Parallax Explanation

[statjunk]

Can somebody please explain parallax? Also I have adjustable objectivess on both of my Leupolds, how does this correct parallax?

Is it better to buy scopes with ao?

Thanks
TT

[Solitary Man]

Okay, I'm no techno wizard, but here's my best attempt to explain it. Parallax is the apparent movement of the reticle in relation to the target when your eye moves from side to side or up and down behind the scope. Lets say you're looking at a target 300 yards away and you move your head side to side a little bit and notice the reticle doesn't stay exactly on the same spot. That's parallax. Scopes without adjustable objectives will generally be parallax free at 100 or maybe 150 yards. So, if you're looking at a target at that distance and move your head around behind the scope, the reticle will stay on the exact same spot. Adjustable objectives allow you to change the distance at which the scope is parallax free. For the average guy who's not going to ever shoot anything over 250 yards or so an adjustable objective is not needed because parallax is pretty much a non issue out to that distance.

You can probably find a better explanation of parallax at any of the scope manufacturer's websites.

[Paul L Mohr]

That's pretty much spot on for a description. The other thing the A/O scopes let you do is shoot close up with a higher power. When you get closer than your scope is pre set for it effects it as well. Most shotgun and rimfire scopes are pre set to 50-60 yards, and others are around 100. Some companies will let you choose what you want and they will adjust it for you in thier shop.

I can shoot at 25 yards and 20 power if I want to and the cross hairs stay welded to the target as I move my head around. Most Air Gun target shooters use high power AO scopes to compete with for utmost accuracy. You have to set them up and verify the markings as well. The correct parallex isn't always what the numbers on the objective say they are.

The draw back to the adjustable objective type scopes is the focus changes at different distances and has to be adjusted. It's not to bad at the lower setting, but crank it up and 15 yards might make a difference. So these scopes work well for target and varmint type shooting, or maybe big game looong range type stuff. Where you have time to range your target and make adjustments. There is a trade off for precision I guess.

I wouldn't advise using one on a hunting rifle for big or dangerous game where you might have to make a quick shot. I tried to use one for deer hunting one season, I managed but it was sort of a pain. The next season my rifle was sporting a 3.5x10x50 with out the adjustable objective. If you have to make a quick up close shot and your parallex is set for farther a way you are screwed. You will pull it up and every thing will be blury. If you do use one, keep it on the lowest power setting and mid range objective setting, like around 100 yards or so. That way if you have to pull it up quick the picture will be pretty decent. And if you have time make any adjustments that you need. Just remember to put things back again after you shoot, or decide not to take the shot.

I have AO scopes on both my .22's and my .17HMR. My savage bolt 22 has a 4x16x50AO barska on it (Cheap, I got it used for 10 bucks!) My Marlin model 60 has a 2x7x32AO BSA air gun scope on it. And my Savage 17HMR has a 6.5x20x44AO alaskan guide scope from cabela's. But my remington inline muzzle loader sports a regular 3x9 type hunting scope for simplicity in the field. If it wasn't for the fact I hunt over a large meadow it would have a lower power scope like a 1.5x4 or something. That would be very fast and bright, perfect for deer hunting in southern MI woods.

Paul

[statjunk]

You explanation was clear. I understand now. I don't even want to understand why that is true. To me it would seem as though it should hold zero at whatever magnification. Ok maybe I do want to know.

Thanks for the info guys.

Tom

It is a thing called the F-Factor. Lets put it that way. Lots of online resources and short class's online for "classical optics". Took me 6 years.

[Paul L Mohr]

It is not the magnification that changes things, its the distance. If your scope changes point of impact at different power settings you need a new scope.

I have always wondered what the reason for the anomoly was myself, but I don't want to take six years of school to know it.

Paul

I have always wondered what the reason for the anomoly was myself,

This is a simple one. Its bad quality and high tolerance of parts. Totally different than parrallax errors. What you are talking about has to do with the eye part of the scope before the recticle. Parrallax happens after the recticle.

[Paul L Mohr]

That's not what I was talking about. I know the reason for the change of impact at different power settings. I was wondering what actually causes parallex. I know what it is, I just always wondered what made it happen and how the adjustment corrects it.

You read my post wrong, but that's ok. That's why I commented about not wanting to take six years of school to understand the physics behind it. I thought it had something to do with line of sight and focus, but I was just guessing.

Paul

[Solitary Man]

Here's a good explanation of parallax:

http://www.usoptics.com/sub_pages/parallax.php

Here's one way to explain it maybe. You know you got a magnifying glass and at one point the light is pinpointed on a object, say an ant. Well changing parralax by moving the magnifingy glass up and down. The more farther you move the glass the wider you beam is, and more chance for parrallax error.