Rifle Scopes How far off is your parallax adjustment?

[ajridgedell]

I know many times the distance indicated on the parallax knob doesn't correspond exactly to when the image is parallax free and that "this is no big deal," but I am curious how far off other scopes are and what is actually the cause of this error? Of the three scope I can think of off the top of my head that I have shot a lot with: SB PMII 5-25 at 100 yards set knob to 130ish and at 400 yards and beyond I set it to infinity. vortex viper HS LR 4-16x50 was pretty much parallax free at the exact ranges indicated. Viper PST 6-24x50 at 100 set knob to 80 yards and at 600 yards set knob to about 500.
Is there a trend for certain scope models to be off in a certain direction? There doesn't seem to be a trend for my eyes to be off in a certain direction. I have learned how to deal with it but I am curious what other shooters experiences have been and what they have found to contribute to this error.

 

[nexusfire]

I hope that this doesn't offend you, but is your ocular adjusted properly? How did you do it?

 

[ajridgedell]

doesn't offend me at all! I usually look through the scope at something that my eyes wont focus on and adjust the ocular till the reticle is as crisp as possible and repeat several times. I have repeated my ocular adjustment in several different ways and always come back to the same adjustment (which i usually mark or take note of). Interesting note about my ocular adjustment is that on all my scopes it winds up being fairly close to adjusted all the way in. Probably about 1/3 turn out. I don't wear any prescriptions and have had my eyes checked throughout my life.

 

[Nik H]

I don't pay any attention to the numbers. They are all off IMHO. My S&B, NF, USO and Khales are never that close but the image is parallax free.

I believe some manufacturers like Tangent Theta have eliminated numbering exactly for this reason.

 

[nexusfire]

Turn your parallax to infinity and your zoom to max. Look at the sky and adjust your ocular until the reticle is crisp.

 

[Birddog6424]

I'm showing the 80 yard mark on the parallax knob at 100 yards, but by the time I get to the 300 yard mark on the knob, it's lined back up and pretty accurate.

That's pretty much every XTRII I own.

 

[CSTactical]

A lot of time the #'s do not line up to the actual distance your at. There are a lot of factors to take into account such as diopter and environmental conditions.

Mike @ CSTACTICAL

 

[ajridgedell]

A lot of time the #'s do not line up to the actual distance your at. There are a lot of factors to take into account such as diopter and environmental conditions.

Mike @ CSTACTICAL

Interested in understanding how environmental affects parallax. I remember reading somewhere about may needing to adjust the ocular in different extreme environments. Is it how light travels, such as mirage that can affect it, or maybe the internals of the scope that change in different temps?

 

[scudzuki]

Incorrect ocular adjustment does not introduce parallax.
Parallax is eliminated when the image focuses directly on the reticle plane, not in front of or behind it.
Once parallax has been dialed out, if the diopter is incorrectly set, the image and the reticle will both be out of focus, as they are then at the same distance from the shooters eye.
I have used this fact to fine tune a diopter that seems to be in perfect focus but the image is not in focus when parallax has been dialed out. In that case I tweak the diopter until the image is also in focus.
With a properly adjusted diopter, the image should snap into focus at the exact same adjustment point of the parallax (side focus) knob where parallax between the image and reticle have been eliminated. At that point the reticle is also in focus by definition because, again, the focused image is at exactly the same distance from the shooter's eye.
From that point forward, once the image is in focus, there's no parallax. Focus and fire.

 

[JMGlasgow]

I have to have the parallax set to 175 to be parallax free at one hundred. And after 300 yards I'm adjusted past infinity. Vortex Razor 2 3-18x50.

My thoughts on the numbers on the parallax knob are if they don't represent the distance correctly, or remotely close, why have the numbers there in the first place?

My Steiner Military 4-16 is spot on at all distances marked, and so is my gen1 Viper PST.

 

[Mordamer]

My NF ATACR F1 4-16x42 has to have the paralax set at about 70 to be paralax free at 100 yards. I'll have to check some of my other scopes. I need to be more careful with this when shooting PRS stages. I usually just set it to what the distance is and go. I probably should check at every distance and record what setting is paralax free at every distance.

 

[ajridgedell]

My NF ATACR F1 4-16x42 has to have the paralax set at about 70 to be paralax free at 100 yards. I'll have to check some of my other scopes. I need to be more careful with this when shooting PRS stages. I usually just set it to what the distance is and go. I probably should check at every distance and record what setting is paralax free at every distance.

Same here, I haven't paid very close attention to it during matches, but I'm thinking it is an important piece that needs more attention. Obviously you don't have the ability to bobble you head around to see if your parallax free off a barricade or other awkward position, and you can't always get perfectly behind the scope in some positions so parallax becomes more important.

 

[ajridgedell]

Incorrect ocular adjustment does not introduce parallax.
Parallax is eliminated when the image focuses directly on the reticle plane, not in front of or behind it.
Once parallax has been dialed out, if the diopter is incorrectly set, the image and the reticle will both be out of focus, as they are then at the same distance from the shooters eye.
I have used this fact to fine tune a diopter that seems to be in perfect focus but the image is not in focus when parallax has been dialed out. In that case I tweak the diopter until the image is also in focus.
With a properly adjusted diopter, the image should snap into focus at the exact same adjustment point of the parallax (side focus) knob where parallax between the image and reticle have been eliminated. At that point the reticle is also in focus by definition because, again, the focused image is at exactly the same distance from the shooter's eye.
From that point forward, once the image is in focus, there's no parallax. Focus and fire.

good explanation, thanks

 

[ajridgedell]

I have to have the parallax set to 175 to be parallax free at one hundred. And after 300 yards I'm adjusted past infinity. Vortex Razor 2 3-18x50.

My thoughts on the numbers on the parallax knob are if they don't represent the distance correctly, or remotely close, why have the numbers there in the first place?

My Steiner Military 4-16 is spot on at all distances marked, and so is my gen1 Viper PST.

Hmm... market for custom laser engraved parallax knobs now??? I would probably buy one if they're reasonably priced.

 

[Nik H]

Provided that you shoot at roughly the same temperature.

I have found that the setting is different when shooting at warm versus cold temps. Doesn't matter what brand I own, it is all a bit different.

 

[Rob01]

Have only had one scope that was even close. The numbers are a guideline and that's why some companies just put dots or other marks from large to small as they can't get them 100% correct. Don't worry about the numbers.

 

[DDT]

parallax error pop up with more magnification you are using. For example SB PMII 4-16x50 is very forgiving with parallax and knob marking is spot on at a sample I am working with. But with more zoom we are using and closer distances we are shooting, parallax become picky and sensitive for setting (and diopter focus) - my personal sample of NF ATACR F1 7-35.

(Diopter adjusted at max zoom ratio 35x, parallax set to infinity, scope pointed to the blue sky or white light wall in room).

 

[Vodoun daVinci]

Mine is off by a bunch. I turn it until the image is crisp and shoot. Works perfectly. Spent a lot of time on the diopter and getting a crisp image from a snap look. No parallax.

VooDoo