Non inverting scope
jsskangas
Im bit interested of optics.
My main coals is to build fixed magnification riflescope.
But for start I would need some help.
magnification of lens system is calculated by deviding focal lenghts.
But if I make lens system includin objective (fl=focal lenght) fl=200mm and two relay lens fl=50mm and some kind of lenses for eyepeace.
Magnification on eyepeace should be about x2.
Then in my undestanding total magnification of tube would be x8??
Problem is are my calculation correct?
If I have objective that has fl=200mm and relay linse fl=50, distance from objective to first relay linse will be 250mm and distance between two relay linse is 100mm. Magnification of this system will be x4.
Then I need some kind of eyepece, this is my problem, what kind of lenses do I need for eyepeace.
One plano-concave and for x2 magnification two biconvex?
focal lengt of biconvex should be in this lens system 25mm for x2?
How to calc plano-concave lens ?
If enyone has info please write here or email at kangas.jussi(at)netikka.fi
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Posted at: http://ForumBreak.com
Helmut Wabnig
Helmut Wabnig
<jssk...@fakeemail.com> wrote:
>Hello from Finland.
>
>Im bit interested of optics.
>My main coals is to build fixed magnification riflescope.
>
>But for start I would need some help.
see the stuff here
http://www.telescopes.ru/software/index.phtml
Helmut Wabnig
<jssk...@fakeemail.com> wrote:
>Hello from Finland.
>
>Im bit interested of optics.
>My main coals is to build fixed magnification riflescope.
>
>But for start I would need some help.
>..........
ZEMAX demo is available
http://www.zemax.com/index.php?option=com_content&task=category§ionid=9&id=68&Itemid=160
dunno about the restrictions
w.
Louis Boyd
> Hello from Finland.
> Im bit interested of optics.
> My main coals is to build fixed magnification riflescope.
Getting the lens focal lengths correct is a small part of of the overall
optical design. The optical design is only a part of designing a
riflescope. The mechanical requirements of a decent rifle scope are
as important and as difficult to achieve than it's optics.
Even if you do learn the optical and mechanical design skills you could
not fabricate the lenses and mechanical parts for a single scope
equivalent to a cheap commercial riflescope for less than you could buy
at top of the line model.
Bob May
field lens. The inverting lens needs to take the focus from the field lens
and put it back to another focus. Jusually youuu take a lens of the douvle
convex design and place it at twice the focal length of the lens and this
puts the second focus point at twice the focal length of the lens. Remember
the formula1/ Fl = 1'F1 + 1/F2 where Fl is the focal length of thee lens and
F1 and F2 are the focus points of the source and destination of the lens.
This formula also tells you why you need to have a focus mechanism for
higher powers of magnification, especially when looking at close things.
--
Bob May
rmay at nethere.com
http: slash /nav.to slash bobmay
http: slash /bobmay dot astronomy.net
jsskangas
"The mechanical requirements of a decent rifle scope are
as important and as difficult to achieve than it's optics."
There is nothin dificult in mechanics.
This design does not have eny kind of adjustments.
Plan is to use max size lenses for better resolution of scope.
All adjustment will be made in mounting base.
Only adjustment will be eyebell focus.
all other lenses including reticlewill be fixed in place.
First thing I need to do is learn about optics.
I need basic info of multi lense systems
Helpful person
> First thing I need to do is learn about optics.
> I need basic info of multi lense systems
>
> ------------------------------------------
If you do not have a basic knowledge of optics you will not be able to
put together a lens system that gives acceptable imagery. As already
pointed out in a previous post designing a rifle scope, although not a
difficult task, still requires lens design skills. You cannot just
throw together catalogue lenses.
aspherix
"Helpful person" <rrl...@yahoo.com> wrote
If you do not have a basic knowledge of optics you will not be able to
put together a lens system that gives acceptable imagery. As already
pointed out in a previous post designing a rifle scope, although not a
difficult task, still requires lens design skills. You cannot just
throw together catalogue lenses.
================================================
Utter nonsense! Any manager worth his salt (*) will tell you that there is
nothing to optical engineering and lens design in particular.
(*) Requisite background EE, ME (plus of course an MBA) or even
better a PhD in particle or low temperature physics or fluid dynamics.
