Don't bother

This isn't exactly a bad product, just not exactly a good one either. The HF-DC1 is essentially a flash unit with a built in optical sensor. In certain situations, with the flash mounted according to directions, it will not fire. Mainly due to the subject not reflecting enough light to trigger it. When mounted as directed, this flash also will double up shadows of close subjects (due to your built-in flash being used as the trigger), or make shadows behind subject harsher.

For the price, this item is definitely lacking in features and usability.

I would recommend grabbing an optical slave hotshoe unit and a good quality flash gun for any photography use you believe this will benefit. I purchased the HF-DC1, used it for 50 or so shots (of which it failed to trigger on 20 or so), and promptly returned it. For the same price, or less, you can buy 2 optical slave shoes from ebay(high range slave unit, or optical flash slave - ebay search) and pick up 2 decent flash guns from a pawn shop.

Using the new setup (2 slaves + 2 flash guns), i am able to highlight the subject, provide various lighting effects, and get very even lighting coverage. The dual setup also provides the added benefit of getting rid of harsh shadowing (1 unit near camera position, 1 unit behind subject to counter shadowing).