The major quality difference that I have encountered between video and film is depth of field. With film, one can shoot focused images of objects that have great depth, by closing down the camera aperture and increase the exposure time. That is, film offers the capacity to vary the depth of field in focus when making a photo. Video has nothing comparable to this - there is only a shallow, invariable depth of field. If you are imaging a deep object, like the occlusal surface of a mammalian tooth crown, only part of the crown will be in focus in a video image. Even using high-resolution frame grabbers (video _per se_ is limited to about 500 lines of resolution, whereas high-resolution grabbers can exceed 2000 lines for any given image field) there is no way that I have encountered to gain depth of field. Moreover, with the higher resolution frame grabbers, as in higher microscopal magnifications, the small depth of the field provided by the instrument decreases compared to the depth of (low-resolution) video imagery. Digital processing of a blurred image is a labor-intensive and ultimately a poor substitute for the depth of field offered by film.

Having a functional video imaging system, I take take a lot more video images than photographs. Video is never quite as good as film, but because it offers "instant gratification" and an acceptable image at low cost, I have migrated to this technique. The quality of the lens on the video camera is of paramount importance -- a low resolution 1-chip CCD video camera (i.e., a cheap camera) mounted on a fine zoom microscope will produce superb imagery. However, if I need a fine, focused image of an object that has depth, I have found no alternative to first photographing the object and then scanning the film.

Other issues to consider in choosing between video and film involve the costs of video/computer/storage equipment vs. costs of film/processing.

If your goal is to widely distribute the imagery, then the images will have to wind up in digital form in the end. In my opinion, the ideal system for imaging museum specimens will include a conventional cameral and lighting system, and a CCD video camera (along with a computer), and a variety of lenses (conventional lenses and microscopes). You'll also need a pathway to digitize the film thatyou do shoot. I prefer a 35mm digital slide scanner (now under $2000) over Kodak's commercial scanning service (Kodak will scan film and dump it to CD-ROM at low cost), because the commercial services make a lot of errors in image orientation, cropping, contrast, and color palette. You'll also need a big hard drive and a second backup device. Lastly, you'll need some means to distribut the imagery, such as a CD-ROM writer or an Internet server.

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