Monday, May 10, 2010

What does "Rendered for neutral gray" mean?

If you take up photography as a hobby, eventually you will come across the sentence at the top of this post.  Most of the time it's tossed out like something that is so obvious that it needs no explanation, like "Rubbing is racing" or "Lindsey Lohan is skanky."

So, in the interest of education, I'm going to attempt to explain what "rendered for neutral gray" means.  My explanation will be concise and easy to understand.  There's a good chance it will be inaccurate.

Think about your camera.  Now think about me.  Camera.  Me.  Feel better?  I know I do.

Your camera has the incredible job of measuring light.  Not just any light either.  It has to measure reflected light.  Let's say you focus your camera on a lovely bride.  The light in the room reflects off her dress and enters the camera where it is measured, cut and told to pick up it's suit a week from Tuesday.

Seriously, the light reflects off an object and enters the camera where the camera decides how much of the light it's getting is necessary to take a properly exposed image.  In order to do this, it has to have a benchmark... a starting point.  The camera has to have a number in it's little brain that says, "X amount of light is the correct amount of light for a properly exposed picture."

So, how does it come up with that magic number?  Neutral gray.

The camera can't distinguish color, only shades of light and dark.  So. it's been programmed with a number that is the exact amount of light necessary to take a picture of something that is neutral gray.  Why neutral gray?  Because it's in-between black and white.  It's the safe middle.

The real questions are:  Why does this matter so much that we are reading about neutral gray at all?  How does this affect our photography?  Why aren't we using jet packs to fly to school?  (Seriously, back in the 60's they were saying we'd have jet packs by now.)

The reason it's important to understand about "rendering for neutral gray" is because it will affect your pictures and you won't know why.  As a wedding photographer, I take a lot of pictures of people who are wearing all white or all black.  I need to understand "neutral gray" if I want to take properly exposed pictures. 

For example, when photographing a bride all in white, I know that her dress is reflecting more light than it would if she were wearing all gray.  But the camera doesn't know that and so it will only let in the amount of light that it needs to illuminate neutral gray.  So, I end up with a dress that looks... you guessed it, gray.

When photographing a groom all in black it's the opposite.  The black tuxedo is absorbing more light so the camera will let in too much light to compensate and the tuxedo starts to look.... wait for it, gray.

You don't notice this sort of thing with other colors because someone in a red shirt looks like someone in a red shirt.  That is, you don't notice that it's a little darker or brighter in the picture.

But you notice a wedding dress that isn't white.

So, how do we fix it?  Easy.  When photographing a white dress we set our exposure compensation to +1 if in an auto mode.  If in manual, just move your light meter to +1.  For dark suits go the other way.

The tricky part is that it seems to go against common sense.  Most people assume that a white object will be brighter so the camera needs to let in less light.  What they forget is that the camera is automatically letting in less light because it wants everything to be gray, so we have to force the camera to let in more light.  More light means more bright and a white dress.

It's one of the professional secrets of the wedding trade.  One of the way's that you can always tell a wedding photographer who understands "rendering for neutral gay" is that the groomsmen will have black suits and the bride will have a white dress.  Even with exposure compensation we can't always get it right.  If you are taking a picture of the bride and groom together, which tends to happen quite a bit during a wedding, then you're screwed.  Let in more light to make the dress look white and the tux looks gray.  Let in less light to make the tux black and the dress will look gray.

That's when Photoshop comes in.  But that's another post completely.

Booray Perry is a wedding photographer in Tampa Florida.