Parallax adjustment

[Steve Donlon]

Is the amount of parallax adjustment from the scope or a persons eye sight? It seems some high priced scope don't have as much parallax as some scopes half the price. Or is it one or the other, clear optics means less parallax? So to have both, it' cost $4000.

 

[Rank Amateur]

Optical clarity is not related to parallax. Parallax is the apparent misalignment of the reticle with the target as the shooter’s eye moves from the central axis of the scope. Regardless of adjustment, if the shooter positions his/her eye directly along the central axis of the scope, there will be no parallax error. Scopes with parallax adjustment minimize parallax error by allowing the shooter to bring the focal plane of the target into alignment with the focal plane of the reticle. When the “focus” is adjusted to bring these focal planes into alignment, the shooter can move their eye off of the central optical axis and there will be no apparent relative motion of the target compared to the reticle.

I don’t think the price of a scope is related to its parallax adjustability. Better/clearer glass, and better/stronger mechanicals (and brand name ) are better correlates to price.

 

[Straightshooter1]

Is the amount of parallax adjustment from the scope or a persons eye sight?

It's the adjustment of the image to the reticle so that when your eye moves its position the image stays on the reticle. Having the ocular lens adjusted so the reticle is in sharp focus according to your eyes is the first stem before adjusting the parallax. Once you get a sharply focused reticle and then a good parallax adjustment, movement of your eye won't shift the image around the reticle.

It seems some high priced scope don't have as much parallax as some scopes half the price. Or is it one or the other, clear optics means less parallax? So to have both, it' cost $4000.

Clarity of lenses themselves is not an issue for parallax. But how well the internal mechanisms are built can be a factor in getting the image to focus on the reticle an be. That has to do with how well the ocular lens can focus on the reticle too. So, I suppose how clear the optics are effects how well focusing can be done, especially in low light.

 

[ELR LVR]

Optical clarity is not related to parallax. Parallax is the apparent misalignment of the reticle with the target as the shooter’s eye moves from the central axis of the scope. Regardless of adjustment, if the shooter positions his/her eye directly along the central axis of the scope, there will be no parallax error. Scopes with parallax adjustment minimize parallax error by allowing the shooter to bring the focal plane of the target into alignment with the focal plane of the reticle. When the “focus” is adjusted to bring these focal planes into alignment, the shooter can move their eye off of the central optical axis and there will be no apparent relative motion of the target compared to the reticle.

I don’t think the price of a scope is related to its parallax adjustability. Better/clearer glass, and better/stronger mechanicals (and brand name ) are better correlates to price.

What about - forget the parallax adjustment aspect but
What about the focus aspect itself
-----------
Some scopes seem to have more range of FOCUS adjustment
When higher priced scopes seem to top out of adjustment once everything is in focus from at about 600 yds on out.
IE: once you reach 600 yds, there is no further difference in focus clarity when adjusting more toward infinity
-----------
I don't know if Mr. Donlon is posting in relation to a reference I made regarding how my Kahles parallax works
but
Example:
If I adjust my SIMMONS scope even - a $300 scope
I can adjust the parallax focus at 2000 yds, and still have more adjustment to focus past that
Same with many Leupolds and my B&L's I have experienced
-----------
However:
With my Kahles, once I adjust focus at 600 yds, turning the dial does nothing further
"AS far as using the Focus aspect " goes.
Or - I cannot adjust focus past that to become fuzzy again.
-----------
Or another way to understand this is:
I can adjust the image to be "Focused" at 1000 yds with a Leupold
And still be able to turn the focus further out to have the image then be fuzzy as we approach the infinity mark
The higher end scopes cannot adjust focus PAST this point and seem to be in "Focus" from 600 yds on out - meaning we cannot adjust focus past this range to be fuzzy again then dial back a little bit to be perfectly sharp
----------
It sucks when even a Simmons, can adjust focus/parallax knob to be clear at 1000 yds
Adjust past that point toward infinity to become fuzzy
then dial back a little bit to be in focus again, so as to adjust the sharpest image possible.
This allows us to perfectly dial it in.
We are often not using the parallax for adjusting parallax but more for image clarity
since as you say - we are not concerned about the parallax aspect
since we know how to put our eye in the middle
-----------
So what we're wondering or trying to understand, is the the result of the higher top tier scopes having better alingment/glass/ etc that once we adjust to a certain yardage such as 600 yds
they cannot adjust focus any further ....
....as we turn the dial toward infinity
Everything from 600 yds on out is in focus no matter how much we turn the dial between the
600 yds mark and inifinity
------------
This reminds me of a pair of binoculars I had that one feature was they did not need nor have a focus wheel
They were in focus by themselves from about 20 yds on out to infinity.
(I dont know how, but it tripped me out that you could pan the landscape and everything was in focus say as you panned from 50 yds to 600 yds)

