Parallax questions

Fret

USAF Retired
Nov 14, 2017
53
4
8
N Idaho
#1
When a scope's parallax adjustment is adjusted for the best focus does it mean the parallax error is taken out at that point? Are there some high end scopes that have the parallax correct when the sight picture is out of focus? How are the Vortex AMG and Razor Gen 2 in this area? Thanks!
 

Lowlight

HMFIC of this Shit
Staff member
Apr 12, 2001
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#2
There are other factors that go into the Focus / Parallax, your eye sight is one of them

Setting up the scope correctly is an important factor, so it depends on your level of competence too.

Any scope can be off, you might get 100 replies that says the Vortex is great, and another 100 that say the focus is soft with that brand. There is a reason most companies keep the yard lines off the parallax, number 1 is the reason you posted. Because it just depends.

Vortex is a quality company, this is not a common consideration when you look at the big picture
 
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scudzuki

Gunny Sergeant
Jul 1, 2012
1,990
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Philadelphia suburbs
#3
Unless there is something wrong with the scope, once the diopter has been properly adjusted to where the reticle is focused to the shooter's eye, when the target image is focused by adjusting the SF/parallax, there should be no parallax error.

Understand that the SF/parallax adjustment moves the focal plane of the image forward and back relative to the reticle plane. When the image plane is at the same distance from the shooter's eye as the reticle plane, there is no parallax error.

In my experience, it's possible to have the diopter (eyepiece) adjusted to where the reticle seems to be focused, but when the image is focused also, moving my eye side to side demonstrated parallax error. When I've experienced that, I've adjusted the SF until parallax was eliminated, then adjusted the diopter until the image was in focus without the reticle still moving out of focus. I never have to touch the diopter again. That one time fine tuning fixes it for me; once the image is focused, there is no parallax error regardless of magnification or distance.
 

Fret

USAF Retired
Nov 14, 2017
53
4
8
N Idaho
#4
Thanks guys for the great info. I didn't think about the effect of adjusting the eyepiece. If the parallax seems off after focusing, I'll work on the eyepiece. Thanks again!
 

wjm308

Send it!
Nov 30, 2012
1,049
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Black Forest, CO
#5
Don't always count on the "perfect focus" to mean parallax free, you can have what you think is an in focus image but still have parallax slightly off. If you adjust your side focus (SF) as Joe mentions above and then wiggle your head slightly and you see the crosshairs move from side to side from your Point of Aim (POA) then your parallax is off and needs to be adjusted; however, if your crosshairs stay right on target no matter the movement then you have set your parallax appropriately.

Setting your diopter correctly can also affect your focus and this is where the waters get muddy. I have tried the sky trick, I've tried the illuminated reticle in the dark trick and I always seem to still have to fiddle with it some, @hk dave recently posted in his TT comparison thread and I'm going to try this method next:

Diopter Adjustment

I feel like it is important to note that with First Focal Plane reticle scopes, your diopter setting can be crucial. It can make the final difference in image quality and whether your optimum point of optical sharpness coincides with it also being parallax free.

There are quite a few posts and “tutorials” on how to do this correctly, from pointing the scope at a clear blue sky to using the illumination in a dark environment.

The only issue I’ve had with these methods is that despite being middle aged, my eyes still focus very quickly and it’s difficult for me to NOT get a sharp reticle.

I reached out to a snipershide member about a problem I was having with my TT, and he explained how he set his up.

So following his lead, I essentially set up a target and used the parallax knob to get the sharpest image possible. I then adjust the diopter to get the sharpest reticle possible then check for parallax. I did this back and forth until I got a parallax free image with the sharpest image possible and sharp reticle. Then tested parallax at different distances to be certain.

I’ve found great success with this method and gave me some relief as I was starting to get concerned that I had a bad TT.

All 5 scopes have euro style fast diopter adjustments. What this means is, it only takes a few turns to adjust the diopter, as opposed to 30+ turns.

I prefer the euro style adjustments considerably more as I have a difficult time even get a reticle to turn blurry on the slower/finer adjustment type diopters.

