Guide Scopes

I don't need a guide scope.  My mount and alignment probably are not accurate enough for guiding to be of much use.  That does not mean I don't want to use guiding!  So I started playing around.  Webcams are cheap and easy, and most guiding software will work with a standard webcam.  My first guiding scope followed an obvious DIY path.  I grabbed a cheap (<$40) telescope from the closet and used some plumbing parts to connect a the webcam.  I 

formed some aluminum flat stock around a gas cylinder to make homemade mounting brackets and bolted it all together. The cheap scope has a camera style tripod connector with a 1/4-20 thread. No tube rings required.  But that does make alignment more difficult. The webcam mounted on the scope is a Logitech QuickCam 3000 Pro.  This has a CCD sensor not CMOS.  The cheap telescope has an aperture around 50 mm and a focal length around 600 mm.  The tiny sensor of the webcam makes the system have incredible apparent magnification, but the cheap glass loses too much light.  Only the brightest stars can be seen on the computer screen and quality is poor. While a department store telescope works as a guide scope, it was less than ideal.

Back to the same closet of junk to retrieve an old camera lens.  A 50 mm f2.8-22 Minolta 35

mm SLR camera lens sees the light of day again. A 1.5" PVC cap fits snugly over the bayonet of the lens.  A hose clamp turns snug to tight.  A gutted Logitech C510 HD webcam carefully glued to the PVC makes for an easy 10 minute test.  I removed the front face and the screw in webcam lens. The tape is just a light shield until I cut some PVC to fit. A 1/4-20 bolt holds the PVC to the aluminum bracket fitted to the telescope OTA in place of a mounting ring.  This set up works great.  The aperture adjustment is very helpful for adjusting the intensity of the stars to make guiding easier.  Focus works smooth and easy just like it did on the camera. Once again, the small sensor creates a high apparent 

magnification. The image quality of this set up is pretty amazing for junk laying around.  The image to the left is a shot of the moon using the webcam through the Minolta lens.  Tracking with both PHD and EqAlign has been successful.   At less than 6 inches long, this system is very unobtrusive as well.  So, I am now using a camera lens as a guiding scope.