 

[Steve Donlon]

What about - forget the parallax adjustment aspect but
What about the focus aspect itself
-----------
Some scopes seem to have more range of FOCUS adjustment
When higher priced scopes seem to top out of adjustment once everything is in focus from at about 600 yds on out.
IE: once you reach 600 yds, there is no further difference in focus clarity when adjusting more toward infinity
-----------
I don't know if Mr. Donlon is posting in relation to a reference I made regarding how my Kahles parallax works
but
Example:
If I adjust my SIMMONS scope even - a $300 scope
I can adjust the parallax focus at 2000 yds, and still have more adjustment to focus past that
Same with many Leupolds and my B&L's I have experienced
-----------
However:
With my Kahles, once I adjust focus at 600 yds, turning the dial does nothing further
"AS far as using the Focus aspect " goes.
Or - I cannot adjust focus past that to become fuzzy again.
-----------
Or another way to understand this is:
I can adjust the image to be "Focused" at 1000 yds with a Leupold
And still be able to turn the focus further out to have the image then be fuzzy as we approach the infinity mark
The higher end scopes cannot adjust focus PAST this point and seem to be in "Focus" from 600 yds on out - meaning we cannot adjust focus past this range to be fuzzy again then dial back a little bit to be perfectly sharp
----------
It sucks when even a Simmons, can adjust focus/parallax knob to be clear at 1000 yds
Adjust past that point toward infinity to become fuzzy
then dial back a little bit to be in focus again, so as to adjust the sharpest image possible.
This allows us to perfectly dial it in.
We are often not using the parallax for adjusting parallax but more for image clarity
since as you say - we are not concerned about the parallax aspect
since we know how to put our eye in the middle
-----------
So what we're wondering or trying to understand, is the the result of the higher top tier scopes having better alingment/glass/ etc that once we adjust to a certain yardage such as 600 yds
they cannot adjust focus any further ....
....as we turn the dial toward infinity
Everything from 600 yds on out is in focus no matter how much we turn the dial between the
600 yds mark and inifinity
------------
This reminds me of a pair of binoculars I had that one feature was they did not need nor have a focus wheel
They were in focus by themselves from about 20 yds on out to infinity.
(I dont know how, but it tripped me out that you could pan the landscape and everything was in focus say as you panned from 50 yds to 600 yds)

Exactly. The eyepiece adjustment for the retical can help at distance also if it's off a little. but running out of parallax at a greater distance, no matter how good the glass is does not help. On some scopes when you get to infinity it's not good enough but it does stay the same at that point and does not get worse as you go out, but the retical is still sharp, Why can't the parallax be just as sharp. Seems a 60 power scope only makes it worse. Is it because the length of the scope limits this?

 

[Rank Amateur]

Perhaps an optics specialist will chime in here to discuss why a scope might be out of focus when the parallax is properly adjusted at a given range. I was taught that the parallax adjustment is not a focus dial. The ocular lens gets adjusted so that the reticle is maximally focused to a particular shooter’s eye. The parallax adjustment then adjusts the objective lens to bring the target image into the same focal plane as the reticle. The adjustment point where parallax is eliminated may not be the same as where the target image is best focused.

To that end, I was taught to adjust parallax while moving my eye around, and to continue adjusting until my eye movement produced no relative motion of the target in relation to the reticle (regardless of whether the target was in focus or not). I.E., the purpose of the parallax adjustment was to eliminate parallax, not to focus the target image. For scopes where there is no further adjustment at the longest ranges (such as 600 yds as @ELR LVR mentions above), that is (should be) because all parallax is eliminated by that 600 yd range.

Shooters CAN use parallax adjustment to focus the target to the optical limits of the scope, acknowledging that a parallax error may exist when the target image is optimally focused. If shooters use physical alignment techniques to avoid parallax errors, there will be no loss of aiming accuracy.

 

[Steve Donlon]

Perhaps an optics specialist will chime in here to discuss why a scope might be out of focus when the parallax is properly adjusted at a given range. I was taught that the parallax adjustment is not a focus dial. The ocular lens gets adjusted so that the reticle is maximally focused to a particular shooter’s eye. The parallax adjustment then adjusts the objective lens to bring the target image into the same focal plane as the reticle. The adjustment point where parallax is eliminated may not be the same as where the target image is best focused.

