Re: Tracking w/ Passil 4 polar alignment

Christopher Erickson

And for FWIW, I have a big, heavy/1.5kg+ (and sharp!) Nikkor 80-400mm AF-S ED zoom lens and if I want to try to image the sky with it, I have to add a Losmandy DVR108 Guide Scope ring to the plate, near the front end of the lens to keep it rigid and stable. The thing will sag/flex/shift quite a bit under its own weight when mounted on it's integral tripod shoe. I assume there are a lot of floating parts inside of that big zoom lens, fighting gravity. If I am using two or more cams on a long plate, I have the telephoto set up rigidly with a secondary lens support and the cams with shorter lenses go on ball heads on the plate. Most ball-heads have a lot of flex so I only put 58mm or shorter lenses on them. My favorite lenses for the second and third cams are 20mm ultra-wide and a 10mm fisheye.

I hope this helps.


On Tue, Jul 21, 2020 at 8:27 AM uncarollo2 <chris1011@...> via <> wrote:
Even if the polar alignment is spot on you will need to use a PEM curve.  I'm guessing here because you did not provide enough information to go on. For instance, what direction did the trailing go, where in the sky did you image. There is no information on how the scope is being held, or the camera, or whether there is focuser sag. Lots of things can add up to give poor results.


-----Original Message-----
From: Wiggins, Rick <rickwiggins@...>
Sent: Tue, Jul 21, 2020 12:58 pm
Subject: Re: [ap-gto] Tracking w/ Passil 4 polar alignment

Hi Roland,
I did setup using the pasill4 polar scope and got good alignment on the two stars through the polar scope. I did not use a PE curve. Do you think slight smearing in 25 secs given that rough setup is reasonable or should it be better?
Thanks, Rick

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