Chick 1 says:

Chick 2 can explain this better than I but for our loyal readers who are wondering, “What is lens flare and why should I care?”  I will attempt to explain. 

Flare is what happens when light reflects within the lens.  This happens when a light source (other than the light that is bouncing off your image) enters the camera and refracts off the glass.  That’s one reason you don’t normally shoot directly toward a light. 

For those of you wondering flare looks like, here are some helpful examples:

Notice something about these pictures.  Yes, they are both from Star Trek.  And they’re just the tip of the iceburg.

In the last decade or so, it’s become more and more popular to use lens flare on purpose.  It can be used for a variety of reasons; like making a film feel “real” or documentary-like or emphasizing how hot or bright a light source is in the story.  (You often see this technique in a “lost in the desert” scene when someone looks up at the sun.)  And when creating a fake environment (like a computer generated scene in space) details like flare can make that CG environment more believable.

Now I loved Star Trek.  I thought it was the best summer movie of 2009.  But the flare in that movie was waaay over the top.  Early in the movie, I did like it.  I thought that having a lot of flare did help set the mood, make the space scenes cool, and even give the film its own style.  But it made it very hard to see the action.  Check out those photos again.  See how fuzzy it looks.  During the movie, I found myself squinting to try and see what was going on.  (Didn’t work.)

I get it.  I get it.  There are a lot of bright lights on the ship and  a lot of shooting into suns &  stars (yes, I realize they are the same things) so naturally there will be some flare but if I can’t actually see the film, there’s a problem. 

So what is lens flare? – light refracting through a lens

And why should I care? – Lens flare can be used purposefully to either enhance a story or obscure that story.

Discuss.

PS.  I still love you, JJ Abrams, and I would like to carry your briefcase and follow you around for a couple of years.