Last updated : October 10, 1999
In the quest to achieve both a fast and ACCURATE focus, I've experimented with several different ways of accomplishing this goal. I've tried both the bloom trail and Hartmann Mask methods with varying degrees of success. Then I remembered an article published by Warren Offutt in the Winter 1995 issue of the now defunct "CCD Astronomy" magazine concerning diffraction focusing. After reviewing this article again (I've saved every astronomy related magazine I've ever received since back to 1963, you never know!), I decided to give the method a quick try to see how it would do. I placed a couple of bungee cords that hold the telescope cover on in front of the telescope's corrector plate to give the method a test. The results were amazing! I now can reach a sharp focus in often less then two minutes from the start of the procedure and know that the focus is right on. What used to be a time consuming and often frustrating exercise that resulted in disappointing images has now become just another pre-imaging checklist item. The following pictures display the method, how it is used and the final results. Hope that if you give it a try it'll work for you as well as it has for me. Good imaging!
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| M57 focused using Hartmann Mask | M57 focused using diffraction method |
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