To that end, I was taught to adjust parallax while moving my eye around, and to continue adjusting until my eye movement produced no relative motion of the target in relation to the reticle (regardless of whether the target was in focus or not). I.E., the purpose of the parallax adjustment was to eliminate parallax, not to focus the target image. For scopes where there is no further adjustment at the longest ranges (such as 600 yds as @ELR LVR mentions above), that is (should be) because all parallax is eliminated by that 600 yd range.

Shooters CAN use parallax adjustment to focus the target to the optical limits of the scope, acknowledging that a parallax error may exist when the target image is optimally focused. If shooters use physical alignment techniques to avoid parallax errors, there will be no loss of aiming accuracy.

Thanks, I think I understand, that at some point I need to move my head around more to find the sweet spot for my eye. More like using a spotting scope.

 

[jelenko]

Remember, adjusting parallax 'simply' brings the image from the objective into focus in the same plane as the reticle.
So, if the reticle is nice and sharp [i.e., it's in focus] and the parallax is NOT adjusted for the actual distance to the target [or whatever you're viewing], the target/whatever you're viewing will not be in focus - because the eye piece is focused on the reticle and the image from the objective is not focused in the same plane as the reticle.

I think the reason images from farther away get less clear is simply due to less light being collected from them and the quality of the optics..

 

[ELR LVR]

Remember, adjusting parallax 'simply' brings the image from the objective into focus in the same plane as the reticle.
So, if the reticle is nice and sharp [i.e., it's in focus] and the parallax is NOT adjusted for the actual distance to the target [or whatever you're viewing], the target/whatever you're viewing will not be in focus - because the eye piece is focused on the reticle and the image from the objective is not focused in the same plane as the reticle.

I think the reason images from farther away get less clear is simply due to less light being collected from them and the quality of the optics..

The images are clear, the parallax knob being used as a focuser...
...wont adjust past that distance to become "unclear again"
IE: not enough past 2000 yd adjustment
IE: we want to make fine adjustments between 1000 and 2500 yds
We want to see a difference in the image with any small minute fine adjustment
Which I think - most scope mfgr's are not considering in their design
----------
I noticed this really well with a friends Leupold I was using at 1000 yds one day
I focused the image with the parallax at 1000 yds and there was still at least 1/4 more turn left of adjustment that you could dial with and have useable adjustment past 1000 yds

 

[Rank Amateur]

So, searching for info from someone more expert than I am, I came across a post from Denys Beauchemin (@Turbulent Turtle) from 2020 in Snipers Hide (https://www.snipershide.com/shooting/threads/parallax-on-infinity-question.6999609/). Denys is an accomplished shooter and I believe is responsible for the F-Class reticle in the March Majesta scope. He was reacting to a question by another shooter about the infinity parallax setting and how it relates to parallax error. I’m extracting this text from his post and very deliberately citing his post and his expertise here:

---

...At infinity, you cannot detect any parallax error for objects at 300 yards or more. The formula to calculate parallax error is: ((0.5 x D x (abs(R-P))/P ) x 0.0393701). That will give you inches. If you want it in mil, just divide the result by 3.6 and then again by (R/100).
D is the diameter of the objective lens in millimeters, in your case 56.
R is the range to target in yards , in your case 300.
P is the parallax setting, since you put it at infinity, let's use 1000yards.

So at 300 yards, the error is .771 inch. That is the maximum error you could see in your scope, if you could not line up behind it at all. If you have any marksmanship skills, that error will be less. At 400 yards, the error is .661 inch; at 500, it's .551 inch; at 600yards, it's .440 inch and so on. This is very small and pretty much undetectable in your optics.

---

 

[Turbulent Turtle]

Is the amount of parallax adjustment from the scope or a persons eye sight? It seems some high priced scope don't have as much parallax as some scopes half the price. Or is it one or the other, clear optics means less parallax? So to have both, it' cost $4000.

Let me address the OP first.

I have written a rather large document in which I talk about how people face challenges when comparing riflescopes and various aspects of optics. A main driver of confusion (there are many) is nomenclature, which is why my paper starts with a detailed glossary of certain terms and dives into them.

When I read the OP's question, I wonder what he means by parallax., especially when I see his first reply to a comment.

