3rd July 2026 Etalon spacing.

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 Friday 3rd I set up the 102mm APO with 60MT etalon in the drive. It was blowing a gale from the NW. So this was the only real shelter where the sun was still visible. In between huge clouds.

 I am using the mini-PC indoors. So it was not readily available for astronomical duties and imaging. I had to make do with visual observation only. All I really wanted was confirmation of surface texture in H-alpha. I made a slight alteration of the spacing to about 18mm of the Omegon extension still visible. 

 The ZWOAM5N mounting is sitting on top of a PE200 pier extension. All mounted upon a Celestron Advanced tripod with 2" stainless steel legs. 

 

The tail end of the H-alpha set up. With the Lunt LS60MT etalon, housing and focuser. 

 I am using a 2x Shorty Barlow. To reach focus with a TS star diagonal and the Magnum 8-24x zoom eyepiece.  A solar wedge [diagonal] is not needed with an H-alpha set-up.

 

 

 

 

 

 

Close-up of  the tail end of the 102mm where the focuser would normally fit. Showing the bored out 2" x 35mm Omegon extension and the Lunt 60MT nose clamped in plumbing fittings.

 Ideally I need to introduce a threaded fitting to allow fine adjustment of the etalon spacing from the objective. Some sort of push-pull arrangement if possible.

 My ZWO174mm camera needs to be fitted in place of the star diagonal and eyepiece. So that I can use imaging software to confirm the best possible spacing between the telescope and the etalon. A much less cloudy day would reduce the considerable frustration of waiting for clouds to clear the sun.

 

 

  

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