New Posts New Posts RSS Feed - black edges in view...paralax?
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

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

black edges in view...paralax?

 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: May/31/2010 at 23:42
tjones96761 View Drop Down
Optics GrassHopper
Optics GrassHopper
Avatar

Joined: May/31/2010
Location: oklahoma
Status: Offline
Points: 30
I've heard different folks call the same issue different names. I need to know the term so I know what to look for in a new scope, I've heard it called paralax free, when you can only look through the scope one way to get a field of view that is clear. Is that right?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/01/2010 at 01:31
cyborg View Drop Down
Optics God
Optics God
Avatar
God of Wind

Joined: August/24/2007
Location: North Georgia
Status: Offline
Points: 12082
That would be focus. Parallax is the moving of the reticle when you change your head position within the eyebox. The eyebox is the sweet spot behind the scope that yields a good sight picture without black edges, or light fade. Some scopes are forgiving in that department others are very finicky. Scopes that aren't parallax adjustable are fixed parallax. The range that they are fixed can vary from maker to maker, or from model to model. Most are 100 yards or meters fixed. Some are 50 yards, or meters.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/01/2010 at 03:41
8shots View Drop Down
Optics Jedi Knight
Optics Jedi Knight
Avatar
Lord Of The Flies

Joined: March/14/2007
Location: South Africa
Status: Offline
Points: 5754
You could also be referring to the tunnelvision effect. Some scopes with poor glass show a lot of black around the edges, which is actually the inside of the scope you are seeing.
 
Then there is also the eye relief. If you hold the scope to close or too far away from your eye you will see a black edge around the field of view. A good scope has a generous eye relief, which avoids becoming a member of the halfmoon club.
 
Maybe if you are more specific we can help more.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/01/2010 at 12:51
RifleDude View Drop Down
MODERATOR
MODERATOR
Avatar

Joined: October/13/2006
Location: Texas
Status: Offline
Points: 14313
Actually, the "tunnel vision" affect is related to eyepiece design and has nothing to do with glass quality or the overall quality of the optic.  Some very expensive scopes can have tunnel vision at low power.  Most scopes have some tunnel vision to some degree, in fact, and it is most prominent at low magnification.  More important is the image quality across the FOV, though excessive tunnel vision can be annoying.
 
Parallax is the apparent shift in position between two objects in your field of view.  In a rifle scope, the term is used to describe the reticle and the target object not being in the same focal plane.  With excessive parallax, the reticle appears to shift away from the point of aim as the shooter's head moves away from the optical center of the scope.  Parallax adjustment or side focus brings both the reticle and the target image to the same focal plane so that the reticle center stays locked onto the point of aim regardless of whether your eye is centered in the optic or not.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/01/2010 at 21:15
tjones96761 View Drop Down
Optics GrassHopper
Optics GrassHopper
Avatar

Joined: May/31/2010
Location: oklahoma
Status: Offline
Points: 30
Let me say that another way. I put the gun in a vise and zero it on a target. If I move my eye around in the eyebox, and the crosshairs move without the gun moving, and there is still a full clear view in the scope. This is paralax correct? same scenario, this time I move my head and get black edges, but crosshairs stay fixed. What do you call this? This is what I like, no matter what position I get behind the gun, as long as I have a clear view, the bullet goes where the crosshairs are. What specification am I looking for to determine if a scope has this attribute without physically looking through the scope? Glass quality, clarity, color, etc. are all second to this one item on my score card.


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/01/2010 at 21:45
cyborg View Drop Down
Optics God
Optics God
Avatar
God of Wind

Joined: August/24/2007
Location: North Georgia
Status: Offline
Points: 12082
If the cross hairs do not move then that is fixed parallax. Bare in mind that if a scope is fixed at 100 yards anything that is below that you will see a tendency for the parallax to present itself.
 
What you are asking for is a fixed parallax scope. Any scope that is not parallax adjustable is a fixed parallax scope.
 
Side focus, rear focus and adjustable objective are examples of Parallax adjustable scopes. If you are looking for fixed Parallax then you will want to stay away from these types. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/01/2010 at 23:31
tjones96761 View Drop Down
Optics GrassHopper
Optics GrassHopper
Avatar

Joined: May/31/2010
Location: oklahoma
Status: Offline
Points: 30
Originally posted by cyborg cyborg wrote:

Side focus, rear focus and adjustable objective are examples of Parallax adjustable scopes. If you are looking for fixed Parallax then you will want to stay away from these types. 


Doesn't that only fixed power? am I miss understanding?


