Visit the SWFA.com site to check out our current specials. |
Parallax error- finally cracked the enigma!!! |
Post Reply | Page 12> |
Author | |
8shots
Optics Jedi Knight Lord Of The Flies Joined: March/14/2007 Location: South Africa Status: Offline Points: 6253 |
Post Options
Thanks(0)
Posted: November/02/2009 at 09:03 |
I have been searching the www for a while now in order to find a definitive work on parallax error and distance to the target.
It is official boys (and girls), the further or closer the target moves away from your parallax free distance (normally 100yds factory set), the greater parallax becomes.
The parallax error increases with objective size.
The parallax error measured in MOA is greater at 25 yds then at 300yds, but not when measured in inches.
EXAMPLE 1:
Assume we have a 3-9X32mm scope, where objective diameter, D = 32mm, parallax range of scope (p) = 100 yards, and the user desires to calculate maximum parallax error for target ranges (t) at 25, 50, 150,175, 200 and 300 yards. Using Equation 3, we get: Maximum PE @ 25 yards = 0.5 * 32* ABS(25-100)/100 = 12mm or 0.47 inches, Maximum PE @ 50 yards = 0.5 * 32* ABS(50-100)/100 = 8mm or 0.32 inches, Maximum PE @ 150 yards = 0.5 * 32* ABS(150-100)/100 = 8mm or 0.32 inches, Maximum PE @ 175 yards = 0.5 * 32* ABS(175-100)/100 = 12mm or 0.47 inches, Maximum PE @ 200 yards = 0.5 * 32* ABS(200-100)/100 = 16mm or 0.63 inches, Maximum PE @ 300 yards = 0.5 * 32* ABS(300-100)/100 = 32mm or 1.26 inches. To convert this to an angular error, in MOA units, divide the maximum PE by t, where t MUST be in same units as linear Maximum PE, and multiply by 3438 to convert radians to MOA. The value t at 25yards = 22860mm, 50yards = 45720mm, 150yards = 137160mm, 175yards = 160020, 200yards = 182880mm, and 300yards = 274320mm. Maximum PE @25 yards in MOA = 12mm *3438/ 22860mm = 1.80 MOA, Maximum PE @50 yards in MOA = 8mm *3438/ 45720mm = 0.90 MOA, Maximum PE @150 yards in MOA = 8mm *3438/ 137160mm = 0.20 MOA, Maximum PE @175 yards in MOA = 12mm *3438/ 160020mm = 0.26 MOA, Maximum PE @200 yards in MOA = 16mm *3438/ 182880mm = 0.30 MOA, Maximum PE @300 yards in MOA = 32mm *3438/ 274320mm = 0.40 MOA. |
|
danjojoUSMC
Optics Journeyman Joined: August/20/2009 Location: NE Ohio Status: Offline Points: 329 |
Post Options
Thanks(0)
|
8shots, did you test it with a few different scopes to see if it holds up?
I've always read parallax error will increase with magnification, is it in the formula?
|
|
"When I let go of what I am, I become what I might be"
"Every part of life comes into focus just as you are about to pull the trigger." |
|
8shots
Optics Jedi Knight Lord Of The Flies Joined: March/14/2007 Location: South Africa Status: Offline Points: 6253 |
Post Options
Thanks(0)
|
Ok for magnification it increases:
PE @ 25 yards with a 1mm offset from optical axis @ 3X = (1.0) (3) ABS(25-100)/100 = 2.25mm
PE @ 25 yards with a 1mm offset from optical axis @ 9X = (1.0) (9) ABS(25-100)/100 = 6.75 mm To convert these PARALLAX ERRORS from linear to angular errors, in MOA units, divide by t, where t MUST be in same units as PE (100 yards = 91440mm in this case), and multiply by 3438 to convert radians to MOA. PE in MOA @ 25 yards with a 1mm offset from optical axis @ 3X = (2.25)(3438)/ 91440 = 0.085 MOA PE in MOA @ 25 yards with a 1mm offset from optical axis @ 9X = (6.75)(3438)/ 91440 = 0.254 MOA |
|
8shots
Optics Jedi Knight Lord Of The Flies Joined: March/14/2007 Location: South Africa Status: Offline Points: 6253 |
Post Options
Thanks(0)
|
I was specifically interested at a set magnification and varying distances.
|
|
danjojoUSMC
Optics Journeyman Joined: August/20/2009 Location: NE Ohio Status: Offline Points: 329 |
Post Options
Thanks(0)
|
Thanks bud, I didn't know if it was so simple to just multiply the 3x value by 3 to show 9x...it makes sense though.
|
|
"When I let go of what I am, I become what I might be"
"Every part of life comes into focus just as you are about to pull the trigger." |
|
supertool73
Optics God Superstool Joined: January/03/2008 Status: Offline Points: 11814 |
Post Options
Thanks(0)
|
Good find 8. Guess that goes to show how important it is to be square behind your scope no matter what distance your at.
|
|
Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.
