Optics: Parallax vs Focus

[Andy Cross]

Andy's two cents worth

Brian, also graticule, not to be picky BUT, using reticule VS reticle isn't like saying "Kelby's" or "Hornaday" or misusing Their/there/they're or two/too/to or the very common "gaulding" and "spaulding" for galling and spalling.............. because all the words (reticle, reticule, graticule) are CORRECT




al

In the world of optical engineering I have seen it spelt different ways depending on where the book was published. Most USA spelling I've seen is reticle which was usually used when describing the crosshairs in a scope. British spelling has usually been reticule but the Brits don't just use that spelling for crosshairs. They use that term for any permanent measuring device or set point in an optical system. The later sounds like and probably comes from the French term graticule which is a term used in Europe for the same thing that the Brits call a reticule. Except the Europeans seem to call it reticle when describing crosshairs and call everything else graticule. In the USA books on optical engineering also talk about graticules but never when describing crosshaira. So if any one else can figure out the origins of where these terms came from and why different regions use each one I would be interested.
Andy.

 

[Brian Adams]

Here is the question I have: how are you adjusting the parallax?

I thought I answered this, but apparently not. The simple, direct answer is: I adjust the parallax for zero parallax using the objective focus adjustment.

If you are asking me how I detect parallax, I move my eye around behind the eyepiece and look for apparent motion of the reticle relative to the target.

Brian

 

[Brian Adams]

If you look in any of Jack O'Connor's books on rifles he spells it reticule as well. A master's degree in journalism and life long writer should know how to spell it. It's like the word "befor". I've seen it spelled with and without an e at the end.

Jack lived his last years in my home town. He was well known to be (to put it politely) something of a curmudgeon. It would not be beyond Jack to to use "reticule" to spite all those who insisted on the less archaic "reticle."

Just wondering - Can you direct me to a single rifle scope manufacturer who, today, use the term "reticule" to refer to the crosshairs or variants in their marketing or product literature?

Brian

 

[ColColt]

Jack lived his last years in my home town. He was well known to be (to put it politely) something of a curmudgeon. It would not be beyond Jack to to use "reticule" to spite all those who insisted on the less archaic "reticle."

Just wondering - Can you direct me to a single rifle scope manufacturer who, today, use the term "reticule" to refer to the crosshairs or variants in their marketing or product literature?

Brian

Frankly, I don't really care. By the way, "crosshairs" is two words.

 

[Brian Adams]

That's what I figured.

I have to defer to Mr Webster on the word count:

http://www.merriam-webster.com/dictionary/crosshair

 

[John Kielly]

I often get lint in my navel.

 

[Brian Adams]

I often get lint in my navel.

You can sell that on Ebay for big bucks. Don't ever say I never threw you a bone.

 

[alinwa]

I often get lint in my navel.

well if you spend time LOOKING at it, you'll be guilty of omphaloskepsis

fer real mate

spelled jus like it sounds

I've a hunch hearing you speak it would be as entertaining (to me ) as hearing a Southerner haggle with Vihtavouri

(which I DO find enjoyable)

al

 

[Dan Conzo]

People probably get upset when they see caliber spelled calibre by our modern day reloading component manufacturers from across the pond.

 

[Boyd Allen]

Damn! And all I was trying to do was to make that little red squiggle go away;-) Winter has officially arrived.

 

[John Kielly]

Don't we all, al?

 

[alinwa]

Om Mane' Padme Ommmmmm

 

[xs hedspace]

OK, all youse experts in optics, why is it I see a slight movement laterally in crosshairs when the vertical is dialed out, when testing for the proper objective setting, by the move the eyeball test when setting up at the bench??? Or vice versa. Maybe if I bought a Nightforce, it would go away. Sorry about the run on sentence.....

 

[Boyd Allen]

I believe that a previous poster mentioned astigmatism as the cause of a situation like yours. I also seem to remember something about a corrective lens on the eyepiece. I think that it was Andy Cross that posted on this.

 

[xs hedspace]

I believe that a previous poster mentioned astigmatism as the cause of a situation like yours. I also seem to remember something about a corrective lens on the eyepiece. I think that it was Andy Cross that posted on this.

I suspect that the astigmatism is in the objective lens, since the image is focused at the crosshair location by the objective lens, not the eyepiece. Noticed it on Nikon Buckmaster 6-18x at 50 yds 22 BR at 18x. Hey, it's better than a Barska!

 

[Joe Salt]

Ok Guys time to throw a curve! The Eyepiece on a Leupold Vari-X 3x9x33 is all there is for adjustment, they say if you are far-sighted turn the eyepiece ring counterclockwise until the reticle is clear and sharp, near-sighted turn the eyepiece clockwise! Then what I did was adjust one way then the other till the parallax was out. So my Question or answer is you have to use the eyepiece to help you get rid of the Parallax to some extent. I have always used the eyepiece to help me clear things up, probably because my eyes are getting so bad.

Joe Salt

 

[Brian Adams]

Update:

Over the weekend I engaged in a heresy - I used the target image to adjust the ocular focus on the reticle plane. Here's what I did:

1. Adjusted the objective focus for sharpest 100-yard target image.
2. Observed significant parallax (by moving my head around behind the scope and seeing lots of apparent reticle motion relative to target.)
3. Adjusted objective to eliminate parallax (which produced out-of-focus target image, but incidentally resulted in objective set at the "100" mark on the bell.)
4. Adjusted ocular focus to bring target image into focus (which also focused the reticle, verified using the "glance between sky and reticle" technique.)

As this process resulted in A) zero parallax, B) sharp target image, and C) sharp reticle image, it is my opinion the target image is projected onto the reticle plane, and the ocular is focused on the reticle plane. I'm satisfied the scope is adjusted properly for my purposes.


Brian

 

[Fred Bohl]

Heresy?

Brian,

You are not alone in the commission of this particular "heresy". After about 50 years of using the "kosher" technique (adjust eyepiece first then parallax) I also discovered and began using the method you described.

I find that the heretical technique you described works more successfully for high magnification and fine cross hair scopes than the kosher method. Another benefit is that it is easier to use when teaching new shooters and/or those just starting with high magnification and fine cross hairs.

Do you have any more pebbles you wish toss into the pond of "common knowledge". Change is good!

Fred

 

[Boyd Allen]

I have to smile. In the past I have posted about making eyepiece adjustments, and going back and forth between those and the parallax adjustment (side or front) so that one would finally arrive at a point where one has zero parallax and maximum target sharpness. You would not believe the sanctimonious condescension that was rained down on me for my heresy, but I persevered, and the flack made me work harder to be able to come up with a logical explanation as to why what had worked so well had worked. Way to go fellows. That is the way that I do it for high power variables and fixed power scopes that I have on my bench rifles. It works.

 

[alinwa]

fun thread, good info

I have to smile too



al