Parallax and focus question

[Dr.Lee]

Does the focus on target coincide with a parallax free setting ?
The reason I ask is because when I look through my Leupold 2.5-8 VX-3 at a tree line 400 yards away from my house on 8 power and then look through my Leupold 4.5-14 VX-3 set on 8 power, I can focus the trees nicely compared to the 2.5-8. The 2.5-8 is only parallax free at 100 yards and focus is not sharp at 400 yards.
So I said nice feature to have on a scope; the side focus or AO. But what about actual parallax. Are you sacrificing one feature to have the other, or can you have both focus and zero parallax at yardage ?
I am sure this would depend on what scope you actually have.

Dr.

 

[ShootDots]

Does the focus on target coincide with a parallax free setting ?
The reason I ask is because when I look through my Leupold 2.5-8 VX-3 at a tree line 400 yards away from my house on 8 power and then look through my Leupold 4.5-14 VX-3 set on 8 power, I can focus the trees nicely compared to the 2.5-8. The 2.5-8 is only parallax free at 100 yards and focus is not sharp at 400 yards.
So I said nice feature to have on a scope; the side focus or AO. But what about actual parallax. Are you sacrificing one feature to have the other, or can you have both focus and zero parallax at yardage ?
I am sure this would depend on what scope you actually have.

Dr.

When you focus on a target at any given distance and you still have parallax, you have what is known as "lash".. I had a brand new Leupold 45X Target scope when they first came out. I mounted it on my rifle and took it to the range. I was at 100 yards to get it sighted in. I got it focused clear>>> but the crosshair/ dot moved more than a little. I went home and took it off and sent it back to Leupold. They repaired it and sent it back>>>fixed..

 

[CatShooter]

Does the focus on target coincide with a parallax free setting ?
The reason I ask is because when I look through my Leupold 2.5-8 VX-3 at a tree line 400 yards away from my house on 8 power and then look through my Leupold 4.5-14 VX-3 set on 8 power, I can focus the trees nicely compared to the 2.5-8. The 2.5-8 is only parallax free at 100 yards and focus is not sharp at 400 yards.
So I said nice feature to have on a scope; the side focus or AO. But what about actual parallax. Are you sacrificing one feature to have the other, or can you have both focus and zero parallax at yardage ?
I am sure this would depend on what scope you actually have.

Dr.

"Fixed focus" scopes are set at one range (usually 100 to 150 yds) At that range. the image is best and they're parallax free.

At any other range, they will have parallax.

Here's a good article that exp;ains it.


http://www.snipercountry.com/Articles/Parallax.asp

 

[Dr.Lee]

Does the focus on target coincide with a parallax free setting ?
The reason I ask is because when I look through my Leupold 2.5-8 VX-3 at a tree line 400 yards away from my house on 8 power and then look through my Leupold 4.5-14 VX-3 set on 8 power, I can focus the trees nicely compared to the 2.5-8. The 2.5-8 is only parallax free at 100 yards and focus is not sharp at 400 yards.
So I said nice feature to have on a scope; the side focus or AO. But what about actual parallax. Are you sacrificing one feature to have the other, or can you have both focus and zero parallax at yardage ?
I am sure this would depend on what scope you actually have.

Dr.

When you focus on a target at any given distance and you still have parallax, you have what is known as "lash".. I had a brand new Leupold 45X Target scope when they first came out. I mounted it on my rifle and took it to the range. I was at 100 yards to get it sighted in. I got it focused clear>>> but the crosshair/ dot moved more than a little. I went home and took it off and sent it back to Leupold. They repaired it and sent it back>>>fixed..

So if a scopes focus and zero parallax setting do not happen together, that is not proper and needs attention ?

Dr.

 

[ShootDots]

Does the focus on target coincide with a parallax free setting ?
The reason I ask is because when I look through my Leupold 2.5-8 VX-3 at a tree line 400 yards away from my house on 8 power and then look through my Leupold 4.5-14 VX-3 set on 8 power, I can focus the trees nicely compared to the 2.5-8. The 2.5-8 is only parallax free at 100 yards and focus is not sharp at 400 yards.
So I said nice feature to have on a scope; the side focus or AO. But what about actual parallax. Are you sacrificing one feature to have the other, or can you have both focus and zero parallax at yardage ?
I am sure this would depend on what scope you actually have.

Dr.

"Fixed focus" scopes are set at one range (usually 100 to 150 yds) At that range. the image is best and they're parallax free.

At any other range, they will have parallax.

Catshooter is exactly right. I have a Leupold 2.5 x 8 mounted on a 308 "carry gun"..At 100 yards it is parallax free. However, move out to 200 yards and you have about 3" of parallax you can easily detect.

 

[ShootDots]

Dr. Lee... If you have a scope that has a Parallax adjustment and you have parallax when you have it at it's clearest adjustment, it needs to go back. That is one MAJOR reason why I started with NightForce scopes. I have yet to see or have any lash with any of mine. When they are "clear and crisp" they are parallax free..

