Using the same phone camera, (10Meg blackberry) if I take a picture when my 1000 W MH with digital ballast and 400W MH with magnetic ballast is on during veg, I have the lines. Then during flower I switched to HPS in the 1K and switch 400W MH to a 600W digital ballast HPS (need to order a 600MH bulb online, can't find one locally), I don't have the lines in my pics, not sure why, could be hps vs mh but the magnetic ballast theory makes a lot of sense from what I see.
Same Camera:
Veg with 400W MH Magnetic ballast in the room.
Same room switched to 600w HPS digital ballast and 12x12
Not scientific but I did notice this when I changed out lights last week to go to flower.