MH/HPS setup reflector

Hey all.
I'm a bit of a newbie when it comes to HID lighting types. I know you need ballast to ignite these types of bulbs, but I'm confused with the sockets, placement, and reflector. I use my room to grow so and enclosed space won't be the problem. I was wondering if its possible to just setup the MH/HPS bulb without one of those fancy reflectors and have the bulb dangling in open space or is it somewhat optimal to have a hood?

Hoods direct the light where they need to go: your plants.


Check out:
http://www.amazon.com/Apollo-Horticulture-GLK400CT24E-Digital-Dimmable/dp/B00547I5I8/ref=wl_it_dp_o_pC_nS_nC?ie=UTF8&colid=1A0TEMZH5F2VM&coliid=I30TGIQRWR5MOA

and

http://www.amazon.com/iPower-GLSETX400DHMWING-400-Watt-Digital-Dimmable/dp/B005DO30MI/ref=wl_it_dp_o_pC_nS_nC?ie=UTF8&colid=1A0TEMZH5F2VM&coliid=I1JZ3OJHQ2AOYV

Look into vertical growing. The bulb hangs vertically and the plants are placed around it.

Hps lamps get very hot. You'd just have to use caution when using a bare bulb.