Fluorescent phenomenon

Ever tried to shoot in fluorescent light?

Tough light. The colour is all green.

So you know what to do: white balance. Set it to “fluorescent” – that will make the colour appear more neutral.

But sometimes it gets really weird. Especially when you shoot with a good lens, i.e. a fast lens, one with a low “f-number”, a lens with a wide aperture. You can get some pretty weird images.

With a slow “kit” lens you get something like this, perhaps:

And then you switch to a faster lens with a wider aperture. Now perhaps you get this:

And then perhaps this:

Huh? What’s up?

The increasingly  blurry background should give you a clue. Can you guess?

Click on “more” to read the answer after the line:

Cheap fluorescent lights are not “on”. They cycle “on” and “off” and then “on” and “off” again, and so on. They repeat their on/off cycle 60 times a second.

So if your shutter speed is slow, and in particular if it is a multiple of that cycle time – like a/30th second say – no problem.

But if it is fast, say 1/800th sec or 1/2000th second, you might well catch the light just when it is off, or only half on.

That is why the bottom pics show the problem. You see the blurry background? That means a wide open aperture, which will mean a faster shutter speed. Mystery solved.

Fortunately, some fluorescents, like the ones in hockey arenas, cycle much more quickly. No problem there. But if you see the issue you are seeing here, try shooting at 1/60-th or 1/30th second in shutter speed priority mode. That should help solve the problem.

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