1.82 rendering 3 times slower then 1.76?

[schizo]

Heyo,

I actually want to render one of my older animations as a stereoversion. It was created in version 1.76. But this version had the bug that the position of the positional light wasn't interpolated for left eye images (this was somewhen fixed on the way to v1.82).
So I wanted to render the animation with version 1.82. Checked first for different colors because of loading a v1.76 file into v1.82, but that seems ok.

Started rendering (only in 640x480 instead of 1280x720 => around 1/3 render time * 2 (left+right) => should take around 2/3 of original render time)
... and after some days I think: Damn, why is it so slow?

I stopped and did some tests. The result for keyframe 21 is here:
v1.76 image: http://psykick.de/share/key21_176.jpg
v1.76 param: http://psykick.de/share/key21_176.m3p
v1.82 image: http://psykick.de/share/key21_182.jpg
v1.82 param: http://psykick.de/share/key21_182.m3p

Rendering this image took around 9 minutes with v1.76, but rendering with v1.82 took around 27 minutes.
Did I something wrong (wrong parameter?) or is this a bug? 
The image from v1.82 looks like rendered with a smaller DE stop, because its too noisy and fine. The image from v1.76 looks much cooler. But the calculation parameters are the same.

Any advice how to solve this problem?

[Jesse]

Hi schizo

yes the Destop value in the parameter is very low 0.031.. so the result must be aliased and noisy...
so the older version is not that accurate in the calculation as the new version, you have to increase the Destop here to somewhat like 1 because the result is downscaled by 0.5.  This value is related to a pixel in a 1:1 non-downscaled image.

But the accuracy of the DEstop value cannot be guaranteed to be 100% correct always, it always depends on formulas etc.  Its a gift if it works however  

ps:
if you use a DEstop value of 1 it renders quite fast again

[schizo]

Hi Jesse,

thank you for the useful hints. I've raised DEstop to 0.5 and it looks fine and renders much faster. 
... only 200 frames to go ... so enought time for a  

thank you for this wonderful piece of software