The TT, Minox and NF have locking diopters, which I think is nice to have so they definitely have an advantage over the others. The S&B and Vortex lack this option however I simply use a sharpie to make a witness mark on the scope so if I ever turn the diopter by mistake, It’s easy to get back to the exact point I want it to be.
 

pmclaine

Gunny Sergeant
Nov 6, 2011
4,541
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MA
#6
Thanks guys for the great info. I didn't think about the effect of adjusting the eyepiece. If the parallax seems off after focusing, I'll work on the eyepiece. Thanks again!

Wait one...

Before doing anything scope set up requires you adjust the eyepiece or diopter.

Do this looking at a neutral bacground, clear sky or white sheet, and only with the purpose of making the reticle clear and sharply defined. Do this with quick looks and breaks so as the instant your eye is in the scope the reticle is clear, than lock it down and never touch it again. (see footnote)

When looking at your target than use parallax adjustments only, never go to the diopter to fine tune.

First understand parallax...

Stand arms length from a light switch.

Hold your finger in front of your eye, halfway to the light switch and focus the tip of your finger on the end of the switch. Marry the tip of your finger on the switch. Now move your head.

What happens?

The switch and finger move in directions opposite of your head movement. The two images are no longer married. You have parallax error because your finger and the switch tip are not on the same focal plane.

Now reach out and put your finger on the tip of the switch. Marry them together.

Now move your head.

What happens?

Switch and finger stay together no matter where your eye/head moves. They are on the same focal plane with no parallax error.

Other factors will play a role. You may find you dont get the clearest scope picture but when you bob and weave behind the scope to check for parallax error your crosshair and target stay married.

Accept the minimal loss of clarity for elimination of parallax.

Decide if you are going to shoot with prescriptions or without when you set your diopter.

Footnote - you can change your diopter if your eyes change perscriptions but do the complete scope setup over again. The diopter is not a mid shooting session adjustment for clarity.
 

Nik H

Constantly Learning
Jan 22, 2014
2,444
148
63
RI
#7
Wait one...

Before doing anything scope set up requires you adjust the eyepiece or diopter.

Do this looking at a neutral bacground, clear sky or white sheet, and only with the purpose of making the reticle clear and sharply defined. Do this with quick looks and breaks so as the instant your eye is in the scope the reticle is clear, than lock it down and never touch it again. (see footnote)

When looking at your target than use parallax adjustments only, never go to the diopter to fine tune.

First understand parallax...

Stand arms length from a light switch.

Hold your finger in front of your eye, halfway to the light switch and focus the tip of your finger on the end of the switch. Marry the tip of your finger on the switch. Now move your head.

What happens?

The switch and finger move in directions opposite of your head movement. The two images are no longer married. You have parallax error because your finger and the switch tip are not on the same focal plane.

Now reach out and put your finger on the tip of the switch. Marry them together.

Now move your head.

What happens?

Switch and finger stay together no matter where your eye/head moves. They are on the same focal plane with no parallax error.

Other factors will play a role. You may find you dont get the clearest scope picture but when you bob and weave behind the scope to check for parallax error your crosshair and target stay married.

Accept the minimal loss of clarity for elimination of parallax.

Decide if you are going to shoot with prescriptions or without when you set your diopter.

Footnote - you can change your diopter if your eyes change perscriptions but do the complete scope setup over again. The diopter is not a mid shooting session adjustment for clarity.
^^^^This

I just got a NF 7-35 with the MIL-C reticle. I found the parallax very difficult to set up compared to my S&B, Khales, USO. I struggled with the fact that even though the reticle was very sharp based on the diopter adjustment, there was always a bit of parallax visible when the target was in sharp focus. I tried all of the methods to setup diopter but as someone else said, my eyes focus quickly. I was really disappointed that I could never eliminate the parallax when the image was sharp.

I called NF and explained the situation I was having and suggested that the scope may need a once over. The gentleman spent some time with me going over setup and method. He explained exactly what @pmclaine described above. Image will not necessarily be at the sharpest focus when parallax is eliminated. I said what the hell and tried it. Guess what...he was right. Parallax was eliminated and the focus was almost at its sharpest.
 
