Originally posted by Galaa
I read from somewhere, that using TC lens will reduce the light coming in as the F stops are lowered(Me newbie so the words I use might not be correct).
Is that true? And is it only for TC lens or does all lens lower F stops?
The TC meant for SLR cameras will reduce 1 or 2 stops depending on its power (1.4x will reduce 1 stop, 2x will reduce by 2).
A properly made TC meant for digital cameras (those which attach in front of the lens) will not have any light reduction. At least the Nikon TC-E2 doesn't.

In any case, you should not need to worry. Your camera will automatically take care of the exposure, no additional settings are required.
Same applies for wide convertors.
Regards
CK