What people call "parallax adjustment knob" is in reality a "side focus turret", but I will accept knob instead of turret. In a riflescope the objective lens (the big-ash doublet at the front) will focus the image of the objective (what you are looking at) onto the first focal plane, an area located at the front of the erector tube hidden inside the riflescope's main body.

In the days of 4X or 6X magnification scopes, the exact focus was not critical, so the objective lens was focused for objects at about 125-150 yards. The vast majority of shooters go to hundred-yard ranges and hunters rarely shoot from much further. Since the magnification was minimal, and the objective lens was small by current standards, with an accompanying low F-stop value (or high depending on how you read it), the depth of field of these riflescopes was very big and people didn't detect they were not focused properly on the target. My little app shows that for a 6X scope with a 32mm objective, the hyperfocal distance is 55.8 yards and the depth of field with a CoC of .020mm starts at 40.5 yards and goes to infinity. All that gobbledygook says that the shooter would deem the image to be in good focus from about 40 yards all the way to infinity (and beyond).

However, the parallax error could byte his or her butt. The focal plane with the reticle, would be set for 125 or 150 yards, but if the target was at 300 or 400 yards, you could have quite a bit of parallax deviation, if your position behind the riflescope was not proper.

As magnifications increased along with the objective sizes, the depth of field plummeted. For instance, at 55X, with a 52mm objective, you have to use a CoC of .010mm and the hyperfocal distance is now 299yards. When the scope is focused at 150yarss, the start of the DOF is 101 yards and ends at 295 yards. As you can see, that is much narrower DOF.

Enter the adjustable objective riflescopes. These are riflescopes with a ring at the front of the objective that allows the shooter to properly focus on the target. Once you do that, and you have a nice crisp image of the target, the attendant parallax deviation essentially disappears. What the adjustable objective has done is to change the focus of the objective lens to place the image of your 400 yards target smack on the first focal plane, where it will merge nicely with the reticle (whether first or second focal plane). By having the image of the target and reticle on the same plane, no parallax deviation.

The evolution from adjustable objective, which is simple and extremely efficient (it's the same way camera lenses do it,) is the side focus turret which control the placement of a focusing lens between the objective lens and the first focal plane. This makes is extremely convenient for the shooter, looks cool in movies and cost more money to engineer. Instead of focusing the objective lens (moving it back and forth), the focusing lens bends the light a little bit and changes the focus point for the image coming from the objective lens. It does the same thing as the adjustable objective but requires more hardware and lenses and grow a side-focus turret.

A more expensive scope usually sports a side focus turret and by virtue of having the shooter adjust it to get a clear crisp picture of the target, the parallax goes away at the first focal plane. The image is then flipped and zoomed in the erector tube and comes out the back at the second focal plane. If there's a reticle there, it will merge with the image and will be in place for the eyepiece. I'll skip the afocal part for now, but simply state that a riflescope and its eyepiece is designed to be viewed with your far vision. The eyepiece adjustment knob is designed to let you adjust the image to your eye. You do NOT focus on the reticle when you do that, you should look through it to the target. If you are focusing on the reticle, you are using your near vision and that's not good, unless you have no correction for reading and seeing far.

On high magnification, high performance riflescopes, it is "a good idea" to touch up the eyepiece adjustment when looking at your target 1000 yards away. Do that once and lock it down.

You have probably noticed that I have deftly avoiding answering the OP's question about why he sees a difference in "parallax" between high dollar scopes and lesser dollar scopes. It's really because I'm not sure what he means by parallax, and I would also love to have examples of riflescopes in which he has detected that. I can then answer better.

 

[Turbulent Turtle]

So, searching for info from someone more expert than I am, I came across a post from Denys Beauchemin (@Turbulent Turtle) from 2020 in Snipers Hide (https://www.snipershide.com/shooting/threads/parallax-on-infinity-question.6999609/). Denys is an accomplished shooter and I believe is responsible for the F-Class reticle in the March Majesta scope. He was reacting to a question by another shooter about the infinity parallax setting and how it relates to parallax error. I’m extracting this text from his post and very deliberately citing his post and his expertise here:

---

...At infinity, you cannot detect any parallax error for objects at 300 yards or more. The formula to calculate parallax error is: ((0.5 x D x (abs(R-P))/P ) x 0.0393701). That will give you inches. If you want it in mil, just divide the result by 3.6 and then again by (R/100).
D is the diameter of the objective lens in millimeters, in your case 56.
R is the range to target in yards , in your case 300.
P is the parallax setting, since you put it at infinity, let's use 1000yards.

