Author Topic: Tonight, where have the clear skies at 6pm gone?  (Read 4485 times)

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mickw

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #30 on: Mar 08, 2011, 14:27:46 »
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
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MarkS

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #31 on: Mar 08, 2011, 15:03:19 »
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

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #32 on: Mar 08, 2011, 16:25:02 »
That's when it started going wrong - The alignment of my finderscope had moved so I couldn't figure out where I was pointing  :oops:
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Ian

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #33 on: Mar 08, 2011, 16:43:02 »
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

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #34 on: Mar 08, 2011, 16:51:20 »
I think I'd just popped round the pub when they were handing out the patience  ;)
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Carole

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #35 on: Mar 08, 2011, 17:01:19 »
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

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #36 on: Mar 08, 2011, 17:22:03 »
Mick, I do chuckle at your terms......................also what is a prism?
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mickw

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #37 on: Mar 08, 2011, 17:47:14 »
Oops, meant diagonal  :oops:
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Mac

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #38 on: Mar 08, 2011, 18:15:48 »
Quote
also what is a prism?
:o

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

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #39 on: Mar 08, 2011, 18:36:55 »
.......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.
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Ian

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #40 on: Mar 08, 2011, 19:16:13 »
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

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #41 on: Mar 08, 2011, 19:20:14 »
Quote
The question is, is a cylinder a circular prism?

Only if you don't read the instructions  8)
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Fay

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #42 on: Mar 08, 2011, 19:40:33 »
I just wondered where Mick was incorporating a prism in his setup
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MarkS

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #43 on: Mar 08, 2011, 19:46:21 »
Quote from: Ian
The question is, is a cylinder a circular prism?

Mathematically it definitely is.

Tony G

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Re: Tonight, where have the clear skies at 6pm gone?
« Reply #44 on: Mar 08, 2011, 21:45:42 »
..also what is a prism?

It's a place where they keep comvicts. :)

Tony G
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