Rifle Scopes How much of a problem does parallax at distance become on a fixed parallax optic?

[TheGerman]

Was wondering this today as I was shooting my Mk12Mod1 with a NF 2.5-10x24 on it at 700 yards. The optic has a 'fixed at 100' parallax with no further method to adjust it. I do notice at distance I can see the reticle moving a bit but was curious as to just how much havoc having such a short, fixed parallax optic is doing on shooting at distances much further than what its parallax setting is to.

Is this basically like setting any optic you have to be parallax free at 100, and then shooting 600 yards with that setting? Or is there something else to this? Why even do this?

 

[Dthomas3523]

Was wondering this today as I was shooting my Mk12Mod1 with a NF 2.5-10x24 on it at 700 yards. The optic has a 'fixed at 100' parallax with no further method to adjust it. I do notice at distance I can see the reticle moving a bit but was curious as to just how much havoc having such a short, fixed parallax optic is doing on shooting at distances much further than what its parallax setting is to.

Is this basically like setting any optic you have to be parallax free at 100, and then shooting 600 yards with that setting? Or is there something else to this? Why even do this?

@koshkin might be the better person to answer. But I’d imagine if you are directly inline behind the optic, not a big deal. If not, problems can ensue.

Have you tested it to see what distance it is parallax free to? I’d imagine that is probably close to the distance NF designed it to be used for.

 

[TheGerman]

@koshkin might be the better person to answer. But I’d imagine if you are directly inline behind the optic, not a big deal. If not, problems can ensue.

Have you tested it to see what distance it is parallax free to? I’d imagine that is probably close to the distance NF designed it to be used for.

I don't notice really anything up to about 200.

At the 685 target I was shooting today with it I could see it move. The problem REALLY becomes evident when you get off the gun to reload or let it cool and then get back on it; even the tiniest difference in anything and you're shooting a small group at a different POI.

The NF booklet says its fixed at 100 yards. I'm not quite sure why this was done; I can't see how this could benefit you at distance for the benefit of it being perfect at 100 yards?

 

[Dthomas3523]

Only explanation I have is it’s intended use us combat effective shots out to 600 or so. And the parallax at those distances isn’t enough to negate it from that purpose.

Precision shots out to 1-200 and combat effective out to 600.

 

[Diver160651]

Take any potential parallax out of play by using scope shadow. It isn’t sexy, it is old school, but it works.

 

[TheGerman]

Only explanation I have is it’s intended use us combat effective shots out to 600 or so. And the parallax at those distances isn’t enough to negate it from that purpose.

Precision shots out to 1-200 and combat effective out to 600.

Yeah,. trust me, I get that part of it.

Just not too condusive to shooting at a 9 inch plate lol

 

[FatBoy]

Take any potential parallax out of play by using scope shadow. It isn’t sexy, it is old school, but it works.

This. Back up an inch and get an even shadow all around outside of the ocular. This forces the head onto the same place.

 

[TheGerman]

Take any potential parallax out of play by using scope shadow. It isn’t sexy, it is old school, but it works.

Yes, dear.

It's just one of those things that makes you wonder, who fucking thought this was a great idea.

I'm sure there's a reason, and I'm sure its probably because I was never too worried about hitting you exactly in your 2nd shirt button at 700 yards. Then again, this is basically already 'old tech' at this point in scope evolution as well.

 

[Diver160651]

Yes, dear.

It's just one of those things that makes you wonder, who fucking thought this was a great idea.

I'm sure there's a reason, and I'm sure its probably because I was never too worried about hitting you exactly in your 2nd shirt button at 700 yards. Then again, this is basically already 'old tech' at this point in scope evolution as well.

G-

Even with the newest tech. sometimes mirage, fog, rain, snow make it hard to focus.. same for ELR.. scope shadow still helps high tech -

 

[Dthomas3523]

Yes, dear.

It's just one of those things that makes you wonder, who fucking thought this was a great idea.

