Hi all --
I recently decided to upgrade my 10-year-old Celestron NexStar 6SE by replacing the stock focuser with a Starlight Feather Touch micro focuser. I didn't encounter any problems during the installation process itself, but when I tested the focuser after installing it, I found that I couldn't get any objects -- celestial or terrestrial -- to come to focus. If I center on an object and turn the focus knob, focus improves up to a point at which the image is maybe 90% sharp, but as I keep turning the focus knob in the same direction, the image becomes progressively *less* focused instead of *more* focused. I get the same result regardless of which direction I approach focus -- the best I can do is get the image about 90% in focus. (As an example, attached below is an iPhone snapshot I took through the eyepiece showing a yellow utility pole guy wire in front of a brick wall with a window.)
I know that focus problems can arise if the focus shaft pushes against the primary mirror at an angle, but I've tried everything I can think of to prevent this from happening. I've uninstalled and reinstalled the Feather Touch focuser several times and taken extra care to make sure that the focus shaft is centered. I've also tried reinstalling the stock focuser with the same results. I'm convinced that I must be doing something wrong, but for the life of me I can't figure out what it is.
One other piece of potentially relevant information is that I recently had Celestron clean and collimate the optics to remove some gunk that had accumulated on the inside of the corrector plate. In hindsight, I should have tested everything as soon as I received the OTA back from the factory, but I was so impatient to use it that I installed the Feather Touch focuser without first checking to make sure that the secondary mirror was properly collimated. (Kicking myself now, but lesson learned!) I mention this because it's crossed my mind that I might be dealing with a collimation issue rather than a focuser issue. But I'm reluctant to start messing with the collimation screws to test that theory because I'm afraid I might just make a bad situation worse.
Does anyone have any thoughts on how to address this issue? I have calls in to both Celestron and Starlight Instruments but I figured someone here might have dealt with a similar problem in the past.