Re: An easier Pasillx N & S Polar Alignment method


dmwmpd <westergren@...>
 

Hi Joe,

Yes you can use a camera to view the PAS. However you have to use
AFOCAL (or eyepiece) projection to have it work. That is using a
camera with it's own lens to replace your eye. Perhaps a video cam
would work - it would be light and small so it could be mounted on
the PAS and be close enough to prevent vignetting.

Try it in your living room first - you might be surprised how well
it works. Just hold the camera up to the PAS eyepiece. You would
leave the PAS focussed for your eyes, but have to adjust the focus
on the camera to infinity.

I haven't tried this with my PAS, but I have taken pictures of
planets with my AP scope this way. The magnification increases with
added camera distance from the eyepiece. The FOV and brightness
decrease with increased distance, so you probably want the camera
lens almost touching the PAS eyepiece.

Good Luck, let us know how it works. It's a great idea.

Don Westergren

--- In ap-gto@..., "Joseph Zeglinski" <J.Zeglinski@...>
wrote:

Hi,

As winter will too soon be here, I am NOT looking forward to
having to shovel a trench in the snow to kneel into, in order to use
the polar scope. It was awkward enough in summer (at 45 deg N).

I wonder if anyone has tried any other way of centering
Polaris through the PAS.

One possibility is to perhaps modify a diagonal, with a
Barlow relay lens, to bring the alignment image to a more
comfortable standing view position. This would be a great "optical"
option for AP to produce for the PAS.

Perhaps a much better method might be to temporarily plug a
standard "guider head", such as your (SBIG RGH, Orion autoguider, or
Trifid autoguider), over the PAS eyepiece, and view the polar
alignment on the laptop screen. In many cases, these guide heads are
just waiting to start use as guiders, so perhaps they can also serve
double duty as a PAS camera. An additional advantage, especially at
light polluted sites, is that the guider will cut through the haze
to bring out the other two dim reference stars, barely visible on
the reticle right now.

I suppose this will be a real bonus for south pole PAS
alignment. In that case, it should be possible to program (or draw)
a laptop screen overlay/template, with a south pole centre point,
using the other reference stars.

Has anyone tried the latter method? I wonder if there might
be some issue with the focus reaching the guider chip - although,
with the camera (or star diagonal) 1.25" eyepiece tube
bottomed "overtop" of the PAS eyepiece, that may not be a problem.
You still would need to make an eyepiece adapter from 1.25" down to
the much smaller PAS eyepiece diameter, with a limiting collar (set
screw ring), to prevent bottoming of the PAS eyepiece onto the chip.

Comments, please?
Thanks
Joe

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