Re: An easier Pasillx N & S Polar Alignment method

Chuck Hancock

Hey Joe,
just like adding shims to the OTA for the same reason. So, if I can't get the mount aligned after a few tries, work on shimming (adjusting set screws) of the finder, and recursively - finally - get the (mount + finder)
All you have to do is get the finder scope orthogonal at the very first. You don't need to waste time with a few tries prior to that. I believe Roland covers this in one of his more recent posts.

Of course, the end result is perfect GOTO for the finder, while the OTA field - and thus the camera view are left permanently "off the mark a bit". I can now see why Roland used that procedure, since he might have only been interested in quickly field testing a mount prior to shipment, but that is not something I would desire as a regular "field set up". Although, if the OTA is not that far off, it might be tolerable - just
Actually, after you polar align, you merely recalibrate using the recal function of the hand controller, and your OTA will be RIGHT on the mark. Until your mount flips sides. Then you just recal again on any object in the database. Quick field test or all night imaging, this method works for polar aligning the mount.
By the way, I find adjusting finders in "double ring mounts" a real ain - 6 screws, and possible dents or scratches on the finder tube!

I found a much better method for the tiny 7x finder on my OTA. I removed the front set of 3 screws from the front ring mount, and put a suitably thick O-Ring on the finder front end, so that the finder fit snugly inside
sliced rubber pipe insulation formed into a donut, instead. Now you only need to futz with the rear mount ring screws to get the OTA orthogonal.
Wish somebody would make this a product. Sure beats adding brass shims to the OTA mount rings!
I think that would speed things up if Roland wanted to always have OTA's quickly orthogonal, and tolerate the finder being slightly off centre - which can be squared up with the OTA much easier, upon completion.
Probably not a very common issue for the OTA, but finders on OTA's get bumped and misaligned after almost every trip.

There's probably no reason to go to that much trouble. The method you describe for your finder scope works OK, I'm sure. However, leaving all the screws in place does the same thing. You just need to choose whether you want to adjust the front set, the rear set, or both. Shimming the scope is another story. I haven't tried it, but having an orthogonal finder scope makes this unnecessary. Still, I may try it sometime just for the satisfaction. At least it would be a "set it and forget it" procedure, given the precision and rigidity of the AP mounting rings. As for your proposed invention, adding resilient (or, indeed, inflatable) components to the mounting system may introduce an unreasonable amount of inaccuracy, especially when you change the scope's angular orientation with respect to the force of gravity. You would then need modeling software, for sure, to compensate! ;)

As for the finder scope staying aligned, I have found over the past few sessions that the finder maintains an excellent degree of alignment every time I remount it on the scope's female dovetail bracket. I do tend to mount the 130EDF the same way in the rings every time, with the finder bracket lined up with the flat top of the mounting rings, so maybe this has something to do with my consistent results between the mount and the finder scope.

Best regards,

Join { to automatically receive all group messages.