Parallax focus

[Varminterror]

I think for the OP's application a typical "rimfire" scope with a 50-yd fixed focus and a 2x-6x magnification would fit the bill perfectly.

Mathematically, shooting a 50yrd parallax from 0-100yrds will introduce greater parallax error on target than will shooting a 100yrd fixed parallax at 0-100. So this advice makes the error worse, not better.

 

[CraigC]

Your problem isn't at 100 yds; it's that you're also trying to use the scope for ranges under 100 yds. An adjustable parallax scope isn't appropriate for that type of usage.

That is patently false. Adjustable parallax is absolutely essential if using a scope that is not rimfire-specific with parallax set at ~50yds, if you are shooting under 100yds. You can get away with it up to 4x but above that, you will definitely see parallax issues if you're shooting 50yds with a scope set at 150yds.

I'm not going to go searching for it but I've always read that the higher the magnification, the more parallax issues are amplified. Experience also bears this out.

 

[wiscoaster]

That is patently false. Adjustable parallax is absolutely essential if using a scope that is not rimfire-specific with parallax set at ~50yds, if you are shooting under 100yds. You can get away with it up to 4x but above that, you will definitely see parallax issues if you're shooting 50yds with a scope set at 150yds.

You're contradicting yourself and therefore making no sense in the context of the OP's problem. I stand by my opinion that adjustable parallax for ranges under 100 yds is not only unnecessary, but further if the minimum parallax adjustment is 100 yds then it's just making the issue worse at lesser ranges. As is the demonstrated case with the OP's scope. And even more so as he stated he wants higher than 4x magnification and needs that at ranges under 100 yds.

 

[wiscoaster]

Mathematically, shooting a 50yrd parallax from 0-100yrds will introduce greater parallax error on target than will shooting a 100yrd fixed parallax at 0-100. So this advice makes the error worse, not better.

Hasn't been my personal experience with my 50-yd fixed focus rimfire scopes at ranges 50 - 100 yds, but then I'm no mathemetician.

 

[someguy2800]

Are you two talking about parallax error or being out of optical focus. Those are two different things. Also I have never seen an adjustable parallax scope with a minimum setting of 100 yards. I have seen quite a few with a minimum of 50, but a lot of them go down to 10 yards. Adjustable parallax is unnecessary for most centerfire rifle uses under 100 yards, but its absolutely critical for stuff like competitive rimfire or air rifle shooting which is often done as close as 50 feet.

 

[Jim Watson]

Twirling the whole eyepiece on its fine thread is a difficult focus and I have not gotten mine to where the side adjustment does not affect both focus and parallax.
On the other hand, a scope with binocular type one turn focus and an adjustable objective was a lot easier to set up.

 

[wiscoaster]

.... Also I have never seen an adjustable parallax scope with a minimum setting of 100 yards. ....

All right. That may be the case. Mine goes down to 25 yds. I took the OP's description of his scope to be that it wasn't adjustable below 100 yds. Perhaps both of us are wrong. Or misread the entire problem. If the parallax on his scope can be adjusted below 100 yds then I don't see what the OP's problem is, and I don't see the reason for this whole discussion. Period.

 

[Varminterror]

Are you two talking about parallax error or being out of optical focus. Those are two different things. Also I have never seen an adjustable parallax scope with a minimum setting of 100 yards.

I was referring to fixed parallax scopes, not variable. The OP asked about fixed parallax scopes in the interest of simplifying life, so I pointed out the problem with trying to do so. It was presented that a Rimfire scope with fixed parallax at 50yrds would be favorable, and I provided then the math to prove why it is not.

Yes, adjustable objective and side focus optics do not typically “bottom out” at 100yrds, rather typically reaching down to at least 50yrds, if not 10, 15, or 25 yards. But again, my comments were addressing fixed parallax scopes (although applicable for simply turning the wrong range on the parallax adjustment as well).

 

[someguy2800]

All right. That may be the case. Mine goes down to 25 yds. I took the OP's description of his scope to be that it wasn't adjustable below 100 yds. Perhaps both of us are wrong. Or misread the entire problem. If the parallax on his scope can be adjusted below 100 yds then I don't see what the OP's problem is, and I don't see the reason for this whole discussion. Period.

