Controlling Depth of Field

[Darkdragon]

Controlling Depth of Field

What is Depth Of Field?

Depth of Field (DOF) is the depth in front of and behind your focus target that is also in acceptable focus. A shallow DOF means that there is very little distance in front or behind the target that is in focus, deep DOF means there is a lot of distance in front and behind the target that is also in focus. Another thing to keep in mind is that DOF is slightly shallower in front of the target (toward the camera) then it is behind the target (away from the camera). For some real in-depth information, see the entry on Wikipedia.

Prerequisites (things we will not be covering)

Know how to use your camera and it's available manual settings.

Know how to choose what you want to focus on or use manual focus.

Know how to set up your lighting for the effect you want.

 

Why should I care about DOF in my comic or film?

Controlling the DOF is controlling what is in focus in your photo. The items that are in focus are the ones the viewer will (obviously) focus on. Keeping unimportant items blurred will keep your frame cleaner and less confusing for the viewer.

All images shot with Canon G9 on manual, macro mode, no flash, ISO 80.

Focus point is always the face of the motorcycle cop-zombie.

Camera was not moved between shots, but the first two shots were cropped to match the general field-of-view of the third photo.

Aperture: f/8 Shutter: 1/10 second

Aperture: f/2.8 Shutter: 1/60 second

Aperture: f/3.2 Shutter: 1/60 second Additionally, the background zombies were moved back (~3 inches) and the zoom was used.

How do I control the DOF?

What does Aperture have to do with it?

Not only the depth of field, but also the amount of blurring your out of focus areas will have can both be controlled by adjusting the aperture or f/stop of your lens. The wider open your aperture is, the shallower the depth of field will become, and also the more blurred the out-of-focus areas will be.

What does Focal Length have to do with it?

The more you magnify your subject, the shallower your depth of field will be. What this means is that the longer your lens' focal length, the shallower your depth of field. It is very difficult, for example, to get a deep DOF using a 100mm lens and, inversely, to get a shallow DOF using a 24mm lens. Of course, it is all relative to the actual magnification of your subject and the distance between the lens and the subject.

What does Shutter Speed and ISO have to do with it?

Absolutely nothing. Shutter speed is the amount of time the shutter is open and letting light hit the sensor. ISO is the light sensitivity setting of the sensor.

Can I fake DOF control?

As great as DOF control is, we are limited by the gear we have available. Luckily there are ways to "cheat" so that our end product comes out looking the way we want.

Blurring in post production

One of the most common solutions suggested is to blur areas you want blurred after you take the photo, using software such as Gimp or Photoshop. This can be an effective solution, but it is not something I recommend. For most folks, the image will end up looking edited and unnatural (because it is). Another reason to avoid this method is the time involved. If it takes you an hour to edit one photo, how long does that add up to when you are working on a film? Hint: there are 15 to 30 images per second for a film.

Stretching the set

With a lot of small cameras, the problem we run into most is that everything is in focus. For most scenes we want shallow DOF but these small lenses don't do it so well. We can fake it by expanding the set and then zooming in. The lengthening of the set will mean that even with a deep DOF we can have our background out of focus. Utilizing the optical effect of zoom compression, by zooming in, can in turn compress the set so that it appears to be not so stretched out. This is the method I recommend because you only need to set it up once for each scene and shoot as many photos as you want to, no extra editing time in post.

Assignments

For these assignments you will be posting images. Be sure to keep your images at or below the 800x600 pixels limit, I'd like them all to be at least 640x480 though.

Assignment 1

Create a small scene with foreground, middle-ground, and background. Your focus target will be an item in the middle-ground. Keep the same target and angle for each photo, preferably the same focal length too, if this is possible with your camera. If you are having trouble with this, take an overhead photo of your set and post it in your student thread, I will help you out with some tips.

Submit three images for grading:

1. ONLY your target in focus (shallow DOF)

2. Foreground AND Middle-ground in focus (mid DOF)

3. Everything in focus (deep DOF)

Once this assignment is passed, move on to Assignment 2 for final grading.

Example

Assignment 2 (final)

Using the skills learned above, create a 4 to 6 panel comic that imparts a story to the reader WITHOUT using any text call-outs or speech bubbles.

• Use post-production techniques sparingly, this assignment is about controlling the Depth-of-Field to convey the message, not about text and special effects.
• You can move the camera and objects in the scene just like any comic production.
• In your submission, use the spoiler tag to describe what is going on in the comic. If the idea came across in the photos you pass, otherwise you'll be given changes and information as to why the task didn't quite work.

Example

Image is a link to a super-sized version. More sizes on

Flickr

 

You can see the actual stage setup on Flickr

 

1. Johnny is walking home from his baseball game.
2. Oh no! A zombie!
3. Johnny: Haha! I've killed it!
4. Oh no Johnny, it was just an actor from a movie.