How to build a webcamscope

Construct a simple and cost-effective imaging device for capturing bright targets

A webcamscope provides a simple and cheap introduction to astrophotography. As its name suggests, it's built around the sort of webcam you might buy for Zoom meetings, rather than a DSLR camera. The components you need to make a webcamscope are widely available and, whether you choose brand-new or second-hand parts, they won't cost much. You may even have some of them in a spare drawer. I paid £11 for the webcam and £16 for the 200mm M42 lens on eBay, while the eyepiece adaptor, which replaces the webcam's lens, was £10.

Second-hand M42 lenses are commonly available and, as they use a screw thread rather than a bayonet fitting, you can make a mount for one from an old rear lens cap. Lenses can be heavy, though, so you can adapt the wooden mount to incorporate a cradle to support the front part as well.

When building your webcamscope, it's important to get the correct distance between the backplate of the lens and the surface of the sensor in your webcam (the registration distance). For M42 lenses, the registration distance is 45.5mm. If you vary this by too much, you might not be able to focus. I drilled a 32mm-diameter hole through the wooden mount to hold the webcam adaptor, with a wider recess for the M42 rear lens cap, so the webcam and camera lens were held close together. A little masking tape wrapped around the adaptor stops it slipping out.