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Side focus vs. AO

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/01/2004 at 18:04
cheaptrick View Drop Down
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How many guys like an AO?? Or do you prefer a side focus??

 

I'm a lefty and have found an AO to be more user friendly.

I also believe an AO to be a superior parallax adjustment.

 

Anybody "see" it differently??  (No pun intended)   

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/01/2004 at 18:26
redneckbmxer24 View Drop Down
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well seeing it from a righties, a side focues is a bit more handy, becuase you can easily see the range marks on it.

 

cory

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/02/2004 at 01:08
cheaptrick View Drop Down
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Originally posted by redneckbmxer24 redneckbmxer24 wrote:

well seeing it from a righties, a side focues is a bit more handy, becuase you can easily see the range marks on it.

 

cory

 

My USO allows me to see the range markings from a prone position as well.

 

Your right, most scopes place the markings where you can't readily see them.

 

As much as I like an AO on a LR rifle, I deplore them on a hunting rifle!! 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/02/2004 at 07:17
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the SS with the rear parralax is also really nice, i can read them awesome, but i cannot see any of the marks on the A/O leupy's

 

cory

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/03/2004 at 16:29
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redneck, I have never seen a SS upclose. People that have them love them though..
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/03/2004 at 16:35
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they are NICE you ought to get one, and see what youve been missing

 

cory

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/10/2004 at 13:57
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Here's the pros and cons of the 3 ways to adjust parallax in a riflescope.

 

1. Front

2. Side

3. Rear

 

 

1. Front

This method moves the objective lens in and out hence the term "adjustable objective".  Its the first way manufacturers figured out how to adjust parallax and it is probably still the best way to do it.  The scope maker can display more yardage markings because of the increased circumference of the adjustment and they can use slow or fast pitched threads.

 

 

2. Side

This method is a side mounted third knob on the center saddle section of a scope. Easily viewed and adjusted (for right hand shooters).

This method uses very fast threads to achieve major adjustments in a short movement because of the limited circumference, making it difficult to fine tune.  This method also adds to the cost of the scope because it is very expensive to manufacturer.  Susceptible to damage because it is the farthest protruding object on the left side of the rifle.

 

 

3. Rear

Located directly in front of the eye piece where you would normally change the power on a variable scope.  Not widely used because it can only be implemented on a fixed power scope.  Easy to access and read for right or left hand shooters.  Quite a bit less expensive to make when compared to front or side.

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/10/2004 at 14:31
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http://www.benchrest.com/forums/showthread.php?t=15138">http://www.benchrest.com/forums/showthread.php?t=15138

 

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

 

 

[quote]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...

Thread link: http://www.benchrest.com/forums/showthread.php?t=15138

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

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