Originally Posted by bobs

Color temp ! = brightness. The 4,200k bulbs will be brighter than 6,000k bulbs, but not as white. In order to get the color temp you want the bulb manufacturer has to put in additives that will absorb the yellow/red end of the color spectrum. The higher the temp the more additives. Your light will be whiter but not brighter. Best visibility is with 4,200k - 5,000k.

My 6,000k lamps are almost a little too blue and I will probably swap them for 4,700k bulbs when the time comes.