Mar 23, 2010
397
24
18
North Carolina
#8
When adjusting the diopter make sure your eyes are relaxed like gazing in the distance. Do not focus on the reticle like on letters in a book.

Also the dimmer the light the more precise the adjustment will be as the depth of field decreases with larger pupil size.

When it is pretty dark -quarter moon or so- you want a -1 diopter setting as the more light sensitive rods in the eye are in a different focal plane than the color resolving cones (google fovea centralis).
Then look around the target in a circular fashion, don't focus on it. That's how we shoot boar at night in Germany where NVG is not allowed for aiming.
 
Last edited:
Likes: Slo cat
Feb 20, 2004
76
1
8
62
Atlanta,GA
#9
great question. I have adjusted parallax according to the numbers on the dial and where the image is sharpest. most often they don't match up.

then I have moved my head around to see if the reticle drifted on target and it usually does. this leads me to believe that with my scopes I have tried, that sharp focus, parallax, and the numbers on the dial do not correlate exactly....
 

Fret

USAF Retired
Nov 14, 2017
53
4
8
N Idaho
#10
Thanks everyone for the education. I guess the bottom line is to always move my head around after focusing to see if the parallax is right on and adjust until there is no more movement.
 

918v

Manipulator of Variables
Jul 15, 2007
1,557
10
38
Miserable CA
#11
^^^^This

I just got a NF 7-35 with the MIL-C reticle. I found the parallax very difficult to set up compared to my S&B, Khales, USO. I struggled with the fact that even though the reticle was very sharp based on the diopter adjustment, there was always a bit of parallax visible when the target was in sharp focus. I tried all of the methods to setup diopter but as someone else said, my eyes focus quickly. I was really disappointed that I could never eliminate the parallax when the image was sharp.

I called NF and explained the situation I was having and suggested that the scope may need a once over. The gentleman spent some time with me going over setup and method. He explained exactly what @pmclaine described above. Image will not necessarily be at the sharpest focus when parallax is eliminated. I said what the hell and tried it. Guess what...he was right. Parallax was eliminated and the focus was almost at its sharpest.
Seems NF ATACR is the only scope with this issue.
 

Lowlight

HMFIC of this Shit
Staff member
Apr 12, 2001
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545
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Base of the Rockies
www.snipershide.com
#13
You cannot watch the reticle when you make the adjustments. Your eyes will adjust.

You have to look away and come back to the reticle after the adjustment. This is why guys will say a reticle will blur and split when they look at it, because they watched the reticle when they were focusing it.

Image focus is definitely secondary, yes we'd like it perfect to match a perfect parallax free system but conditions don't always allow for that. Sometimes you have to suffer a tiny bit of a soft focus here and there
 

Nik H

Constantly Learning
Jan 22, 2014
2,444
148
63
RI
#15
My S&B is more forgiving and I haven't noticed it. My other NF ATACR 4-16 F1 also doesn't exhibit it. That is why I was perplexed.

Now that I know about it, I can say that two of my other scopes I own show it. My Khales is no different than the NF. Khales checked it and all was good. My USO SN3 also exhibits it.
 
Feb 13, 2017
295
9
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#19
The thing about setting the diopter, as some have mentioned, is you shouldn't focus ON the reticle. Your eyes have the ability to focus at varying distances. And it can be hard to consciously control this. That means you can actually set the diopter so the reticle is in focus, but it's not at the "right" focus. If your eyes had a manual focus control, you would want to fix them focused at infinity when you set your diopter. Why? Because that is where they are the most relaxed and free of strain. That means when you're behind the rifle, there is less muscle contraction and less eye fatigue.

Some say to aim scope at the sky and all that. But I've tried it many times and I just wind up focusing on the reticle. You need an object for your eyes to look at. A stark blue or white background doesn't work for me. That is why I told HKDave my method of setting diopter and parallax, that works for me.

