Question on scope

Norski · 08-13-2006, 07:04 PM

Looking at a 3X9X40 Simmons scope, it has on the end bell from 25 yards with adjustment out to 1000 yards, what is this adjustment for??? sounds like a dumb question, but if you don't ask yell never know.
Thanks "Norski"

baltz526 · 08-13-2006, 07:25 PM

paralax focus.

raptorschild · 08-13-2006, 07:56 PM

If you are looking out farther you need to adjust that thing out farther as well. You'll get a clearer look. Also if your hunting in close you'll need to adjust it down to get a clear shot in tight. I usually leave mine at around 100-200 depending on what kind of range i'm comfortable at.

Killertraylor · 08-13-2006, 08:49 PM

That's called an adjustable objective lens (AO) and it will help remove the parallax from your scope at various ranges. You rarely see them on a 3x9 - usually they are on higher power scopes - I think the lowest "top end" power I've seen an AO on is 12 power. Most of my 4.5-14's have the AO. I leave it set on 100 most of the time - on the Zeiss Conquest, the focus is on the side of the scope, so it's easier to adjust when you are hunting. If you want to know more than you ever wanted to about scopes and which ones to buy, go to www.swfa.com and read their forums. Good luck!

Norski · 08-14-2006, 06:07 AM

Thanks Killertaylor for the site, lots of good info, again Thanks Norski.

Hunt'nFish · 08-14-2006, 08:31 AM

Parallax, what it is it?
Parallax is when you have objects in differant focus planes. The object your viewing is in one plane and the reticle is in another.

So, who gives a hoot. Why is it important?
Say you have a 7mm Rem Mag with a Tasco 3-9x40mm scope mounted on it. So you shoot it at 100yds...~3" high and it's grouping very well...near moa, or 1.00" groups. You move out to 300yds expecting something close to 3" groups and you shoot 6-7" groups. WHY not 3"? One reason can be parallax.

Parallax is the apparent movement of the reticle w/ respect to the object when you move your eye around a little. This means the object and reticle are slightly out of sync. So everytime you took your head off the stock to look at the target & put your head back down on the stock, your eye was not in the exact spot as the previous shot. Parallax error made you move the rifle slightly to re-line up the target and reticle for the new eye position and BANG, the bullet goes to a different spot.

Most of the time it's not really very important for ranges under 200yds & your basic 3-9x scopes. Simply because most modest magnification scopes have fixed objectives that are preset at the factor to be parallax free at 100-150yds and the error is minimized by the relatively short distances..

However as ranges get father and the scopes get higher magnification, the error is magified. This is why most scopes from 4-12x and up have adjustible objectives (AO). If your shooting longer distances, best to set it to the appropriate setting.

So next time your out with your rifle check for parallax, look at some distant target and wiggle you eye around and not how the crosshairs move........something to think about.
Hunt'nFish

Norski · 08-14-2006, 06:01 PM

Thanks Hunt&fish

Hogwild · 08-14-2006, 06:22 PM

Hunt'nFish summed it up very well.

When it comes to parallax I have found a surprizing number of hunters who don't know what it is or how to check for it or how it can effect their down range groups. Parallax can cause you to pull your hair out if your scope has it and you don't know how to check for it. They usually end up just blameing the gun or the ammo for poor groups, which can be the case as well.

adobe wall · 08-14-2006, 07:10 PM

Hunt'nFish put up a good accurate description of parallax.

Generally the parallax error is greatest up close, past 250 or 300 yards it's minimal. Learning to keep a very consistent cheek weld on the rifle minimizes it if you don't have the objective lens adjusted properly. Odds are very good that the settings on the scope will not be what your eye requires so don't kid yourself into thinking that dialing in 200 yards on the objective is correct 'cause that's what your rangefinder is telling you. The actual setting may be well off from what the objective is marked.

As if all that ain't enough, you can get overly concerned about it and blow a shot at a critter if you're more worried about twisting the objective lens of the scope than you should be. There are things that are more important, like getting a good stable shooting position. Set the parallax at 2 or 3 hundred yards, thereabouts, and generally fergit it while hunting. If you get a 30 yard shot the parallax won't be right- the crosshairs will move as you shift your head- but guess what, you'll still kill the everlivinell outta the deer. An adjustable objective is much more of an interest to varmint shooters and target shooters, that's why there are a holy plethora of hunting scopes that have fixed objective lenses.

If you want to see how much you are "risking" with parallax error, set the scope for around 50 yards, then put up at target at 200. Do the "head bobbin'" test- move yer head around- and see where the crosshairs end up. That's how much you may be off, generally. Now set it at 200 yards and try the same thing with a target at 50 yards. Yes there is an error, yes it can be significant, but generally not enough to cause heartburn at most hunting distances. It will most assuredly screw up a good group if you are shooting at paper and don't know how to keep your head in the exact same place on the rifle stock for each shot.

jmho, aw