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Fluorescent tubes as practicals?
  • Hi, I want to use practicals in a class room. There are normal fluorescents tubes mounted to the ceiling, which can easily be replaced. But the room is also flooded with daylight through windows (which will be "dimmed" by using ND gels). I want a good colour match between the tube-light and the daylight from the windows.

    Would this tubes do the trick: (6500K, RA 93)

    Or do I have to use the more expensive ones: (6500K, RA 98)

    I think 50Hz flickering is not much of a problem, as there is no fast motion in the scenes and I can adjust the shutter speed as needed (using a BMPCC at 24 fps).

    Any input about using fluorescent tubes are welcome:-)

  • 10 Replies sorted by
  • After all that NAB-news...maybe now there is time to share some experience? ;-)

  • use shutter 40 no fliker on that mode or even 30.

  • it's not the tubes you should be worried about, it's the ballasts. Magnetics will flicker, electronic won't... but with rolling shutter cams you'll get slow horizontal bands that wash across the screen vertically. Use this tool to determine shutter angle for your region and power state.

  • Thanks @shian and @sage

    Ok, I'm aware of the 50Hz flickering problem and the BMPCC can be set to the needed 172,8° shutter angle. If electronic ballasts are cheaper than magnetic, than thats what they use (as its always the cheapest for the schools, but its a very new installation).

    What about the colour of the tubes? I have daylight flooding throu one side of the room, dimmed down by 3 stops with ND gels. Will the lights I postet (RA 93 and RA 98) give any ugly colour (green?) on video?

  • Most builders looking to save cash go with magnetics cuz they're cheaper. But flicker like mad.

    As long as they are "daylight colored" 5000k - 5600k, you can adjust everything in the grade. The tubes you listed are quite a bit bluer than sunlight, you'd have to search the web for any articles mentioning a green spike in them. I try to use 5000K Sylvania tubes for off-the-shelf applications.

  • @shian Ok, so I will have to check the ballasts.

    The sun is never directly shining into the room (windows faceing east, 3rd floor), its just the sky - blue or overcast. So, I was thinking that "shade = 6000K-7000K" would be a better match, but I really have no clue what will work. What do you think?

  • well for me, I like a little variance. In one of my tutorials I used half CTB gels in daylight to get a slightly warmer tone mixed with sunlight. Cuz sometimes everything all one color is boring.

  • @Psyco Those tubes I linked are the best in the biz, specifically because they formulate the coatings to result in spectrum spikes that only occur in CMOS blind spots.

    That said, sunlight is sunlight, and this is the only light that can be indistinguishable:

  • @Sage I had a look at the Kinoflos, but they have the wrong socket (I need G5) and are a bit expensive - thats why I was asking about the "normal" tubes.

    Those LEDs look interesting, but I need something affordable now;-)