scope tunnel effect

[parkj5]

OK guys i have acquired a older Khales Helia L 3-12x56 scope a a good price. After mounting and trying to get the eye relief set the scope has a lot of tunneling effect on lower power ranges. What i mean by this is the glass is clear but on lower power i can see black ring inside the scope like im looking thru a tunnel. What is the cause of this scope defect ? i have moved it forward and backwards without much help. Thanks guys.

 

[Dosh]

Parallax. Does the scope have an adjustable objective?

 

[parkj5]

No sir its fixed

 

[parkj5]

Seems like 5 or 6 power the black is almost gone.

 

[Will16]

Call kahles customer service and talk to them about it.

 

[Laelkhunter]

I bought a Zeiss Conquest 4.5-18x44 that did the same thing. I bought it to replace the Zeiss Dialyt 3-9 X 42. Don't know why, because the Zeiss Dialyt 3-9 didn't do it. When I zoomed the scope (power up or down), I got the same effect as yours, like looking through a black long toilet paper tube. I couldn't get used to it, so now I have a Swarovski Z5, and love it. No tunnel effect.

 

[Joefrazell]

Wow that's would bother me!

 

[parkj5]

Going to call today see if something can be done.

 

[parkj5]

Has to go to Austria after they start taking them middle of the month.

 

[josef]

Tunneling is usually caused by manufacturers trying to get more zoom range than the erector can support. A bunch of Schmidts do this as well. Essentially towards the lower end of the mag range you stop getting a change in FOV and while the image gets smaller (appears to be zooming out). Its likely a design issue rather than a manufacturing issue.