I have read several different sources of how to eliminate parallax. 1st-adjust eyepiece so that the reticle is in sharp focus. 2nd-after starting with setting the objective to infinity, while aiming at a distant target, adjust objective so that the target and reticle are "locked" together. Some things that aren't completely clear to me are: 1. when focusing the eyepiece what power should the scope be set to: max or min or doesn't it matter? 2. Should the objective be set to infinity or does that matter? 3. If you wear corrective lenses, as I do for far-sightedness, should you be wearing them or do you/can you wear plain shooting glasses and correct for vision with the eyepiece adjustments while focusing the eyepiece for sharp reticle focus? Today I tried adjusting my scope for parallax while wearing corrective eyewear. I seemed to get the reticle in focus without problem. But, I could not eliminate parallax at the target set at 200 yds. It seemed when I adjusted the objective to the least, but not quite eliminating parallax, the target was not in sharp focus. I am wearing WileyX shooting glasses with progressive lenses. My scope is a NS 12-42x56 BR. Help would be greatly appreciated because I know I am not making best use of my rifle/ammo inherent accuracy.
Adjusting scope for parallax
- Thread starter medic727
- Start date
Fred Bohl
Gold $$ Contributor
Re your questions for your or similar rear reticule design scopes:
1 - it doesn't matter what power your scope is set for when adjusting eyepiece focus.
2 - it doesn't matter what objective focus/parallax your scope is set for when adjusting eyepiece focus.
IMHO you will find the best combination of eyepiece focus, zero parallax error, and image/target focus if you do not wear any glasses or contacts and use the eyepiece focus to correct for your vision abnormality.
As to "safety eyewear" concerns - I've been shooting in peaceful competition and at times in warfare for 59 years now and have never seen or known anyone to have had an eye injury do to any failure of the gun or ammunition.
1 - it doesn't matter what power your scope is set for when adjusting eyepiece focus.
2 - it doesn't matter what objective focus/parallax your scope is set for when adjusting eyepiece focus.
IMHO you will find the best combination of eyepiece focus, zero parallax error, and image/target focus if you do not wear any glasses or contacts and use the eyepiece focus to correct for your vision abnormality.
As to "safety eyewear" concerns - I've been shooting in peaceful competition and at times in warfare for 59 years now and have never seen or known anyone to have had an eye injury do to any failure of the gun or ammunition.
BoydAllen
Gold $$ Contributor
On the other hand I have seen the results of several blowups that turned the shooter' s face into a pattern of small cuts that would have extended into the eyes if glasses had not been worn. IMO really bad advice. :-[
Having been the president of a large range that was open to the public and members seven days a week, I can speak with some authority on the subject of length of shooting experience and attitude about strict compliance with range rules, including safety procedures. Many times they do not correlate.
Having been the president of a large range that was open to the public and members seven days a week, I can speak with some authority on the subject of length of shooting experience and attitude about strict compliance with range rules, including safety procedures. Many times they do not correlate.
Generally speaking, while adjusting the eyepiece, I suggest you look at the distant sky with the parallax set to infinity and at the highest magnification.
On safety eyewear: I have had a rifle blow up in my hands (due to a factory ammunition) problem. Had I not had safety glasses on, I would have not had eyes right now.
ILya
On safety eyewear: I have had a rifle blow up in my hands (due to a factory ammunition) problem. Had I not had safety glasses on, I would have not had eyes right now.
ILya
I have posted this on other sites in the last few years, hope it helps,
oin date: Jun 2004
posts: 6
Proper Scope Adjustment
Ok, I am going to post this document. I would like to give a little info on how I got it. And the tone used by the author. I copied this and pasted it to MS Word off another site. And was sent a copy by the author after I contacted him directly. His tone may be a bit harsh, but this was written after responding o numerous questions about scope adjustment then having the person asking the question say well that's not how I was told to do it. Or another guy said to do it this way. The author is a man named Paul Coburn and his job is evaluating optics for a living. He is highly regarded in the field and does testing for some major companies. So no if's, and's or but's regardless of if you agree or disagree with the writting style he is giving the straight poop on the subject. Here it goes...
I've answered questions about scope parallax about 300 times, and it's always a long drawn out thing, going several e-mails, and a few phone calls. It doesn't seem to make any difference how long the guy has been shooting, this one always keep screwing guys up.
OK... here goes (Whew, this is gonna be a long one).
There are several things that go on inside a scope, and in the eyes at the same time. Some of them workie against each other.
But some terminology first... and we'll leave out lenses that are there to correct some optical or color errors, but don't have anything to do with image forming.
We'll start at the front of it all, and work back.
