For best imaging you need to guide - even with the best mounts. Finding a guide star and centring it on webcam (or other guide camera) can be almost impossible. This device makes it easy!

Invented by Gerald 10 years ago, this device is probably the biggest time-saver in imaging there is. Many try to move a guide telescope to a star - I've been there and tried it and it is at best haphazard. The guide-star finder instead keeps the guide telescope fixed and moves the webcam over the focal plane. You need your guide telescope securely ffastened otherwise flexure will ruin the guiding.

How it works. Just pop in a wide-field eyepiece – see where there is a bright enough star – turn the knob and rotate the top and magically the star moves to the centre of the field of view in seconds - ready for the guide-camera. The unit provides full movement across and around (on ball bearings) – so it’s really an XR finder. Using a Toucam for guiding, it increases the area swept for a star by about 100 times.

These are the upgraded latest version with spring-loading to carry a heavier guide camera and/or cabling. They have a 2-inch OD tube on the focuser side and 1.25 inch ID tube on the eyepiece/camera side. I’ve been using the prototype for 12 months and it is a big improvement.

Made by the Brian Webber of the Bolton Group. Price is £50 plus postage. See below for purchase details.

Finally - How not to find a guide-star! That moveable telescope is a disaster waiting to happen.

I have always used diffraction focusing and found it simple and reliable. To do this I place parallel bars across the front of the tube and locate a bright star - 1st magnitude if possible. Then, with no binning (i.e. 1x1) and the visualization set to “MAX”, I adjust the electric focuser until a single bright spike is visible (see below). It’s as simple as that. The method is absolute. When you see a single slender long spike you know it’s at focus. There’s no need to try to see if it’s better by pushing the focus button once more. The tricky bit is to remember to take the bars off!

The triple bar shown below was the prototype but I now use twin bars. The latest version (shown above) is made from high density plastic so as not to damage the telescope. They now have a single thumb-screw for locking. They are equally suitable for use with Digital SLR cameras - in fact with the poor viewfinders of most DSLRs it is the only way to focus them reliably.

They are made to order and are priced at £25 plus postage.