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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/11/2012 at 11:23
hot30 View Drop Down
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Have not been here in ages. I hope the knowledge base remains since my absence.

I have a question that concerns "magnification" and how its built into  the mechanics of a rifle
scope.

Lets say you have a 50x scope. The erector is responsible for a 5x boost. Will the  "eye box"
or ocular assembly play a key role in the total magnification? If it does, what percentage would
the ocular assembly be responsible for in the system?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/11/2012 at 13:55
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( I think that knowledge base has gone away...)  
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/11/2012 at 16:19
hot30 View Drop Down
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No more Koshkin or on his order?Shocked
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/11/2012 at 19:07
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I am still around.  Just busy (you do not get rid of me that easily Ed  Devil)

Generally speaking, since the question is badly stated in every possible way I can think of, there is no answer I can come up with that would make any more sense than the question does.

I will give it a shot though.

Short answer: everything in the scope has something to do with the magnification and magnification range.  It is an optical system and all parts of it work together to deliver the image to your eye.  You can not try to divvy it up in terms of percentages.

There are three distinct optical systems inside a rifle scope: objective system, erector system and ocular system.  Each contains multiple lenses in it.

The erector system is responsible for the magnification range.  However, both ocular and objective play a role as well.

For example, since yo mentioned 50x magnification, let's consider Sightron S3 10-50x60 scope.

It all starts out with the objective lens system.  Its focal length will determine how the rest of the scope is designed: the size and focal lengths of the remaining lenses, the focal length of the ocular, etc.

The erector system is primarily responsible for the magnification range, i.e. when you turn the magnification ring to transition between 10x and 50x, the optical elements in the erecor system are repositioned.

ILya


Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/11/2012 at 19:22
hot30 View Drop Down
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Koshkin, your gettin cranky with age.  Sorry I constructed the question in such a fashion.  You have answered my question regardless.

The erector providing the primary magnification was my issue. The objective, erector and ocular focal lengths remain arbitrary to me.....






Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/11/2012 at 19:25
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Cranky??? That was nice...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/11/2012 at 19:26
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It runs in the family.  My grandfather got a bit on the cranky side with age if memory serves me right, so I must be heading in the same direction.

To make sure there is no misunderstanding:  the erector system has everything to do with magnification variation built into the scope, but not all that much, comparatively speaking, with the amount of magnification.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/11/2012 at 21:27
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I was headed for the rack, thought I would stop back here before dropping dead.

Koshkin, if cranky dont bother you lets talk abit......

I understand optics somewhat. I was not sandbagging.  Moving the erector to" change "magnification (front to rear etc.) typical of a variable power scope, ok. 

If my scope is a fixed power, the erector not only erects the image from the objective lens(from infinity) but will the erector dictate the primary magnification?

If you can bare with me just a tad, I will make my logic known to you. 

Let me add this; just for the moment lets focus on the objective lens focal length  and the erector assembly (5x erector) and discuss the ocular lenses abit later.   Lets think "fixed magnification" for the duration. With a mechanically stationary erector, will it still be the primary magnification dictator?

What do ya say Koshkin?  One crank to another.Wink


Edited by hot30 - December/11/2012 at 21:40
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 10:21
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That "primary" is really what gives me trouble.

For a fixed power scope, the biggest driver of the magnification is the ratio of the focal lengths of the ocular and objective lens systems.  The erector gets the image oriented correctly and it is a part of what sets the magnification, but you can not say that one optical system is more important than the other for setting magnifiaction.

To get back to my cranky nature though: if you have something specific in mind, how about you just come out with it and I'll help if I can?  Asking more badly phrased and factually wrong questions is unlikely to help.

How the hell is this supposed to work?  You say "If you can bear with me just a tad, I will make my logic known to you."  How about you just make that logic known and we go from there?  If I do not know what you are trying to achieve I can absolutely guarantee that I will not be able to offer any assistance.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 14:44
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Good! Yippee

Your not so bad after all.

Its my intention to build my "OWN" rifle scope.  Now if my badly phrased or factually incorrect questions make you cranky, I have your attention regardless. Thats why I am here, to access information.  I gathered that you would be helpful.

