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Small objective lens vs Large in low light
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Looking at buying another scope. Shooting deer, ranges out to 400yards. I use it in low light, particularly evenings half the time.

I was looking at a Nightforce 2.5-10x24 NXS. Very nice bit of kit. The only thing I was worried about was at low light. That last 20mins before night time.

The other scope I was looking at was one of the new Leupy VXL scopes. I have heard their low light capabilties arent as good as a Swaro/Khales etc.
Other than that I have looked into a Swarovski 1.7-10x42 Z6i

If I could get the same light transmission out of the Nightforce at that critical last 20mins of light I would go with that choice. The only thing I have against large objective lenses is you have to mount them that much higher above the bore line.

I like illuminated reticles. Not for the low light feature but the quick target acquisition.

Thoughts?
 
Posts: 86 | Registered: 28 July 2005Reply With Quote
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Well, if You wanna hunt in low light: Take a Swarovski Z6i 2-12x50 or a PV-N 3-12x50, illuminated

They are perfect tools out there - I use my for pig hunting during night and all I need is some reflected light from the clouds in a lot of nights...


life is too short for not having the best equipment You could buy...
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Posts: 759 | Location: Germany | Registered: 30 March 2006Reply With Quote
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Thoughts?[/QUOTE]


p67, You may know this, but;

I've been reading our eyes can only handle 5mm of light width. So "they" devide (I think) 5 into the objective size to get the max power you can utilize for best results in the gloom.

So, 5 into your Nightforce 24 lense gives about 5 power, and after that your loosing something.

And you would probably want much more power at up to 400 yards, and a 50mm front lense gives you 10 power or more to use.

Then there is quality of glass to worry about, but you'd think high end stuff would be similar.
 
Posts: 2355 | Location: Australia | Registered: 14 November 2004Reply With Quote
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quote:
Originally posted by JAL:

p67, You may know this, but;

I've been reading our eyes can only handle 5mm of light width. So "they" devide (I think) 5 into the objective size to get the max power you can utilize for best results in the gloom.

So, 5 into your Nightforce 24 lense gives about 5 power, and after that your loosing something.

And you would probably want much more power at up to 400 yards, and a 50mm front lense gives you 10 power or more to use.

Then there is quality of glass to worry about, but you'd think high end stuff would be similar.


That pretty well sums it up... The actual number for a dark adjusted pupil is 7mm but age will decrease that so 5mm is a good number... The larger the objective the more light it is capable of gathering... The number of lenses and their quality as well as the coatings will determine how much of that light is "transmitted" back to your eye...

Ken....


"The trouble with our liberal friends is not that they are ignorant, but that they know so much that isn't so. " - Ronald Reagan
 
Posts: 5386 | Location: Phoenix Arizona | Registered: 16 May 2006Reply With Quote
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JJHack did what I'd call the most comprehensive investigation of low light performance in scopes. Basically he found that they all work down to about a 32mm objective size. I believe he was refering to fully multicoated scopes.
Low light/twilight no darker than requiring a 5mm exit pupil from what I've seen. Full dark might require a 7mm exit pupil. But, with clear skys and a full moon, I've done well with only a 4mm exit pupil even at night. So that varies too.
Most of us have also found that a 40mm objective is plenty, even for night hunting.
The one other factor is the need for a heavy enough reticle. For night hunting or when using the smaller scopes, a heavier reticle may be needed. You don't need to see much of the image, but you must be able to see the reticle. You will loose it before you loose too much of the image as a rule.
Aging eyes is another problem. It is not at all uncommon for eyes of those in their 40's and 50's to not be able to use any more than a 4mm exit pupil. Truly night blind persons can't use more than a 2mm exit pupil. E
 
Posts: 37 | Registered: 05 January 2007Reply With Quote
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quote:
Originally posted by oheremicus:
JJHack did what I'd call the most comprehensive investigation of low light performance in scopes. Basically he found that they all work down to about a 32mm objective size. I believe he was refering to fully multicoated scopes.
Low light/twilight no darker than requiring a 5mm exit pupil from what I've seen. Full dark might require a 7mm exit pupil. But, with clear skys and a full moon, I've done well with only a 4mm exit pupil even at night. So that varies too.
Most of us have also found that a 40mm objective is plenty, even for night hunting.
The one other factor is the need for a heavy enough reticle. For night hunting or when using the smaller scopes, a heavier reticle may be needed. You don't need to see much of the image, but you must be able to see the reticle. You will loose it before you loose too much of the image as a rule.
Aging eyes is another problem. It is not at all uncommon for eyes of those in their 40's and 50's to not be able to use any more than a 4mm exit pupil. Truly night blind persons can't use more than a 2mm exit pupil. E



Most of this post is BS.

First of all in the woods or overcast conditions there have been several times a 40mm scope has faded out well before legal shooting time. There is a valid reason for using the larger objective scopes.
I'm 46 years old and before I had Lasik surgury they measured my pupils without dialation in a darkened but not completely dark room (you could see light shining under the door and a slight glow on the wall). My pupils measured 7.2mm (over 11 something when they dialated them). Your eyes might be smaller than the average or larger but too many people throw around 4-5mm figures without having a clue what their eyes really are.
The one thing I agree with is that a heavier reticle is needed for late evening shooting. My favorite is a German #4 (three fat rectangular post with a thinner crosshair in the middle). The Fat rectangles help to center it even in very nearly dark conditions...........................DJ


....Remember that this is all supposed to be for fun!..................
 