I'm sure there's a reason, and I'm sure its probably because I was never too worried about hitting you exactly in your 2nd shirt button at 700 yards. Then again, this is basically already 'old tech' at this point in scope evolution as well.

There’s also the “fuck it, the g-man will buy anything we make cause we’re NF” approach?

 

[TheGerman]

There’s also the “fuck it, the g-man will buy anything we make cause we’re NF” approach?

Probably also true.

My ModH has the 3.5-10 Leupold on it though

 

[FatBoy]

Scope was perfect for it's intended use. Mk12s had the old M3 variables off the mk11s when they rolled out the uppers. M3 variable is a Great scope, but the image suffers past 300y when you don't re-set parallax, which takes time. Using the mk12s in the city, the 24mm with fixed parallax was faster. Especially if you set a 500y a zero, confirm your hold unders and hold over. You can put one in the triangle from 0y to 600y quickly with a M262 and a little practice.

When I first started using a fixed parallax scope I hated it, but in pure hunting situations they have an advantage. What's a mk12 if not a hunting rifle....

I'll close with, fucking Jarheads made a fixed parallax 10x into the stuff of legends. If those knuckleheads can make them work, anyone can.

 

[goosed]

There is a calculation for parallax error:

[ 0.5 x O x ( Abs ( R - P ) ] / P

O = objective diameter
R = range to target
P = parallax distance
Abs = absolute value, as error amount can never be less than zero

In your example NF 2.5-10x24, 100 yd parallax, range 700 yds =absolute maximum error is .112 mil

Edit: to add technically speaking that is the distortion free maximum. Assumes that you're looking through center of scope. You can nearly double that error if you were looking through the very edge, but who does that?

 

[newguy2k3v2]

Calculator

I always wondered if it could be a reason for some of my fliers with some optics but with smaller objectives it doesn't seem to be a big deal really.

 

[Dthomas3523]

There is a calculation for parallax error:

[ 0.5 x O x ( Abs ( R - P ) ] / P

O = objective diameter
R = range to target
P = parallax distance
Abs = absolute value, as error amount can never be less than zero

In your example NF 2.5-10x24, 100 yd parallax, range 700 yds =absolute maximum error is .112 mil

Edit: to add technically speaking that is the distortion free maximum. Assumes that you're looking through center of scope. You can nearly double that error if you were looking through the very edge, but who does that?

Well shit.

#endthread

 

[260Bryce]

Was wondering this today as I was shooting my Mk12Mod1 with a NF 2.5-10x24 on it at 700 yards. The optic has a 'fixed at 100' parallax with no further method to adjust it. I do notice at distance I can see the reticle moving a bit but was curious as to just how much havoc having such a short, fixed parallax optic is doing on shooting at distances much further than what its parallax setting is to.

Is this basically like setting any optic you have to be parallax free at 100, and then shooting 600 yards with that setting? Or is there something else to this? Why even do this?

I found this article on parallax error interesting. http://www.rimfirebenchrest.com/articles/parallax.html

 

[George P. Burdell]

There is a calculation for parallax error:

[ 0.5 x O x ( Abs ( R - P ) ] / P

O = objective diameter
R = range to target
P = parallax distance
Abs = absolute value, as error amount can never be less than zero

In your example NF 2.5-10x24, 100 yd parallax, range 700 yds =absolute maximum error is .112 mil

Edit: to add technically speaking that is the distortion free maximum. Assumes that you're looking through center of scope. You can nearly double that error if you were looking through the very edge, but who does that?

So you are saying absolute worst case scenario you are looking at about double that value?

 

[Burdy]

There is a calculation for parallax error:

[ 0.5 x O x ( Abs ( R - P ) ] / P

O = objective diameter
R = range to target
P = parallax distance
Abs = absolute value, as error amount can never be less than zero

In your example NF 2.5-10x24, 100 yd parallax, range 700 yds =absolute maximum error is .112 mil

Edit: to add technically speaking that is the distortion free maximum. Assumes that you're looking through center of scope. You can nearly double that error if you were looking through the very edge, but who does that?

Just when you thought you knew it all....
Nice.