Hexagon Esprit Download
Alberta Hagley
Well, a clear night finally came along. It's been a disaster. I have had problems working out tilt, problems with tracking, problems with drift or differential flexure (although, I'm using OAG??), and apparently am having problems with hexagonal star shapes:
Darn scope sat untouched since the last use, so I am not sure why the heck I'm having so many problems. But this hexagonal star thing is very, very odd. It does not look quite like pinched optics issues I've seen shared in the past, which tends to exhibit as three dark shadows on brighter stars. Brighter stars in my case are just brighter, but still hexagonal, without any kind of shadow... Maybe it still is pinched optics somehow, just exhibiting differently?
NiteCrawler is connected. I've never used the stock focuser. I put the NC on there for the first use. I was not having hexagonal star problems before, as far as I can recall. I am pretty sure the pickoff prism for the OAG is well outside the sensors field. Clouds rolled in, and I made one adjustment. I loosened the Moonlite rings for the FSQ106 until they were loose, then re-tightened just to the point where any play in the upper clamshells stopped. I am wondering if I may have tightened those down too much...
The one thing I think may have happened is the scope rings, which are Moonlights FSQ106 rings, may have been too tight. I put them on during winter when it was much colder, and the scope slightly smaller in size. If the scope expanded due to the warmer temps of summer, then the tightness at which I had the scope rings may have resulted in some pinch last night. While the outer machining of the Moonlite scope rings is hexagonal shaped, the inner machining is indeed round. That said, the scope rings don't seem to be quite large enough for my version of the FSQ106...so the rings (which have a top and bottom half) may pinch right at the joint of the two halves, which I have to leave detached with the bolt going through empty space between them. I think if I tighten the rings too much, it'll pinch at the sides, but not the top or bottom. I am honestly not sure how that could create a hexagonal OOF shape, so maybe its a stretch...
So I stated the above earlier...but, having looked at the image more, maybe I am seeing the hexagonal shape on these more defocused stars. It seems slighter, but I think it is still there. At least, on the outside of the profile...the rings in the center seem to be perfectly circular.
My Esprit 100 gave hexagon shaped stars in cold weather, exactly as you're describing. The stars returned to normal when temperature increased. I assumed it was somehow related to tube contraction. I never thought to reset the tube ring tension - perhaps that's the culprit. Although in my case I put the tube rings on in summer and got hexagons in winter.