Depth of Field / Zoom and Dolly

Following on from a previous entry about still vs video and how the aperture can control the depth of field in Stop Motion. I got thinking more about adding a depth of field effects to the close up shots of the flea circus to help focus the attention on the acts and emphasis that it's a close up shot that's being magnified. You can see below how the settings affect the scenes. I'm not convinced that it's a significant difference and it does take a bit of extra effort to setup so I'm not sure that I'll apply it to the cameras in the flea film.


This lead on to some experiments with zoom lenses. The software Carrara that I use provides three default lens sizes for cameras, wide angle 25mm, normal 50mm, telephoto at 200mm. It also has a zoom option with a variable length. Changing the focal length of the camera allows you to "zoom" in on a object just like a conventional still or video camera.
If you zoom in whilst dollying out you get the classic effect sometimes used in horror films, the video below shows an example of this, as it zooms from 25mm to 500mm the scene flattens and the depth of the image is shortened till at 500mm its almost isometric providing a quite spooky effect.


References
An article on Depth of Field from Mason Resnick
All about CGI cameras fromthe Advanced Computing Centre in Ohio