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On November 10th, 2008, tests were conducted at my residence to compare images between two different Meade DSI-2 cameras. The first was a DSI-2c, modified with a cooling unit. Initial tests on the modification showed serious vibration from the units fan. This was most visible with the LX200 when viewing double stars, and even more so when using a "barlow" lens. The Manufacturer, Ed Thomas of Deep Space Products ( http://deepspaceproducts.com/products.html ), made some further modifications to reduce or eliminate the vibrations, and this test is to check performance after those further modifications. The second camera is a new DSI-2Pro (mono), unmodified. The cameras were tested on both the Meade LX200rGPS (8"), and the Meade 80mm ED APO. Early tests (before the second mod) showed that with the fan off, I could use a Hartman focusing mask on an object, and focus to the point of the Diffraction Spikes showing nicely, but when the fan was then turned on, the image was a "mess". Total loss of diffraction spikes, and total loss of a clear image. This was on both telescopes, without need of a barlow to demonstrate the problem. Here then, are the images from November 10th. The first target is SAO 21609, or Alpha Cassiopeiae, also known as "Schedar". It is the brightest star in the Constellation Cassiopeiae. It was the second automatic "alignment" star that evening, and was thus an easy selection. As luck would have it, Alpha is a "visual" double star, and also a "variable" star. Ed's new "Variable Fan Speed Mode" seems to have eliminated the problem Well done, Ed! You can click on each image for an enlarged view.
The second target was SAO 67451, Beta Lyrae, also known as "Sheliak", which I had earlier images of from the 2c camera.
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