My first test of my Ed Stevens mirror was in my back yard with significant light pollution, but fairly steady seeing (CSC labeled as average seeing). The most striking first image was a very symmetric star test virtually identical either in or out focus. At the start the mirror fan was not running due to expended batteries. However, as soon as the fan was turned on the star test improved considerably. It still took about 15 to 20 more minutes to get a decent star test.
My astigmatism makes any bright star show spikes, but less bright were pin points in my 9 T6 with 1.5 X barlow (204X). M13 was faint due to sky glow but star resolution was much improved. I masked the double double with a 4" offset hole and checked all 4 quadrants. Prior tests showed significant difference in each quadrant, but tonight there was essenitally no difference with airy discs and one diffraction ring. Viewing in my back yard is limited to a strip of sky about 35 degrees NS by about 50 degrees EW. I estimated the sky to be somewhere between mag 3 and 4. Only 3 stars in Ursa Minor were visible.
Specs on the mirror were listed as better than 1/15 wave, Strehl of .998, and RTA of .31. Hopefully weather will hold and next weekend we will venture to Spruce Knob in West Virginia. Current results are very encouraging to me and are consistent with my expectations based on mirror data. Also, note that secondary was replaced with a 1/30 wave Antares. only the exteme edge of the mirror brings the mirror smoothness down to its stated criteria.
Jud
My astigmatism makes any bright star show spikes, but less bright were pin points in my 9 T6 with 1.5 X barlow (204X). M13 was faint due to sky glow but star resolution was much improved. I masked the double double with a 4" offset hole and checked all 4 quadrants. Prior tests showed significant difference in each quadrant, but tonight there was essenitally no difference with airy discs and one diffraction ring. Viewing in my back yard is limited to a strip of sky about 35 degrees NS by about 50 degrees EW. I estimated the sky to be somewhere between mag 3 and 4. Only 3 stars in Ursa Minor were visible.
Specs on the mirror were listed as better than 1/15 wave, Strehl of .998, and RTA of .31. Hopefully weather will hold and next weekend we will venture to Spruce Knob in West Virginia. Current results are very encouraging to me and are consistent with my expectations based on mirror data. Also, note that secondary was replaced with a 1/30 wave Antares. only the exteme edge of the mirror brings the mirror smoothness down to its stated criteria.
Jud
I Yam What I Yam!
Hope next weekend works out for you at Spruce Knob. How long of a journey is that for you?? Is there an event?