Author Topic: 100 yard. set paxallax scopes  (Read 1083 times)

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Offline Barriebill

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100 yard. set paxallax scopes
« on: January 18, 2018, 11:20:05 PM »
Would you use a scope with paxallax set at 100yds by factory (not adjustable) for shooting 25,50,and 100 yard targets ?

Offline SerenityNetworks

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Re: 100 yard. set paxallax scopes
« Reply #1 on: January 19, 2018, 06:29:09 AM »
That depends on the accuracy you wish to achieve for the type of shooting you are going to perform.  There is a useful article on parallax posted at Rimfire Central (http://www.rimfirecentral.com/forums/showthread.php?t=257018).  I used the formulas in the article to create an Excel spreadsheet that illustrates the various derivations you can get.  The last update of WordPress killed my hobby site, but you can still get the Excel workbook here:  fshrmen.net/wp-content/uploads/Derivation_of_Riflescope_Parallax_Equation.xlsx  The workbook is currently set to illustrate the inaccuracy for a setup like you have described.  For example, with a typical scope and an eye that is just offset 1.5mm from center, you can have a parallax error of .40".  With an adjustable parallax you effectively eliminate that error. 

I hope this helps.

Andrew
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There are some ideas so preposterous that only an intellectual will believe them. - Malcolm Muggeridge

Offline Barriebill

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Re: 100 yard. set paxallax scopes
« Reply #2 on: January 19, 2018, 06:27:01 PM »
Thank you for the great link Andrew ,excellent in depth explanation .

Offline SerenityNetworks

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Re: 100 yard. set paxallax scopes
« Reply #3 on: January 19, 2018, 10:47:25 PM »
You are very welcome.  I too found it fascinating.  Enough so that I made the workbook to visualize the potential inaccuracies, make it easier to calculate them and make comparisons.  It surprised me just how little off-center the eye had to be to make a measurable and significant difference on the POA, when using a scope without parallax adjustment.  Hence on my rimfires I use peeps and on my centerfire long-range or target guns I use a scope with adjustable parallax. (I like Vortex.)  But on one of my deer guns I use a Crossfire II.  It's adequate for the rifle and I don't care if I'm off even a half inch.

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NRA Life Member
There are some ideas so preposterous that only an intellectual will believe them. - Malcolm Muggeridge