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Instruments.


The homemade 10 inch F/20 refractor. Any small refractor can be mounted on top of the large tube, by sliding it over the dovetail. Often the Pronto is mounted on it.

 

For observing the Sun a Herschel prism is used. The prism shown here was furnished by Wolfgang Lille from Germany, it has a 65 mm full size prism with the long side used as the reflector. To reduce the brightness of the image a ND 3,0 filter (=1:1000) is used in the prism housing, while a single polarising filter is used on the eyepiece. This allows me, only by twisting the eyepiece in its holder, to get the correct brightness of the Sun.        The eyepiece shown here is a 40 mm Erfle from Baader, giving a magnification of X 125.                                    


The 6 inch F/15 folded refractor. This telescope is still portable, but about the maximum that I would like to move around because of its size and weight.


In need of a very portable telescope for both white light and H-alpha light, I combined my Televue Pronto with the 60 mm Coronado and a Zenithstar FL 80 from Williams on an azimuth mount. Both little telecopes are real performers. I use this setup whenever I want to have a quick look at the Sun.


The 5 inch refractor is mounted alongside the 10 inch refractor tube using Baader mounting rings. It is equiped with the 20/20 H-alpha system from W. Lille and a 4 inch IR/AR filter in front of its object glass to keep heat out of the instrument. To get the necessary F/30 focal length, a 3,8 telecentric lens is used in front of the etalon.


Often I am working together with other amateur solar observers. Here I am with one of my best friends, Gerard Deman, at his observatory. He has a 4 meter domed observatory, equipped with 4 inch (Polarex) and 6 inch F/15 (Lichtenknecker) refractors on an Alt6 mount.


Gerard is observing sunspots here. He uses a Baader Herschel prism with a ND3 filter and a polarising filter on the eyepiece. His favorite eyepiece is a 22 mm Panoptic from TeleVue, it gives him very good contrast and a magnification of  X 102. It is nice to see the whole Sun at once with his telescope.


The instruments of Mr. Deman in his observatory. The Alt-6 mounting holds the 6 inch F/15 Lichtenknecker refractor and the 4 inch F/15 Polarex refractor. On the 4 inch a 10 cm IR/AR red filter is mounted over the object glass to keep heat out of the instrument. At the focuser the Lille 20/20 system is shown, it is different from my own system because it has a telecentric lens that extends the focal length 2 times, making it F/30 and thus 3 meter focal length.

A 40 mm eyepiece gives a magnification of 75 times and very good resolution on the prominences and the disc as well. Because of the size of the filter elements about 2/3rds of the Sun can be seen at once.

Here the H-alpha system is shown in more detail. The system has no heating elements and has separate adjustments on the etalon and the blocking element.