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Why 8x56for moonlight hunting?

21 Apr 2014
@ 05:18 am (GMT)


I note that Nightforce has a 4-14x56 scope out for the everyday hunter. I'm sure its a great scope but my question is why is there a strong preference by some manufacturers for a 8x56mm. And I do remember Nick Harvey saying something about the 8x56 being the better combination.

Why? Anyone got any leads on this.



21 Apr 2014
@ 05:47 pm (GMT)

Nathan Foster

Re: Why 8x56for moonlight hunting?
I really don't know the answer to this sorry beyond the basics.

From memory, I believe the theory is that a 32mm Objective scope has best light gathering at 4 power (4x32 is common for commercial spotlighting in NZ as is 4x40). A 40mm Objective scope has best light gathering at 6 power. A 50-56mm Objective scope at 8 power. But in reality, you will find that most folk prefer a wider field of view at or after dark. I tend to stick with 4 power when doing night work on possums (.22LR) and 6 power (50mm Obj) if hunting with a centerfire at dusk. If I am using a standard 3-9x40 scope, I will wind down to 3 power for close work or 6 power if watching a valley floor.

At a guess, I would say that the new NF scopes are made in Japan at the Sightron plant. All NF scopes regardless of model are fitted with Sightron glass. I cannot at this time remember the name of the plant. It is not actually called Sightron as this the name of a particular scope made at the plant for the U.S Sightron company. You name it, they build it, you nominate the specs and calibration, they build it. The onus is completely on the client, the Japanese will build whatever is asked for at whatever level of quality is nominated. The Japanese are extreme when it comes to work ethics.

22 Apr 2014
@ 02:07 am (GMT)


Re: Why 8x56for moonlight hunting?
Hi Nathan,
What I have read is that if you divide the objective lens size by the magnification you are left with the exit pupil size of the scope. So, if you have a 40mm bell and its a 4x then you have a 10mm exit pupil. The other thing I've heard is that the most the average pupil dilates to is about 7mm and that anything over the 7mm is a waste. Also take into account that as you get older (that's me) the dilation gets smaller.

That said, I did read somewhere that the ideal night scope is the 8x56. Using the above that would mean a dilation of 7mm. So that works, but I was told somewhere that there is a more complex model that determines scope ability to see in the night and it is that model that supports the 8x56mm scope. Its that model I am looking for 0 just for interest sake.

If I find it I'll post it.

22 Apr 2014
@ 04:23 pm (GMT)

Nathan Foster

Re: Why 8x56for moonlight hunting?
Thanks for taking the time to post the math in the new thread Danny. It has been a very long time since I looked into this.

If we have a full moon, I can use either the Sightron SII 6.5-20x50 or SIII 6-24x50 out to just over 300 yards when both are set on 6 or 6.5 power. Nevertheless, I find this somewhat pointless as the moon is only full and high at certain times and I do not plan a hunt based on the full moon. If anything, I prefer to hunt nearer the new moon. The Sightrons give me around 5 to 10 minutes hunting after dusk during a new moon out to a range of again, around 300 yards. But even then, I tend to use my binos as much as possible, then switch to the scope if I have found something.
08 May 2014
@ 10:11 pm (GMT)

Alvaro Piqueras Alonso-Lamberti

Re: Why 8x56for moonlight hunting?
I think that the "exit pupil" is just one of the reasons... And, in fact, thats why the magnification and objective diameters used to be "7x" (6x42, 8x56...)

The other reason is that a fixed power scopes had less lenses and simplier optical systems, so a fixed scope is brighter than a variable power scope (all variables being the same, not comparing a 6x42 hakko with a 2,5-10x40 khales).

European high brands offers the best light transmission (but for punchs in the eyes, please ask Nathan. I´m sure he will kick as a 300RUM and for sure make a discount!).



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