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Sightron Big Sky vs. SIII

Printed From: OpticsTalk by SWFA, Inc.
Category: Scopes
Forum Name: Target
Forum Description: Paper punchin' scopes
Printed Date: September/21/2018 at 22:55
Software Version: Web Wiz Forums 11.10 -

Topic: Sightron Big Sky vs. SIII
Posted By: FreeJersey
Subject: Sightron Big Sky vs. SIII
Date Posted: July/08/2011 at 18:45
I am looking to upgrade my big sky 4-16 to a 6-24. How much better is the glass and overall construction of the SIII? I see it only focusses down to 50yds. How will the sight picture be at 25 yds? If it's not really useable at 25yds, I'll have to settle for the big sky.

Posted By: kesi
Date Posted: January/06/2012 at 10:07

Glass is the same, tube diameter S3 is 30 mm -> more light, I believe that at 25 yard at 6x magnification is not a problem focus.

(oops, I used the google translator).

If you are still interested in it. Big Grin

Posted By: jjrgr21
Date Posted: January/06/2012 at 14:21
you don't get more light with a 30mm tube. you get more internal adjustment most of the time.

going to a bigger objective will gain light transmission

Posted By: kesi
Date Posted: January/08/2012 at 10:02
Of course, the larger objective, more light, perhaps a better resolution, at the same quality glass. Smile

Posted By: dillon_h
Date Posted: January/13/2012 at 12:21
But... at the same glass quality, higher magnification + same glass coatings= less light transmission.
I have heard many great things about the SIII. What I like are the clicks. Clean, crisp and the few I have handled lined up hash to hash quite nicely. I took one outside and looked at a sign in the shadows at 10 yards and it was not as bad as I first thought. It was a bit fuzzy but, on 6x its not to bad, 25 yds was fine. clear and ready to shoot.  If you are needing more magnification, willing to give up the FOV and a little bit of eye relief I would say go for it.
Like jj said, the 30mm tube is going to give you no advantage to light transmission. The sole purpose of the larger tube is to give you more room for adjustments.
At optimum conditions the most light that your eye can take in at one time is 7mm.

"Adversity is a flame that melts the weak and tempers the strong"

Certified Law Enforcement Armorer @ SWFA

Posted By: krmcne
Date Posted: August/24/2013 at 22:21
I believe the general formula I saw was to take the objective lens diameter, divide by the power, and you end up with the usable light coming through the scope. For example, using a 4x32 scope, take 32 and divide by 4 and you end up with 8mm. That's actually more light coming through than a young eye can use, since 7mm is the widest your young pupil will open. The older you get, the smaller your pupil will open, maybe down to 5 or even 4mm. Of course, I would assume that poor optics would also limit the light transmission, so the general formula may not be totally accurate. 
My experience with close focus is you just have to try it and see how close you can get. Specs may say 50 yds, but you may have no problem focusing closer on low power. I had one 16x target scope I got to focus at 50ft, although the side focus only went down to 50 yds.

Posted By: 338LAPUASLAP
Date Posted: August/25/2013 at 09:33
Are you going to use the higher power is the question?

Why not look at the the 3-10?  If you don't need the higher magnification.

I own all the scopes in question.

For 25yrds that is an awful lot of magnification.
I have a SIII 6-24 -  .

No one

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