~*~
Wednesday the 6th Bresser has returned my Lunt 60MT solar telescope form their repair department. With the blue and UV/IR filters replaced free of charge under guarantee.
I was able to sharply focus several group of sunspots but no sign of any other details. I unscrewed the pressure tuning knob completely to zero to atmospheric air pressure. Then began to screw it gently back in.
Just as I reached the fully inwards position I was rewarded with sharply defined prominences. Though still no surface detail on the sun. This coincided with 100% cloud cover! So it all had to come back indoors again.
It occurs to me that the tuning pressure could be increased with a taller piston. Which means the same thing as adding something to displace air volume above the piston inside the brass cylinder. This would achieve tuning with the tuning knob further out for exactly the same pressure.
Which might be useful where the knob must be screwed fully in to tune to H-alpha. Whatever I use to boost the piston volume should have a central hole. To allow the compressed air to freely enter the etalon housing. There is no need for the packing piece to be fixed. Because it cannot escape.
Though it must be made to match the cylinder bore with some clearance. If it were much smaller it might jam between the piston and cylinder face. Before the necessary compression is achieved. It must be made of some reasonably dense material. Like metal or plastic. To avoid it simply absorbing air as it is compressed in the cylinder. So foam, for example, would be a poor choice.
There were fleeting moments of sunshine in the afternoon. I tried again and was able to tune with the knob well unscrewed. Unfortunately the sun was never truly clear of cloud. So I was denied a sharp view in H-alpha. Though it did look promising. With lighter areas clearly defined in better moments. I tried taking a few snaps with my phone but the sun was completely overexposed.
~*~
