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Showing results for tags 'baader zoom'.
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Telrad fitted. Baader zoom has to be used in place of the 1.25" focuser, straight into the 2" focuser. Had a go at collimating first and managed to mess it up. All I could see after pointing at Vega first was a blob of light. Collimated again and was better, but realised it's too far from the secondary mirror. Removed the 1.25" focuser and fitted straight into the 2" one and that's perfect. Need to grease the focuser. Found Double-Double but was unable to split the 2 stars into 4 at 162x. Jupiter at 162x fitted 4 moons in the fov and shows nice banding. Saturn at max zoom a bit fuzzy but still can see the rings very nicely. Forgot to look for Cassini division but probably need Barlow for that. Was still to bright for Andromeda and was getting late so looked at Mizar but haven't seen the second star, I think. Need to check sky maps. (Turns out my zoom was too big and missed Alcor)
Field stop (FS) is an important measure of an eyepiece, it determines the True Field of View(TFOV) we can see through it, many EPs donot give FS by some reasons, and many have provided Aparant Field of View(AFOV) more in generic terms than actual measurements. The weather hasn't been great lately, I decided to do some measurement of FS, with method by Andreas , pretty simple setup, and easy calculations, Here's my result: The first three EP's FS were assumed to be quite accurate, and used here to get the distances, and the averaged distances are used for calculatiing the Field stop bu the measured TROV projections. As we can see, the numbers are quite close to the known EPs, therefore I'm pretty sure the FS for the MV, Tak orhtho, 50mm Superview etc should be very close. Another measument done on the Zooms: Leica's numbers are very close to Andreas measurement in another thread (one single decimal deviation in the 30x setting), despite the measuring scope/condition difference, so I' can be quite confident about my Baader zoom's FSs. David Knisely has describe some methods for measruing AFOV, the flash light method is recommended by many knowledgeable folk too. The setup and measurement are straight forward, here's my result(averaged 6-10 measurements) Some first impressions: 1. Wider AFOV results in more deviations from simple calculation, especially when there're AMD involved. 2. BCO 18 has AFOV >55°, larger than plossls. 3. Flash light needs to have larger diameter than EP's FS to get proper projected diameter. longer than 20x EP focal length distance is recommended. So, this are ways to have some scope/EP time when it is PS. You're welcome to PM me if you need help with the calculations