New Posts New Posts RSS Feed - Real world effect of parallax to lower lower scope
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Check GunBroker.com for SWFA's No Reserve and No Minimum bid firearm auctions.

Real world effect of parallax to lower lower scope

 Post Reply Post Reply   Topic Search Topic Search  Topic Options Topic Options
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/05/2016 at 15:17
Canuck Bob View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: April/07/2010
Location: Alberta, Canada
Status: Offline
Points: 59
This comes up a lot but there is some variation reported in the real world effect of parallax.  My question revolves around a specific type of scope.  Fixed power, 6X or less, set at a parallax of either 50 (rimfire) or 100 yards (centerfire).  My rifles regarding this question are springer air rifles, 22s, and a 223 bolt.

Is it possible to estimate the effect of 50 yard focus at air rifle distances or conversely 223 distances, again 4X or 6X fixed scopes?

Same general question regarding using a 100 yard focus scope at air rifle ranges, 15 to 25 yards, and 22 ranges, 25 to 75 yards?

My scope choice is used or new Leupold.  Their Canadian warranty center is excellent and a few miles from my house.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/05/2016 at 17:56
koshkin View Drop Down
MODERATOR
MODERATOR
Avatar
Dark Lord of Optics

Joined: June/15/2004
Location: United States
Status: Online
Points: 10961
It is possible, but depends on the objective lens diameter.  Knowing magnification is not enough.

A related topic was discussed here:

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/06/2016 at 11:59
Canuck Bob View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: April/07/2010
Location: Alberta, Canada
Status: Offline
Points: 59
I own two scopes and am considering seriously a third.

2.5X20 M8 Compact, Leupold, adjusted to 100 yards not the reported 150 for Leupold. This is being considered for an air rifle or 9422.

4X28 M8 Compact RF, adjusted to 60 yards as reported.  This one is being considered for an air rifle or 22rf.

6X36 FX-II, Leupold, adjusted to 150 yards from reports. This one is under consideration for my 223 CZ527.  However it may end up on an air rifle or 22rf or 22Hornet eventually.

The question arose from a desire to understand the effect of using unaltered scopes at the short range of the pellet rifles mainly.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/06/2016 at 12:10
Canuck Bob View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: April/07/2010
Location: Alberta, Canada
Status: Offline
Points: 59
One other thought as the importance of objective lens size was pointed out.

I read in research that understanding optical design was about working with triangles.  Please straighten me out on the following assumptions.

A large objective allows a larger parallax effect than scopes of equal magnification with smaller objectives.

Low magnification has higher parallax effect in scopes of equal objective size.

The effect grows greater the further the target is from the focus distance in either direction.  This one is a bit confusing because of the effect of the converging triangle close to the scope when inside the focus distance preset.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/06/2016 at 12:14
Canuck Bob View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: April/07/2010
Location: Alberta, Canada
Status: Offline
Points: 59
Dark Lord K, thanks for the link.  One quick question, does the formula work the same when calculating for parallax error in ranges shorter than the preset focus distance?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/06/2016 at 17:40
koshkin View Drop Down
MODERATOR
MODERATOR
Avatar
Dark Lord of Optics

Joined: June/15/2004
Location: United States
Status: Online
Points: 10961
My first question would be why not use a rimfire/airgun scope to start with and void the whole mess with worrying about parallax.  If you like Leupold, they make a very respectable 3-9x33 EFR scope that would work well for you.

To answer your questions:

A large objective allows a larger parallax effect than scopes of equal magnification with smaller objectives.
Correct

Low magnification has higher parallax effect in scopes of equal objective size.
That depends on what you mean.  Theoretical maximum parallax error is the same as long as the objective is the same.  In practice, you can see more parallax error with the same objective at lower magnification because your eye pupil takes up a smaller portion of the exit pupil and can deviate further form the optical axis.

The effect grows greater the further the target is from the focus distance in either direction.  
Correct

One quick question, does the formula work the same when calculating for parallax error in ranges shorter than the preset focus distance?
Yes, it works the same.  Whether ranges are short or longer, just take the absolute value of the difference for your calculation.


I made an excel calculator for this since the question comes up occasionally.  Here is a snapshot for a typical 2.5-10x42 scope.

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/07/2016 at 11:31
Canuck Bob View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: April/07/2010
Location: Alberta, Canada
Status: Offline
Points: 59
Thank you for your excellent answer.  This is as much an educational exercise as a specific request.  Your a good tutor.

To answer your question regarding scopes, I am looking for used scopes because the cost of American imports because of our dollars value.  The EFR rimfire scope never surfaces used in Canada it seems.

I'm much more likely to end up with a M8 fixed 6X33.  I like fixed power as well and end up with 150 yard parallax focus.  The Leupold station is close and they have done work for me.  Readjusting the focus is a reasonable cost and simple to achieve.  Rare in Canada.

I am also trying to figure out if the EFR feature is worth the price difference.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/07/2016 at 12:42
koshkin View Drop Down
MODERATOR
MODERATOR
Avatar
Dark Lord of Optics

Joined: June/15/2004
Location: United States
Status: Online
Points: 10961
Well, the choice of whether the EFR feature is worth the money largely comes down to what you are trying to achieve.

If you are trying to shoot the smallest groups at the smallest targets, being able to adjust focus and parallax down to your distance of choice is important.  

If all you are doing is plinking and you are never going to be shooting at distances that are too close to get a decent image, then EFR is not critical.

Personally, I think that buying a used Leupold and then messing with getting the parallax adjusted down is more hassle than it is worth.   Then again, I do not live in Canada, so I am not sure what the prices are there like.

M8 6x was a decent scope for its time, but the times have moved on some.

If I were lookign for compact rimfire/airgn scopes I would pay close attention to Weaver Classic Rimfire scopes (4x28, 2-7x28 and 3-9x32).  They are pretty similar to Leupold's, but at half price of the new models.  The smaller two scopes are factory set for 50 yard parallax, while the 3-9x32 has an adjustable objective.

Vortex Diamondback 2-7x35 rimfire is also factory set for 50 yard focus.

ILya



 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Similar Threads: "Real world effect of parallax to lower lower scope"
Subject Author Forum Replies Last Post
low dollar low end scopes atwisted1 Rifle Scopes 12 10/30/2007 10:52:24 AM
Low power parallax anweis Rifle Scopes 2
Does parallax effect target image? houser52 Rifle Scopes 4 2/22/2007 7:48:19 AM
Parallax effect at 10X 9x23w Rifle Scopes 0 6/21/2004 9:02:48 AM
Good low-light Hunting Scope? luke_duke Rifle Scopes 34
Low Light Scope Advice davisj3537 Rifle Scopes 24
Vortex Strikeforce Red Dot real world experience? donlipa Tactical Scopes 8
real world improvements? rooshooter Reloading & Ballistics 44
Low or Super Low Rings for M1a snewsom2997 Rifle Scopes 2
Meopta discontinued R2 low light scopes dw0229 Rifle Scopes 9


This page was generated in 0.375 seconds.