Tonight, where have the clear skies at 6pm gone?

[mickw]

Top Tip is bang on my point of focus with the camera when imaging

I think I've added a bit randomness (yes it is a word) with my farting around.

The farthest thing I can see when sorting out the focusing is a roof about 150 metres away so I'm guessing everything is to cock.
The camera now focuses 20mm closer than on a star, or 580mm instead of 600mm as suggested in Top Tip.

Focuser has 80mm of travel
Light path of prism (measured from mating surface) 36mm
2 eyepieces I tried on the prism come to focus at 48mm and 62mm either of which added to the prism is greater than the 80mm of travel in the focuser.
But the difference identified in top tip for the ground target should give me an extra 20mm of travel - just enough.

I think last night was always going to be a failure once the first thing started going wrong.  In future, I'll do the alignment etc. using the prism with eyepieces before hooking up the camera - I'll also check out the eyepieces again without the prism if we ever get to see the sky again

[MarkS]

Mick,

Instead of swapping eyepiece and camera for alignment, you could use a finderscope.  When the alignment star is visible in the finderscope it is easily bright enough to be visible in the camera viewfinder through the scope.

You can then make final adjustments using "frame and focus" in Nebulosity to get it exactly central in the camera field of view.

Mark

[mickw]

That's when it started going wrong - The alignment of my finderscope had moved so I couldn't figure out where I was pointing 

[Ian]

Or you can use a long focal lenth eyepiece and sight along the telescope tube. Or if you're feeling very patient you could try an astrometry solve.

Are you sure you weren't just looking for a beer excuse?

[mickw]

I think I'd just popped round the pub when they were handing out the patience 

[Carole]

After a whole night imaging Sunday and a late night last night I'm too Knac tired to get around to processing what I've done so far and looks like another clear start tonight even if it doesn't last.

I need to try my spare mount out tonight before I take it to Kelling in case there's a problem, so I'll be doing it the hard way tonight, i.e. sitting outside in the freezing cold!!! Might still see if I can network the laptops though.

Carole

[Fay]

Mick, I do chuckle at your terms......................also what is a prism?

[mickw]

Oops, meant diagonal 

[Mac]

also what is a prism?

Its an object designed to split light into its component wavelengths?

[PhilB]

.......what is a prism?

It's also a device that, on a short focal length 'scope, puts a lovely greenish yellow ring round a full moon.

[Ian]

a prism is a geometric shape constructed from a two dimensional polygon that is then extended along a third perpendicular axis.

The question is, is a cylinder a circular prism?

[mickw]

The question is, is a cylinder a circular prism?

Only if you don't read the instructions 

[Fay]

I just wondered where Mick was incorporating a prism in his setup

[MarkS]

The question is, is a cylinder a circular prism?

Mathematically it definitely is.

[Tony G]

..also what is a prism?

It's a place where they keep comvicts.

Tony G