1 - The "Object"... the thing that you are looking (shooting) at.
2 - The "Objective". The front lens is called the "Objective"... it forms the first image of the "object" we are looking at (that why they call it the Objective
It is the lens that "captures" all the light, that is solely responsible for the image quality of the scope... if it is poor, you can't fix the poor image later.
This lens is usually made of two different types of glasses (called "elements") sandwiched together, and is called an "Achromat".
The Achromat is fully color corrected for blue and green. The red wavelengths are partially corrected, but have what is called "residual color errors".
This is the normal type of objective used in shooting and spotting scopes. In quality, they can vary from badd, through sorta OK, to pretty damn good.
If one of the elements is made of an "ED" glass, or a "Fluorite" (CaF) glass, the two element lens can be very good to friggin' outstanding.
In some instances, objective lenses are made of three elements, and all three colors (blue, green, and red) are completely corrected. This type of lens is called an "Apochromat", and this is the finest lens that can be bought. The best of these can also have "ED" glass, or Fluorite as one of the elements.
3 - The "First image plane". The Objective focuses the light to make an image of the subject, just like a camera lens. This image is upside down, and right/left reversed. This is the first image plane, but NOT the "First image plane" that is talked about when shooters talk about reticles.
4 - The "Erector lens"... (if it is a group of lenses, it is called the "Erector cell"). Because the first image is upside down/wrong way around, we (as shooters) can't use it... so we flip it around with a simple optical group called the "erector cell". This cell gives us a new image that is right way around, called the second image plane. Moving this cell causes this second image plane to move... so micrometer spindles are put against the cell, to get elevation and windage adjustments.
5 - The "Second image plane". This is the second real image plane in the scope, and this is the image plane that shooters call the "First image plane" when talking about reticles. In a fixed power scope, or in a variable with a "First image plane reticle", the reticle would be placed in this image plane.
This is where Premier Reticle puts those magical "Gen II" reticles.
6 - The "Zoom group". In a variable scope with standard (non-magnifying) reticle, the zoom group of optics would follow #5. This group of lenses can change the size of the image plane in #5 and then form a new (third) image plane behind it.
7 - The "Third image plane" In variable power scopes, this is the plane that the reticle is placed in. By being here, it allows the image to change sizes, but the reticle to stay the same size. In the context of reticles, this is the image plane that is referred to as the "second image plane"
8 - The "Eyepiece". This optical group is like a jewelers loupe. Is is (or should be) a super fine magnifier. It's only job in the whole world, is to focus on the reticle.
Let me repeat that for those that live in Rio Linda...
THE ONLY JOB FOR THE EYEPIECE IS TO FOCUS YOUR EYE ON THE RETICLE!!!!
It CANNOT adjust, or compensate for, or do anything else when things look bad in the scope, or when you can't hit the target... and you CANNOT use the eyepiece to try to correct for parallax. That is sheer folly at best, and raw stupidity at worst.
If you expect it to do anything else, then stop wasting your time with long-range shooting, cuz you are never gonna make it past mediocre... and take up golf!!
OK... now that you know what the insides are like... lets move on. We'll use the zoom scope for our examples. cuz if you can understand the zoom scope, then the fixed scope is a walk in the park.
In the scope that is set for infinity range, the object forms an image behind the objective (the first image plane)... the erector cell "sees" that image, and flips it over and makes it right way around in a NEW image plane (the Second image plane). The zoom group adjusts the size of this image plane, and makes a NEW image plane (the Third image plane) that is the desired size. There is a reticle placed in this last image plane, and the eyepiece focuses on the reticle AND the image at the same time.
When things are good, that's how the scope workie!
---
But... now the booger falls into the soup... IF the third image plane and the reticle are not exactly, (and I mean EX-ACT-LY) in the same place, then your eye cannot see them LOCKED together as one picture.
It sees them as two separate pictures, and the eye will look at each separately, and the eye can also look AROUND one to see the other.
---
Lenses are measured in metrics (aka Millimeters). Not because the Europeans wanted the metric system 20 years ago, but because optical strings and chains of lenses (like scopes) are really a string of numbers.
There are constant ratios of "this divided by that's" that give image sizes, "F-ratios", and image locations. It's so damn easy to do the engineering using a 10 based system that the optical guys were using the metric system way back in the 1800's.
The objective has a "Focal length"... this is the distance behind the lens that the first image plane falls when making an image if a subject that is at infinity (or very damn far away).
If the objective has a focal length of 100mm, then the image of that 1000 yd target is 100mm behind the lense.
But the problem with geometric optics (which is what we are dealing with here), is that they follow the laws of geometry... and optics make triangles like rabbits make babies.
AND... in an optical chain, when you change one thing, one angle, one ANYTHING, everything else follows along and changes BASED on the ratios involved at THAT stage.
If we take that same target, and move it to 100 yds, the image in the scope moves BACKWARDS, going further into the scope. Not by much, but it doesn't take much, cuz we're dealing with very small distances inside the scope, and very high magnifications.
How far the image moves back, and what it's new position is, is predictable by the mathematical ratios of the angles formed by the subject and the first image... OR (for us dummies that lost our slip sticks) by the ratio of the distances to the Target and the focal length, multiplied by the focal length. then ADDED to the focal length.
The target is at 100 yds (91440mm), the focal length of the objective is 100, so the displacement is 1/914 x 100, which means that the first image is now at ~100.1mm. Hmmm only .1mm, that doesn't seem like much.
Read the following paragraph twice...
In a 1x scope, 0.1mm would mean nothing... but this displacement is repeated throughout the chain, AND if any of the optical groups change the image ratio (aka image size), then the displacement (aka ERROR) is changed in direct proportion to the increase in magnification. So in a 3x scope, it would be .3mm, and in a 10x scope, it would be 1mm, and in a 30 power scope, the image would be 3mm behind the reticle.
Now, you should have seen a pattern in this last paragraph.
READ THIS TWICE!!
With the same error in the objective (scope focused at 1000, and target at 100), the parallax INCREASES WITH MAGNIFICATION... got it?
If not, READ IT TWO MORE TIMES!!
OK... now, if we do the same math for closer distances, like 50 yds, and 25 yds we will see that the error gets really big, so that with a target at 50 yards, and the scope set at 35 or 65 yds, the parallax makes the combination un-usable.
---
Parallax is... when the image of the target, and the reticle, are NOT in exactly the same plane, and by moving the eye up and down... or side to side, either the target OR the reticle appears to move in relation to the other.
You might see the target move and the reticle stay still, or you might see the target stay still and the reticle move over it... both are exactly the same, and which you see, is only a matter of your OWN perception.
It is NOT possible to have parallax while moving up and down, but not have it when you are moving side to side.
If you think that is what you have, you have other problems... either you are moving the rifle, or you have eye problems.
---
HOW TO SET UP A SCOPE!
This is the only way to do it...
First, screw the eyepiece out (CCW) all the way, until it stops.
If you wear glasses, put them on.
Hold the scope up and look OVER the scope at the sky, and relax your eyes. Then move the scope in front of your eye.
The reticle should look fuzzy
Turn the eyepiece in 1/2 turn, and do the same thing again. You will have to do for a while before the reticle starts to look better. When you start getting close, then turn the eyepiece 1/4 turn each time.
Do this until the reticle is fully sharp and fully BLACK immediately when you look through the scope.
Than back off one turn and do it again to make sure you are in the same place.
Then LOCK the ring on the eyepiece, and leave it alone forever!
Second.
Set the scope down on something sold, where it can see something at a long distance... half a mile of longer is good.
It can be on the rifle, and rested in sand bags at the range... but pick something at least 1000 yds away... even further if possible.
If the scope has an "AO" Adjustable objective, then set it for infinity, and look at the distant object, and move your head from one side to the other, or up and down if you prefer.
If the reticle seems to move, there is parallax.
Change the distance setting and try again... if you are very careful, you can move your eye, and adjust the distance at the same time, seeing which direction gets better.
With front objective adjustments, you can turn them either way without worry... BUT with side adjustment scopes, like the MK4-M3, the M3-LR, or the other LR family of scopes, the adjustment must ALWAYS be made from the infinity end of the dial. Turn the adjustment all the way until it stops (past infinity), and then start turning it in a little at a time, until there is no parallax. If you "overshoot" the proper setting, you can't just turn back a little, you must go back to stop at the end of the dial, and start over again.
While "AO"s dials are locked in place, and if the indicated distance doesn't match the real distance, there's nothing you can do about it... the side focus dials are not locked in place.
Once you have found the setting for infinity on the side focus models, then (CAREFULLY) loosen the screws, and set the dial so that little sideways infinity symbol is lined up with the hash mark, so it is calibrated. You can also make little marks or put on a paper tape for other ranges instead of using the round dots that don't match any range.
Now you can set it to infinity, but remember that you MUST turn the dial all the way past infinity to the stop, EVERY TIME before going from a close range to a longer range.
If you are set for 500 yds, you can go directly to 100 yds, but if you are set for 100 and want to set it to 500, you MUST go all the way back to the stop, and then go to 500
This is because there is a fair amount of backlash (aka SLOP) in this wheel linkage to the focusing cell, so you can set it only from one direction to make sure the slop is always on one side. The other problem with it is, even if you decided that you wanted to calibrate from the other end... the recoil will push the cell back. SO you must ALWAYS set these dials from the infinity end of their scales.
To make it easy to not have to remember... I always start from the end stop, when I change range, no matter which direction I'm going in... it adds about 0.023 seconds!
---
Now... you gots a friend that says to set up a scope a different way???... he don't know doodly-squat about scopes.
The guy at the range said to do it a different way... he don't know either.
You know some guy who's in the Marines says to use your eyepiece to correct parallax... he doesn't know about optics either.
You got a friend that shoots benchrest and says something different... he don't know crapola!
This is the way, the only way, there is no other way.
... as Rushbo would say... this is from GOD-da .
You gots questions, just e-mail me.
You wanna "debate it", then go play golf, cuz you're wasting my time!
'lito (gettin' grumpy in my old age!)
I hope this was helpful and did not burn up to much bandwidth. Again Paul deserves all the credit for the information not me...
Dirty Steve, Out.
Reply With Quote
The entire thread can be accessed here http://www.benchrest.com/forums/show...t=15138&page=2 if anyone's interested.
I bedoubt that Dirty Steve's still open on his offer to email ever'body but he pretty well nails it DOWN anyways eh???
oin date: Jun 2004
posts: 6
Proper Scope Adjustment
Ok, I am going to post this document. I would like to give a little info on how I got it. And the tone used by the author. I copied this and pasted it to MS Word off another site. And was sent a copy by the author after I contacted him directly. His tone may be a bit harsh, but this was written after responding o numerous questions about scope adjustment then having the person asking the question say well that's not how I was told to do it. Or another guy said to do it this way. The author is a man named Paul Coburn and his job is evaluating optics for a living. He is highly regarded in the field and does testing for some major companies. So no if's, and's or but's regardless of if you agree or disagree with the writting style he is giving the straight poop on the subject. Here it goes...
I've answered questions about scope parallax about 300 times, and it's always a long drawn out thing, going several e-mails, and a few phone calls. It doesn't seem to make any difference how long the guy has been shooting, this one always keep screwing guys up.
OK... here goes (Whew, this is gonna be a long one).
There are several things that go on inside a scope, and in the eyes at the same time. Some of them workie against each other.
But some terminology first... and we'll leave out lenses that are there to correct some optical or color errors, but don't have anything to do with image forming.
We'll start at the front of it all, and work back.
1 - The "Object"... the thing that you are looking (shooting) at.
2 - The "Objective". The front lens is called the "Objective"... it forms the first image of the "object" we are looking at (that why they call it the Objective
It is the lens that "captures" all the light, that is solely responsible for the image quality of the scope... if it is poor, you can't fix the poor image later.
This lens is usually made of two different types of glasses (called "elements") sandwiched together, and is called an "Achromat".
The Achromat is fully color corrected for blue and green. The red wavelengths are partially corrected, but have what is called "residual color errors".
This is the normal type of objective used in shooting and spotting scopes. In quality, they can vary from badd, through sorta OK, to pretty damn good.
If one of the elements is made of an "ED" glass, or a "Fluorite" (CaF) glass, the two element lens can be very good to friggin' outstanding.
In some instances, objective lenses are made of three elements, and all three colors (blue, green, and red) are completely corrected. This type of lens is called an "Apochromat", and this is the finest lens that can be bought. The best of these can also have "ED" glass, or Fluorite as one of the elements.
3 - The "First image plane". The Objective focuses the light to make an image of the subject, just like a camera lens. This image is upside down, and right/left reversed. This is the first image plane, but NOT the "First image plane" that is talked about when shooters talk about reticles.
4 - The "Erector lens"... (if it is a group of lenses, it is called the "Erector cell"). Because the first image is upside down/wrong way around, we (as shooters) can't use it... so we flip it around with a simple optical group called the "erector cell". This cell gives us a new image that is right way around, called the second image plane. Moving this cell causes this second image plane to move... so micrometer spindles are put against the cell, to get elevation and windage adjustments.
5 - The "Second image plane". This is the second real image plane in the scope, and this is the image plane that shooters call the "First image plane" when talking about reticles. In a fixed power scope, or in a variable with a "First image plane reticle", the reticle would be placed in this image plane.
This is where Premier Reticle puts those magical "Gen II" reticles.
6 - The "Zoom group". In a variable scope with standard (non-magnifying) reticle, the zoom group of optics would follow #5. This group of lenses can change the size of the image plane in #5 and then form a new (third) image plane behind it.
7 - The "Third image plane" In variable power scopes, this is the plane that the reticle is placed in. By being here, it allows the image to change sizes, but the reticle to stay the same size. In the context of reticles, this is the image plane that is referred to as the "second image plane"
8 - The "Eyepiece". This optical group is like a jewelers loupe. Is is (or should be) a super fine magnifier. It's only job in the whole world, is to focus on the reticle.
Let me repeat that for those that live in Rio Linda...
THE ONLY JOB FOR THE EYEPIECE IS TO FOCUS YOUR EYE ON THE RETICLE!!!!
It CANNOT adjust, or compensate for, or do anything else when things look bad in the scope, or when you can't hit the target... and you CANNOT use the eyepiece to try to correct for parallax. That is sheer folly at best, and raw stupidity at worst.
If you expect it to do anything else, then stop wasting your time with long-range shooting, cuz you are never gonna make it past mediocre... and take up golf!!
OK... now that you know what the insides are like... lets move on. We'll use the zoom scope for our examples. cuz if you can understand the zoom scope, then the fixed scope is a walk in the park.
In the scope that is set for infinity range, the object forms an image behind the objective (the first image plane)... the erector cell "sees" that image, and flips it over and makes it right way around in a NEW image plane (the Second image plane). The zoom group adjusts the size of this image plane, and makes a NEW image plane (the Third image plane) that is the desired size. There is a reticle placed in this last image plane, and the eyepiece focuses on the reticle AND the image at the same time.
When things are good, that's how the scope workie!
---
But... now the booger falls into the soup... IF the third image plane and the reticle are not exactly, (and I mean EX-ACT-LY) in the same place, then your eye cannot see them LOCKED together as one picture.
It sees them as two separate pictures, and the eye will look at each separately, and the eye can also look AROUND one to see the other.
---
Lenses are measured in metrics (aka Millimeters). Not because the Europeans wanted the metric system 20 years ago, but because optical strings and chains of lenses (like scopes) are really a string of numbers.
There are constant ratios of "this divided by that's" that give image sizes, "F-ratios", and image locations. It's so damn easy to do the engineering using a 10 based system that the optical guys were using the metric system way back in the 1800's.
The objective has a "Focal length"... this is the distance behind the lens that the first image plane falls when making an image if a subject that is at infinity (or very damn far away).
If the objective has a focal length of 100mm, then the image of that 1000 yd target is 100mm behind the lense.
But the problem with geometric optics (which is what we are dealing with here), is that they follow the laws of geometry... and optics make triangles like rabbits make babies.
AND... in an optical chain, when you change one thing, one angle, one ANYTHING, everything else follows along and changes BASED on the ratios involved at THAT stage.
If we take that same target, and move it to 100 yds, the image in the scope moves BACKWARDS, going further into the scope. Not by much, but it doesn't take much, cuz we're dealing with very small distances inside the scope, and very high magnifications.
How far the image moves back, and what it's new position is, is predictable by the mathematical ratios of the angles formed by the subject and the first image... OR (for us dummies that lost our slip sticks) by the ratio of the distances to the Target and the focal length, multiplied by the focal length. then ADDED to the focal length.
The target is at 100 yds (91440mm), the focal length of the objective is 100, so the displacement is 1/914 x 100, which means that the first image is now at ~100.1mm. Hmmm only .1mm, that doesn't seem like much.
Read the following paragraph twice...
In a 1x scope, 0.1mm would mean nothing... but this displacement is repeated throughout the chain, AND if any of the optical groups change the image ratio (aka image size), then the displacement (aka ERROR) is changed in direct proportion to the increase in magnification. So in a 3x scope, it would be .3mm, and in a 10x scope, it would be 1mm, and in a 30 power scope, the image would be 3mm behind the reticle.
Now, you should have seen a pattern in this last paragraph.
READ THIS TWICE!!
With the same error in the objective (scope focused at 1000, and target at 100), the parallax INCREASES WITH MAGNIFICATION... got it?
If not, READ IT TWO MORE TIMES!!
OK... now, if we do the same math for closer distances, like 50 yds, and 25 yds we will see that the error gets really big, so that with a target at 50 yards, and the scope set at 35 or 65 yds, the parallax makes the combination un-usable.
---
Parallax is... when the image of the target, and the reticle, are NOT in exactly the same plane, and by moving the eye up and down... or side to side, either the target OR the reticle appears to move in relation to the other.
You might see the target move and the reticle stay still, or you might see the target stay still and the reticle move over it... both are exactly the same, and which you see, is only a matter of your OWN perception.
It is NOT possible to have parallax while moving up and down, but not have it when you are moving side to side.
If you think that is what you have, you have other problems... either you are moving the rifle, or you have eye problems.
---
HOW TO SET UP A SCOPE!
This is the only way to do it...
First, screw the eyepiece out (CCW) all the way, until it stops.
If you wear glasses, put them on.
Hold the scope up and look OVER the scope at the sky, and relax your eyes. Then move the scope in front of your eye.
The reticle should look fuzzy
Turn the eyepiece in 1/2 turn, and do the same thing again. You will have to do for a while before the reticle starts to look better. When you start getting close, then turn the eyepiece 1/4 turn each time.
Do this until the reticle is fully sharp and fully BLACK immediately when you look through the scope.
Than back off one turn and do it again to make sure you are in the same place.
Then LOCK the ring on the eyepiece, and leave it alone forever!
Second.
Set the scope down on something sold, where it can see something at a long distance... half a mile of longer is good.
It can be on the rifle, and rested in sand bags at the range... but pick something at least 1000 yds away... even further if possible.
If the scope has an "AO" Adjustable objective, then set it for infinity, and look at the distant object, and move your head from one side to the other, or up and down if you prefer.
If the reticle seems to move, there is parallax.
Change the distance setting and try again... if you are very careful, you can move your eye, and adjust the distance at the same time, seeing which direction gets better.
With front objective adjustments, you can turn them either way without worry... BUT with side adjustment scopes, like the MK4-M3, the M3-LR, or the other LR family of scopes, the adjustment must ALWAYS be made from the infinity end of the dial. Turn the adjustment all the way until it stops (past infinity), and then start turning it in a little at a time, until there is no parallax. If you "overshoot" the proper setting, you can't just turn back a little, you must go back to stop at the end of the dial, and start over again.
While "AO"s dials are locked in place, and if the indicated distance doesn't match the real distance, there's nothing you can do about it... the side focus dials are not locked in place.
Once you have found the setting for infinity on the side focus models, then (CAREFULLY) loosen the screws, and set the dial so that little sideways infinity symbol is lined up with the hash mark, so it is calibrated. You can also make little marks or put on a paper tape for other ranges instead of using the round dots that don't match any range.
Now you can set it to infinity, but remember that you MUST turn the dial all the way past infinity to the stop, EVERY TIME before going from a close range to a longer range.
If you are set for 500 yds, you can go directly to 100 yds, but if you are set for 100 and want to set it to 500, you MUST go all the way back to the stop, and then go to 500
This is because there is a fair amount of backlash (aka SLOP) in this wheel linkage to the focusing cell, so you can set it only from one direction to make sure the slop is always on one side. The other problem with it is, even if you decided that you wanted to calibrate from the other end... the recoil will push the cell back. SO you must ALWAYS set these dials from the infinity end of their scales.
To make it easy to not have to remember... I always start from the end stop, when I change range, no matter which direction I'm going in... it adds about 0.023 seconds!
---
Now... you gots a friend that says to set up a scope a different way???... he don't know doodly-squat about scopes.
The guy at the range said to do it a different way... he don't know either.
You know some guy who's in the Marines says to use your eyepiece to correct parallax... he doesn't know about optics either.
You got a friend that shoots benchrest and says something different... he don't know crapola!
This is the way, the only way, there is no other way.
... as Rushbo would say... this is from GOD-da .
You gots questions, just e-mail me.
You wanna "debate it", then go play golf, cuz you're wasting my time!
'lito (gettin' grumpy in my old age!)
I hope this was helpful and did not burn up to much bandwidth. Again Paul deserves all the credit for the information not me...
Dirty Steve, Out.
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The entire thread can be accessed here http://www.benchrest.com/forums/show...t=15138&page=2 if anyone's interested.
I bedoubt that Dirty Steve's still open on his offer to email ever'body but he pretty well nails it DOWN anyways eh???
BoydAllen
Gold $$ Contributor
This fellow obviously knows a lot about scopes BUT his explanation is flawed. He assumes that if one follows his directions for focusing the eyepiece that you will get it exactly right. For a couple of reasons, this is commonly not the case. Unlike the objective, the eyepiece has very fine adjustment threads, and considerable depth of focus. Add to this the fact that if you pause too long in your consideration of whether the reticle is sharp, your eye will compensate for a slight eyepiece focus error, and, indeed it will look as it should, even though it is slightly off. It is the instantaneous impression that you are looking for, just as you open your eye, with it in the correct position relative to the scope.
