You need to know why some digital cameras will not let you zoom when recording a video.
Because some cameras are letting you zoom, with a handicap.
Most cameras zoom motors are noisy and the video microphone will pick up the noise when you zoom during video recording.
To prevent this from happening, they prevented you from zooming during video recording.
Now, many of the camera makers are letting you zoom while recording video.
Some tell you in the User Manual about the noise and let it go at that.
Some turn off the microphone during video zooming.
Some lower the sensitivity of the microphone during video zooming.
If audio is important to your video, you will not like any of the solutions mentioned above.
The only camera maker that I know of that makes a silent zoom motor is Canon.
Canon does use the ultrasonic silent zoom motor on their most expensive super zoom cameras (SX20IS and SX30IS).
I don't know of any database that tells you what cameras does what regarding zoom motor noise during video recording.
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