Author Topic: Rifle sciopes and parallax? (Read 898 times)

Questor · « **on:** October 27, 2003, 07:52:20 AM »

What's the greatest power scope that doesn't need an adjustable objective to correct for parallax?

Graybeard · « **Reply #1 on:** October 27, 2003, 10:17:34 AM »

9X in my opinion. Most 2.5-8s and 3-9s don't really seem to have a noticeable problem. Most 3.5-10s do unless they have an adjustable objective.

GB

Zachary · « **Reply #2 on:** October 27, 2003, 10:32:54 AM »

I have never seen a scope with an AO (adjustable objective) under 10x. Conversely, most scopes that I see that are 12x or higher do come with an AO.

Zachary

Dave in WV · « **Reply #3 on:** October 27, 2003, 01:58:33 PM »

10x on a variable is the highest I've seen without it. Dave

jhm · « **Reply #4 on:** October 28, 2003, 04:31:43 AM »

A few years ago Weaver made a 3x9 vx11w that had a paralex adjustment as I have one in the safe on a ruger 77 tang 270 and it does a fine job.

JIM

Graybeard · « **Reply #5 on:** October 28, 2003, 11:00:08 AM »

We have a couple of Leupold Compact 3-9s with AO and used to have a Leupold 6X Compact with AO.

GB

Lawdog · « **Reply #6 on:** October 28, 2003, 12:31:34 PM »

I just mounted a Burris Black Diamond 4X-16X-50mm that has their new side focus parallax adjustment feature on my Ruger No.1 in .25-06. So far it really makes adjusting the focus much easier. The Posi-Lock system is great. Once you lock it nothing moves until you want it to. The more I use this scope the more I like it. Lawdog

gunnut69 · « **Reply #7 on:** October 28, 2003, 01:33:47 PM »

A lot depends on the use to which you intend to put the scope. Any 1 inch tube scope not paralex corrected for 50 yards or so needs the adjustment if used on a 22 rimfire, or any really close range target. Some airgun scopes as low powered as 4x have parallex adjustment.. A lot of the old 3X9 Weaver steel tube scopes had the adjustment and they make excellant candidates for use on 22 rimfires.

Iowegan · « **Reply #8 on:** October 29, 2003, 06:37:53 AM »

Parallax is the least understood and one of the most important scope parameters. Explanation: Place your rifle in a vise or cleaning jig where it can be aimed down range, hands off. Adjust position until crosshairs are dead on target. Parallax is evident when the crosshairs appear to move on the target when the rifle is stationary and your eye position moves. All scopes have some parallax, however it becomes more evident at 9X and above. The more powerful the scope, the more parallax you will experience. This is bad because you must have the same exact hold and view for each shot to keep the rifle on target. Many scopes above 9X have a parallax correction ring or side dial that is calibrated in yards/meters. If your target is at 200 yds, make sure the ring is set for 200 yds, otherwise you will still get parallax. This will keep you busy when hunting. Many shooters think their rifle shoots bad groups when the blame is really on scope parallax.

Lee D. · « **Reply #9 on:** October 29, 2003, 07:29:53 AM »

Iowegan,
Also I have found that the yardage marks on the cheaper scopes (Bushnell etc.) are not neccessarily accurate. You are better off focusing the parralax with your eye than using their yardage marks.

eroyd · « **Reply #10 on:** October 29, 2003, 08:05:45 AM »

Will not having the correct parallax setting effect the point of impact? It appears in my scope that the adjustable objective also effects the target focus and sometimes that focus does not alway agree with the numbers that line up on the bell. This occur's in my Burris and Weaver Scopes.

gunnut69 · « **Reply #11 on:** October 29, 2003, 09:20:03 AM »

Adjusting parallex is actually adjusting where the reticle is in focus. No matter how it seems the reticle can only be in focus at one distance. When the reticle and the target are at different focal planes they will appear to move in relation to one another as the eye that's viewing them moves. This movement can alter the relationship between the reticle(bullets point of impact) and the target. Higher magnifications or shorter target distances will make the effect more pronounced, as will smaller targets. The targets size allows for less aiming error.. Adjusting the parallex should have no bearing on focus.. most telescopes have a focus adjustment on the eyepiece end of the scope. It is unlocked and turned in or out to alter the visual focus of the optical system. The Parallex adjustment alters where the reticle is focused. If it alter the optical focus perhaps a call the the manufacturer might be in order?

Iowegan · « **Reply #12 on:** October 29, 2003, 10:32:55 AM »

Eroyd,
Good observation. Yes, parallax will have an affect on point of impact. If your scope is set improperly, the cross hairs can drift as much as several inches at 100 yds, so will your groups if your eye position changes. Next time you go to the range, try the experiment in my previous post. Set your AO ring to 100 yds and see if it is really calibrated. If you have a range finder, try sighting at different distances. What you are looking for is cross hair drift, not actual focus. I tested several scopes and found the distance marks were fairly close to proper parallax correction. On some scopes, the focus was slightly off when the parallax was properly adjusted. My Leupold Vari-X 3, 4.5X14 50mm, seemed to track best and maintained proper focus at 100-500 yds. A BSA Contender 3-12X 50mm was the worst. The marks were way off and the focus didn't track well. I have a Burris Full Field 2, 3.5-10X, 50mm that doesn't have an AO. It's about 2 " off at 75 yds, 1" at 100 yds, dead on at 150 yds, and 1" off at 200 yds.

Lee D, Focusing "with your eye" may satisfy target clarity but has little to do with parallax. Again, try the experiment above. Adjust for best focus then see if you get cross hair drift.

Gunnut, On some scopes, the parallax adjustment has a definate affect on focus. I think they move different lens elements. For sure more noticable on cheaper glass. It takes some pretty good optics to make the retical focus and optical focus track properly.

Lee D. · « **Reply #13 on:** October 29, 2003, 01:06:08 PM »

Iowegan,
I will try that but if I find what you said to be right for my scopes I still prefer to see clearly and will put up with the little extra paralax if need be.