Rifle Scopes Parallax questions

[m1ajunkie]

I have a question I believe I know the answer to but I'm not 100% sure.

Lets use 300yds for example with a NF 3.5-15x scope. If I set my scope to parallax free at 300yds, then move to 500yds and adjust accordingly, will the parallax setting for 300yds be the same spot orginally found.

What I'm asking is, is the 300yd parallax setting always going to be the same point on my knob? Likewise will 500yds always be the same position? Can I find the correct value and then mark the knob to make it easy to set the parallax?

Also, why does my leupold mk4 2.5-8x mr/t scope not have a parallax adjustment? I don't believe it has ever been an issue, but why does it lack the knob while higher power optics have the adjustment?

 

[dcjs]

Re: Parallax questions

Parallax free distance will change with atmospheric conditions because the air between the target and the scope acts as a "lens" that changes its properties with changing temperature, pressure, humidity etc. Also, temperature changes to the scope itself can change the position of the lenses minimally due to expansion/contraction of the materials used. Especially at longer ranges the differences between the position of the focusing element are very, very small, and the influence of atmospheric conditions grows bigger, so you really shouldn'n mark your parallax knob for say 600 and 700 meters and expect those numbers to be correct every time. They won't.

Parallax markings are roughly comparable to a generic ballistic reticle or BDC turret, meaning you'll get reasonably close under most conditions, but the correct way to do it is to take the current conditions into account, which is fortunately a lot easier with parallax adjustment than it is with bullet drop - just dial until your reticle doesn't move on target when you move your head.

Nothing wrong with putting marks on the parallax knob for quick reference, but remember that for critical work, you shouldn't rely on them completely.