How far is it "normal" for parallax to be off for Vortex Strike Eagle 5-25?

[LostInTranslation]

I've noticed that my Vortex Strike Eagle scope is a bit off on parallax - at 200 yards I have to set them somewhere to 150-170. I've decided that by fixing gun/scope on target and moving my head a bit seeing if reticle and target move relative to each other. At 200 yard setting (on dial) they did, and at one I came up with they did not. Target was still fairly sharp.

Is what I am seeing normal? Would make it interesting when distance varies - would have to make a parallax correction table that is scope specific or take accuracy hit. My understanding is that one of my contributing factors is inconsistent head placement (working on it) and parallax error amplifies it...

Is there a rule of thumb how much parallax error can contribute to inaccuracy?

Thanks

 

[Evintos]

The parallax knob markings can be considered a rough guideline. The numbers and lines are calibrated at factory specific conditions but real world environmental conditions and your diopter setting will change how much parallax adjustment is actually needed - resulting in the parallax markings on your scope rarely being 100% right.

 

[MDof2]

If I know I'm shooting at 300 I'll visually set the parallax knob at 300, then put eyes on target and adjust from there to get focused. I don't pay attention to the knob markings at that point.

 

[gconnoyer]

The parallax knob markings can be considered a rough guideline. The numbers and lines are calibrated at factory specific conditions but real world environmental conditions and your diopter setting will change how much parallax adjustment is actually needed - resulting in the parallax markings on your scope rarely being 100% right.

This.

They are a guideline/starting point to get you close. Your indiviaul scope "settings" will change what the knob is correct at.
A lot of manufacturers use a non numbered scale to avoid this because people think something is broken if it doesnt line up.

 

[LostInTranslation]

The parallax knob markings can be considered a rough guideline. The numbers and lines are calibrated at factory specific conditions but real world environmental conditions and your diopter setting will change how much parallax adjustment is actually needed - resulting in the parallax markings on your scope rarely being 100% right.

Thank you for feedback - but...

I thought parallax adjustment brings target focal plane to where reticle is. The only factor would be distance involved and physical build of scope. Diopter adjustment would allow reticle/target focus/sharpness. So with properly adjusted parallax I'd expect visual alignment of reticle and target to remain same as I move eye. They may be out of focus - and that'd what diopter adjustment would fix.

Am I mistaken? Is diopter setting having notable impact on parallax? If so - that could explain what I am observing as I did change diopter settings from factory...

 

[Evintos]

Thank you for feedback - but...

I thought parallax adjustment brings target focal plane to where reticle is. The only factor would be distance involved and physical build of scope. Diopter adjustment would allow reticle/target focus/sharpness. So with properly adjusted parallax I'd expect visual alignment of reticle and target to remain same as I move eye. They may be out of focus - and that'd what diopter adjustment would fix.

Am I mistaken? Is diopter setting having notable impact on parallax? If so - that could explain what I am observing as I did change diopter settings from factory...

To get slightly more in depth about the environmental conditions, the role environment plays would be for example changing scope temperatures that affect the internal adjustment mechanisms or cause mirage that can affect perception of distance, lighting conditions such as intensity (sunny, cloudy, noon, dawn dusk, etc) and direction that affect how the lenses of your scope refract light, amongst other things such as humidity. All of which basically affect how light enters your scope, passes through all the lenses and into your eye.

The diopter focus should only be used to focus your eye to the reticle. Set parallax to infinity, look at blue sky or white wall, make subtle adjustments looking away then looking through optic until reticle is crisp. If you constantly look through your scope as you're making the adjustments your eye will compensate for the slight focus variation without you knowing. You shouldn't have to touch the diopter again until your eye prescription changes.

With your diopter set correctly the parallax will bring the focal plane of the target and reticle inline with each other and the reticle and target image will be crisp and clear (exception - mirage distortion). The diopter should not be used to fix a blurry target image.

 

[Johnny00K]

You would be better off to just take a sharpie and get rid of all the numbers on the knob. Those numbers are worthless. Adjust it until it looks right at whatever distance you are shooting and don't think about it again.