So at 300 yards, the error is .771 inch. That is the maximum error you could see in your scope, if you could not line up behind it at all. If you have any marksmanship skills, that error will be less. At 400 yards, the error is .661 inch; at 500, it's .551 inch; at 600yards, it's .440 inch and so on. This is very small and pretty much undetectable in your optics.

---

You woke me from my slumber and dragged me here, you fiend. Indeed, people get worked up over "parallax" and checking with a parallax calculator is always a good thing. Now, for us F-Class shooters, we do want to eliminate every error we can, and setting the side focus properly on the target goes a very long way to eliminate parallax. Also, one needs to remember that at high magnification, the exit pupil is rather small, and you have to be set behind the scope properly to even see the image, let alone eliminate the vignetting to get the full picture. That action also guarantees the elimination of parallax.

 

[Steve Donlon]

Let me address the OP first.

I have written a rather large document in which I talk about how people face challenges when comparing riflescopes and various aspects of optics. A main driver of confusion (there are many) is nomenclature, which is why my paper starts with a detailed glossary of certain terms and dives into them.

When I read the OP's question, I wonder what he means by parallax., especially when I see his first reply to a comment.

What people call "parallax adjustment knob" is in reality a "side focus turret", but I will accept knob instead of turret. In a riflescope the objective lens (the big-ash doublet at the front) will focus the image of the objective (what you are looking at) onto the first focal plane, an area located at the front of the erector tube hidden inside the riflescope's main body.

In the days of 4X or 6X magnification scopes, the exact focus was not critical, so the objective lens was focused for objects at about 125-150 yards. The vast majority of shooters go to hundred-yard ranges and hunters rarely shoot from much further. Since the magnification was minimal, and the objective lens was small by current standards, with an accompanying low F-stop value (or high depending on how you read it), the depth of field of these riflescopes was very big and people didn't detect they were not focused properly on the target. My little app shows that for a 6X scope with a 32mm objective, the hyperfocal distance is 55.8 yards and the depth of field with a CoC of .020mm starts at 40.5 yards and goes to infinity. All that gobbledygook says that the shooter would deem the image to be in good focus from about 40 yards all the way to infinity (and beyond).

However, the parallax error could byte his or her butt. The focal plane with the reticle, would be set for 125 or 150 yards, but if the target was at 300 or 400 yards, you could have quite a bit of parallax deviation, if your position behind the riflescope was not proper.

As magnifications increased along with the objective sizes, the depth of field plummeted. For instance, at 55X, with a 52mm objective, you have to use a CoC of .010mm and the hyperfocal distance is now 299yards. When the scope is focused at 150yarss, the start of the DOF is 101 yards and ends at 295 yards. As you can see, that is much narrower DOF.

Enter the adjustable objective riflescopes. These are riflescopes with a ring at the front of the objective that allows the shooter to properly focus on the target. Once you do that, and you have a nice crisp image of the target, the attendant parallax deviation essentially disappears. What the adjustable objective has done is to change the focus of the objective lens to place the image of your 400 yards target smack on the first focal plane, where it will merge nicely with the reticle (whether first or second focal plane). By having the image of the target and reticle on the same plane, no parallax deviation.

The evolution from adjustable objective, which is simple and extremely efficient (it's the same way camera lenses do it,) is the side focus turret which control the placement of a focusing lens between the objective lens and the first focal plane. This makes is extremely convenient for the shooter, looks cool in movies and cost more money to engineer. Instead of focusing the objective lens (moving it back and forth), the focusing lens bends the light a little bit and changes the focus point for the image coming from the objective lens. It does the same thing as the adjustable objective but requires more hardware and lenses and grow a side-focus turret.

A more expensive scope usually sports a side focus turret and by virtue of having the shooter adjust it to get a clear crisp picture of the target, the parallax goes away at the first focal plane. The image is then flipped and zoomed in the erector tube and comes out the back at the second focal plane. If there's a reticle there, it will merge with the image and will be in place for the eyepiece. I'll skip the afocal part for now, but simply state that a riflescope and its eyepiece is designed to be viewed with your far vision. The eyepiece adjustment knob is designed to let you adjust the image to your eye. You do NOT focus on the reticle when you do that, you should look through it to the target. If you are focusing on the reticle, you are using your near vision and that's not good, unless you have no correction for reading and seeing far.

On high magnification, high performance riflescopes, it is "a good idea" to touch up the eyepiece adjustment when looking at your target 1000 yards away. Do that once and lock it down.

