Scope Tunnel effect

[Audioslave82 2]

Hey all,

 

Firstly im new to shooting, I dont have my rifle yet (paid for and awaiting license).

 

I was out shooting with a friend at the weekend. I was using his rifle and found the scope very difficult and annoying, i kept getting a tunnel like effect and had to constantly adjust the position of my head to get a clear view but i could not sustain it long enough to settle the cross hair onto the target.

 

I put this down to the scope being set up to his preference of distance from eye lense and position on rail etc. and im hopeing im right as my scope has arrived in the post this morning and at first glance im seeing the same thing. With adjustment of my head i can see a clear image.

 

Is this just some tweeking on postion and dials and setting it on the rifles scope rail or is this an annoying feature of lower priced scopes?

Edited October 22, 2012 by Audioslave82

[De_Tomaso 0]

Mostly this is a problem of low priced scopes. So called Eyebox is better with scopes of higher quality.

 

Some adjustments can be made if you use the scope at lower magnifications and if the mounting is good enough that no major adjustments have to be made with turrets when zeroing.

[mealiejimmy 1]

Riflescopes have a couple of things which affect how well you can see through them.

 

One is "eye relief" - this is the distance from the back of the scope at which the image will be in focus. This is typically 2-4 inches depending on the scope and the magnification it's set to. Your eye needs to be at or very close to this distance to get a clear picture.

Adjusting the position of the scope on the gun or adjusting the stock might be needed to put your eye in the correct position

 

Another is "exit pupil" - this is the diameter in mm of the focused image at the eye relief distance.

Exit puil size is calculated by dividing the diameter of the objective lens at the front of the scope by the magnification. So, for example, a 6-20x50 scope would have an exit pupil diameter of more than 8mm at x6 magnification (50/6) but only a diameter of 2.5mm at x20 magnification (50/20).

The diameter of the pupil in your eye varies with the amount of light hitting it, but rarely is it larger than 7mm (5mm for an old git like me)

When the scope magnification is low, the exit pupil is large and it's easy to get your eye into a position where it can get all the light it can handle.

When the scope magnification is high, the exit pupil may be smaller than the pupil in your eye and it becomes much more difficult to get your eye into the exact spot where the light can enter it.

 

So, it's likely that the "tunnel" effect you saw was probably a combination of high magnification and not having your head in the right place.

 

 

Hope that helped

 

Cheers

 

Bruce

[Audioslave82 2]

Thanks for the replies lads, it is more than likely thats its just my positioning from the scope lens. I'll wait until i get the rifle and then i'll bring it to my dealer and ask if he can assist in setting the scope.

 

As for the scope, its a Hawke SPORT HD IR 4-12X50 AO MIL DOT 1".

[JohnGalway 1,043]

High mag will cause that problem but it's more likely that it's the eye relief which your mate will sensibly have set to suit himself.

 

When you get your rifle find the lowest mounts you can get away with, once the scope isn't touching the barrel you're good to go.

 

Then you'll need to think about what position you'll be shooting the rifle from the most. I shoot prone so I lay down with the rifle, get comfortable and having the scope in the mounts but not tightened I will play moving the scope forward or back a little at a time. There are guides online how to do it, if you can't find any I think it's in the Nightforce scope manual which IS available online as a .pdf file I think.

 

Be consistent, find a comfortable, natural spot on the stock for your chin or cheek whichever applies and keep it there. It should feel natural and comfortable to look through your scope, if it doesn't something isn't quite right.

 

Some scopes are fussier on eye relief than others. I had a lovely Leupold scope which I sold to a guy on here, think it was Deker, I just couldn't get on with it. I think Snap Shot has a eupold and he loves his so try out as many as you can.

[GEOFF.223 83]

i have to short friend who i have taken them out for a bit of plinking with my hmr and .22 they have the same problem so the next i went out with them i took the alen keys with me to adjust scope alot more fun when u have the eye relief set to ur own preference it makes the day alot more enjoyable after i set it up for them the very nxt day they went and got f.a.c applications so to a simplest thing as eye relief has changed the out come of to people who had no interest in shooting .