The Iris Nebula, also known as NGC 7023, is a bright reflection nebula in the constellation Cepheus. NGC 7023 is actually the cluster within the nebula, LBN 487, and the nebula are lit by a magnitude +7 star, SAO 19158. It lies 1,300 light-years away and is six light-years across. The dark areas, dust lanes, block the light from the stars behind it, causing blank, dark spots in the sky. 

Technical info:
TS 80mm f6 APO triplet refractor - Canon 40D - total exposure (8hrs 30min)