You have probably noticed that I have deftly avoiding answering the OP's question about why he sees a difference in "parallax" between high dollar scopes and lesser dollar scopes. It's really because I'm not sure what he means by parallax, and I would also love to have examples of riflescopes in which he has detected that. I can then answer better.

So is 1st focal plane better for long distance? It seems for my eyes it is. But I have trouble seeing at longer distance and can no longer correct it with eye glasses. I'm at the limit of what can be done. But I have learned how to deal with it out to 1000 yards until eye fatigue sets in then I must correct by lowering the magnification and renew the retical. It seems easier to correct with FFP scopes. But that could just be me.

 

[Silo1616]

Let me address the OP first.

I have written a rather large document in which I talk about how people face challenges when comparing riflescopes and various aspects of optics. A main driver of confusion (there are many) is nomenclature, which is why my paper starts with a detailed glossary of certain terms and dives into them.

When I read the OP's question, I wonder what he means by parallax., especially when I see his first reply to a comment.

What people call "parallax adjustment knob" is in reality a "side focus turret", but I will accept knob instead of turret. In a riflescope the objective lens (the big-ash doublet at the front) will focus the image of the objective (what you are looking at) onto the first focal plane, an area located at the front of the erector tube hidden inside the riflescope's main body.

In the days of 4X or 6X magnification scopes, the exact focus was not critical, so the objective lens was focused for objects at about 125-150 yards. The vast majority of shooters go to hundred-yard ranges and hunters rarely shoot from much further. Since the magnification was minimal, and the objective lens was small by current standards, with an accompanying low F-stop value (or high depending on how you read it), the depth of field of these riflescopes was very big and people didn't detect they were not focused properly on the target. My little app shows that for a 6X scope with a 32mm objective, the hyperfocal distance is 55.8 yards and the depth of field with a CoC of .020mm starts at 40.5 yards and goes to infinity. All that gobbledygook says that the shooter would deem the image to be in good focus from about 40 yards all the way to infinity (and beyond).

However, the parallax error could byte his or her butt. The focal plane with the reticle, would be set for 125 or 150 yards, but if the target was at 300 or 400 yards, you could have quite a bit of parallax deviation, if your position behind the riflescope was not proper.

As magnifications increased along with the objective sizes, the depth of field plummeted. For instance, at 55X, with a 52mm objective, you have to use a CoC of .010mm and the hyperfocal distance is now 299yards. When the scope is focused at 150yarss, the start of the DOF is 101 yards and ends at 295 yards. As you can see, that is much narrower DOF.

Enter the adjustable objective riflescopes. These are riflescopes with a ring at the front of the objective that allows the shooter to properly focus on the target. Once you do that, and you have a nice crisp image of the target, the attendant parallax deviation essentially disappears. What the adjustable objective has done is to change the focus of the objective lens to place the image of your 400 yards target smack on the first focal plane, where it will merge nicely with the reticle (whether first or second focal plane). By having the image of the target and reticle on the same plane, no parallax deviation.

The evolution from adjustable objective, which is simple and extremely efficient (it's the same way camera lenses do it,) is the side focus turret which control the placement of a focusing lens between the objective lens and the first focal plane. This makes is extremely convenient for the shooter, looks cool in movies and cost more money to engineer. Instead of focusing the objective lens (moving it back and forth), the focusing lens bends the light a little bit and changes the focus point for the image coming from the objective lens. It does the same thing as the adjustable objective but requires more hardware and lenses and grow a side-focus turret.

A more expensive scope usually sports a side focus turret and by virtue of having the shooter adjust it to get a clear crisp picture of the target, the parallax goes away at the first focal plane. The image is then flipped and zoomed in the erector tube and comes out the back at the second focal plane. If there's a reticle there, it will merge with the image and will be in place for the eyepiece. I'll skip the afocal part for now, but simply state that a riflescope and its eyepiece is designed to be viewed with your far vision. The eyepiece adjustment knob is designed to let you adjust the image to your eye. You do NOT focus on the reticle when you do that, you should look through it to the target. If you are focusing on the reticle, you are using your near vision and that's not good, unless you have no correction for reading and seeing far.

On high magnification, high performance riflescopes, it is "a good idea" to touch up the eyepiece adjustment when looking at your target 1000 yards away. Do that once and lock it down.

