sunrise brightness flickering

[super gnu]

im just doing some fairly rough test renders of a shot, with a higher noise threshold that the final ( 0.01, basically the default so not absurdly low quality)

its a sideways pan across a desert, with the sun rising offscreen.. idea is to get shadows in the sand bumps shifting as sun rises..

ive noticed a very obvious overall variation in the brightness levels frame to frame. (i dont mean it gets smoothly brighter as it should, it *flickers* subtly in brightness level as the sun rises.-- an overall effect, not just in specific areas)

ive got my LC on retrace 8, so id assume it wasnt the gi.. and its all rendered on one machine, so i cant blame the renderboxes.

hard for me to post an example scene.. anyone got any suggestions?

[super gnu]

ok i tried rendering with a lower noise threshold.. there is definitely a noticeable jitter to the brightness as it increases with the sun rising. once the sun stops moving, the lighting is rock solid, so its not the gi..

[Svetlozar Draganov]

Can you show us a few frames or send us simplified version of the scene?
If you add all render elements in which one the flickering is most obvious?