Using a flat bladed screwdriver, fit it into the open area around the exposed prism, with the blade laying along side the prism. Try to position the screwdriver's blade so that when you twist the screwdriver you cause the prism to shift position slightly.

Look for a couple of other places around the prism where you can insert the screwdriver, and by twisting it, slide the prism. These will be your adjustment points. Thank you dannewberry of http://practicalrifler.fr.yuku.com/topic... for this tip.

Play with moving the prism until the image looks immediately clear when you bring the binoculars up to your eyes. Remember that your eyes will have a natural tendency to align themselves with the misaligned binoculars if you stare too long (and get eyestrain).

Close your right eye and check that the image is clear on the left, then close your left eye and focus the right occular, then look away at an object (without the binocs) so that your eyes are in normal convergence -- and then look quickly into the binocs to see if the collimation is good.

The night sky is more prone to double-image because there is less information in the image for your brain to work with.