I have received a few questions about the height of the Crayford focuser on my 300mm Orion Optics UK Dobson. Here are three images that show the Crayford in its different positions. On the first image you can see the height of the focuser when it's inside the tube, 6 centimeters. The second image shows the focuser when completely outside, 9 centimeters. So you only have 3 centimeters of travel. On the third image you see the focuser with an extension and completely outside. The total height is 14 centimeters. I have to use the extension on all my 1.25 eyepieces as well as on the Zeiss zoom-eyepiece. For my 32mm Televue plossl, the extension is just a few millimeters to short. I have to pull the eyepiece a little out to get it into focus.



Image 1



Image 2



Image 3