You have probably noticed that I have deftly avoiding answering the OP's question about why he sees a difference in "parallax" between high dollar scopes and lesser dollar scopes. It's really because I'm not sure what he means by parallax, and I would also love to have examples of riflescopes in which he has detected that. I can then answer better.

"...eyepiece is designed to be viewed with your far vision. The eyepiece adjustment knob is designed to let you adjust the image to your eye. You do NOT focus on the reticle when you do that, you should look through it to the target. If you are focusing on the reticle, you are using your near vision..."

This statement contradicts anything I have ever read on use/set-up of the ocular lens (eyepiece). What method do you follow if not focusing on the reticle?

 

[jelenko]

"...eyepiece is designed to be viewed with your far vision. The eyepiece adjustment knob is designed to let you adjust the image to your eye. You do NOT focus on the reticle when you do that, you should look through it to the target. If you are focusing on the reticle, you are using your near vision..."

This statement contradicts anything I have ever read on use/set-up of the ocular lens (eyepiece). What method do you follow if not focusing on the reticle?

When focusing the eye piece we are supposed to NOT focus on the reticle. We are supposed to look away and look back without focusing. The eye piece is focused on the reticle when the reticle is sharp when we first look into the eye piece [i.e., our eye is still relaxed at our far vision].

If you do focus on the reticle as you use the eye piece to focus, you'll be using your near vision which requires muscles in your eye to bend the lens in your pupil. Then, when you go to take a shot it's VERY easy for your eye to get tired and relax a bit, hence losing focus on the reticle.

 

[Steve Donlon]

When focusing the eye piece we are supposed to NOT focus on the reticle. We are supposed to look away and look back without focusing. The eye piece is focused on the reticle when the reticle is sharp when we first look into the eye piece [i.e., our eye is still relaxed at our far vision].

If you do focus on the reticle as you use the eye piece to focus, you'll be using your near vision which requires muscles in your eye to bend the lens in your pupil. Then, when you go to take a shot it's VERY easy for your eye to get tired and relax a bit, hence losing focus on the reticle.

That's why for me, it's good to reset the reticle when you change distance, not for the retical but to reset me and me eyes Even if the retical does not change it's position, it changes me.

 

[Turbulent Turtle]

So is 1st focal plane better for long distance? It seems for my eyes it is. But I have trouble seeing at longer distance and can no longer correct it with eye glasses. I'm at the limit of what can be done. But I have learned how to deal with it out to 1000 yards until eye fatigue sets in then I must correct by lowering the magnification and renew the retical. It seems easier to correct with FFP scopes. But that could just be me.

There are always two focal planes in a riflescope. The first or front focal plane is where the image from the objective lens is first "rendered". This FFP is at the front of the erector tube and it is the size of the inner diameter of the main tube. The front end of the erector tube is moved up and down and side to side by the elevation and windage turret and simply looks at a different spot on the focal plane as it moves. The erector tube massages the image it sees at the front and "renders" an image at its rear, at the second focal plane. The eyepiece transmits the image of the second focal plane afocally to your eye, which then focuses the image onto your retina. The eyepiece does NOT focus the image to your eye, it collimates the rays (keeps them parallel) to your iris, which does the focusing.

The difference between FFP and SFP is that in an FFP riflescope the image of the reticle (notice the spelling), is merged with the image of the target (and whatever else the erector tube sees) and is then flipped and zoomed before being "rendered" on the SFP. This means the FFP reticle will remain in proportion with the remainder of the image and as you zoom, the FFP reticle will grow, whereas an SFP reticle will remain the same size and will shrink in relation to the image.

Lots of people swear by FFP reticle for its proportion retention, great for corrections and so on. But for us F-class shooters, the FFP reticle is something to be avoided at all costs. We love that our reticles get more precise, more surgical as we twist that zoom. Placing the MTR-WFD reticle at 80X on an F-class target is pure sex. (Ok, I'm old.)

So FFP or SFP is not the issue for you. As I explained earlier, the riflescope is essentially an afocal device through which you look with your far vision. The riflescope does NOT magnify the target; it brings it closer. I am not an eye doctor (an ophthalmologist) and I don't play one on TV or on the internet, so I cannot help you much, except perhaps to explain how a riflescope works. I think you are having issue setting the eyepiece correction (diopter) properly and are definitely trying to focus on it, thereby defeating yourself. I would suggest you place it a 0 or -0.5 and spend more time playing with the side focus. I would also suggest you find an eye doctor that's also a shooter. They can better help you.