I believe he is saying that his scope has a short depth of field, meaning that when he sets the parallax adjustment to 100 yards that it is unable to focus at 75 yards without readjusting the the parallax adjustment. Some scopes have much wider depth of field than others and will stay in optical focus over a much wider range. I don't think he particularly cares about the parallax error, just the optical focus.

I was referring to fixed parallax scopes, not variable. The OP asked about fixed parallax scopes in the interest of simplifying life, so I pointed out the problem with trying to do so. It was presented that a Rimfire scope with fixed parallax at 50yrds would be favorable, and I provided then the math to prove why it is not.

Yes, adjustable objective and side focus optics do not typically “bottom out” at 100yrds, rather typically reaching down to at least 50yrds, if not 10, 15, or 25 yards. But again, my comments were addressing fixed parallax scopes (although applicable for simply turning the wrong range on the parallax adjustment as well).

I wasn't referring to you. I agree with you that a rimfire scope is not the solution.

We still don't know what the application is. 100 yard benchrest competition? Shooting pop cans on a berm? Defensive training from 0-100 yards?

 

[Varminterror]

Typically, when a shooter observes focus shift with parallax adjustment, it indicates:

1) Terrible quality scope which changes objective plane focus with magnification change, or worse, with parallax adjustment.

2) Incorrect ocular focus.

Many folks believe they have the ocular focus dialed in, but unfortunately do so not at max magnification (shallowest DoF) or do so on a white wall too close to themselves. Our eyes and brains WANT things to be in focus, so it happens very easily that we’ll find the focal plane with our eye in the scope… however, it may not actually align with a representative intersection of focal planes for the reticle and the objective picture, so when we challenge the focus in the field, it falls apart.

This is a very common issue, and almost unilaterally, it typically is resolved by correcting ocular focus.

 

[Walkalong]

.22 LR scopes are generally set parallax free at 50 yards, and most centerfire scopes are set parallax free at 100 yards, because it has proven to work well. Some higher power scopes with fixed parallax are set at 150 yards.

I don't buy the more parallax error at higher magnification thing, I just don't see it. As with wobble, you can more easily see the parallax movement at higher power, but there doesn't seem to be any more.

The OP has a nice scope, and I still think it will serve him better if he can get used to it, but what he wants to do with a scope is not particularly demanding, and a good fixed parallax scope set at 100 yards will serve him well. If he intends to shoot under 50 yards a lot, one set at 50 yards might be better, dunno for sure, the only .22 LR scopes I still have are FFP parallax adjustable, one will adjust down to 25 yards and the other to 10 yards.

 

[Jack Ryan]

Bought a Zeiss scope the other day, a V4 Conquest 4-16X44. First scope I've owned with a parallax adjuster. I understand parallax and how/why to adjust it. But what surprised me was that the parallax adjuster impacted focus a great deal. I started at 25 yards to get the scope sighted in. First look down the scope, the target was way out of focus. Finally realized I could get it sharp with the parallax adjuster. But I had to refocus with the adjuster at 50, 75 and 100 yards. Even with lower magnification levels.

I like the scope overall. Awesome reticle and very accurate, but being this is my first scope with an adjuster for parallax, I don't know if the focus issue is normal or not. I'm not happy about having to refocus for each of these ranges, and not sure the wife will deal with it well either. I put the scope on a nicer AR, and am not looking to shoot more than 100 yards with it.

So is this normal? Are there scopes with the parallax adjuster that do not suffer from this issue? If so, please let me know which brand/style they are.

Three pages of posts to explain something the OP understands in the first post?

Mount the scope on the rifle with the appropriate eye relief.

Remove the bolt and unload the rifle.

Turn the magnification to the highest setting.

Loosen the eye focus on the scope, NOT THE PARALLAX ring, so you are ready and it is easy to move.

Now put the rifle to your shoulder in a shooting position and look through it at a light sky.

In that first moment or so if the reticle is blurry and then clears a little the focus of the scope for YOUR eye is WRONG.

Bring the gun down, rest, relax, blink a few times and look around, get ready and put the gun to your shoulder again and look at the light sky through the scope and adjust the eye ring to make it sharp. Soon as it is STOP moving it and let the rifle down.