Posts: 3976 | Location: Oklahoma,USA | Registered: 27 February 2004Reply With Quote
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I am 56 years old.

I paid $1300 and can't see anything with a 8.5X and 50mm objective at dusk.

My exit pupil needs must exceed 6mm at dusk.

Lucky me, my big eyes mean I get to pay extra.
 
Posts: 9043 | Location: on the rock | Registered: 16 July 2005Reply With Quote
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quote:
Originally posted by oheremicus:
JJHack did what I'd call the most comprehensive investigation of low light performance in scopes. Basically he found that they all work down to about a 32mm objective size. I believe he was refering to fully multicoated scopes.
Low light/twilight no darker than requiring a 5mm exit pupil from what I've seen. Full dark might require a 7mm exit pupil. But, with clear skys and a full moon, I've done well with only a 4mm exit pupil even at night. So that varies too.
Most of us have also found that a 40mm objective is plenty, even for night hunting.
The one other factor is the need for a heavy enough reticle. For night hunting or when using the smaller scopes, a heavier reticle may be needed. You don't need to see much of the image, but you must be able to see the reticle. You will loose it before you loose too much of the image as a rule.
Aging eyes is another problem. It is not at all uncommon for eyes of those in their 40's and 50's to not be able to use any more than a 4mm exit pupil. Truly night blind persons can't use more than a 2mm exit pupil. E



That's you isn't it Eremicus......


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Posts: 5077 | Location: USA | Registered: 11 March 2005Reply With Quote
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That 24mm objective isn't going to do much for you when the light starts fading. I'd guess it would be pretty much useless. If you're trying to shoot into the shadows then good optics are needed with a large objective and good crosshairs. There's really no substitute for it. FWIW, I think way too much issue is made over the high scope mounting with the big scopes. I typically mount my scopes using the lowest rings I can, but high scopes don't bother me much. I haven't found it to be nearly as big a problem as some make it out to be.
 
Posts: 1173 | Registered: 14 June 2000Reply With Quote
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Thats the only thing that concerns me about the 2.5-10x24nxs,otherwise I luvs em'.
Really need to grab one and see how it does in the real world of low light.
A Leup6x42 is hard to ignore.
 
Posts: 2134 | Registered: 12 May 2005Reply With Quote
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I am leaning away from the NF scope now. The fact that they cant supply the one I want is also a factor [cant be that serious about selling them can they?].

Thinking Swaro/Khales/Zeiss now.
 
Posts: 86 | Registered: 28 July 2005Reply With Quote
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Where have you looked? Try Hunters Edge at 660-627-2277

Nightforce has a huge Military Contract.

http://www.defenseindustrydaily.com/107m-in-7700-specia...s-rifle-scopes-0832/


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A 9mm may expand to a larger diameter, but a 45 ain't going to shrink

Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened.
- Winston Churchill
 
Posts: 5077 | Location: USA | Registered: 11 March 2005Reply With Quote
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Choosing a 24mm objective for low light shooting is.....hmmmmm, how can I put this politely......just plain dumb.

The Europeans hunt legally at night often and they tend to use 56mm. There is a reason why. If scope size is a consideration then the 1.75x6x32 Leupie is the absolute minimum I'd choose and I really think you need to start at about 50mm for best performance.

Anyone who thinks the twilight factor doesn't basically sum up low light ability assuming comparing apples and apples(there are other factors such as reticle choice and number of lenses) hasn't tried to shoot in low light any or very much. The main factor is being able to see the reticle and have enough glass to pick out the object from the background, and if you can't find the animal with binos and the scope, then you need a starlight type scope, not normally used in hunting game or pigs (which is where most of my low light experience comes from). The Euro 4a or some similar type with VERY HEAVY lines works well, normally you are close enough (under 100 yds in my area) that absolute precision in bullet placement is not required. The less common heavy post is very good as well. Illuminated reticles work fine except that it must be variable and set on the lowest possible illum setting for conditions so that it doesn't "blind" out the object. It will vary with available light but you'll find that your best "seeing" for shooting will be somewhere around 6 to 8x with a large objective.


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Posts: 17099 | Location: Texas USA | Registered: 07 May 2001Reply With Quote
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quote:
Originally posted by Gatogordo:
Choosing a 24mm objective for low light shooting is.....hmmmmm, how can I put this politely......just plain dumb.

The Europeans hunt legally at night often and they tend to use 56mm. There is a reason why. If scope size is a consideration then the 1.75x6x32 Leupie is the absolute minimum I'd choose and I really think you need to start at about 50mm for best performance.


Thats the answer I was after. I thought as much but the Nighforce sales rep at a show I was at reckons that the 24mm on this scope would beat a 50mm objective on a Leuy any day. I cant find many people so far who would back that claim.

Agree on your other comments re the reticle choice. Cheers.

Looking at the Khales/Zeiss/Swaro etc now. $$$$!!!
 
Posts: 86 | Registered: 28 July 2005Reply With Quote
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Originally posted by p67: I thought as much but the Nighforce sales rep at a show I was at reckons that the 24mm on this scope would beat a 50mm objective on a Leuy any day. I cant find many people so far who would back that claim.


Well, all that proves is that he's a liar. I would tend to discount everything else he told you after he said that.
 
Posts: 1173 | Registered: 14 June 2000Reply With Quote
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