Contrast/brightness fades in and out on its own when playing games (Samsung TV)

Hi, I have a TXR2765 (dirt cheap TV, admittedly) and when playing certain games (FPS in particular) where there's varying levels of contrast (really bright patches and dark patches), there's a strange lag effect as the TV "adjusts". For example, if I make the character look at the sky, over a split second the screen will dim slightly, and likewise if I look into a dark area immediately after looking at the sky, over a split second it will brighten. It's sort of an iris effect - a gradual shift over the split second. It's also very annoying. Also, if there's something bright on the screen, everything around it will look darker unless I move it out of my field of vision, in which case I'll get the iris effect where everything brightens by itself again.


I hope this is reasonably clear, it's a bit tough to explain. It's likely just a problem with having a cheap TV, but maybe there's a service menu option that could help?


Thanks for helping out a newbie...