Adjusting fixed parallax?

[Jahnj0584]

Found this and am curious. Does it release the argon purge from inside the scope? Do you think it actually works? I don't see how it's any different than what happens with a bell-side AO adjustment ring (think of bushnell banners)

Tl;dw: rotate the objective lens to adjust parallax
https://youtu.be/FgwmKHhtk0g

 

[cosmic]

Well - That is how parallax is adjusted. Funny thing is, most scopes leave the factory with parallax claimed to be set for 100y. If you test them, you will often find the actual parallax is quite different. I had one scope, of decent quality, display minimum parallax at 400y.
Regarding purge, I would guess that most scopes loose their purge within a year or two, simply through diffusion.

 

[Walterfisher]

I have done it before on some scopes when I wanted to shoot air rifles at 10m. It works just like that but that guy is really twisting on the scope.
Theres no need for that. Easy does it. It doesn't take much rotation of the objective lense to change the parallax distance.

 

[Dogleg]

I've done it many times; mostly to use big game scopes on 22s. There have been times that I've adjusted scopes to make them more usable at longer ranges by finding a better compromise distance to set them at.

Something to consider though is that if your scope has developed a parallax issue is that it is both a problem and a symptom. Since the chances of someone sneaking in at night with a filter wrench are slim, its a pretty good guess that since the objective carrier never moved, something else must have shifted.