Scope question

[madmixerman]

I have seen a dark ring put on the objective lens of a scope. What are they called and what is the purpose? Something to do with mirage?

 

[bugman]

here...check this out........https://www.eurooptic.com/March-52mm-MD-Disk-DB062-0.aspx

 

[divingin]

My Golden Eagle came with one. I haven't noticed it being all that effective on mirage, but it does help dim the view a bit on a really bright day. I still use it when mirage appears, just in case it helps without me seeing it do so.

 

[ebb]

Some are magnifiers that boost the power of the scope.

 

[Dgd6mm]

My Golden Eagle came with one. I haven't noticed it being all that effective on mirage, but it does help dim the view a bit on a really bright day. I still use it when mirage appears, just in case it helps without me seeing it do so.

^^^^^ this, I use it on my Golden Eagle. I believe it does help a little with mirage.

 

[Lesloan]

As I understand it, the ring is to improve depth-of-focus on the scope, much like the pinhole attachment to eyeglasses used by many pistol shooters to help them see both sights in focus. I don't think it's intended to have anything to do with reducing mirage, though I suppose it might have that effect.

 

[F Class John]

^This

Much like ‘stopping down’ a camera lense by making the aperture (iris) smaller, it makes the depth of focus longer in a effort to flatten out the mirage (or mirage bounce more specifically). The mirage is till there, it’s still bouncing around and it still has the same effect but you’ve essentially tricked your eyes into seeing a more stable version of it.

 

[divingin]

As I understand it, the ring is to improve depth-of-focus on the scope, much like the pinhole attachment to eyeglasses used by many pistol shooters to help them see both sights in focus. I don't think it's intended to have anything to do with reducing mirage, though I suppose it might have that effect.

Mirage through the scope is due to varying air density across the field of view, causing slightly different refraction as you move across the objective lens. The ring theoretically cuts that down as there is less FOV to be affected.

It will also act as an aperture (think either a camera lens iris or a rear peep sight on a rifle) giving you greater depth of field.

You may be correct though; the Vortex manual says it is to increase DOF and sharpen the view without specifically mentioning mirage.

 

[fyrewall]

It will reduce the size of the scope's exit pupil and clarify (improve focus) of the image and increase depth of field (DOF)

https://physics.stackexchange.com/q...ure-size-affect-depth-of-field-in-photography

Light goes thru central portion of lens instead of entire lens.

I had a 6-24X50 Burris Signature (1 inch tube) and it had a camera type iris in back of the objective lens assembly - on a bright hot day the iris was cranked down to minimum to provide exquisite views of hapless rodents.