Practical DV FilmMaking
Aperture and depth of field
Aperture refers to the opening or iris which allows varied amounts of light through the lens. Aperture affects both the light entering the camera and the range of the frame that is in focus, known as depth of field. Attaching other lenses also affects the range of your focus. For example, wide-angle lenses allow for a far greater range of focus, from objects far away to those near the camera, while telephoto lenses have very little depth of field.
Altering the iris
As we saw in the earlier section on how cameras record, the iris can be altered for creative uses, using manual controls:
• Closing the iris so that it is very small will let less light in and also enable objects in the foreground and background to be in focus - something that may look unnatural or could be just the effect you want
• Closing the iris can also result in well-lit sets appearing to have extreme contrast - the dark areas are unreadable and the white areas are strong and bright
• Opening up the iris will result in a narrow band of focus, so that objects or people moving towards or away from the camera are easily thrown out of focus
• Opening up the iris will also make normal lighting conditions seem over-lit - even an average lamp will seem to glow unnaturally.
If you manually operate the iris, beware of distortion at the edges of the frame.
Light and the camera
The automatic features of your camera are going to affect how you shoot. In auto setting, the camcorder thinks it is doing you a favour by removing some of the light on a bright scene or opening itself up to lighten a dark interior. This automatic light meter causes problems as it is going to stop you from using creative lighting effects. Video, in general, does not like to be deprived of light and will react badly if you try to work in conditions that differ from the norm. Just about all filmmaking involves using lighting in some creative way and your auto functions will do their best to cancel out any effects you set up.
To make sure you get a good image, light the scene well but try removing the lit areas and increasing shadow. You can learn a lot about lighting by trying to create shadow rather than create light
