K3's AstroPhotography
"When I consider your heavens, the work of your fingers, the moon and the stars which You have set in place, what is Man that You are mindful of him?" -- Psalm 8:3,4

Homemade GEM1 Autoguiding Setup

The core of my homemade autoguiding setup consists of GEM1 equatorial mount. Its hand controller was modified in order it was possible to control it by computer. The cradles delivered with my Europa scope have four holes with M4 threads on their top. I used that holes for attaching a homemade base plate construction which carries a guide scope. As a guide scope I used my second scope - 80mm F5 refractor.

Here there are some pictures which describe the whole setup. Click the images to see higher resolution photos. My SC modified webcam with Peltier cooling is attached to the main scope. The second webcam (non SC modified) is attached to guiding scope with 2X Barlow lens. Result focal length of guiding scope is 800mm. I could also use 3X Barlow lens, but the whole system is not stable enough, and then it is very difficult to find guiding star.

The overall look at autoguided scope. The base plate for guiding scope in the picture is and old version - it was replaced by better plate making possible setting up guiing scope direction.

The view from oposite side.

Another view - from back of scope to heavens.
Unfortunatelly it was not clear sky then, only Vega is shining through the clouds (upper right from scope).

The same view, but photo was taken with flash (sky seems to be darker now;-)) and some details are better visible.

New base plate for guiding scope - 2 nuts enable to set up direction of guiding scope in radius of 5.

Detailed view of base plate.

Another view of base plate.

The overall look at "double cradle".


The system is controlled by computer. Two Philips webcams (Vesta 675SC2 and Vesta Pro 680) are connected to a single computer (look at trick, how to do it).

The webcams are handled by 2 running instances of K3CCDTools:

Click the picture to see the full resolution image.

Experience of using the system

As I my measuring results show, the system is quite stable and accurate for guiding. The weakest point is fixation of the guiding scope. It is hard to aim it to guiding star. The process of aiming the main scope and guide scope is like iteration (adjusting guide scope usually moves photographed object from center FOV of main scope) and must be repeated several times.
But at the end the result is promissing - look at my first photo of M57 with autoguiding system.

See Tests and Analyses of Homemade GEM1 Guiding System

See Modification of GEM1 mount for computer control

Back to Equatorial Mount Tracking Errors page

Back to AstroPhotography page

Computer generated images, real images, drawings and texts are property of the author and may not be reproduced or used without permission of author.


Last Update: 07.10.2002