I'll do the typical aim at a wall or sky trick and get it as good as I can. Then I'll aim at some distant building out past 800 yards or so. But first I'll look at that building with my naked eye, focus my eyes on it. Then close my eyes, open them to make sure the building is still focused, and then bring the scope up to my eye and see if the reticle is still focused. If not, I'll slowly adjust diopter until it is while my eyes are still relaxed and focused on something at "infinity." This lets me focus the reticle to my eye, rather than focusing my eye to the reticle.

Now... for parallax, I'll get behind my rifle and check parallax at whatever distance. Get target perfectly sharp with parallax control. And then make my eyes focus on the target, so that my eyes are relaxed. Is the reticle still focused? If not, adjust diopter. Check for parallax. Rinse repeat until both target and reticle are perfectly focused. Only need to do this once. After that, you're good to go.

Why do I do this?

Because your eyes can focus on an unfocused reticle, making it appear focused. But as Frank said above, this will cause the reticle to "split" and go blurry at some point because your eyes become tired and strained and fatigued. It's because your diopter isn't set properly but you're forcing your eyes to focus the blurry reticle so it appears sharp. You want to be able to "fall asleep" behind your rifle and look through your scope with a relaxed gaze and still have everything nice and sharp.

We talk about Natural Point of Aim. But nobody ever mentions this includes your eyes. You don't want to be forcing your eyes to focus. This uses muscle. Muscle gets tired. Tired eyes = blurry.

When you've got your scope set up like this, you aren't focusing on your reticle a few inches in front of your face. It should be like you're looking out at the horizon, miles and miles and miles away.
 
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scudzuki

Gunny Sergeant
Jul 1, 2012
1,990
22
38
52
Philadelphia suburbs
#20
The thing about setting the diopter, as some have mentioned, is you shouldn't focus ON the reticle. Your eyes have the ability to focus at varying distances. And it can be hard to consciously control this. That means you can actually set the diopter so the reticle is in focus, but it's not at the "right" focus. If your eyes had a manual focus control, you would want to fix them focused at infinity when you set your diopter. Why? Because that is where they are the most relaxed and free of strain. That means when you're behind the rifle, there is less muscle contraction and less eye fatigue.

Some say to aim scope at the sky and all that. But I've tried it many times and I just wind up focusing on the reticle. You need an object for your eyes to look at. A stark blue or white background doesn't work for me. That is why I told HKDave my method of setting diopter and parallax, that works for me.

I'll do the typical aim at a wall or sky trick and get it as good as I can. Then I'll aim at some distant building out past 800 yards or so. But first I'll look at that building with my naked eye, focus my eyes on it. Then close my eyes, open them to make sure the building is still focused, and then bring the scope up to my eye and see if the reticle is still focused. If not, I'll slowly adjust diopter until it is while my eyes are still relaxed and focused on something at "infinity." This lets me focus the reticle to my eye, rather than focusing my eye to the reticle.

Now... for parallax, I'll get behind my rifle and check parallax at whatever distance. Get target perfectly sharp with parallax control. And then make my eyes focus on the target, so that my eyes are relaxed. Is the reticle still focused? If not, adjust diopter. Check for parallax. Rinse repeat until both target and reticle are perfectly focused. Only need to do this once. After that, you're good to go.

Why do I do this?

Because your eyes can focus on an unfocused reticle, making it appear focused. But as Frank said above, this will cause the reticle to "split" and go blurry at some point because your eyes become tired and strained and fatigued. It's because your diopter isn't set properly but you're forcing your eyes to focus the blurry reticle so it appears sharp. You want to be able to "fall asleep" behind your rifle and look through your scope with a relaxed gaze and still have everything nice and sharp.

We talk about Natural Point of Aim. But nobody ever mentions this includes your eyes. You don't want to be forcing your eyes to focus. This uses muscle. Muscle gets tired. Tired eyes = blurry.

When you've got your scope set up like this, you aren't focusing on your reticle a few inches in front of your face. It should be like you're looking out at the horizon, miles and miles and miles away.
Which is why I advocate fine tuning the diopter.