"A Liberal is a person who will give away everything they don't own." |
|
Dale Clifford
Optics Jedi Knight Joined: July/04/2004 Location: United States Status: Offline Points: 5087 |
Post Options
Thanks(0)
|
higher magnification-- it magnifies the error already there, doesn't increase it per se.
the parallax increases with increases in diameter or objective in the case of scopes
the refinement in the screw mechanism used to adjust for parallex becomes more difficult the greater the range, becomes more of a depth of field problem. (one of the reasons small diameter objectives) don't have ao.
|
|
Dale Clifford
Optics Jedi Knight Joined: July/04/2004 Location: United States Status: Offline Points: 5087 |
Post Options
Thanks(0)
|
|
|
Longranger
Optics GrassHopper Joined: January/05/2013 Location: New Zealand Status: Offline Points: 15 |
Post Options
Thanks(0)
|
What is the best method to adjust for parallax error if there is a mirage running?
|
|
koshkin
MODERATOR Dark Lord of Optics Joined: June/15/2004 Location: United States Status: Offline Points: 13181 |
Post Options
Thanks(0)
|
A couple of comments:
- Where did you exactly dig this up? - I need to think about it a little, but offhand I would say that these calculations are likely not applicable to riflescopes. I would really like to see how the person who came up with these formulas compensated for focal length differences in different scopes and how those pertain to actual reticle size and focal point errors. ILya
|
|
stickbow46
Optics Master Extraordinaire Joined: January/07/2009 Location: Benton, Pa Status: Offline Points: 4678 |
Post Options
Thanks(0)
|
.....Glad I'm smart enough to stay out of this one!
|
|
Pearls of Wisdom are Heard not Spoken
|
|
BobbyH
Optics Apprentice Joined: April/25/2012 Location: ARKANSAS Status: Offline Points: 137 |
Post Options
Thanks(0)
|
I'm with Stickbow on this one. |
|
budperm
Optics Retard show me your sheep!! Joined: January/01/2009 Location: Pennsylvania Status: Offline Points: 31710 |
Post Options
Thanks(0)
|
ILya will identify the truth!
Wouter I thought you had lost interest in Optics.
|
|
"Peace is that brief glorious moment in history when everybody stands around reloading".
--Thomas Jefferson |
|
Bitterroot Bulls
Optics Master Extraordinaire Joined: May/07/2009 Location: Montana Status: Offline Points: 3416 |
Post Options
Thanks(0)
|
Those posts are from 2009.
|
|
-Matt
|
|
budperm
Optics Retard show me your sheep!! Joined: January/01/2009 Location: Pennsylvania Status: Offline Points: 31710 |
Post Options
Thanks(0)
|
Whow...totally missed the date wouter posted the chart...
How observant of me!!!
|
|
"Peace is that brief glorious moment in history when everybody stands around reloading".
--Thomas Jefferson |
|
Bitterroot Bulls
Optics Master Extraordinaire Joined: May/07/2009 Location: Montana Status: Offline Points: 3416 |
Post Options
Thanks(0)
|
ILya,
I started a thread about this equation in 2011, after reading this article: Rimfire benchrest parallax article No matter what, parallax error is mitigated by properly keeping your eye's axis centered in the exit pupil. |
|
-Matt
|
|
koshkin
MODERATOR Dark Lord of Optics Joined: June/15/2004 Location: United States Status: Offline Points: 13181 |
Post Options
Thanks(0)
|
Yikes. I did not notice this is from 2009. I'll need to look through that link. Bottom line though is that I have a hunch that the calculation is wrong. I played with this some time back when I had a bunch of similarly configured scopes with adjustable parallax that I was testing for an article. I had them all set parallax free at 100 yards and then looked at parallax error at various distances without messing with the side focus. It varied from scope to scope and not insignificantly. ILya
|
|
Kickboxer
MODERATOR Moderator Joined: February/13/2008 Status: Offline Points: 23679 |
Post Options
Thanks(0)
|
Sometime back, author's name omitted, I read an article in a highly touted gun magazine that said "you have to be certain to ensure the parallax setting is set on the proper distance, ie., 100 for 100 yards, 200 for 200 yards, etc, to ensure it is properly adjusted. I threw the magazine away and have not picked one of those up since. I've never found the parallax adjustments on any scope, including my Hensoldt, to be very close to the distance dial adjustment. If it ever is, it is an accident. Someone's eyes may match those dials, but mine sure don't...
|
|
Opinion,untempered by fact,is ignorance.
There are some who do not fear death... for they are more afraid of not really living |
|
Longranger
Optics GrassHopper Joined: January/05/2013 Location: New Zealand Status: Offline Points: 15 |
Post Options
Thanks(0)
|
It may be 2009, but still misunderstood. How are you guys adjusting for parallax with mirage running?
|
|
stickbow46
Optics Master Extraordinaire Joined: January/07/2009 Location: Benton, Pa Status: Offline Points: 4678 |
Post Options
Thanks(0)
|
I have found the best solution with what we are talking about as far as parallax goes is the one on my Premier,there are no numbers.I thought I could resist jumping in but my stupidity got the best of me.....Stop laughing BUD
PS: Hows your mom feeling?
|
|
Pearls of Wisdom are Heard not Spoken
|
|
Post Reply | Page 12> |
Tweet
|
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |