Parallax adjustment

[Turbulent Turtle]

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.

That's because you have not focused properly yet. At longer distances, it becomes difficult to do so sice the DOF expands rapidly with distance. This is exactly why I am a big proponent of the large wheel on the side focus turret, as it provides much better granularity of focus.

 

[ELR LVR]

"...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?

You have it backward my friend
The Objective lense is not the Ocular lense
Ocular is the rear lense (The eypiece)
Objective is the Front Lense (where you take in the light of the object viewed)
You adjust your OCULAR (REAR) lense adjustment so that your reticle is sharp.
The Objective (Front lense ) adjustment is to adjust image focus for different yardages
----------
When you first get a new scope, You must first adjust the OCULAR (rear lense) so the reticle is sharp at infinity
After that you leave it alone - forever - unless your vision changes
----------
Why scope makers ever installed a quick adjustment ocular instead of a lock ring ocular
I will never understand since that lense is not supose to be adjusted back and forth continuously
----------
The Objective, or side focus WILL BE adjusted continuously as you move to different yardages to adjust the focus of the image for your eye, the image, not the reticle which should already always be sharp due to first having adjusted your ocular

 

[ELR LVR]

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 rector 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.

So it sounds as though what you are saying is, due to the change in engineering of how the Objective is adjusted with a side focuser, there are limitations in range of adjustment?
Or limitations in how the image focus can be adjusted
----
What it seems nobody is getting or nobody is understanding or addressing is
----
Since most of us LR shooters are aware of the fact that parallax error is minimal past 300 yards
we do not care about adjusting for parallax error
What We want to be able to use that adjustment for is....Image Focus only
To be able to adjust our focuser knob, for the image to become clear then suddenly blurry as we turn it toward the infinity setting
then dial it back a tad bit again for the image to be back into crisp focus
- Front Objective Parallax adjusting scopes do this
- Side focus Parallax scopes do not
------
Similar to how we adjust our occular, when you adjust the reticle to be in focus, then go past that a little bit, then dial back to be in perfect focus again to ensure your eye did not compensate while you were adjusting

 

[Turbulent Turtle]

You have it backward my friend
The Objective lense is not the Occular lense
Occular is the rear lense (The eypiece)
Objective is the Front Lense (where you take in the light of the object viewed)
You adjust your OCCULAR (REAR) lense adjustment so that your reticle is sharp.
The Occular (Front lense ) adjustkent is to adjust image focus for different yardages
----------
When you first get a new scope, You must first adjust the OCCULAR (rear lense) so the reticle is sharp at infinity
After that you leave it alone - forever - unless your vision changes
----------
Why scope makers ever installed a quick adjustment occular instead of a lock ring occular
I will never understand since that lense is not supose to be adjusted back and forth continuously
----------
The Objective, or side focus WILL BE adjusted continuously as you move to different yardages to adjust the focus of the image for your eye, the image, not the reticle which should already always be sharp due to first having adjusted your occular

Now you're confusing things. You said:

The Occular (Front lense ) adjustkent is to adjust image focus for different yardages

That's exactly reversed. The ocular is NOT the front lens; the front lens is the objective lens. The adjustable objective is the ring at the front.

 

[ELR LVR]

Now you're confusing things. You said:

The Occular (Front lense ) adjustkent is to adjust image focus for different yardages

That's exactly reversed. The ocular is NOT the front lens; the front lens is the objective lens. The adjustable objective is the ring at the front.

Good call Thanks for catching that so quickly
yeah the last sentence in that one paragraph I did make that mistake
I said the 2 (O) words too many times and have limited focus of my objective myself early in the morning
Corrected

 

[ELR LVR]

Maybe a dumb question. Can you see target shift behind the reticle at distances past 600 yards?

No, none perceptible, I have checked
Also I seem to naturally put my eye in the middle of the eyebox without having to move side to side to double check, I still double check but it is always correct to begin with.
I envision the eyebox or round image of the scope as a peep sight and line my vision up with the center of the ring
But on my LR guns I have a cheekrest also which facilitates in proper eye placement in the eyebox

 

[Turbulent Turtle]

So it sounds as though what you are saying is, due to the change in engineering of how the Objective is adjusted with a side focuser, there are limitations in range of adjustment?
Or limitations in how the image focus can be adjusted
----
What it seems nobody is getting or nobody is understanding or addressing is
----
Since most of us LR shooters are aware of the fact that parallax error is minimal past 300 yards
we do not care about adjusting for parallax error
What We want to be able to use that adjustment for is....Image Focus only
To be able to adjust our focuser knob, for the image to become clear then suddenly blurry as we turn it toward the infinity setting
then dial it back a tad bit again for the image to be back into crisp focus
- Front Objective Parallax adjusting scopes do this
- Side focus Parallax scopes do not
------
Similar to how we adjust our occular, when you adjust the reticle to be in focus, then go past that a little bit, then dial back to be in perfect focus again to ensure your eye did not compensate while you were adjusting

I was explaining the two different methods used to focus the image from the objective lenses to the first focal plane. Adjustable Objective (AO), where you move the objective lenses back and forth, and Side Focus (SF) where a focusing lens positioned between the objectives lenses and the FFP moves back and forth to change the focus point.

An AO is simple, time-proven and very cost effective. Just don't believe the numbers on the ring. The SF is convenient to use, but requires more engineering, and costs money (and weight). The SF will also introduce design decisions which will cause debate among users. Among these design decisions will be the range of adjustments, as well as the granularity of the turret. If it's too granular, it takes more movement to effect a change. If it's not granular enough, it's difficult to get the exact focus point. On my Majesta, I elect to err on the side of more granularity by using a large wheel to focus. It also helps with my arthritis. Let me assure you that I plainly see the change in focus when I move the SF turret.

Also, the March riflescopes have a ring to lock the fast focus eyepiece. Add to that, the markings on the eyepiece will show if you mistakenly move it.

 

[Woollybugger]

No, none perceptible

Then it works

 

[Turbulent Turtle]

Good call Thanks for catching that so quickly
yeah the last sentence in that one paragraph I did make that mistake
I said the 2 (O) words too many times and have limited focus of my objective myself early in the morning
Corrected

Too many Os and too many Cs. Ocular.

 

[Steve Donlon]

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 rector 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.

You know what they say about opinions. Especially about someones eyes, when you know nothing about them. but thanks. I have the ocular almost all the way out on NF and Leupold scopes regardless of what plane they are on. This is the scope I'm talking about, the Ares FFP Athlon 4.5-30x56 MOA reticle seems to work best with more adjustment on the objective and ocular. There are plenty of us shooters out there that can't see those fine lines very well but can still shoot pretty good with FFP scopes. I'm sure some F class shooters use FFP scopes for that reason. So my question has been answered, it's from both the eyes and the scope and we all have to choose what works best each of us. No one size fits all. And a $4000 scope is not the answer. .16 subtensions are better than .016 subtensions and parallax is overlooked.

 

[Steve Donlon]

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.

I went out today and shot at 500, 800 and 1000 yards with my NF X8 4-32x50 scope. Parallax was at max at 500 yards. But I really worked at keeping my eyes centered in the objective and ocular lens. Shot the best group at 1000 yards that I have in a long time. It works, thanks

 

[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.

I did use a bracket aliment to forget about the parallax and the center of the reticle by having the 2moa target in the center of the 2moa section of the retical then just focusing on the center of the target and nothing else. I think I was trying to look at to many things at the same time. You and jelenko made more sense to me when I got out to 1000 yards. It made a big difference.

 

[Rank Amateur]

@Turbulent Turtle. Thanks Denys for all the info!

 

[Turbulent Turtle]

@Turbulent Turtle. Thanks Denys for all the info!

You're welcome. I'm considering posting my big article here somewhere, it answers a lot of questions and will probably create more questions.

I love your avatar. Integrity?

 

[Rank Amateur]

You're welcome. I'm considering posting my big article here somewhere, it answers a lot of questions and will probably create more questions.

I love your avatar. Integrity?

Thanks. Yes, Makoto, interpreted as sincerity/integrity/honesty/genuineness/authenticity

 

[danny]

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.

Needing to "focus a scope". Well, like you say, focusing is done by the eyepiece to sharpen the reticle to a person's eyesight and focusing anything else is most likely done by getting some vision correction "(glasses).

Danny

 

[Turbulent Turtle]

Needing to "focus a scope". Well, like you say, focusing is done by the eyepiece to sharpen the reticle to a person's eyesight and focusing anything else is most likely done by getting some vision correction "(glasses).

Danny

Wow. And the side focus turret or the adjustable objective ring are just for decoration? You have it exactly backwards.

 

[danny]

Wow. And the side focus turret or the adjustable objective ring are just for decoration? You have it exactly backwards.

I don't have it backwards, actually. The front objective ring is not for decoration, and it's not for focus, it's for parallax adjustment. That's two different things. Everyone erroneously calls it "focus". I assume that the side knobs are also parallax adjustment, too, but I have never had one of those. I see all kinds of weird things, such as postings about "3x9 scopes". That's a three power scope with a 9mm objective.

Danny

 

[ELR LVR]

I don't have it backwards, actually. The front objective ring is not for decoration, and it's not for focus, it's for parallax adjustment. That's two different things. Everyone erroneously calls it "focus". I assume that the side knobs are also parallax adjustment, too, but I have never had one of those. I see all kinds of weird thigs, such as postings about "3x9 scopes". That's a three power scope with a 9mm objective.

Danny

Once we're past a yardage where parallax is negligible such as past 500 yds
We use it for focus, even though it's function, is to adjust parallax
---
While many of us understand it's "MAIN" purpose is for parallax adjustment
it has a side benefit of also adjusting Image Focus.
Since at 500 yds the most parallax error we can have is 0.551"
and it gets less and less the further out we go,
it is more important for our "IMAGE" to be in as crisp of focus as possible once past 500 yds

 

[jelenko]

The way parallax errors are removed is through focusing the objective/side focus [i.e., the image] onto the same plane as the reticle. Changing the objective/side focus will bring into focus different distances as they are adjusted.
Note to self: I wonder why that knob is called side 'focus'?