WO Fluorostar 110 (FLT110) Lens Cell Problems
I had an issue with my WO FLT where right across the field the stars appeared to be suffering
the effects of coma. This effect is usually seen at the corners and edges of an image due the the focal plane not being flat. Usually with coma the
resultant deformation of the stars is oriented away from the centre of the field. In my case the deformation
was identical right across every image. To the right is a diagramatic representation of the
deformation of stars due to coma.
What I found was that the lens cell had become loose. I guess this introduce a bit of slop that
resulted in the deforned stars. Once I tightened the cell the problem disappeared for some time. However, I
regularly checked and tightened it.
Some months later the problem reappeared. I could not tighten the cell and have the problem
dissapear. I also noticed that the cell got tight quick but could still be tightened further with more effort.
Things did not appear to be normal. I removed the lens cell to investigate the problem. What I found was that there
are two rings that are used to hold the glass in place. The outermost one had unscrewed quite a lot. I guess this
had gradually unscrewed and I have been only tighening the telescope body against this ring. After screwing in the
ring as far as I could and replacing the lens cell the problem was resolved.
If you have had this problem please let William Optics know. This is an engineering problem that
they should fix. I read on a forum that a member almost dropped his lens cell because it had worked its way