Meade II 90mm User Manual - Page 6

in operating conditions (such as barometric pressure that can change with elevation changes.) The adjustable tuner is located right at the end of the optical tube assembly where it merges to the rectangular body of the PST, and is easily recognized by the knurled rubber ring (see Pg. 5). The minute spectral adjustment of the etalon filter is accomplished by simply rotating this knurled ring in either direction. In most instances the filter adjustment will not be required - the PST is delivered properly tuned by Meade engineers. The judgment about occasional adjustment is made based on overall image quality and the ability to see the image details with a satisfactory contrast. NOTE: The maximum possible extent of a (relatively tight) rotation of the adjustable tuner is approximately 130°. No excessive force should be applied in an attempt to rotate the knurled ring further than mechanically allowed. The best achievable contrast of the image will be found within the limits of adjustment, and, once such image is obtained, no further improvement of the image quality can be gained by forcing the tuner. In search for a better solar image, the astronomer should first find the "sweet spot" by appropriately focusing the telescope using the focusing knob. Once the PST is appropriately focused, the edge of the solar disk will appear sharp. However, if, for example, the prominences are not seen after the telescope has been focused, the tuning lever for the internal etalon may be of help. In this case the knurled ring of the adjustable tuner should be appropriately turned until the sought contrast of the Sun's chromosphere is apparent. Surface details will generally require one setting, while prominences will require a different setting for maximum detail. Tuning PST Double Stack 40 with RichView tuning - With a double stack system, follow this procedure for best results: After the PST telescope is pointed at the Sun and the image has been focused, rotate the knurled ring on the telescope in either direction slowly while looking at the image in the eyepiece to get the most detail and contrast. Now adjust the tilt of the external Etalon on the front of the telescope with the T-Max wheel to achieve the brightest image while eliminating any reflections. Finally, adjust the RichView tuning ring on the external Etalon to get the most detail and contrast for the feature you are viewing. Because double stacked systems operate at a very narrow band pass of only 0.5 Angstroms or less, more tuning is needed for different areas and features on the Sun. Double Stacking - This greatly increases contrast by narrowing the bandpass to