I know this picture won't be of much value since I can't compare the lighting with that of T-12, T-8, or T-5, but it will perhaps give you some idea of the brightness that T-5HO fixtures produce. You are seeing the light transmitted not only through polycarbonate but also 16 mil solar blanket material. Also, in the greenhouse on the left, the right side is illuminated by T-5 fixtures and the left side is illuminated by T-5HO fixtures, two fixtures on each side. My more light-sensitive plants are positioned under those standard T-5 fixtures.
Click on the picture to see both greenhouses.
