Is that initial zero a typo? I'm asking that because #0F0000 is practically black; by "dark red" people typically refer to colours around #7F0000, with a seven.
Either way, see picture:

The colours in the second and third columns are 1/2 and 1/16 the value of the first. The fourth column is black for comparison. This was done by linear equivalence, not perceptual equivalence, so the oranges will look a bit brighter than the red.
I've included two oranges there; middle row is what I learned to be orange (1 part red, 1 part yellow), and bottom row is what CSS calls orange (1 part red, 1.8 parts yellow).