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scope light gathering ability ??

Printed From: OpticsTalk by SWFA, Inc.
Category: Scopes
Forum Name: Rifle Scopes
Forum Description: Centerfire long gun scopes
URL: http://www.opticstalk.com/forum_posts.asp?TID=24601
Printed Date: October/23/2017 at 21:13


Topic: scope light gathering ability ??
Posted By: Al in SC
Subject: scope light gathering ability ??
Date Posted: August/06/2010 at 12:40
Fact or Fiction?  A 56 mm objective will gather more light and be clearer than a 40 mm. one.



Replies:
Posted By: brav302
Date Posted: August/06/2010 at 12:45
Fiction.  The amount of light that the eye sees is a result or the objective size and power setting.  This is called exit pupil. 


Posted By: supertool73
Date Posted: August/06/2010 at 12:58
Technically a scope does not actually gather light, it transmits light.

But all else being equal, a 56mm objective will offer a brighter image than a 40mm objective.

A good example are the guys that run Trijicons 3-9x40 and the 2.5-10x56.  They all say the 56 is brighter and offers a better image, but most like the 40 because of the smaller size and less weight. 

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Posted By: Al in SC
Date Posted: August/06/2010 at 13:06
What about a 30 mm tube v.s. a 1 inch tube?


Posted By: SVT_Tactical
Date Posted: August/06/2010 at 13:07
Originally posted by Al in SC Al in SC wrote:

What about a 30 mm tube v.s. a 1 inch tube?
http://opticstalk.com/forum_posts.asp?TID=3828 - http://opticstalk.com/forum_posts.asp?TID=3828


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Posted By: Kickboxer
Date Posted: August/06/2010 at 13:09
Originally posted by Al in SC Al in SC wrote:

What about a 30 mm tube v.s. a 1 inch tube?
Welcome to the OT Forum, Al in SC. 
No difference in light transmission (unless there is a design flaw somewhere). 


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Posted By: Al in SC
Date Posted: August/06/2010 at 14:37
very enlightening. Thanks very much.


Posted By: pyro6999
Date Posted: August/06/2010 at 16:39
lens coatings can also effect things as well since we are on the subject.

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Posted By: HuntMaster
Date Posted: August/06/2010 at 20:39
Generally a 56 will transmit more light than a 40 in like scopes, that is, a 56 Zeiss will transmit more than a 40 Zeiss. That does not mean a 56 Tasco will transmit more than the 40 Zeiss.
Usually a 30mm tube only offers more windage and elevation than the 1" tube. Nothing more.


Posted By: HuntMaster
Date Posted: August/06/2010 at 20:39
Originally posted by pyro6999 pyro6999 wrote:

lens coatings can also effect things as well since we are on the subject.
+1


Posted By: jleinum09
Date Posted: August/06/2010 at 21:43
Originally posted by HuntMaster HuntMaster wrote:

[QUOTE=pyro6999]lens coatings can also effect things as well since we are on the subject.
+1
+1 for that as well!!  Thunbs Up

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Posted By: stickbow46
Date Posted: August/06/2010 at 21:56
If I remember correctly 30mm tube when it first came out was called the European tube.HM was is correct in that it is just for elevation & wind resistance but it does so by giving each turret it's own leaf spring there by giving way to more turret accuracy.The larger size tube adds to the rigidity but does nothing for the  light factor.

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Posted By: tejas
Date Posted: August/07/2010 at 07:38
Originally posted by Al in SC Al in SC wrote:

What about a 30 mm tube v.s. a 1 inch tube?
Dont know if your interested in this or not, but a couple years ago, I bought an Ar-10. At the time I had a one inch scope "lying around" but knew that I eventually wanted a Trijicon 2.5-10X56 which is 30mm. Didnt want to buy two seperat mounts so i bought some ring inserts. Bottom line is, you can use a one inch scope with 30mm rings but not vice versa. Just something to think about, these will also keep you from marring the finish on your scope when you install it.


Posted By: Dale Clifford
Date Posted: August/07/2010 at 20:24
objective lens gather light in the same manner as a tub gathers rain water, the larger the surface area the more light can be gathered, the lens coatings and quality determine the amt. transmitted to the next set of lens.When the image is inverted the path the light takes is smaller so the dia of the tube has less effect than transmission of something like a liquid.

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