Repeat. Bring the gun down, rest, relax, blink a few times and look around, get ready and put the gun to your shoulder again and look at the light sky through the scope and adjust the eye ring to make it sharp. Soon as it is STOP moving it and let the rifle down.

Repeat until you lift the rifle, look at the sky and the cross hairs are instantly sharp and clear. Tighten the locking ring for it and never let any one fool with it again. Not even "an expert". (Unless you get new glasses)

NOW you are ready to address the parallax.

This has nothing to do with making any part of the sight picture "clear".

Set the rifle on a steady rest like you are taking your fist test shot to sight it in. A hundred yard target is pretty good to start. Get the cross hairs on the center of the target. Now back away so you have no contact with the gun or scope and look at the setting on the parallax adjustment. 100 yard target, should be set on 100 yards p. adjustment. Now try to look through the scope and see the target. If everything is good the cross hair should still be on the CENTER of the target. No matter if you are a little left, a little right, a little up or down. Not the circle of your field of vision, just the cross hair should stay on the target regardless.

If everything is SET for 100 yards and the X moves around on the target, then the LABEL yardages on your parallax ring are WRONG. NOT A BIG DEAL. VERY COMMON SITUATION.

Sit down SOLID like you are gonna take a shot, everything rock solid on the rest. Now instead of shooting, look through the scope and turn the P adjustment just a tiny bit. Now let your head/eye move a little and see if the X moves more or less than before. Adjust again accordingly until the X on the target stays on the bull regardless of your cheek anchor point on the stock.

NOW take note of that KNOWN distance and KNOWN adjustment point and put a dot of white out on the TRUE P adjustment for 100 yards.

Repeat as needed for your range requirements.

 

[wiscoaster]

Three pages of posts to explain something the OP understands in the first post?...

It must be too much time to kill during the holidays....

 

[Varminterror]

I don't buy the more parallax error at higher magnification thing, I just don't see it.

I really don’t buy it either. But a lot of folks sing that gospel, so I’m waiting for someone to back it up with more than conjecture - or a reference to conjecture in some online blog or forum. I’ve never seen a field demonstration nor mathematical/physical evidence that magnification has any influence.

I’d be fairly certain I could count on both hands, at worst both hands and one foot how many scopes I’ve owned in the last 30yrs without AO or SF. It’s important enough to me in almost all applications that I’ll almost always gladly pay the extra money to have that control.

 

[someguy2800]

From my meager understanding of what is going on inside a rifle scope I don’t see how the changing the magnification setting could possibly affect the amount of parallax error since the parallax error is created in the objective section of the lenses and the magnification happens in the erector section of the lenses. But on the other hand every scope I’ve ever owned, the depth of field does appear to change as the magnification goes up, and I don’t understand why that is either.

 

[Jack Ryan]

From my meager understanding of what is going on inside a rifle scope I don’t see how the changing the magnification setting could possibly affect the amount of parallax error since the parallax error is created in the objective section of the lenses and the magnification happens in the erector section of the lenses. But on the other hand every scope I’ve ever owned, the depth of field does appear to change as the magnification goes up, and I don’t understand why that is either.

If the highest power is 9 or below, you will never see it. That is why hardly any scope of 9 power or less even has a parallax adjustment.

 

[someguy2800]

If the highest power is 9 or below, you will never see it. That is why hardly any scope of 9 power or less even has a parallax adjustment.

I agree except at very close range where you would not normally be at the higher power settings anyway. It’s not solely a function of the magnification though. I once had a sig tango5 2-10x42 non adjustable that had an absolutely terrible depth of field, and it was a $850 scope. Meanwhile my sig tango4 4-16x44 has a very good depth of field and was half the cost. I am picky about these things and end up sending a lot of scopes back for having poor depth of field or having the parallax setting being way off. I had a new 3-9x40 once that when I tested it on the kitchen table in my normal manor the parallax was set at about 35 yards.

 

[HowieG]

This is what I do as well, but I’m adjusting the ocular to bring the reticle into the sharpest focus while looking at either a blue sky or white background.

Then I adjust parallax based on the distance I’m shooting. It’s usually, but not always, the clearest focus on the target. To ensure you have dialed out all your parallax you move your head slightly up and down and side to side and see if the reticle is moving. Keep adjusting until you can not detect any wobble in the reticle based on your head position.