 

[Turbulent Turtle]

"...eyepiece is designed to be viewed with your far vision. The eyepiece adjustment knob is designed to let you adjust the image to your eye. You do NOT focus on the reticle when you do that, you should look through it to the target. If you are focusing on the reticle, you are using your near vision..."

This statement contradicts anything I have ever read on use/set-up of the ocular lens (eyepiece). What method do you follow if not focusing on the reticle?

@jelenko did a superb job explaining things to you. Let me just reiterate that you should position the eyepiece adjustment in the middle, at 0 or -0.5 and then take some very quick peeks looking at infinity. If you spend more than a second looking at the reticle, your eye will focus on it and start using your near vision, bad, bad, bad. Also, when you look away, I don't mean to look at the turrets of the back of the riflescope, I mean look at the forest in the distance or the Moon in the sky or the cloud that looks like a horsie. Get your eye to stay in far vision, in other words, relaxed.

Story time.

I was explaining some things about a riflescope design to a very good friend of mine recently at a match. He was complaining that he had problems looking through his riflescope. We'll call him Ray. So, Ray said that he was wearing contacts and that he had a pair that had his far vision prescription in on, and his near vision prescription in the other. That piqued my interest. He then said that he had his near vision contact in his shooting eye to be able to see the reticle, but the image was crap. I explained about afocal, and the need to use far vision to see through a riflescope. I was met with skepticism. A little later, he switched them around and everything worked great. He beat me during the match. Silly me, I should never have told him.

End of story.

 

[Woollybugger]

What about - forget the parallax adjustment aspect but
What about the focus aspect itself
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Some scopes seem to have more range of FOCUS adjustment
When higher priced scopes seem to top out of adjustment once everything is in focus from at about 600 yds on out.
IE: once you reach 600 yds, there is no further difference in focus clarity when adjusting more toward infinity
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I don't know if Mr. Donlon is posting in relation to a reference I made regarding how my Kahles parallax works
but
Example:
If I adjust my SIMMONS scope even - a $300 scope
I can adjust the parallax focus at 2000 yds, and still have more adjustment to focus past that
Same with many Leupolds and my B&L's I have experienced
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However:
With my Kahles, once I adjust focus at 600 yds, turning the dial does nothing further
"AS far as using the Focus aspect " goes.
Or - I cannot adjust focus past that to become fuzzy again.
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Or another way to understand this is:
I can adjust the image to be "Focused" at 1000 yds with a Leupold
And still be able to turn the focus further out to have the image then be fuzzy as we approach the infinity mark
The higher end scopes cannot adjust focus PAST this point and seem to be in "Focus" from 600 yds on out - meaning we cannot adjust focus past this range to be fuzzy again then dial back a little bit to be perfectly sharp
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It sucks when even a Simmons, can adjust focus/parallax knob to be clear at 1000 yds
Adjust past that point toward infinity to become fuzzy
then dial back a little bit to be in focus again, so as to adjust the sharpest image possible.
This allows us to perfectly dial it in.
We are often not using the parallax for adjusting parallax but more for image clarity
since as you say - we are not concerned about the parallax aspect
since we know how to put our eye in the middle
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So what we're wondering or trying to understand, is the the result of the higher top tier scopes having better alingment/glass/ etc that once we adjust to a certain yardage such as 600 yds
they cannot adjust focus any further ....
....as we turn the dial toward infinity
Everything from 600 yds on out is in focus no matter how much we turn the dial between the
600 yds mark and inifinity
------------
This reminds me of a pair of binoculars I had that one feature was they did not need nor have a focus wheel
They were in focus by themselves from about 20 yds on out to infinity.
(I dont know how, but it tripped me out that you could pan the landscape and everything was in focus say as you panned from 50 yds to 600 yds)

Maybe a dumb question. Can you see target shift behind the reticle at distances past 600 yards? Parallax is not just image focus. I have scopes that will look sharp but if I move my eye in the eye box the target shifts off of the cross hair. Tweak the parallax a little and this shift lessens or goes away.

 

[Turbulent Turtle]

That's why for me, it's good to reset the reticle when you change distance, not for the retical but to reset me and me eyes Even if the retical does not change it's position, it changes me.

You really are defeating yourself. In my experience, once you have set the reticle properly it should be fine for all distances. When I first mount a riflescope and do the first eyepiece adjustment, I do tweak it at a 1000-yard match, because that is at a very long range and that's the perfect time to tweak it since you should be looking at infinity or a very long distance when you adjust. But that's all you need. You only do it once.