Understanding parallax in rifle scopes
You're looking through a scope with no parallax adjustment, placed 17m from the target. Note the shift of the crosshairs on target as your eye moves off-centre

Personal problems with parallax, and how to solve them

Whenever a hapless young soldier fronted his unsympathetic mates or his seniors about things that pissed him off, he’d be told, “Sounds like a personal problem. Go see the padre.” 

In my local rifle association, the MRCA, a few of us crusty military rifle shooters dreamed up a couple of small-bore service rifle shoots to occupy us in a newly reopened 50-metre range. One, a British invention, the Mini Methuen, was shot at a variety of very challenging targets on an A2-sized card at a short 25 yards (23m). We permitted scoped and iron-sighted categories. 

Understanding parallax in rifle scopes
This section of the Mini Methuen target shows parallax error at work; Eye perfectly aligned behind scope for first (left) target; a little mis-alignment of the eye for the second (middle) target), and complete mis-alignment in the final one. In each case, the shooter saw the crosshairs lined up on bullseye

The five rings or zones were about a centimetre or less for prone and there were strict time limits, making the whole shoot a challenge. At its completion we were breathing hard and appreciating a rest. 

Due to complaints to the padre of degree of difficulty, it is now rolled out only occasionally for very competitive types.

Good guys with iron sights on accurate rifles were not as disadvantaged as one may think, because shooters using standard fixed-parallax hunting-style scopes on their .22s would lose flyers out of proportion to their proven abilities. 

Talking about this with a knowledgable friend, he confided that significant parallax error at very short range will throw shots further than you may think possible.

The top image shows correct parallax, where the projected target image is in the same focal plane as the scope reticle. The bottom two images explain uncorrected parallax error. Moving your aiming eye away from the ocular lens centre will result in a change in point of impact.


A simple definition of parallax: a noticeable shift in reticle placement while looking through your scope at different angles. 

If you notice your reticle is moving off target while changing your viewing angle, that’s parallax. You need to adjust for parallax to ensure your reticle will be accurate at any viewing angle.

Or alternatively: “Scope parallax is an inconsistency in the view that you see when you look down the rifle scope. It causes the crosshair to move across the target when you shift your eye position. This means the reticle will not accurately reflect where your rifle is pointing,” which will result in (unwanted) shift in your point of impact.

Understanding parallax in rifle scopes
You’re looking through a scope with no parallax adjustment, placed 17m from the target. Note the shift of the crosshairs on target as your eye moves off-centre

At this stage, it is appropriate to inject the following snippet. If your eye is perfectly aligned at 90 degrees to the dead centre of the ocular lens you will not experience flyers at any range, pursuant to having an appropriate zero, as parallax error will not manifest.

BUT when you are shooting a rifle rapidly and reloading under timed pressure, while moving across a large target card from close range to engage different individual targets in sequence, two factors come into play. 

They are that your natural point of aim necessarily degrades as you will not be in as perfectly aligned as when you started. Cheek weld can change, sight picture may degrade and a scope’s parallax error WILL make a difference.

And this difference be greater at 25 metres than at 50 metres, all things being equal.

I had an old 4x Leupold hunting scope on my Brno Model 2 when I became aware of this phenomenon. I replaced it with a Leupold VX2 3-9×33 EFR (Extended Focal Range) scope and my scores improved for two reasons:

1. I could correct for parallax at short ranges and 

2. I could see where my bullets hit at 50 metres and was able to make corrections.

Understanding parallax in rifle scopes
With parallax corrected for the target’s 17m range, there is little to no apparent movement of the crosshairs if your eye is not centred in the scope


I shared this information with my shooting mates. Old hand Peter Birchall told me his scores out of 150 had improved by at least three points after using his new EFR.

A few of the boys wanted to get scopes with parallax correction after this and, not wanting to stump up several hundred smackers for a Leupold, ended up buying the Nikon ProStaff equivalents and were happy they did. 

Plenty of other parallax-adjustable scopes are available. 

Understanding parallax in rifle scopes
The parallax-adjustable objective lens of this Leupold scope permits critical correction of focus for all ranges


Most sporting optics manufacturers now market compact 3-9x or 4-12x rimfire riflescopes which come fixed at the factory to be parallax free at 50 yards (46m). These are designed to be used as all-purpose hunting scopes on .22 LR-chambered rifles as, when you are out in the long grass going after rabbits, hares or foxes, you won’t likely be adjusting back down for close-in shots. Rather, you will be engaging at typical small-game ranges from your feet to 100 metres maximum. 

Field expediency makes these scopes perfectly versatile for placing shots where they need to be over these ranges, provided the operator is doing their bit.

If you are going to shoot rimfire Field Class or reduced-range service rifle matches, however, an EFR variable scope with a handy maximum power of 12 or 16 (tops) is better.


How much error can occur due to parallax? I conducted a limited trial using the following:

  • My Brno Model 2 scoped with the Leupold EFR set on 9x
  • My Mauser M12 scoped with a Zeiss Conquest 3-9x40MC with parallax factory fixed at 100 yards
  • A Bushnell 1 Mile Arc laser rangefinder
  • A BOG Deathgrip carbon-fibre clamping tripod
  • A 4cm red circular aiming mark tacked to my back fence at 17 laser-measured metres from the turrets of the scopes
  • A couple of cameras.
Understanding parallax in rifle scopes
Testing tools: a parallax-adjustable Leupold scope (left) and a non-adjustable Zeiss. Rifles were clamped in a BOG Deathgrip tripod to ensure consistency

I started with the Brno clamped in the tripod. Turning the parallax setting on the Leupold to about halfway between the 15 and 20 marks on the objective bell, I lined up the crosshairs on the aiming mark at a little off centre towards 1.30 o’clock.

Then, I buggered around for a while with my mobile phone getting the focal length right, taking one photo hand-held as dead centre behind the ocular lens as I could manage. 

Next, I took another two pictures where the image was vignetted off centre to the left and the right.

Taking into account the size of the aiming circle, I believe that there was less than half a centimetre variance, as close as I could determine. 

Bear in mind that I did not fiddle around getting the parallax objective setting absolutely correct, but merely interpolated between the 15 and 20 marks on the adjustment ring.

I can live with that.

Understanding parallax in rifle scopes
This horrendously difficult 25-yard target shot in incredibly demanding rapid timings prompted Marcus to get an EFR scope

I replaced the Brno with the Mauser and repeated the process with the fixed-parallax Zeiss, ie, no parallax correction for 17 metres. 

It was enlightening and all I can say is that I would not like to go back to using a fixed-parallax hunting scope at close range. The crosshairs moved across the interior of the red circle with what I estimate to be more than 2cm shift from side to side. See the accompanying pictures.

This did not prove anything but the fact that a fixed parallax setting for 100 yards is unsuitable for fine, hair-splitting work at rimfire-appropriate ranges. Would I want to use it in the field after deer or dangerous game where reliability and engagement ranges stretch to 400 metres? Yes, absolutely!

I love shooting .22 rimfire rifles, specifically accurate ones that produce insane consistency out of cheap standard-velocity ammo at ranges out to 100 metres. When you get good with an accurate .22 in field positions, people will marvel at your seeming inability to miss game, large or small, with any old rifle you are carrying.

I kind of wish we had squirrels in Australia, because I could then give all of my .22s a good run in the field plugging the little varmints through the eye.




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Marcus O'Dean