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From: Rune S  Johansen
Subject: Lenses
Date: 12 Apr 1999 16:42:07
Message: <37124c8f.0@news.povray.org>
Is there any tutorials on how to make lenses that works in POV-Ray?
I mean how to use lens shapes with ior cleverly.
F.x., is it possible to make two lenses that gives different zoom
when back and forth away?

Thanks,

Rune S. Johansen
http://hjem.get2net.dk/rsj


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From: Ken
Subject: Re: Lenses
Date: 12 Apr 1999 16:54:20
Message: <37124CAD.AC97C08D@pacbell.net>
Rune S. Johansen wrote:
> 
> Is there any tutorials on how to make lenses that works in POV-Ray?
> I mean how to use lens shapes with ior cleverly.
> F.x., is it possible to make two lenses that gives different zoom
> when back and forth away?
> 
> Thanks,
> 
> Rune S. Johansen
> http://hjem.get2net.dk/rsj

  I'll make this response as simple as I can. I know if no such tutorials.
I also don't believe you could obtain all of the infomation on this kind
of subject from a few relpies in a new group. Your best bet is to see if
you can order the free optics catalog from Edmund Scientific. It has
several pages of lens data, material properties and useful examples of
the diffeerent uses of lens's and combinations of len's.
  This is not a remedial subject and takes a bit of knowledge to accurately
calculate lense curvatures and focal point distances for the different lens
shapes and types. I think that you will find that the majority of optical
lens's fall into a fairly close range of ior values. Once you find one that
works that is the least of your problems. It is calculated the lens focal
point, distance to the next lens, how they work together, and the location
of the observer that will determine their usage.



-- 
Ken Tyler

mailto://tylereng@pacbell.net


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From: Chris Huff
Subject: Re: Lenses
Date: 12 Apr 1999 18:43:02
Message: <37126976.1B3DB397@compuserve.com>
Do you want to make lenses that focus light? That is only possible with
Nathan Kopp's photon patch. I have done some experimenting with it, and
it works very well.
As for the lens shape, do you want to duplicate an actual real world
lens, or are you just looking for a lens that doesn't have spherical
distortion? I would do some experimenting with scaled spheres and
intersections of spheres, many real lenses are actually spherically
ground.

"Rune S. Johansen" wrote:

> Is there any tutorials on how to make lenses that works in POV-Ray?
> I mean how to use lens shapes with ior cleverly.
> F.x., is it possible to make two lenses that gives different zoom
> when back and forth away?
>
> Thanks,
>
> Rune S. Johansen
> http://hjem.get2net.dk/rsj


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From: Bob Hughes
Subject: Re: Lenses
Date: 13 Apr 1999 00:51:59
Message: <3712BF2E.1A88B07B@aol.com>
It is possible, funny I haven't seen any serious optical things done
with POV-Ray yet. There was a telescope animation (or still) posted not
too long ago here at news.povray.org and it showed rather well how the
lenses can be set up to magnify. I myself did this long ago and was
confused at the results. I did scaled sphere intersections for convex
and concave lenses in a rather crude telescope setup. Believe I must've
done an internet search before for optics using POV-Ray however I don't
recall finding anything then. Far as following true physical properties
I can only guess there might be approximation possible after all.


"Rune S. Johansen" wrote:
> 
> Is there any tutorials on how to make lenses that works in POV-Ray?
> I mean how to use lens shapes with ior cleverly.
> F.x., is it possible to make two lenses that gives different zoom
> when back and forth away?
> 
> Thanks,
> 
> Rune S. Johansen
> http://hjem.get2net.dk/rsj

-- 
 omniVERSE: beyond the universe
  http://members.aol.com/inversez/homepage.htm
 mailto:inv### [at] aolcom?Subject=PoV-News


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From: ingo
Subject: Re: Lenses
Date: 13 Apr 1999 14:40:22
Message: <37138186.0@news.povray.org>
for constructing a positive lens use a sphere-sphere intersection, for a
negative one a difference of a cylinder with two spheres. To calculate the
radii of the lens you need the lens-makers formula (could simply be made
into a macro)
P=(nl-n0)((1/R1)-(1/R2))
P=n0/f

P=power of the lens
nl= ior of the lens (put this one also in your interior)
n0= ior of air (~1)
R1, R2= radius of the lens-surface
f=focal distance of the lens

for construction of optical systems you need Newtons and/or Gauss' lens
equation.
For looking through a system POV-Ray is ok, for making the path of light
visible you need Nathans' uv-patch. POV lenses are perfect, no abberations
or dispersion. I constructed a fresnel-lens that works fine, the macro is at
twyst's macroscope.

Ken posted a URL with a lot of optics info a few days ago. ( I lost the url
already, Ken how do you maintain  400+ bookmarks? A utility or just your
neural network?)


ingo
--
Met dank aan de muze met het glazen oog.