The result of this slight error in eyepiece adjustment is that you may not be able to achieve peak target sharpness and absolute zero parallax at the same objective setting. This problem MAY be able to be resolved by revisiting the eyepiece adjustment, and doing a little experimenting, going back and forth between it and the objective focus until the desired result is achieved. I have done this several times, and have had one experience where no amount of adjustment would resolve the problem, but sending the scope to the manufacturer did. To be clear, I am not saying that I adjusted the parallax, or target sharpness by adjusting the eyepiece, but corrected the eyepiece setting so that zero parallax and peak target sharpness occurred at the same point of objective adjustment.
At this point, the reader is faced with a problem as to who to believe, the self proclaimed expert (who I agree is quite knowledgeable, but who seems to have missed the mark on this one point) or me, who only has his experiences to report. To assist the reader with this problem I leave you with this link, and refer you to the bottom paragraphs, and below that the source, which I have not verified. http://rimfirebenchrest.com/articles/parallax2.html
For those of you who require a good measure of bombastic condescension to be persuaded.... get your heads out of your .... and read the page that the link leads to ;D Just kidding.
The result of this slight error in eyepiece adjustment is that you may not be able to achieve peak target sharpness and absolute zero parallax at the same objective setting. This problem MAY be able to be resolved by revisiting the eyepiece adjustment, and doing a little experimenting, going back and forth between it and the objective focus until the desired result is achieved. I have done this several times, and have had one experience where no amount of adjustment would resolve the problem, but sending the scope to the manufacturer did. To be clear, I am not saying that I adjusted the parallax, or target sharpness by adjusting the eyepiece, but corrected the eyepiece setting so that zero parallax and peak target sharpness occurred at the same point of objective adjustment.
At this point, the reader is faced with a problem as to who to believe, the self proclaimed expert (who I agree is quite knowledgeable, but who seems to have missed the mark on this one point) or me, who only has his experiences to report. To assist the reader with this problem I leave you with this link, and refer you to the bottom paragraphs, and below that the source, which I have not verified. http://rimfirebenchrest.com/articles/parallax2.html
For those of you who require a good measure of bombastic condescension to be persuaded.... get your heads out of your .... and read the page that the link leads to ;D Just kidding.
To generate some discussion here is a very different method of adjusting a scope. The article unfortunately has been written to provide so much clarification, that it gets confusing. The simplified version is:
1. Put up a very fine print target with very small text at your minimum focus distance plus one yard.
2. Set the scope on max power (need minimum of 18X). Use the objective to bring the target into clear focus. I wear my corrective lenses.
3. Use the head bop method of checking for parallax. Adjust the eye piece (yes I said eye piece) to eliminate parallax.
4. Repeat step 2, and then 3 until you have perfect focus and zero parallax at the same time.
This method works for me, and I love having the zero parallax match with perfect focus, because I find it is much easier to set focus than it is to check for parallax error. Also it is nice to have the target in perfect focus when you have zero parallax.
http://ateam.100free.com/ateamh/A_Team_Parallax_adj.htm
This may be very similar in outcome to what BoydAllen is suggesting.
1. Put up a very fine print target with very small text at your minimum focus distance plus one yard.
2. Set the scope on max power (need minimum of 18X). Use the objective to bring the target into clear focus. I wear my corrective lenses.
3. Use the head bop method of checking for parallax. Adjust the eye piece (yes I said eye piece) to eliminate parallax.
4. Repeat step 2, and then 3 until you have perfect focus and zero parallax at the same time.
This method works for me, and I love having the zero parallax match with perfect focus, because I find it is much easier to set focus than it is to check for parallax error. Also it is nice to have the target in perfect focus when you have zero parallax.
http://ateam.100free.com/ateamh/A_Team_Parallax_adj.htm
This may be very similar in outcome to what BoydAllen is suggesting.
BoydAllen
Gold $$ Contributor
One of the reasons that I am somewhat disinterested in theoretical discussions, or recitations of credentials as they relate to this subject is that I have done what I described, several times, and I believe that my results are reproducible. I have 20-15 vision (corrected), know what parallax is, and know how to focus an image. IMO actually doing a thing trumps theory every time.
I've tried every way I have read or heard about to eliminate parallax. I think I've got it down pretty good but no way do I have the guts to tell anyone that they don't know crapola! They'll probably outshoot me on the spot and laugh in my face and tell me it was the parallax's fault that my group size sucks! Lol! I've learned a bunch from this site and love it because of all of the info available. Keep it coming guys, I love to hear it all!
CaptainMal
Silver $$ Contributor
Simple.
Loved Tunered's -"Dirty Steve's"- article. Looked simple and correct to me. You hang around a rifle range any length of time and you will be appalled at the level of stupidity passing for knowledge.
