This one is a big update today; I re-rendered the caustics glass scene & added finally working caustics to it, took me 2.5 hrs to make it work good
I first rendered the scene at 640X480, 1-16 Samples Super sampling with Mitchell Filter,
Mental Ray indirect Illumination
Energy - 3, 00,000
Caustics Photon – 2, 00,000
Decay – 2.0
GI Photons – 10,000
Rendering Algorithm -> Ray trace with Large BSP
Caustics – 1000 samples
GI – 500 Samples
Average caustics photon per light – 1000
Final Gather – 500 samples
It took me a staggering 10 minutes to render, & I as an idiot, just rearranged the light & re-rendered which took me again 11 mins, then I increased the light intensity to 1.5 & took me 15 mins to render, Dam
After this I came to my senses & started optimizing it, I disabled GI & Final gather from the rendering menu, decreased the energy to 1, 50,000, decreased the caustics photos to 50, 000 & GI photos to 10,000 for the light
I found that for at least this scene, going to 1-16 Mitchell Super sampling was useless, it provided almost negligible difference over 1-4, although it did helped when I streached the image to 1024X768 with Photoshop, the quality loss was negligible due to high value of sampling, & then re- rendered, with hardly any noticeable difference in caustics the rendering time decreased to 3 mins
*img324.imageshack.us/img324/760/caustics2mc.th.jpg
To further increase the caustics sharpness, all which is required is to increase the value of Caustics photons to even higher, maybe up to 2, 00,000 & set the light intensity to 2.0