playing with lenses

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lego
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playing with lenses

Post by lego » Fri Nov 03, 2006 5:25 am

After reading about some experiments with indigo and lenses, I decided to try something :)
they have absolutely no scientifical value, as the lenses are just made of resized spheres and are not accurate :)

the material of the lenses is glass (ior 1.5)

I put the camera inside a box with a hole
the hole is big enough so that you can't see the box
this is a render without any lens
Image

let's call the lens' side near the camera "A" and the other one "B"

the first experiment is with a lens with concave A and convex B
Image

as you can see there's almost no deformation

concave A and B:
Image

convex A and B:
Image

ok, I was expecting this :)

flat lens (a short glass cylinder )
Image

now that's strange! I was expecting an image similar to the one without lens, but this is the most deformed one! And why is there just a small circle visible with all black around? :shock:

maybe it's just for some modeling flaws?


last experiment: all the lenses together, random order :)
Image
mmm :?:

ok, this thread is pretty useless...
Next time I'll try to do some renders with "real" lenses :D

atmmatt
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Post by atmmatt » Fri Nov 03, 2006 5:34 am

Heh if you wanted to get real fancy you would replicate the lens of a nikon or canon with + 10 elements :) Also you would match the index of refraction to each species of glass used in the lens.

Anyone know if it's possible to replicate a multicoating on the psuedo lens?
"To be, or not to be" That is a question?

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zsouthboy
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Post by zsouthboy » Fri Nov 03, 2006 6:05 am

A multicoating on a lens could *probably* be faked with a very very slight SSS effect.

I have nothing else to add.

I want to try replicating my 70-200VR, one day, just for fun.

lego
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Post by lego » Fri Nov 03, 2006 7:05 am

I'm trying to recreate my fotocamera objective now... it's a bit hard, as I only have a drawing of the lenses :)

here's my first attempt:
Image
very artistic :D


second one:
Image
there's heavy deformation here :P
it seems like I achieved to recreate dof... the image is too small to tell however. I'll do a bigger render :)

edit: lensflare final version... it was a very slow render, like 8k mutations/sec :(
Image
everyone loves (hates :P) lensflare!

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dogfin
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Post by dogfin » Fri Nov 03, 2006 10:33 am

Just out of curiosity, wouldn't you need an orthographic projection? In real life the film is a flat area, but the camera in indigo is a perspective point. I seem to remember a few years ago someone made a lensed camera in povray using the orthographic projection to get real lensflares and such.

That last pic with the flare in it is the best. Keep going man.


dogfin -
Image

atmmatt
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Post by atmmatt » Fri Nov 03, 2006 5:04 pm

Tomorrow I will try and model a telescope, newtonian and then a simple refractor. I can also try some cat systems to see if it gives any nice effect. The trick will be putting that parabolic surface onto the mirror surface and then spinning it smooth. I have all the numbers, I'll just model it after my 12.5" mirror but don't know if it will give a magnified image or not.
"To be, or not to be" That is a question?

lego
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Post by lego » Fri Nov 03, 2006 11:44 pm

mm what is it?
Image


let's try with my new telescope!
Image

sigh I knew I had to buy the expensive one :oops:


p.s. suzanne should be red...

lego
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Post by lego » Sat Nov 04, 2006 1:55 am

this one works a little better :)

Image

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OnoSendai
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Post by OnoSendai » Sat Nov 04, 2006 6:21 pm

Great stuff Lego, very interesting experiments.
Any chance of some schematic wireframe renderings of your lens assemblies?

Love the lens flare render!
That's the first render I've ever seen with a properly simulated lens flare :)

If any of you guys have any information on how cameras are set up in terms of lens configurations, lens flare etc.. I'd like to see it.

About simulating non-reflective coatings on lenses, this could probably be done just by scaling down the reflectivity from that given by the Fresnel equations by some amount, perhaps just by a constant factor.
Just out of curiosity, wouldn't you need an orthographic projection? In real life the film is a flat area, but the camera in indigo is a perspective point
The camera in indigo has a non-zero sized aperture and a non-zero sized sensor, it's not modeled as a point.

lego
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Post by lego » Sat Nov 04, 2006 9:57 pm

sure :)

this is the dof and lens flare setup

Image

it's the objective of my camera... no measurements, I just copied the scheme from the istructions booklet :)


this is the telescope

the shape of the two lenses
Image

all together to get the scale
Image

on the top there's suzanne, on the bottom the camera and the small lens ("oculare". I don't know how to say it in english)

The telescope experiment went much better, as I tried to calculate the correct measures for the lenses and distances

atmmatt
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Post by atmmatt » Sun Nov 05, 2006 2:46 am

In english we usually call them eyepieces.

The trick with the refractor is it's usually an doublet, two lens stuck together like a camera lens. The eyepiece however can be a simple 4 surfaced one or up to 15 surfaces just for that.

I'll try and gather some schematics of the lenses and telescope specs.
"To be, or not to be" That is a question?

atmmatt
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Location: Pennsylvania - USA

Post by atmmatt » Sun Nov 05, 2006 3:03 am

While laying out a newtonian I got a weird optical illusion.

Image
"To be, or not to be" That is a question?

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Kosmokrator
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Post by Kosmokrator » Sun Nov 05, 2006 3:35 am

atm-matt heheh nice illusion man....... :wink:
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