What happens when you have parallax error is you’ll end up with flyers in your group. Not that big of a deal for hunting level accuracy but for precision shooting it is. Having said all of that, if your head position is consistently in the same exact spot for every shot parallax error doesn’t play a factor

Exactly right.

 

[HowieG]

Just a few comments. Nature Boy is absolutely right when he states that if you keep your head still and centered up behind the scope, parallax is not a factor. He is also correct when he talks about target focus and the parallax free point not being exactly the same. Remember, everybody's eyes are different. Some eyes suck and some don't. Eyes get tired. Eyes get dust blown in them. Anyway, if you are in a hurry, just get the target in focus for you and you likely will be fairly close to parallax free. Or get a fixed parallax scope and don't worry about it.

Don't pay too much attention to the yardage markers on the objective or SF knob. Just because the marker says 200 yards when you focus up a particular target, that doesn't mean it really truly is 200 yards to that target. Remember, your eyes are unique. Frankly, scope manufacturers could just put marks without labels on the knob. Or label the marks A, B, C, D. They are just reference marks.

Fixed parallax scopes intended for centerfire cartridges are normally adjusted for 100 or 150 yards depending on the manufacturer. I noted a small amount of parallax at 100 yards with a Leupold scope, so I called them and asked them at what range they set their scopes, and they told me 150 yards. I have other scopes that have less parallax at 100.

Finally, you can shoot long range without a parallax adjustable scope or a scope of a bazillion power. You can do so without a scope at all for that matter. Riflemen have been doing that for a very long time. The Wimbledon Cup was first awarded in 1875. I am pretty sure none of those riflemen had a kestrel or a ballistics program. I am also pretty sure there are more technicians than riflemen out on the range these days.

 

[CraigC]

You're contradicting yourself and therefore making no sense in the context of the OP's problem. I stand by my opinion that adjustable parallax for ranges under 100 yds is not only unnecessary, but further if the minimum parallax adjustment is 100 yds then it's just making the issue worse at lesser ranges. As is the demonstrated case with the OP's scope. And even more so as he stated he wants higher than 4x magnification and needs that at ranges under 100 yds.

Nonsense. I'm not contradicting myself and you are still wrong. Conventional wisdom is that if you put a centerfire scope on a rimfire, you're basically pissing into the wind. You've obviously never tried it.

If you are shooting a fixed parallax (100-150yds) centerfire scope at 50yds, you will absolutely see parallax error. Enough to be frustrating.

I really don’t buy it either. But a lot of folks sing that gospel, so I’m waiting for someone to back it up with more than conjecture - or a reference to conjecture in some online blog or forum. I’ve never seen a field demonstration nor mathematical/physical evidence that magnification has any influence.

I’d be fairly certain I could count on both hands, at worst both hands and one foot how many scopes I’ve owned in the last 30yrs without AO or SF. It’s important enough to me in almost all applications that I’ll almost always gladly pay the extra money to have that control.

As I said, I have no proof. No appeal to authority and nothing to quote but I've seen it with my own eyes. I've experienced no issues up to about 4x, with centerfire scopes used on rimfires and tested at 50yds. Conversely, I've found a centerfire 2-7x to be absolutely worthless under 75yds when twisted to 7x. A run of the mill 3-9x, forget it. Of course when you get much more than that, it's almost a given that they're parallax adjustable.

Just a few comments. Nature Boy is absolutely right when he states that if you keep your head still and centered up behind the scope, parallax is not a factor.

Sounds good in theory. Maybe it'll work on the range or if you just have a handful of rifles. Can you maintain that consistency between shot strings when you're breaking cheek weld? When you have literally dozens of rifles and need to make the first shot count, it's a little different.

 

[JEBruns]

I believe he (the OP) is saying that his scope has a short depth of field, meaning that when he sets the parallax adjustment to 100 yards that it is unable to focus at 75 yards without readjusting the the parallax adjustment. Some scopes have much wider depth of field than others and will stay in optical focus over a much wider range.

Correct. This thread has helped me a lot, and I thank everyone for their input. I understand the issue now, and know what my options are.

