Florescent and neon lighting gives me fits.
Those are indeed difficult. There are a few varieties of fluorescent, like Cool, Warm white, Daylight, all being different colors, and there are variations in each type. Generally we don't have a way to know what type of bulb is installed there. Or even if we bought them, they still vary. Florescent also has a CRI rating (Color Rendering Index) on the better of them, how well they reproduce a few general colors. High CRI is 80 or 90, still less then 100. If it does not say, it is not good CRI. The best is decent, but not perfect color.
And there are another two types of fluorescent, those using old magnetic ballasts (1990s and older). CFL and desk lamps bulbs use electronic ballast, as do many new new lighting fixtures, but it is not a sure bet at all. We can still buy magnetic ballasts.
Electronic ballast creates a very high frequency, so no flicker issues. Magnetic ballast causes flicker at the 60 or 50 Hz line frequency (technically, at 2x that rate). So we have to use a slow shutter speed (ideally precisely 1/60 or 1/120 second shutter in North America) to capture whole cycles, or else we get random dark and dirty (brownish) color from them. A 1/150 second shutter is guaranteed to see only a partial cycle, with random poor color results. This is part of the art of shooting under (older) fluorescents. Those with electronic ballast (including CFL) are no issue about flicker.
Incandescent lights vary color too, a few different types and colors too, and it even varies with watts, and age, but at least they are the definition of CRI 100. They are Orange, but a complete spectrum, and we can correct them.
Neon seems hopeless. IMO, probably the best general effect is to use Daylight White Balance, to show their actual colors?
Direct sunlight on a clear day is pretty much the only constant color we have, always same as expected by the camera Daylight WB, but of course cloudy and shade and sunsets, etc are a different story.
Flash WB is about the same as Daylight, but flash color varies with flash power level. Also with specific flash tube, and age of that flash tube.
WB varies.
So learning how to correct White Balance is a pretty necessary thing to know. Fundamentally important to good picture results. There are several methods, and any try is better than no try.
In the old days, a good film photo lab would do much of the WB correction for us. It was not even required that we use blue flash bulbs, many labs would simply fix it for us. Digital however is our job to do.
Cameras now offer Custom WB, which is a way to aim the camera at a white or gray known-neutral card (neutral meaning known to be made with equal RGB components of its own color, i.e., no color cast... i.e., a white balance card). Card should fill the entire frame (proper focus is not actually necessary). Then it lets Auto WB correct that view of that card (of only the card), in the same light that is on the subject. This works only because the card is a known-neutral color (and the light is the same on the subject). Then we shoot the subject using that custom WB. The problem with Auto WB in general is that it has no clue about the actual color, but using the neutral card, any color cast is incorrect and should be removed.
This Custom thing seems tedious to do to me, and an easier way that I much prefer is to just put the card in the scene at the subject, in the same light as the subject, and take one test picture, including the card. Then remove the card, and shoot away (preferably using raw images). IF it will be in the
same light as the subject, we can often just hold the card at arms length in front of the camera (clear focus not required). Then later, the raw editor will have a White Balance Tool, we simply click the card in the first test shot, which can simultaneously correct all frames in that same session (same light on the subject). Ought to be perfect color, no color cast.
Or, an old time way that still works, certainly in emergencies (just meaning no prior planning), maybe not always perfect, but generally works quite well... far better than no try at all. Many if not most scenes already have something white in them. I don't mean off-white like normal walls, but things that were intended to look actually white.. a white envelope, or a table cloth, or a piece of white paper, or china plate or dish, or plastic bottle cap, or a common sign about pizza or smoking, or a church steeple, or a picket fence, or a T-shirt, or a shirt collar, or maybe a white cruise boat, or the polka dots on the kids pajamas, etc, etc..
White things are common. Not all are equal, but just click that actually white object for generally pretty good results, not fail safe, but works pretty good very often. If you have no other plan or opportunity, why not try it? The white thing should be in the SAME light as the main subject.
Clicking the white thing tells the computer "This spot is white, make it look white" (white meaning neutral, no color cast - gray cards work too, but they are pretty dark to show slight color cast well). That result goal would be pleasing color, if not precisely accurate color... Precisely correct depends on using a known neutral card. But pleasing is good too.
Far better than no try or no clue.
More of this at
Easy White Balance Correction, with or without Raw
