Monday, October 20, 2008

Getting a Shallower Depth of Field with Small Camcorders

One of the greatest challenges in working with today’s smaller camcorders (with smaller chips) is getting a shallow depth of field for your shot. In my opinion, this is one of the major limitations of these cameras. Since this is a well recognized problem, video professionals have come up with a variety of ways to handle this problem, which I will share here.

First off, if you have one of the higher-end cameras with a large diameter lens front (82mm or similar) there are 35mm lens adapter systems you can use that will cut down the light reaching the chips and make your depth of field more shallow. These are great if you can afford to purchase or rent them for your shoots AND if your camera is compatible with them.

The next common technique is to use the camera’s neutral density filter or, for even more dramatic effect, add a neutral density filter to the front of the lens. These filters are designed to cut the amount of light reaching the chips and are generally rated with a number denoting how many f-stops you will have to open up to keep the exposure consistent with the non-filtered image. The higher the number, the darker the filter, and, the shallower your resulting depth of field will be.

The final, and less well known technique, is to increase the shutter speed of the camera. Generally speaking, each incremental increase in shutter speed will result in one less f-stop of light reaching the image sensors (or will require one more f-stop open to achieve the same exposure.) In situations where the other two options won’t work, this is a great third option to have in your bag of tricks. The only caveat to this is that at a certain point (maybe 250th/sec) motion will start to have a very different look. While this might be great for certain things that have fast motion like animals, the same effect might look strange on other subjects (like in an interview where every detail of a person’s blinking eye is now visible.)

Keep in mind that these tricks are limited to what can be done on the camera to limit depth of field. There are many other things that can be done in your environment (like changing a location or changing the lighting) that also play an important role.

Check THIS out for more on depth of field. Happy Shooting!

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