15.2.19 Moon, M42 and miscollimation.

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Went over to look at the half moon up high in the SE for an hour before being called in for dinner. Back up to 220x [20mm x2 Barlow] but I just couldn't resolve any craters in Plato. A quick check with the Cheshire showed that both the focuser and objective were slightly offset.

The plan is to add a locking nut on each of the objective cell push screws. I think the  ends of the present screws are pressing into the plywood ring. Which is repeatedly throwing off the collimation. I don't have any aluminium sheet large enough to cover the entire plywood ring. Though pads could be placed where the screws meet the plywood ring.

 

The sandwiched, aluminium dewshield used to protect the plywood from the screws but not any longer. Adding Nyloc nuts will greatly increase the surface area of the ends of the push screws. There is room for them between the cell flange and lens cell itself. I just have to make sure the nuts don't get compressed between the cell parts or it will lock up the adjustment range.

The focuser backplate is also adjustable but with springs as the push element. This is obviously not ideal since it keeps moving relative to the main tube. I have repeatedly replaced the compression spring with stronger examples without reaching a satisfactory result.

It looks as if I really need to replace the springs with serious push screws like an objective cell. The weight of the solar prism is obviously a new factor in resisting misalignment. With the added weight of a binoviewer attached it wood all get a bit risky for continuously stable collimation.

I looks at M42 in the wrong order! After time spent, even at high powers with a dark green SC filter, I was made Moon blind. So I struggled to see the full extent of the nebula.  

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