Video Q&A

Q. I have come across the term "after image" in an instructional manual. Could you please tell me what this term means and how one achieves it?
Laurence Lattman
Albuquerque, New Mexico

A. After image commonly describes two entirely different things. In older cameras that used tubes as imaging devices, after image (often referred to as smear, or image lag) caused bright areas of the image to blur and leave "light trails" across a moving picture. This was a problem with the Vidicon and some other tubes.

After image also refers to the burnt-in image sometimes seen on monitors that have held the same unmoving image for long periods of time (like old store security monitors). The image literally burns into the phosphorus on the back of the screen. You don't want to achieve either type!

Q. Please give me some explanation as to why 3/4-inch and Betacam are so much sharper than Hi8 and S-VHS. Does bandwidth have something to do with it?
Jay Anderson
Elburn, Illinois

A. To begin with, 3/4-inch is not "sharper" than Hi8. In fact, the resolution of 3/4-inch is only slightly better than standard VHS. But the image quality of 3/4-inch excels in other areas, especially color reproduction. The format's high signal-to-noise ratio often makes it look "cleaner" than the smaller formats.

Betacam is a different story altogether. Here, extra bandwidth means more resolution, but also the individual chrominance and luminance components record separately on the tape. The result is a high-resolution, noise-free image considered by most to be superior to that of any consumer format.

Q. I would like to record my ride on Thunder Mountain during my trip to Disney World this year. Can my camcorder handle the ride?
Charles Rhodes
Youngsville, North Carolina

A. In most cases, professional production teams place temporary mounts right on the car to get those smooth, exciting amusement ride shots. In this way, the camera or camcorder escapes inevitable damage from bouncing into car or camera person.

The question is whether you can keep your camcorder still enough to minimize damage and still get some usable shots. You could try making a mount of your own to clamp your camcorder to the safety railing, but you'd to contact the theme park in advance. The camcorder itself, if not bumped around, should handle the G-force fine.