You guys did good bunky.
Loved Tunered's -"Dirty Steve's"- article. Looked simple and correct to me. You hang around a rifle range any length of time and you will be appalled at the level of stupidity passing for knowledge.
You guys did good bunky.
BoydAllen
Gold $$ Contributor
You know, I have been doing the all wrong. I should start posting under a screen name, post a bullet proof resume, declare myself to be an expert (which I am not) and decry anyone that disagrees with me to be an idiot...naa; that would be way too easy. I'll stick to relating what I have actually done.
BoydAllen
Gold $$ Contributor
The sad part is that it is not even based on a correct understanding, but dogmatic repetition of an oversimplification. The combination of your eye's optical system, any corrective lenses that you wear, and the scope's eyepiece must be adjusted by moving the eyepiece so that there is a focal plane that is exactly coplanar with the reticle. Then the objective is focused to that plane, BUT it is very very easy to follow the correct procedure and still be slightly off on eyepiece focus, in which case peak target image and zero parallax will not occur at the same objective setting. With the objective adjusted for zero parallax, the target image will be slightly out of focus, and if it is adjusted for clearest target image there will be a slight amount of parallax. When this situation occurs, the correct solution is to correct the focus of the eyepiece so that it does fall in the plane of the reticle. When this is done, the objective will need to be refocused to get a sharp target image. At that point one checks for parallax, and if it is not perfect, another slight eyepiece adjustment made, after noting whether the previous adjustment improved the parallax or made it worse. This trial and error may have to be done several times.
The reasons that it is difficult to get the eyepiece perfectly adjusted in one try are that there is a range of adjustment in which there will appear to be little difference in reticle sharpness. This is because of the depth of focus of the eyepiece optics, the fineness of the usual adjustment threads, and the eyes ability to adjust to slight imperfection of reticle focus.
Another contributing factor is that even though the shooter nods his head and claims to understand that it is the instantaneous impression that one adjusts to when looking at a featureless sky or out of focus ceiling, one often observes shooters staring at the reticle image while they try to decide if it is sharp, which is completely wrong. You must open your eye, then close it, and consider what you just saw. Form my experience, very few non competition shooters have actually properly adjusted a high magnification scope, but they read, and have opinions based primarily on what they have read, and so the dogma is passed down, without critical examination, defended because everyone knows that that is the way that it is done.
If you go to the page that I included a link to in an earlier post in this thread, your will read an explanation of what I have just written, an the source given is....Leupold. I was so glad to have found it. It is not that I doubted what I had done, but that simply truthfully recounting what has been done is not enough for many. Some higher authority is required. So now you have it, and I have... vindication ;D
Note: I repeat all of this to hopefully make the point that what I have said and done is, in fact, NOT in conflict with optical theory, but based on it.
The reasons that it is difficult to get the eyepiece perfectly adjusted in one try are that there is a range of adjustment in which there will appear to be little difference in reticle sharpness. This is because of the depth of focus of the eyepiece optics, the fineness of the usual adjustment threads, and the eyes ability to adjust to slight imperfection of reticle focus.
Another contributing factor is that even though the shooter nods his head and claims to understand that it is the instantaneous impression that one adjusts to when looking at a featureless sky or out of focus ceiling, one often observes shooters staring at the reticle image while they try to decide if it is sharp, which is completely wrong. You must open your eye, then close it, and consider what you just saw. Form my experience, very few non competition shooters have actually properly adjusted a high magnification scope, but they read, and have opinions based primarily on what they have read, and so the dogma is passed down, without critical examination, defended because everyone knows that that is the way that it is done.
If you go to the page that I included a link to in an earlier post in this thread, your will read an explanation of what I have just written, an the source given is....Leupold. I was so glad to have found it. It is not that I doubted what I had done, but that simply truthfully recounting what has been done is not enough for many. Some higher authority is required. So now you have it, and I have... vindication ;D
Note: I repeat all of this to hopefully make the point that what I have said and done is, in fact, NOT in conflict with optical theory, but based on it.
Boydallen,
Much appreciate your explanation. My scope adjustments according to (the long version above) have always left me wondering whether the eyepiece was set right. There seemed to be a wide range where the crosshairs were sharp and black. Will revisit my method based on your comments to narrow it down. I use a special scope adjustment target (available in free targets) that seems much better than a regular target for this work.
Much appreciate your explanation. My scope adjustments according to (the long version above) have always left me wondering whether the eyepiece was set right. There seemed to be a wide range where the crosshairs were sharp and black. Will revisit my method based on your comments to narrow it down. I use a special scope adjustment target (available in free targets) that seems much better than a regular target for this work.
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