The mechanical requirements have been solved. I build the parts etc. myself.  Build my stocks, chamber and crown my barrels or whatever I need.  If I dont know something, I will learn it as required.

I have completed a "primary ray trace" to a full scale drawing thus far.  The lenses and tube diameters that I have chosen for the project allow the primary ray to pass unobstructed.  It is the "ocular" assembly that has me thinking way too much.  I have either solved the problem or I might not have a problem.  The eye piece lens part of the system adding to the magnification of the entire process cannot be solved  by the way I am thinking, I believe?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 15:14
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Out of curiosity, why exactly are you trying to build your own scope?

It sounds like an entertaining exercise, of course.

Which software are you using for the raytrace?  Have you done an aberration analysis?  How about tolerance analysis?

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 15:35
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Originally posted by koshkin koshkin wrote:

Out of curiosity, why exactly are you trying to build your own scope?
Because he saw mine and got jealous!
 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 15:38
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Originally posted by jonoMT jonoMT wrote:

Originally posted by koshkin koshkin wrote:

Out of curiosity, why exactly are you trying to build your own scope?
Because he saw mine and got jealous!
 


I think you've got the ocular issue resolved...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 15:45
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It's a true 1X, dude. Only a select few optical engineers can make that claim.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 15:50
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Originally posted by jonoMT jonoMT wrote:

It's a true 1X, dude. Only a select few optical engineers can make that claim.

Weeeellll...  technically, that is not correct.  It is not 1x, in the same way that Aimpoint or Eotech are not 1x.

Still, it is your invention, so you can claim it.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 16:00
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Koshkin, I didnt say I was an optical engineer.  I choose to build my very own rifle scope because I can.  Im going to keep it simple(in my mind) so I will be thinking along the lines of Lyman, Unertyl, Fecker and early Tasco target optics. My library contains some very simple formula and drawings dated from the late 50s and 60s while crude by your standards look like just plain fun to me.

jonoMT, only thing your missing is an optical bench to determine your system focal lengths.  You might not believe how close you are in starting your own project. Paper tubes, electrical tape etc.  Fine cross hair reticles (etched) can be pirated from many sources.Excellent
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 16:04
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Originally posted by hot30 hot30 wrote:

Koshkin, I didnt say I was an optical engineer.  I choose to build my very own rifle scope because I can.  Im going to keep it simple(in my mind) so I will be thinking along the lines of Lyman, Unertyl, Fecker and early Tasco target optics. My library contains some very simple formula and drawings dated from the late 50s and 60s while crude by your standards look like just plain fun to me.

jonoMT, only thing your missing is an optical bench to determine your system focal lengths.  You might not believe how close you are in starting your own project. Paper tubes, electrical tape etc.  Fine cross hair reticles (etched) can be pirated from many sources.Excellent

So, you have an optical design from an old book somewhere? That was the gyst of my question: how did you pick the lenses?

If you have a design from an old book, then I do not get the complication you are having with the ocular.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 16:20
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jono, that's a helluva scope. Any marketing ambitions?  Hippie
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 16:39
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tp roll and plastic wrap???
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 16:39
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  ocular oblong like the mil dot sweet.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 17:08
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I'm thinking make the tube out of copper pipe.... Look really sweet as it petina's in the weather. That and it's easy to work with to make the bells on each end. Need higher quality Saran Wrap than JonoMT is using though.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 17:37
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Originally posted by jonoMT jonoMT wrote:

Originally posted by koshkin koshkin wrote:

Out of curiosity, why exactly are you trying to build your own scope?
Because he saw mine and got jealous!
 


Isn't this a Counter Sniper copy?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 18:00
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Don't forget to divide by the square root of the international dateline...
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: December/12/2012 at 22:08
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Koshkin, simple formulas and the ray trace instruction came from an old book. From then on adaptions and substitutions were made. Never said the lenses were suggested from the books. Focal lengths, infinite and finite conjugates were determined from research, reading and learning.

The goal with the project is to build a rifle scope using modern lenses and components not available when my resources were written.  The ocular assembly plays a part in the system as far as total magnification is concerned.  If you dont have a % of the total magnification that can be applied to the ocular assembly as a rule, I dont believe we need to discuss my query further.

I will do this; when completed I will return with photos.
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