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/01/2010 at 23:34
cyborg View Drop Down
Optics God
Optics God
Avatar
God of Wind

Joined: August/24/2007
Location: North Georgia
Status: Offline
Points: 12082
No fixed power is a single power scope like say 10X
Variable scopes are say 2.5-10X.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/02/2010 at 17:22
RifleDude View Drop Down
MODERATOR
MODERATOR
Avatar

Joined: October/13/2006
Location: Texas
Status: Offline
Points: 14313
Originally posted by tjones96761 tjones96761 wrote:

Let me say that another way. I put the gun in a vise and zero it on a target. If I move my eye around in the eyebox, and the crosshairs move without the gun moving, and there is still a full clear view in the scope. This is paralax correct? same scenario, this time I move my head and get black edges, but crosshairs stay fixed. What do you call this? This is what I like, no matter what position I get behind the gun, as long as I have a clear view, the bullet goes where the crosshairs are. What specification am I looking for to determine if a scope has this attribute without physically looking through the scope? Glass quality, clarity, color, etc. are all second to this one item on my score card.


 
Crosshair moving on target without the gun moving = effects of parallax.
 
Losing all or part of the field of view as you move your eye slightly away from the centerline of the scope is likely the effect of a small exit pupil and/or critical eye relief.  This is what you get with high magnification scopes with relatively small objective lens diameters.  The exit pupil is the diameter of the column of light exiting the eyepiece of the scope.  The larger the exit pupil, the easier it is to get behind the scope and get the full sight picture.  A small exit pupil makes head position behind the scope more critical and will cause the blackout when you move your eye away from the optical center of the scope.  To give you a more forgiving "eye box," pick a scope with at least 5mm or so of exit pupil and a generous eye relief.  Simply divide the scope's objective diameter (in mm) by the magnification you plan to use frequently to get the exit pupil diameter.  For example, a 42mm objective scope at 6X = 7mm exit pupil.  So, as you move up in magnification, there has to be a corresponding increase in objective lens diameter to maintain the forgiving eye position you desire.  Low powered scopes are therefore usually easier to get behind.  Choosing a scope with a long eye relief also helps in this regard, but it doesn't change the exit pupil issue.  The downside to longer eye relief is that it usually comes at the expense of field of view.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/02/2010 at 17:44
BeltFed View Drop Down
Optics God
Optics God
Avatar

Joined: February/12/2008
Location: Ky
Status: Offline
Points: 16086
Get Your Popcorn Ready
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/02/2010 at 19:51
tjones96761 View Drop Down
Optics GrassHopper
Optics GrassHopper
Avatar

Joined: May/31/2010
Location: oklahoma
Status: Offline
Points: 30
Originally posted by cyborg cyborg wrote:

 
Side focus, rear focus and adjustable objective are examples of Parallax adjustable scopes. If you are looking for fixed Parallax then you will want to stay away from these types. 


I typo'd. If you take side, rear, and AO out of the running, doesn't that only leave fixed power scopes?


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/02/2010 at 22:18
cyborg View Drop Down
Optics God
Optics God
Avatar
God of Wind

Joined: August/24/2007
Location: North Georgia
Status: Offline
Points: 12082
Not at all. Variable scopes are just that they have a power range. Example is a 3-9X 42. Here I will pull up a couple of examples for you.
 
This is an example of a fixed Parallax variable power scope. Note that there is no mention of adjustable Objective, Side Focus, or Rear Focus.
 
Here is an example of a parallax adjustable scope. Note it says side focus.
Here is another adjustable Parallax variable scope. Note it says Adjustable Objective.
This is an example of a fixed power, and adjustable parallax scope. Note it says rear focus/parallax adjust.
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/02/2010 at 22:48
tjones96761 View Drop Down
Optics GrassHopper
Optics GrassHopper
Avatar

Joined: May/31/2010
Location: oklahoma
Status: Offline
Points: 30
Thank you Cyborg. Understand fully now. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: June/02/2010 at 22:50
cyborg View Drop Down
Optics God
Optics God
Avatar
God of Wind

Joined: August/24/2007
Location: North Georgia
Status: Offline
Points: 12082
I am and any of us here are always happy to be of assistance.
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Similar Threads: "black edges in view...paralax?"
Subject Author Forum Replies Last Post
Binocular View turned Black mtmander Binoculars 17
SS 10x won't focus to edges ba_50 Tactical Scopes 11
Savage Edge Series... The Apostle Firearms 3
Savage Edge SVT_Tactical Firearms 5
Leupold Mojave grey&white picture on the edge MassterMark Binoculars 2
Valdada 1X Edge Red Dot riverrat373 Tactical Scopes 3
IOR Valdada EDGE red dot scope Exporter Tactical Scopes 3
Zen Ray ED3: extended viewing Stud Duck Binoculars 8
Savage Axis/Edge thoughts? RotoReuter_DM Firearms 8
paralax and glasses garageman51 Rifle Scopes 1


This page was generated in 0.125 seconds.