Rune S. Johansen heeft geschreven in bericht <37124c8f.0@news.povray.org>...
>Is there any tutorials on how to make lenses that works in POV-Ray?
>I mean how to use lens shapes with ior cleverly.
>F.x., is it possible to make two lenses that gives different zoom
>when back and forth away?
>
>Thanks,
>
>Rune S. Johansen
>http://hjem.get2net.dk/rsj


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From: Ken
Subject: Re: Lenses
Date: 13 Apr 1999 16:36:23
Message: <37139B69.C67E6D52@pacbell.net>
ingo wrote:
> 
> for constructing a positive lens use a sphere-sphere intersection, for a
> negative one a difference of a cylinder with two spheres. To calculate the
> radii of the lens you need the lens-makers formula (could simply be made
> into a macro)
> P=(nl-n0)((1/R1)-(1/R2))
> P=n0/f
> 
> P=power of the lens
> nl= ior of the lens (put this one also in your interior)
> n0= ior of air (~1)
> R1, R2= radius of the lens-surface
> f=focal distance of the lens
> 
> for construction of optical systems you need Newtons and/or Gauss' lens
> equation.
> For looking through a system POV-Ray is ok, for making the path of light
> visible you need Nathans' uv-patch. POV lenses are perfect, no abberations
> or dispersion. I constructed a fresnel-lens that works fine, the macro is at
> twyst's macroscope.
> 
> Ken posted a URL with a lot of optics info a few days ago. ( I lost the url
> already, Ken how do you maintain  400+ bookmarks? A utility or just your
> neural network?)
> 
> ingo
> --
> Met dank aan de muze met het glazen oog.
> 
> Rune S. Johansen heeft geschreven in bericht <37124c8f.0@news.povray.org>...
> >Is there any tutorials on how to make lenses that works in POV-Ray?
> >I mean how to use lens shapes with ior cleverly.
> >F.x., is it possible to make two lenses that gives different zoom
> >when back and forth away?
> >
> >Thanks,
> >
> >Rune S. Johansen
> >http://hjem.get2net.dk/rsj

It would be nice to have a utility that I could feed the entire book mark file
into and have it report back all non working links. I have yet to find a
bookmark in my collection to a utility that will allow this sort of function
but someone surely has made one in the past.


I think the link you were referring to was:
http://www.physics.umd.edu/deptinfo/facilities/lecdem/demolst.htm#l3

-- 
Ken Tyler

mailto://tylereng@pacbell.net


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From: Julius Klatte
Subject: Re: Lenses
Date: 13 Apr 1999 20:00:24
Message: <3713cc88.0@news.povray.org>
>It is possible, funny I haven't seen any serious optical
things done
>with POV-Ray yet. There was a telescope animation (or
still) posted not
>too long ago here at news.povray.org and it showed rather
well how the
>lenses can be set up to magnify. I myself did this long ago
and was
>confused at the results.

I just posted an example of this in binaries.images

Julius Klatte
http://surf.to/jkhome


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From: Chris Huff
Subject: Re: Lenses
Date: 13 Apr 1999 21:13:00
Message: <3713DE20.51C614E@compuserve.com>
> POV lenses are perfect, no abberations
or dispersion.

Actually, you can have dispersion if you want if you use a patched version of
POV-Ray, and I think that these lenses will still suffer from spherical
abberation. In real life, some lenses are spherically ground because it is
cheaper and easier, some more expensive lenses are not spherically ground.
However, I have no real experience in this area, so correct me if I am wrong.


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From: Markus Becker
Subject: Re: Lenses
Date: 14 Apr 1999 06:24:09
Message: <37145F6B.3133D1FC@zess.uni-siegen.de>
Ken wrote:
> 
> It would be nice to have a utility that I could feed the entire book mark file
> into and have it report back all non working links. I have yet to find a
> bookmark in my collection to a utility that will allow this sort of function
> but someone surely has made one in the past.

If you're using Netscape (since 4.5)  has the ability to do
exactly this: Chose Bookmarks->Edit Bookmarks and then View->
Update Bookmarks and go have a coffee ....

Markus
-- 

 Ich nicht eine Sekunde!!!" H. Heinol in Val Thorens


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From: Marc Schimmler
Subject: Re: Lenses
Date: 14 Apr 1999 10:14:41
Message: <371494C0.62F5A5AC@ica.uni-stuttgart.de>
Markus Becker wrote:
> 

> Ken wrote:
> >
> > It would be nice to have a utility that I could feed the entire book 
mark file
> > into and have it report back all non working links. I have yet to fin
d a
> > bookmark in my collection to a utility that will allow this sort of f
unction
> > but someone surely has made one in the past.
> 

> If you're using Netscape (since 4.5)  has the ability to do
> exactly this: Chose Bookmarks->Edit Bookmarks and then View->
> Update Bookmarks and go have a coffee ....
> 

> Markus
> --

lst?
>  Ich nicht eine Sekunde!!!" H. Heinol in Val Thorens

Hey that's nice!

Marc
-- 

Marc Schimmler


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