 

[CatShooter]

Dr. Lee... If you have a scope that has a Parallax adjustment and you have parallax when you have it at it's clearest adjustment, it needs to go back. That is one MAJOR reason why I started with NightForce scopes. I have yet to see or have any lash with any of mine. When they are "clear and crisp" they are parallax free..

If the eye piece is properly focused (not too often), and the target is properly focused on the reticle, then it is not optically possible to have parallax.

 

[Dr.Lee]

Thanks Cat, makes sense.

Dr.

 

[M-61]

From CATSHOOTER

"...If the eye piece is properly focused (not too often)...."

That's for sure.

 

[BCoates]

Dr. Lee... If you have a scope that has a Parallax adjustment and you have parallax when you have it at it's clearest adjustment, it needs to go back. That is one MAJOR reason why I started with NightForce scopes. I have yet to see or have any lash with any of mine. When they are "clear and crisp" they are parallax free..

If the eye piece is properly focused (not too often), and the target is properly focused on the reticle, then it is not optically possible to have parallax.

Catshooter - So you are saying if I have the parallax adjusted out of the scope but the image is not as clear as it can be, then I need to adjust the diopter? I ask because I have experienced this with a few scopes I have.

 

[JamesnTN]

Dr. Lee... If you have a scope that has a Parallax adjustment and you have parallax when you have it at it's clearest adjustment, it needs to go back. That is one MAJOR reason why I started with NightForce scopes. I have yet to see or have any lash with any of mine. When they are "clear and crisp" they are parallax free..

If the eye piece is properly focused (not too often), and the target is properly focused on the reticle, then it is not optically possible to have parallax.

So how do you guys go about focusing the eye piece on your scopes? Do you aim it a a clear blue sky or aim at some writing on paper?

 

[CatShooter]

Dr. Lee... If you have a scope that has a Parallax adjustment and you have parallax when you have it at it's clearest adjustment, it needs to go back. That is one MAJOR reason why I started with NightForce scopes. I have yet to see or have any lash with any of mine. When they are "clear and crisp" they are parallax free..

If the eye piece is properly focused (not too often), and the target is properly focused on the reticle, then it is not optically possible to have parallax.

Catshooter - So you are saying if I have the parallax adjusted out of the scope but the image is not as clear as it can be, then I need to adjust the diopter? I ask because I have experienced this with a few scopes I have.

Yes.

The objective makes an image - if that image is in the same place as the reticle - then there is (by definition) no parallax.

If your eye is focused on the reticle, then it must (by definition) be focused on the image, ergo, no parallax and focused image.

 

[CatShooter]

Dr. Lee... If you have a scope that has a Parallax adjustment and you have parallax when you have it at it's clearest adjustment, it needs to go back. That is one MAJOR reason why I started with NightForce scopes. I have yet to see or have any lash with any of mine. When they are "clear and crisp" they are parallax free..

If the eye piece is properly focused (not too often), and the target is properly focused on the reticle, then it is not optically possible to have parallax.

So how do you guys go about focusing the eye piece on your scopes? Do you aim it a a clear blue sky or aim at some writing on paper?

At a solid color with nothing to look at - clear sky, white wall... and start with the eye piece turned all the way out, and then move it in, in tiny bits.

 

[michaelnel]

When adjusting, I find it helpful to not stare at what you are adjusting. If you do, your brain will get your eye to focus on it.

Instead, start with eyes closed. Open your eyes and look at the reticle. You want to adjust it so that when you first open your eyes, it is in focus... not kinda blurry and then having your eye pull it into focus. Repeat as necessary.

 

[savagedasher]

When I adjust a scope. I try to get the best picture Possible with out the cross hairs moving.
Larry

 

[TrapperT]

Parallax and focus are two different aspects of the optical system. In a system where you have a parallax adjustment (whether it is a side parallax or it is on the bell of the scope) and eyepiece focus, it is best to focus the eyepiece first. The eyepiece focus is used to adjust the focus of the reticle, NOT THE SCOPE IMAGE. What I mean by this is the intent of the eyepiece lenses is allow you to adjust diopter for your eyes in order to see the reticle clearly. In order to set this correctly you need to move the eyepiece so that the reticle is intentionally out of focus (normally turning the eyepiece counter clockwise - but honestly is doesn't matter). Then by looking at a plain background (clear sky or white wall) you turn the eyepiece clockwise small increments at a time. This could be a 1/4 to 1/2 turn. But do not continue to look through the scope when you adjust the eyepiece. The reason for this is that your eye needs to be relaxed. If you continue to look through as you adjust, your eye will start to compensate and you will not get a true focus. So you look at the reticle and see if it is in focus. If it is not, bring the scope down away from your eye, adjust the eyepiece and look at the reticle again. Keep doing this until the reticle is nice and sharp.

Parallax is adjusted when looking through the scope at the target. What parallax does is make sure that the reticle and target are on the same image plane within the optical system by adjusting a compensating lens which sits in front of the reticle or erector tube. When they are not, the reticle will "wander" on the target as you move your head back and forth.

I hope this helps to understand the difference between the two.

Tony

 

[tonysnoo]

Great topic.......Cool info....thanks guys!

 

[Dr.Lee]

Thanks for all the help, guys.
Happy New Year,

Dr.Lee