Fluorescent Lighting

[Andrew Patterson]

What is the downside to Fluorescent Lighting? It seems MUCH cheaper and easier to get Daylight Balanced? I know you have to use more bulbs to get the same output and brightness as Tungsten or HMI, but what are the other downsides?

Can I mix 5500k and 5600K without it being noticeable? 5500k Fluorescent Bulbs are easier to find (and cheaper) -- so can they be mixed with 5600k?

Thank You.

 

[Terry VerHaar]

One downside is the Color Render Index (CRI). Flo's tend to top out in the high 80's (unless they are really expensive) while tungsten gets much closer to 100. Also, more obviously, flo light is soft; great if that's what you want, but you can'h "harden" soft light while you can soften hard light (at a price of cutting the output, of course).

Since most flo lights are now electronic ballasts (vs. old magnetic), flicker should not be an issue but one can still get a spike in the green spectrum with fluorescents which you might want to filter out or you might have to deal with in post.

Can't imagine anyone is sharp eyed enough to notice mixing 5500s and 5600s, especially since the rating of them is probably not that accurate anyway.

Stay tuned as there are probably some better and more informed answers coing from others more knowledgeable than I! :001_smile:

 

[Alexander Ibrahim]

Can't imagine anyone is sharp eyed enough to notice mixing 5500s and 5600s, especially since the rating of them is probably not that accurate anyway.

Terry is perfectly right that the rating isn't that accurate.

What I want to add is that if you do compositing or color correction ... well you may never see a difference with your eyes, but your computer will note a difference as you try to manipulate the image. Soemtimes that difference will be critical. For example if you are getting a green spike on footage you want to composite by keying out a green screen.

Conversely ... a lot of green spikes are actually an absence of magenta! So if in color correction, you want to select some magenta's and amp them up -say a young maiden's rosy cheeks - then you may find that the color you want to select that was on your actresses face wasn't in the light ... and thus isn't in your image.

So, these are simple examples ... but using a high CRI light can be very important.

Using a consistent color temperature is also important for similar reasons.

One of the reasons cheap bulbs are cheap is because quality control is poor. So ... if you want to save on lighting it may be smart to get a light temperature meter and test your fixtures for consistency on shots where its important. Basically you are doing the quality control they didn't!

This is why I usually specify KinoFlo flourescent fixtures when flourescent lighting is appropriate. They do it right, so I can just light and shoot without doing any light engineering on set.

 

[Terry VerHaar]

Alexander brings up another good point... fixtures are one thing, bulbs another. Depending on your needs, simple and inexpensive fixtures might work just fine if you put good bulbs in them.