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| jsskangas... |
 Posted: Wed Oct 14, 2009 8:15 am |
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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.
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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| Helmut Wabnig... |
| Posted: Wed Oct 14, 2009 9:18 am |
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On Wed, 14 Oct 2009 09:15:23 -0500, jsskangas
<jsskangas at (no spam) fakeemail.com> wrote:
[quote:955b61727a]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.
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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[/quote:955b61727a]
get the free EDU version or get the 30 day trial OSLO
http://www.lambdares.com/
w. |
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| Helmut Wabnig... |
| Posted: Wed Oct 14, 2009 9:21 am |
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| Helmut Wabnig... |
| Posted: Wed Oct 14, 2009 9:22 am |
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On Wed, 14 Oct 2009 09:15:23 -0500, jsskangas
<jsskangas at (no spam) fakeemail.com> wrote:
[quote:b33603d2a2]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.
[/quote:b33603d2a2]
see the stuff here
http://www.telescopes.ru/software/index.phtml |
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| Louis Boyd... |
| Posted: Wed Oct 14, 2009 12:23 pm |
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jsskangas wrote:
[quote:340405cc60]Hello from Finland.
Im bit interested of optics.
My main coals is to build fixed magnification riflescope.
[/quote:340405cc60]
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. |
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| Bob May... |
| Posted: Wed Oct 14, 2009 4:46 pm |
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INverting an image is simple. Just put a third lens between the eye and
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 |
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| Helpful person |
| Posted: Thu Oct 15, 2009 2:06 am |
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Joined: 22 Jun 2004
Posts: 838
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On Oct 15, 5:35 am, jsskangas <jsskan... at (no spam) fakeemail.com> wrote:
[quote:e5dd119314]First thing I need to do is learn about optics.
I need basic info of multi lense systems
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[/quote:e5dd119314]
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.
www.richardfisher.com |
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| jsskangas... |
| Posted: Thu Oct 15, 2009 3:35 am |
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Hello
"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
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| aspherix... |
| Posted: Thu Oct 15, 2009 7:18 am |
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"Helpful person" <rrllff at (no spam) 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.
www.richardfisher.com
================================================
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?" |
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| Helpful person |
| Posted: Thu Oct 15, 2009 8:39 am |
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Joined: 22 Jun 2004
Posts: 838
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On Oct 15, 9:18 am, "aspherix" <cartesysdropiotaz... at (no spam) gmail.com> wrote:
[quote:84c5f504ed]"Helpful person" <rrl... at (no spam) 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.
www.richardfisher.com
===============================================
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?"
[/quote:84c5f504ed]
There goes another ignoramus.
www.richardfisher.com |
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| jsskangas... |
| Posted: Thu Oct 15, 2009 12:50 pm |
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Hello
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
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| Louis Boyd... |
| Posted: Thu Oct 15, 2009 4:55 pm |
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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 wrote:
[quote:ba7c46dec6]Hello
"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
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Posted at: http://ForumBreak.com[/quote:ba7c46dec6] |
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| jsskangas... |
| Posted: Fri Oct 16, 2009 4:04 pm |
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Hello
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
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| aspherix... |
| Posted: Wed Oct 21, 2009 8:32 pm |
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Guest
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"jsskangas" <jsskangas at (no spam) fakeemail.com> wrote
[quote]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.).
[/quote]
what's a mortal gun?
a gun which dies as opposed to one which kills?
what's the nra position on this one?
[quote]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.
[/quote]
tsk, tsk, not concerned about global warming?
[quote]List goes on....
[/quote]
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! |
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| David Combs... |
| Posted: Sun Nov 01, 2009 10:00 pm |
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In article <hb899t$obk$1 at (no spam) onion.ccit.arizona.edu>,
Louis Boyd <boyd at (no spam) apt0.sao.arizona.edu> wrote:
....
[quote]one of a few companies in the world which know how to do it right.
In your opinion, which companies are they?[/quote]
Thanks,
David |
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