lighting - How does light quality vary between fluorescent (CFL) and incandescent?

I have two sets of soft boxes. One has incandescent bulbs (3,200k) and the other uses compact fluorescent bulbs (CFL @ 5,500K).

I'm trying to sort out some of my understandings regarding the light types and their qualities / attributes.

The basis of my question centers around this piece of information: I've heard many times from others "I look horrible when seeing my reflection in the mirror when in a room that's lit with fluorescent lights" and I myself have experienced the same thing. The skin looks harsh and it seems every blemish / bump, bruise, discoloration of the skin, etc. is accentuated.

Now, my question is: Is this due to the TYPE of lighting (Fluorescent vs Incandescent), or is this a function of the lighting temperature typically found in Fluorescent as opposed to Incandescent?

If its merely a function of the lighting temperature, then technically you should be able to get two different types of bulbs at the same temperature and get the exact same quality of lighting with the same attributes, correct?

Additionally, I have heard (if I recall correctly) that fluorescent lighting lacks the magenta color? Is this true? If so, how does this manifest itself when it comes to lighting quality?

Answer

There are two things at play. One is the spectrum and the other is the shape of the light-source.

If you place both types of light in a soft-box, you will be wipe out the difference in shape which will make the harsh look and appearance of imperfections, bumps, wrinkles match more closely.

The spectrum of an incandescent bulb is more more uniform and evenly distributed than that of a fluorescent. This means that all colors are present and so a subject can reflect its true colors. However, the color-temperature adds a bias which you can shift by correcting for white-balance. This happens since an incandescent bulb produces more light which we consider warm. Different tints painted on the bulb often shift this towards cooler color to produce cool-white or daylight bulbs.

The spectrum of a fluorescent bulb is highly irregular and some colors are indeed missing or very low, depending on the exact type of fluorescent. When it happens, the missing colors cannot be reflected back by the subject and no amount of white-balance correction can compensate.

Since fluorescent are more and more used, there are now many types of lights which offer improved coverage of the color-spectrum. You can even buy full-spectrum lights that output colors covering a very similar spectrum as the sun, including UV.