Lens Thickness setting?

Serefina_Moon

Search is giving me no love in the shape of answers,...

Anybody know what Lens Thickness settings does?
I'm playing with a simple scene, Xin Xin and some Dystopian city blocks, 3 point lighting on Xin Xin, and the base Iray shader on the street marker poles, with them as an emissive light source, and the environment skydome.
And I'm using a giant cube with SSS for some atmosphere.

The difference between the thickness set to 0mm and then swapped to 100mm, there's just the barest difference in the emissive light sources, and maybe in the 'atmosphere',..

So, does the Thickness setting affect the way light bounces around Inside the lens ??
Is it a setting to alter the light blooming, or even flares?

Tobor

There's this:

http://londons3dpics.deviantart.com/art/Iray-Lens-Thickness-Test-539474011

and a note of when it was added (but not what it does):

http://docs.daz3d.com/doku.php/public/software/dazstudio/4/referenceguide/scripting/api_reference/object_index/basiccamera_dz#a_1a7007146bc62b5b88d8572298071aeeb6

Serefina_Moon

Yes, saw those, not a great deal of information....

Stepping from 100mm to 1000mm certainly changed things - It was like a zoom in to an out of focus image.
I'm wondering if the Thickness setting interacts with the focal length.

And it's time to put a spotlight in the frame.

Fishtales

I'm not sure but I think the thickness adds volume to the 'glass' in the lens which will cause bending of the light as it enters. In a real lens this causes the centre to be brighter than the edges causing a vignetting effect, the corners and edges get darker.

https://en.wikipedia.org/wiki/Vignetting