Are the Ray-tracing Simulations Accurate?
To test whether the preceding simulations accurately represent the performance of the real telescope, we printed on white photo quality paper a pattern of black bars identical to that used in the simulations, and to a scale such that when taped to a light pole 214 feet from the front of the telescope the bars would appear, to the unaided eye, to subtend an angle of 10 arc-seconds between centers. The target was cut to a size subtending a total angle of 2 arc-minutes and pasted to a black velvet background. We shot a focus sequence of this target using the website Galilean telescope and C-3000 camera at various exposure settings on January 12, 2005. As in the simulations, the drawtube was moved in steps of 5 millimeters, although the exact distance from objective to eyepiece was not accurately measured. In the following, a thumbnail of the actual test photo is shown below a thumbnail of the corresponding simulation. Click on any of the thumbnails to see the full size image. The full-siz
