Fishnhunt New Zealands main hunting and Fishing Forum. millions of posts on fishing and hunting, dogs, 4x4 vehicles, outdoors and much more Welcome, Guest. Please Login or Register
Page Index Toggle Pages: 1 [2]  Send TopicPrint
Normal Topic Using the vari power on scopes (Read 1696 times)
chainsaw
Full Member
***
Offline


I Love The FishNhunt Forum

Posts: 278
Joined: Aug 27th, 2012
Gender: Male
Re: Using the vari power on scopes
Reply #15 - Jul 25th, 2017 at 1:08pm
Print Post  
another consideration is light transmission, or more correctly the match between the scopes ability to transmit light and your eye's ability to perceive it.  For most scopes this is around 7x magnification. No use in the bush, but if your facing a shot at a couple hundred yards in very low light then try the 7x setting rather than 9x.
  
Back to top
 
IP Logged
 
Kalahari-hunter
Full Member
***
Offline


Walking my rifle

Posts: 279
Location: Avondale, Auckland
Joined: Sep 15th, 2015
Gender: Male
Re: Using the vari power on scopes
Reply #16 - Nov 10th, 2017 at 9:51am
Print Post  
POI on the crosshair does not change in  2nd or 1st focal plane, only the holdover positions (hash marks below the crosshair) their poi changes with a second focal but not in a first.

I have scopes ranging from $100 to $1600 and none changes poi at any magnification on the crosshair, the movement you see is YOU the guy behind the gun moving around. unless you have a really junk  scope maybe and its broken.
  

NZDA Rotorua Member
Back to top
 
IP Logged
 
Gerry Atric
Donor Member
*****
Offline


I Love The FishNhunt Forum

Posts: 1252
Location: Raggaro
Joined: Jul 11th, 2008
Re: Using the vari power on scopes
Reply #17 - Nov 12th, 2017 at 8:22am
Print Post  
I would say that the POI could shift on a SFP scope and itīs due to the construction of those scopes.

Someone has explained it this way:

"It's easy enough to check. Just adjust your scope for the appropriate range and center it on a target at that distance with the rifle sitting on a solid rest. Adjust out the parallax with the objective focus. Then carefully zoom the scope and look for any shift between the target and the reticle. Repeat to be sure any movement is caused by the zoom and not by rifle movement. If zooming does not cause relative movement of the image relative to the reticle then it's not affecting POI. If there is relative motion between the reticle and the target image then it must affect POI. If the reticle is located AFTER the zoom mechanism then there is potential for the POI to be affected. How well the scope is designed and constructed will determine if it actually takes place.

Obviously if you're using a second focal plane reticle for hold offs using reticle markings as the reference you will get large POI errors as you change the magnification. That will also happen if a second focal plane reticle isn't properly centered on the optical axis and you use only the crosshair center."

NOTE: The text above was written 2011. "After the zoom mechanism" is SFP

POI-shifts may be present in any SFP-scope due to the construction (in fact Zeiss guaranteed a POI-shift less than 10 mm (?) on their first SFP-scopes) This "malfunction" has almost disappeared or is not measurable in modern good optics but was relatively common in cheap optics back when.

Gerry Atric
  
Back to top
 
IP Logged
 
Page Index Toggle Pages: 1 [2] 
Send TopicPrint
 

FishnHunt - New Zealands Famous Hunting and Fishing Forum Since 1995 » Powered by YaBB 2.6.11!
YaBB Forum Software © 2000-2017. All Rights Reserved.
Site Design By Alan Simmons - PRism and all rights are reserved from 1995 and onwards