New Posts New Posts RSS Feed - Sight picture question
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

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

Sight picture question

 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/02/2007 at 08:36
stumpy View Drop Down
Optics GrassHopper
Optics GrassHopper


Joined: March/14/2006
Status: Offline
Points: 5
This question may of be covered before but I could not find a good answer. Its hard to explain my question but here goes...If you have your scope zeroed for your rifle and the scope WE adjustments happens to be perfectly in the center of thier adjustment range any error/canting in your hold of the rifle (sight picture) would have no effect on the POI except accounting for bullet drop...however if your scope is zeroed for your rifle and as is common the scope WE adjustments are offset from the center of the adjustment range of the scope then any error in your sight picture (canting) would be more exgagerated resulting in a more open shot group....Of course the scope is mounted some distance above the bore thus in the adjustment perfectly centered sitution the worst cause would be a group which would equal the diameter of this scope to bore distance but how much effect or difference does the reticle adjustment away from center have on your POI if canting occurs .. is the effect a function of the actual distance the retitcle actually moves inside the scope as compared to the scope to bore for example 1/64" actual reticle movement plus the scope to bore distance or is this a function of the percieved distance at the target for example 1/4" per click?
Clear as mud

Thanks in advance

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/02/2007 at 09:23
Urimaginaryfrnd View Drop Down
MODERATOR
MODERATOR
Avatar
Resident Redneck

Joined: June/20/2005
Location: Iowa
Status: Offline
Points: 13882
Koshkin  will gladly tell us no doubt.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: February/02/2007 at 22:08
koshkin View Drop Down
MODERATOR
MODERATOR
Avatar
Dark Lord of Optics

Joined: June/15/2004
Location: United States
Status: Offline
Points: 10975
First of all, as far as group size is concerned it really does not matter whether the rifle/scope is canted or not, as long as it is held the same way for every shot.

Now, POI will certainly depend significantly on how you hold your rifle.  What you posted about the scope having to be in the center of W/E adjustment range is not strictly speaking correct.  The center of the W/E adjustment range is something called the Mechanical Center (or sometimes referred to as Mechanical Axis).  There is also an Optical center (or Axis) which does not always coincide with the Mechanical Center.  If your scope is in its Opical Center, then canting the rifle will cause a comparatively small difference in POI. 

Here is a description of the difference between optical and mechnical centers:

With the scope in v-blocks, align the crosshairs with a distant point, then turn the scope in the v-blocks.  If the crosshairs wobble, if they move off the distant point, then adjust them until they do not move relative to the distant point when the scope is rotated around its axis.  That is what most people mounting scopes refer to as the "optical center".  That is, the crosshairs are aligned with the centerline of the optics.

Keeping track of the dials, turn the elevation knob until it stops.  Then turn it the other way until it stops.  Set it halfway between those stopping points.  Do the same with the windage knob.  That is what most people mounting scopes refer to as the "mechanical center".  That is, the adjustments are in the center of their  mechanical range.

On a good scope, the twocenter will more or less coincide.  Any significant misalignment of the ""center"s can indicate a problem with the scope.

ILya
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Similar Threads: "Sight picture question"
Subject Author Forum Replies Last Post
Help with Sight Picture Division 3 Rifle Scopes 1 11/30/2005 9:10:23 AM
Super Sniper 20X Blurred Sight Picture dropd57 Tactical Scopes 13 9/9/2006 3:15:41 AM
Sight Picture. LRSMike Rifle Scopes 6
DSLR and SLR Picture Thread Skylar McMahon Hot Shots 43
Pictures of a Firedot 4 reticle on a Leupold VX-6 Rifleman1981 Rifle Scopes 0
We took a vacation - picture heavy sucker76 Hot Shots 10
Israeli Elbit Falcon MK II red dot sight Marine24 Tactical Scopes 8
Lunar eclipse pictures help sucker76 Cameras, Equipment and Settings 18
Problem sighting in scope chadfite Rifle Scopes 1
Red Dot Sight Abitnutz Rifle Scopes 13


This page was generated in 0.344 seconds.