    Lloyd Smale Member

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    haxey makes a good point. the European scopes tend to have large objectives because they do a lot of there hunting at night. Here in the states No state I know of allows big game hunting past sundown. If you stick to the legal shooting hours and allow for the fact your eyes need time to ajust to the dark and take a typical 3x9 scope anything more then about a 45mm objective lenses is a waste and id bet using comparable glass the average guy couldn't get more then 2 more minutes using a 45mm vs a 40mm and in most states those two minutes are past legal shooting hours anyway. Im not going to give up being able to mount my scope low enough that it fits me naturally when I throw the gun to my shoulder to get a big giant objective lens that has to use high mounts that make it awkward to use and add another half a lb of weight to my rig just to be able to violate a bit longer. Buy yourself a GOOD 3x9x40 like a vx2 leupold or a Nikon monarch or a 4200 bushnell or a ziess conquest and youll have all the light gathering you need to shoot any deer during any legal hunting hours. If you feel better about yourself for buying a euopean 56mm scope the size of a telescope for 2k then go for it but youll never convince me your buying any advantage in the big game hunting field.
     
  19. Haxby

    Haxby Member

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    I had a 32mm scope on a Winchester 70 in Leupold medium rings. It fit fine. Took it off and put a 50mm scope in the same rings. It fit fine.

    Be sure not to compare them for yourself.
     
  20. Ankeny

    Ankeny Member

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    Looks like we have a winner. I recently sold a scope that would have worked for you. It was a Schmidt and Bender Summit. Perhaps the most brilliant 1 inch tube scope ever produced.

    As far as size, I spoke to an engineer at Schmidt and Bender (on this side of the pond) and he told me the size of the objective lens wasn't as important and the lens, the coating, etc. If you call Zeiss, Leica, S&B, etc., they will be more than happy to visit with you.

    Having said all of that, legal hunting hours in Wyoming is 1/2 hour before sunrise to 1/2 hour after sunset. There is a large variety of scopes in the 40-44mm objective range that will transmit enough light to get you arrested for shooting during illegal hours.
     
  21. taliv

    taliv Moderator

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    i believe that is demonstrably untrue.

    scopecalc is an online tool that calculates the information we are discussing. without expending a great deal of effort, i simply entered 4 scopes to compare.
    assume two great scopes like S&B with 97% light transmission, one with 56mm and one with 40mm obj
    and assume two totally crappy scopes with 90% light transmission, also one with 56mm and one with 40mm

    look at the tool and you will see the two scopes with 56mm objectives are grouped together and the two with 40mm are grouped together.

    go ahead and play with it. do a little what-if... despite the fact that even barska claims 95% light transmission, if you set the light transmission at only 50%, the 56mm crappy scope still has higher realistic light gain and low light performance than the 40mm 97% scope.

    change the high end scope to 99%. it won't make a difference.

    what WILL make a difference is changing the objective and the magnification (i held the latter constant as it wasn't part of our discussion here)

    here's a link that i believe saved my settings
    http://www.scopecalc.com/?EyePupilD...ameter4=&BrightnessCalcType=Stevens+Power+Law
     
  22. coloradokevin

    coloradokevin Member

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    First, scopes don't "gather" light, they allow the transmission of ambient light through the lens, to some measurable degree that is always less than what is actually there (no scope transmits 100% of the light it is exposed to… that's the nature of glass. Some come very close to doing so, but none do it 100%).

    Anyway, as others have already mentioned, a larger objective lens diameter on a scope is going to allow for more light transmission, all else being equal. But, things aren't always equal.

    I personally think there's a lot to be said for high quality glass in this regard (both in terms of glass quality and coatings). I can use my S&B in conditions that I'd never get by in with a comparable size/magnification scope that cost $300. My S&B has a 50mm objective lens, and I have no doubt whatsoever that it would give me better low light performance than a Barska scope with a 56mm lens.

    Magnification is another issue. As you increase magnification you'll have a harder time seeing your target in low light. I'm not a scope engineer, so I can't explain exactly how that works out, but it does.

    All else being equal you are going to get better performance with these three factors accounted for:

    1) Larger Objective
    2) Better glass
    3) Lower magnification
     
  23. Haxby

    Haxby Member

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    You get best low light performance from a variable scope when the magnification is adjusted so the exit pupil of the scope is about the same size as the entrance pupil of the eye.
    People who use telescopes use the 'light gathering' term. I go along with them.
     
  24. coloradokevin

    coloradokevin Member

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    Meh. In my experience the term "light gathering" in the scope world is used mostly by marketers who want to convince an unassuming consumer that their optic is capable of doing something it isn't. A scope is limited by the quality of its glass and the size of its objective lens. It doesn't "gather" light from elsewhere, or amplify the available light, it merely transmits the light that available on the objective lens.

    I certainly don't mean to get lost in a jargon debate here, but I did mean to emphasize the fact that there is no "magic" involved with modern optics. A lot of people I've talked to seem to think that is the case. But, as others have already explained, the recipe for decent low-light performance is rather simple (though we can argue over which of these factors is more important).
     
  25. Field Tester

    Field Tester Member

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    With this are you looking at the backside of the paper where the light shines through, or where the light shines on the paper directly after the eye piece?
     
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