"All there is to know in optics was discovered by Descartes, Huygens
and Newton more than 300 years ago. Do I have to teach you your own
job?"
Helpful person
jsskangas
For "helpful person":
jaada jaada jaa.
To everyone else:
I got really good answer by email and plenty of material to study.
I will get back to this tread when i have studyed more about optics.
Jussi
Louis Boyd
If the riflescope you make has only an eyepiece adjustments at best it
will be in focus without parallax error at only one distance. You can
buy a Chinese made scope which includes that adjustment about $30 USD.
Let us know when when you get you're riflescope working and mounted
on a rifle how much you've spent (in money and hours of labor) and what
size of groups it shoots. Sure, some people build ships in bottles
just to see if they can, not because it's remotely cost effective.
Mechanical design of a riflescope is easy? How about the acceleration
forces from recoil? Actually thats not what usually breaks riflescopes.
Dropping a rifle with it's scope from a meter onto a hard surface
produces much higher peak forces which a decent riflescope must be able
to survive.
Easy? My profession is designing and building astronomical research
telescopes and instruments. My hobby is long range target shooting. I
know better than to try to make my own riflescopes. I'll leave that to
one of a few companies in the world which know how to do it right.
jsskangas
My work is mechanical desing, FEM design and calculation.
CAM desing and training.
I have lot of experience, high speed and
high acceleration parts (semiautomatic mortal gun part, ect).
When i say mechanical design and contruction is not a proplem, I mean it.
Yeah and Im too long range shooter.
Collecting riflescopes is my other hobby.
Building my own CNC-machines is one.
Training and huntig whit my akitas another one.
Building Drifting and drag racing cars one.
List goes on....
http://picasaweb.google.com/JSSKangas
aspherix
"jsskangas" <jssk...@fakeemail.com> wrote
> My work is mechanical desing, FEM design and calculation.
> CAM desing and training.
> I have a lot of experience, high speed and
> high acceleration parts (semiautomatic mortal gun part, etc.).
what's a mortal gun?
a gun which dies as opposed to one which kills?
what's the nra position on this one?
> When i say mechanical design and construction is not a problem, I mean it.
> Yeah and I'm too a long range shooter.
> Collecting riflescopes is my other hobby.
> Building my own CNC-machines is one.
> Training and huntig with my akitas another one.
> Building Drifting and drag racing cars one.
tsk, tsk, not concerned about global warming?
> List goes on....
So many talents! I am so humbled.
I am glad that you did not mention optical engineering,
at least I have one "skill" which you don't have!
David Combs
Louis Boyd <bo...@apt0.sao.arizona.edu> wrote:
...
>one of a few companies in the world which know how to do it right.
>
In your opinion, which companies are they?
Thanks,
David
jsskangas
LouisBoyd:
" If the riflescope you make has only an eyepiece adjustments at best it
will be in focus without parallax error at only one distance."
All riflescopes whitout parallax compensation have this proplem.
Most of rifle scope models are whitout parallax adjustment.
Parallax wilbee set to 100m this is usual arragement.
aspherix:
Here is small 30mm automatic mortal gun.
http://www.youtube.com/watch?v=LJh6gcwmWPw
Optical desing is not my area of experties, but I´m studying.
Some day..
My coal is not to make most best riflescope, my coal is prove my self that I can
make one. And most of all to learn optics design.
Brian
>
> Optical design is not my area of expertise, but I´m studying.
> Some day..
>
> My goal is not to make most best riflescope, my goal is prove my self that I can
> make one. And most of all to learn optics design.
>
Jussi, I wish there were more people like you. Please don't be put off
by pessimists who can't believe that an intelligent person doesn't
need 5 years' postgraduate study plus 3+ years in the optical industry
before he can design a good lens. Persist, and I want you to come back
to this NG in 6 months and post your design for us all to see it. I
gave a paper on this topic at Education and Training in Optics (ETOP
09) in St Asaph in July this year:
http://spie.org/etop/2009/etop2009_9.6.1.pdf
Brian
Ancient and Modern Optics
jsskangas
Thank for supportive words.
I use lot of my free to study optics.
I wil get back here when I have something to show.
Jussi