Rifle Scopes Paralax in a 1-4 on 1x?

[GasLight]

Hello,

I just got my first ever 1-4x optic. I don't know if this is normal or not, but I wanted to ask to make sure. If it is normal, this is definately not my cup of tea...

When I have the scope on 1x, and I look through it at 50 yards I can see 2 targets, the image through the scope is noticably lower than view through my 'weak' eye. When I am looking through the scope at any power, as I move it, there is obvious distortion at the edges of the field of view.

Can anyone tell me if this is normal, or if perhaps my scope is out of spec?

Thanks

Dave

 

[match308]

Re: Paralax in a 1-4 on 1x?

I dont get that with my SWFA SS 1-4. What kind of scope do you have?

 

[GasLight]

Re: Paralax in a 1-4 on 1x?

an SWFA 1-4HD ffp

 

[dcjs]

Re: Paralax in a 1-4 on 1x?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GasLight</div><div class="ubbcode-body">When I have the scope on 1x, and I look through it at 50 yards I can see 2 targets, the image through the scope is noticably lower than view through my 'weak' eye.</div></div>

Are you running an angled base/mount?

What you are seeing is a peculiarity with 1x scopes (any <span style="font-style: italic">scope</span> starting at 1.1x or 1x that allows binocular vision with both eyes open) that is an issue with all such scopes, yet I've never seen this talked about anywhere.

The way a scope is constructed, the image you see will shift up or down when dialing elevation, so when looking "straight ahead" with both eyes open, there will be an offset between the "bare eye" image and the one the "scope eye" picks up. As long as this offset is small (meaning the scope being near optically centered), this is not an issue. The further you get from optical center, the harder it gets for the brain to get the two images to match. This is very much like looking through a misaligned pair of binoculars. (Note: this does not apply to red dot sights since they don't use an erector system like a scope).

Normally, dialing large amounts of elevation only happens at longer ranges, but you'll use higher magnification at those longer ranges anyway, so no problem here. The problems start when putting such a scope on an inclined base/mount, because then you're way off optical center at short ranges. The same thing might happen if the base is crooked and lots of elevation/windage from optical center is necessary to zero the rifle, but since you are mentioning that the image through the scope is "lower", I'd guess there's a good bit of forward cant in your setup.

Bottom line: <span style="font-weight: bold">Do not use an angled base/mount for a 1-Xx scope!</span> It's not a fault of your individual scope but a result of being off optical center at short ranges. You will be able to "dial away" the effect by cranking in a couple mils of elevation (adjusting for long range).

Distortion at the edge of the FOV is generally a property of the optical design and as such varies when looking at different models.

 

[glock24]

Re: Paralax in a 1-4 on 1x?

I'd also recommend playing with your diopter adjustment. Particular to 1x scopes, the diopter adjustment has a huge effect on the <span style="text-decoration: underline">perceived</span> size of a target. I find that if my 1x scope is telling my shooting eye that a target is larger/smaller than my weak eye, my brain freaks out and tries to give me two images.

Instead of the usual method of adjusting diopter while pointing at the sky, try adjusting it while viewing a 10-15 yard target with both eyes open. You should see that when the diopter adjustment dials in the target so that <span style="text-decoration: underline">both eyes </span>see it as the <span style="text-decoration: underline">same size</span>, a lot of the problems you decribe will go away.

 

[GasLight]

Re: Paralax in a 1-4 on 1x?

This is holding the scope in hand without it being mounted at all. I can't shift the scope in any fashion to make the images align.

I played with the diopter adjustment to make sure everything is sharp. I can see more size variation when I move my head closer and further away from the scope, I'm not too worried about the size discrepency, but this scope looks like as stated above, 'looking through binoculars with the prism mis-aligned'.

If this is how they work, then I am not sure how people can shoot on 1x... at least with both eyes open, it almost makes me feel queasy to look through it for any length of time.

Thanks for the info

Dave

 

[dcjs]

Re: Paralax in a 1-4 on 1x?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: GasLight</div><div class="ubbcode-body">This is holding the scope in hand without it being mounted at all. I can't shift the scope in any fashion to make the images align.</div></div>
You have to <span style="font-weight: bold">turn the elevation knob</span>. Holding the scope at whatever angle won't help you. Turn the elevation knob up and down through its range and look through the scope with various amounts of elevation dialed in. The effect should change and disappear altogether at a certain setting (which is optical center).

 

[GasLight]

Re: Paralax in a 1-4 on 1x?

Yes! I played around with the windage and elevation and was able to basically eliminate the effect, now I just hope that I can zero with it somewhere close to this!

I greatly appreciate the help, I was very concerned as I had not heard of this before.

Thanks much David S!

Dave