Optics Question for Peter (Wizard) Smith

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bobeager
Posts: 411
Joined: Wed Jun 22, 2005 1:29 pm
Location: Goulburn NSW Australia

Optics Question for Peter (Wizard) Smith

#1 Postby bobeager » Mon Aug 28, 2017 5:09 pm

Peter, my eyes are old and buggered. What sort of eye glasses do I need for viewing through scope? Close up viewing similar to reading, middle or long vision?

How far from the eye is the scope image?

Hope you understand what I am getting at

pjifl
Posts: 883
Joined: Fri Jun 17, 2005 12:15 pm
Location: Innisfail, Far North QLD.

Re: Optics Question for Peter (Wizard) Smith

#2 Postby pjifl » Mon Aug 28, 2017 9:36 pm

Bobeager wrote

What sort of eye glasses do I need for viewing through scope? Close up viewing similar to reading, middle or long vision?

I am assuming you mean a riflescope but it is similar with a spotting scope.

For the image through the scope, unless you have much astigmatism, and you are not very long or short sighted, you do not need glasses with a scope because the eyepiece focus will achieve what your glasses do. Even if you have a small amount of astigmatism, at very high magnification, image deterioration is quite minimal or not even evident because the cone of light entering your eye is very narrow so only passes through a small part of your cornea and lens in the eye.

What is probably more important is wearing 'normal' spectacles that lets you see the flags clearly or a plot sheet or your scope level and knobs clearly. I would first try different options here until you have the best compromise.

Then, you simply focus the eyepiece with those glasses for best Graticule sharpness. Best done with no detail showing through the scope if it is a riflescope. Like looking against a pure white part of a target or the sky or clouds.

Finally, of course, for a riflescope, you use your objective or side focus for target sharpness. Preferably using parallax for the final tweak.

How far from the eye is the scope image?

The user can control this simply by the eyepiece focus setting. All the way from infinity to reading distance.
Temporarily keeping both eyes open with the spare eye looking at flags or plotting book etc while setting the eyepiece focus will allow you to force your eye to any scope image distance.

It is normal for quite young people to set the scope image very close. Children are notorious for this.
Adults usually set the scope image for a much longer distance.

Hope this helps.

Peter Smith.

bobeager
Posts: 411
Joined: Wed Jun 22, 2005 1:29 pm
Location: Goulburn NSW Australia

Re: Optics Question for Peter (Wizard) Smith

#3 Postby bobeager » Tue Aug 29, 2017 8:24 am

Thanks Peter. Very informative and I think will be helpful for others as well. However, i will go get my eyes examined to make sure I do not have a cataract in my aiming eye.


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