Light Distance. Does a HPS or MH need to be a certain distance?

[amdp]

Just wondering if the HPS or MH needs to be a certain distance away from the plant or is it all a matter of heat? If I move the light closer to the plant but control the temp on the plant will it make a difference?

Thanks in advance.

[Pothead4204life]

yes it does make a difference............if you can put a fan blowing on the bulb get it close as you can to the plant....... just watch the temp on the top......

[amdp]

so the closer the better as long as the temp stays around 80 degrees F.