Parallax Adjustment

[camies 1]

This is a bit long winded but bear with it as it might just save you money.

 

There are loads of descriptions on what parallax is so I'm not going into it in depth here.

There are however two types of telescopic sights one uses a fixed parallax and the other is adjustable (sometimes called AO or adjustable Objective).

Fixed parallax sights are set to work at a nominal range typically 20-25 yards for scopes designed solely for airgun only, 40 yards for rimfire and shotguns, and 100 yards for the rest. (Check your manufacturers data).

 

On some forums there are instructions on how to re-parallax fixed scopes to suit airgun hunting at round 30-35 yards.

The instructions are not wrong BUT there is a danger that it will in time ruin the scope.

 

These instructions call for you to break the seal on the object lens (one nearest the target) and adjust it to give a sharp 'focus' at that range. The problem is that most scopes are filled with an inert gas called Nitrogen during manufacture and it's job is to keep the optics free of moisture and other impurities.

Open the scope tube to play around with the lenses and out goes the nitrogen and in comes air which contains moisture (damp).

 

Going from your warm house to the field is a steep tempreture drop and that causes the moisture inside the scope to condense to water. Results vary but if you can see fogging, moisture is in the scope and corrosion will follow. Etched reticules are very easily damaged by moisture as is the fine adjusters in the scope.

 

That's it. Again, the instructions I've read on adjusting the parallax are not necessarily wrong but could be dangerous in the long run to your pocket.