I'd guess we'll be keeping the scope. I took it out to the range again yesterday and I still like it very much overall. I think the depth of field issue is more pronounced at close in ranges, like when I was at 25 for initial scope zeroing. But I don't plan to shoot much at that range. It was not much of a change to the parallax knob to go from 75 to 100 yards yesterday. Still need to get the wife to try it. She's practicing for some qualifying she has coming up, so is only shooting her pistols right now though.

Again, thanks for all the input.

 

[wiscoaster]

Nonsense. I'm not contradicting myself and you are still wrong. Conventional wisdom is that if you put a centerfire scope on a rimfire, you're basically pissing into the wind. You've obviously never tried it. If you are shooting a fixed parallax (100-150yds) centerfire scope at 50yds, you will absolutely see parallax error. Enough to be frustrating..

(emphasis added to quote)

BS. I've put 100 yd fixed-focus "centerfire" scopes on rimfires and 50 yd fixed-focus "rimfire" scopes on centerfires and both worked just fine for me at all ranges 25 - 100 yds. I can't explain why your experience is different. I use magnification appropriate for distance. I don't crank a scope up to 24x for 25 yds. (A scope at that range is ridiculous, anyway). Maybe your usage is different, and thus your experience of frustration.

For me, whatever works, works. "Conventional wisdom" be damned ... it's usually a collection of BS passed on from one to another and just given automatic credence without actual experience to verify it.

 

[HowieG]

Nonsense. I'm not contradicting myself and you are still wrong. Conventional wisdom is that if you put a centerfire scope on a rimfire, you're basically pissing into the wind. You've obviously never tried it.

If you are shooting a fixed parallax (100-150yds) centerfire scope at 50yds, you will absolutely see parallax error. Enough to be frustrating.



As I said, I have no proof. No appeal to authority and nothing to quote but I've seen it with my own eyes. I've experienced no issues up to about 4x, with centerfire scopes used on rimfires and tested at 50yds. Conversely, I've found a centerfire 2-7x to be absolutely worthless under 75yds when twisted to 7x. A run of the mill 3-9x, forget it. Of course when you get much more than that, it's almost a given that they're parallax adjustable.



Sounds good in theory. Maybe it'll work on the range or if you just have a handful of rifles. Can you maintain that consistency between shot strings when you're breaking cheek weld? When you have literally dozens of rifles and need to make the first shot count, it's a little different.

You are absolutely right. Humans aren't perfect. Still, it is correct that if you can lock your head down in the sweet spot, parallax would not be an issue, unless something is grossly wrong with the scope. Frankly, most shooters don't do the kinds of shooting that would require them to worry about it.

 

[CraigC]

(emphasis added to quote)

BS. I've put 100 yd fixed-focus "centerfire" scopes on rimfires and 50 yd fixed-focus "rimfire" scopes on centerfires and both worked just fine for me at all ranges 25 - 100 yds. I can't explain why your experience is different. I use magnification appropriate for distance. I don't crank a scope up to 24x for 25 yds. (A scope at that range is ridiculous, anyway). Maybe your usage is different, and thus your experience of frustration.

For me, whatever works, works. "Conventional wisdom" be damned ... it's usually a collection of BS passed on from one to another and just given automatic credence without actual experience to verify it.

Maybe you've been lucky but if you take this rhetoric to RimfireCentral, you'll hear the same story. I would NEVER put a centerfire scope on a rimfire that didn't have adjustable parallax. It is absolutely an issue, I have absolutely seen it but what I do I know, I only have 70 of them.

And I'm not talking about gun shop myth and legend. Rather information from folks like John Lachuk who had a .44 magnum wildcat before Elmer Keith bugged S&W about it. Proven through experience. It's almost laughable that this is a foreign concept to any serious shooter.

 

[Varminterror]

If the highest power is 9 or below, you will never see it. That is why hardly any scope of 9 power or less even has a parallax adjustment.

Failing to observe parallax “float” in the scope is not the same thing as being free from the parallax induced error on target.

Parallax error doesn’t care about magnification - low magnification simply allows shooters to remain ignorant to the fact they are vulnerable to it.

A 3-9x40 with a fixed 50yrd parallax fired at 100yrds, going edge to edge, will allow a group spread of 1.6”. I’m certainly not comfortable with adding 1.6” to my 100yrds groups.