OGEvilgenius
Well-Known Member
If you are going to use it at 400 for the most part, I'd get a 400 bulb. In my opinion it will perform better than the 600 @ the lower wattage. Also it might not be good for a bulb to be under powered. Not sure about that at all, i just know that lost of things like being powered at a certain level and performance and lifespan drop off when the proper power isn't supplied.
Plus a 400 should be a little cheaper than a 600.
It's true, running a bulb at a different than intended setting can pretty dramatically effect the spectrum of light it's putting out too.