Wednesday, July 8, 2009

Depth of Field Tutorial

I'm not only hoping that you will look at this blog and gain a greater appreciation for my work, but that I'll also be able to share some secrets of the trade with you. On the surface that may seem counter productive. Giving trade secrets away, but I'm not giving you ALL my secrets.

For starters, we'll do a short series on making your everyday pictures better.

Ever wonder why a paid photographer's pictures look .... uhhh good? It's because they have a grasp on a lot of simple concepts and they put them together.

One of those techniqus is depth of field.

Last night I got the chance to shoot two images of the same person at the same time. The only difference between the two pictures was that I changed the depth of field (DOF) or "F-Stop", on my camera. Well, that and my subject is 6 and she moved between shots!

In this first image, you will notice that this picture looks a lot like many of the pictures you take at home. It was shot at an f-stop of 22, which means the little diaphragm in the camera was about the size of a pin hole. It let in very little light, BUT, it captured tons of detail BEHIND my subject. The DOF ( of view ) is very deep.

As a result my subject is competing with the objects behind her - the curb, the shrubs, the flag poles and buildings behind her.

Now, take a look at this image. It was shot with an f-stop of f4. A much lower f-stop, which means the little diaphragm thingy is wide open letting in as much light as it can on this camera with this lens. As a result, my subject is sharp, but my background is blurry. I've effectively isolated my subject, but given you an idea of where she is, but they are not competing for attention.

The result is an image focused on the subject and not the surrounding.

The trade offs ...

If I was wanting to shoot a landscape I would not want a shallow DOF. Also, if I have multiple subjects at differing distances from each other I would not want a shallow DOF. Also, because we are letting so much light in with the f-stop thingy, we have to let the shutter open on our camera a longer amount of time. If we leave the shutter open longer we are more prone to what I call "shake" which is nothing more than a blurry image.

This makes sports at night REALLY hard to shoot because you want to get the football player ( stop his action ) catching the pass 20 yards from the sideline ( deeper DOF ), BUT you don't want to have the visiting fans in focus ( shallow DOF ). Plus it's dark and you have to slow the shutter speed down to let in light, AND they are moving ... I'm getting a headache. But those guys are good at what they do.

So how do I get a shallow DOF with my little point and shoot?

A typical point and shoot camera will have something called a "portrait" mode and on the little selection wheel you will probably see something like a lady with a hat. That seems to be the universal symbol for portrait.

To set a shot up with a simple digital camera, set to portrait

  • Give yourself as much room behind the subject as possible ( if there is a wall behind the subject it will be in focus, things farther away will be blurry).
  • Get your subjects as close together as possible and fill the view finder with the subject.
  • Try to shoot with light that is not too harsh, but not too dark that it fires your flash. If possible shoot in the shade if its the middle of the day. A flash requires the camera fire at certain parameters which could change your DOF.
See? Easy

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