Have you ever wondered what goes on inside a zoom lens as you turn the ring through the various focal lengths? If so, this brilliant X-ray video will help you better understand what mechanics are involved in moving the various optical elements around inside the lens.
Ben Krasnow, the human behind the YouTube channel Applied Science, took a broken X-ray sensor and repaired it so he could capture timelapse and stop-motion animation films. While much of the 21-minute video explains how he built his at-home X-ray camera system, a very small clip shown within the video (1:50 time mark) shows what a zoom lens looks like as it expands and contracts through its focal length range.
Krasnow says this stop-motion sequence was captured with between 200–300 frames and notes he used a stepper motor to drive the zoom ring of the camera in-between each shot. What we see in the resulting video is three independent optical groups moving in conjunction with one another to achieve the proper focal length inside a Panasonic 14–42mm F3.5–5.6 ASPH MEGA O.I.S. Lumix G Vario lens attached to a Panasonic Lumix G1 Micro Four Thirds camera system.
In his introduction, Krasnow says ‘I strive to share something unique in each of my videos.’ To that end, I think it’s safe to say Krasnow achieved his goal. If you have the time and enjoy technical DIY videos, I suggest watching the entire video to see how Krasnow got his DIY X-ray camera up and running (safely, mind you). To keep tabs on his latest happenings and to support his work, you can follow him on his YouTube channel, Applied Science and follow his blog.