Using the Telrad as a polarscope?

[Demonperformer]

I have always found the polarscope on the EQ6 to be nigh-on impossible to use. I know there are some who use a webcam successfully - my attempts (either due to the quality of the webcam or my failure to get the attachment as required) was not successful. However I find my Telrad an absolute delight to use.

So I started thinking (always dangerous!) ...

Assumption:
a polarscope does not reverse anything (either Left/Right or Up/Down). I am basing this assumption on the fact that you have to align it with stars outside its field (UMa/Cas) with naked eye observation - if I am wrong, I'm sure someone will let me know.

Therefore:
the position of Polaris in the Polar Scope View window of EQMOD is the same as the position of Polaris that you should see through the Telrad, if the scope is in the home position on a perfectly aligned mount (so if the EQMOD window is showing Polaris in the one o'clock position, that is where it should be in the Telrad).

Now:
* The innermost circle of the Telrad is 1/2^o (30') in diameter, so is actually 15' from the centre.
* Polaris is ~45' from NCP.
* So in the above example, getting Polaris to a point 1 diameter of the inner circle (30') away from the inner circle (15') at the one o'clock position (using the altaz bolts), will mean that it is going to be close to polar aligned.

Caveats:

* This relies on the Telrad being closely aligned to the axis of the mount (but if it is well-aligned to the scope and that is well-aligned to the mount then that should be ok)
* It is clearly not going to be as accurate as placing Polaris in the middle of a small circle, but it is going to be a lot easier on my knees/back
* Aligning on a polarscope is not going to be enough for AP anyway
* All I am after doing is getting the mount close enough to PA so that when I use alignmaster, the stars will not fall off the edge of my webcam chip (which is about 6' across)

Practical? Stupid? Something in between? What do people think?

Thanks.

[tomato]

Sounds good to me. I use the telrad to roughly polar align as you describe. I then use a star diagonal (to put the FOV the right way up and use an eyepiece that provides a 1 degree FOV.

I then use Stellarium and zoom in to give the same FOV around the NCP, then adjust the mounts Alt/Az screws to align on the pole.

This is usually good enough to then use AlignMaster or drift align.

Steve

[Demonperformer]

Thanks, Steve.

My main concern with my approach was the orientation of the polarscope. I get very confused with the way various optical instruments reverse images in one direction or another, but the more I thought about it, the more I thought it couldn't reverse things because then the etched asterisms would be wrong. But nice to have it confirmed.