What a RELIEF! – NOT!! – since I’m confused about Scope Eye Relief

[JungleShooter]

Help me out, would you?  How much eye relief does a scope have?

I’m not sure if that is even the right question to ask:
What I need is a larger range where I can still see the scope image and it does not turn dark. I call this the the eye relief range.
A short eye relief range means you move your head/ eye just a twitch, and the scope turns dark.


I thought eye relief referred to the distance that the eye has to be from the ocular lens. Most manufacturers give that data.
Some mfctr. give a range which I thought referred to the eye relief range. Like this:
Eye relief 3.7" – 4.0"


But today I stumbled upon a catalog from Nikko Stirling* and on p. 57 it gives a certain eye relief distance for different powers of the scope. Like this:
High power: eye relief 3.7"
Low power: eye relief 4.0"
Does this refer to the fact that the eye needs to be closer when using high power magnification?
*www.nikkostirling.com/Images/catalogue/NScatalogue2016.pdf


So, in the end, how does a buyer know how much eye relief range a scope has? 

[Motorhead]

Yes ... eye relief with many scopes changes slightly with magnification AS DOES the size of exit pupil you are viewing typically being larger and less sensitive to position at lower mag and getting smaller and more critical as mag goes higher.

Most quality optics state what the eye relief range is with some also stating exit pupil size at a given X power.

[Frank]

Correct me if I am wrong. Yes, it means that your eye must be within this range to have a full view through the scope. You must mount your scope to be in this range so your head and eye will be at comfort when you site. At times you will have trouble if the scope is mounted to high or low for that comfort point. It should be mounted so it is natural for your head position and you have a clear view.  Rifle scopes do have a short eye relief usually. Now pistol scopes can have ten inches and not suitable for rifles.

[Roadworthy]

If you can't get the eye relief you want on a given gun you can purchase extended rails which allow you to position the scope closer or further from your eye.

[Motorhead]

Correct me if I am wrong. Yes, it means that your eye must be within this range to have a full view through the scope. You must mount your scope to be in this range so your head and eye will be at comfort when you site. At times you will have trouble if the scope is mounted to high or low for that comfort point. It should be mounted so it is natural for your head position and you have a clear view.  Rifle scopes do have a short eye relief usually. Now pistol scopes can have ten inches and not suitable for rifles.

Or a scope like the MTC "Connect" which is a ZERO eye relief scope where the supplied adjustable ocular shade is set to rest on your brow bone,  eye glasses etc.  * No recoil rifles only !!  PCP's generally.

[Frank]

No recoil rifles only !!  Reminds me of the time I handed my 350 to a person to shoot. Was not aware that they did not know of scopes and rifles. They put the scope on their brow and pulled the trigger before I could see what they were doing. The black eye was not funny but could not avoid the snicker !!

[JungleShooter]

Thanks for those replies.

What I’m asking about is not the general distance D from the eye to the ocular lens. My problem with the scope is that it only gives me a very small tolerance of distance D (what I called eye relief range). Like this:
D = 4.0"
Tolerance of around 0.2"
So, at 4.1" and 3.9" I can still see well.
BUT at 4.2" or more, or 3.8" or less, the scope lens turn black.

How can I know that my next scope has more than 0.2" eye relief tolerance? 

[bandg]

Eye relief distance and range varies from scope type to scope type.  It's been quite a while since I bought a scope but seems I recall these stats being provided for most that I have bought.

[Motorhead]

IMO it appears that in scopes that I own, SFP ( Second focal plane ) tend to be more forgiving than FFP ( first focal plane ) in size and critical positioning of the eye box.
It is the nature of optics in general tho some are more/less critical than others .... Shoot with lower X power to give you the most leeway.

[QVTom]

Exit pupil diamter is what make your axial alignment fussy.  Generally speaking,  it is a function of objective diameter / magnifaction.  Small objectives with high mag. Will be fussier.  Also lagrer tube diameters like 30, 34, and 40mm will provide a larger eye box which give more comfortable viewing.

Tom