Re: Backlash issue or something else?
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Tom Carrico
Testing last night and I got the same results...I am not sure
where to go next. The plot is nearly identical to the one the
night before. This is after I backed off the dec motor to allow
the gear in the motor box to turn more freely. To be clear, I never adjusted anything inside the gear box, all I
did was remove the outer most gear to look at the spur gear. I
then replaced it. Verified that it spins freely. Wiggling the
telescope in dec, it feels like there is a bit of backlash. I decided to change scopes and go back to one that I have used
for years with no problems. Figured the C8 with the off axis
guider and camera hanging sort of far of the back might be
presenting too many variables. So, I put on my FSQ 106,
re-balanced the mount and started everything up. In the past, this
system has worked wonderfully. It also has a OSC camera and I
guide with a 120 mm guide scope. The resolution with the FSQ is
1.4"/pixel I slewed to a couple of different objects and took some guided
exposures up to 7 minutes in length. I did not see anything like
the graph above, the rms errors were typically 0.3". There were
some dec corrections, but they were nothing like the above graph.
In other words, it looked like things were back to normal. I
chalked this up to too many variables with the C8 and would check
on that at some future time. At this point I decided to do a new
Pempro run, get a model with APCC and get to some serious imaging.
This is when I learned that if I did not have bad luck, I would
have no luck at all. Did all the wizards in Pempro and got started. The graph below is
what I got. I moved the scope around a few degrees in either
direction to see if that would help and I always got this graph.
Watching the star in SGP it would jump back and forth. These are
20" jumps, they would completely mess up an image, but my images
looked great. I got out of Pempro and fired up PhD to see if
guiding had also gone to pot. As mentioned, I use a guide scope so
I am not looking at exactly the same thing, but that should not
matter with excursions like this. The guiding was fine, no jumps
like this. I made sure corrections were off, but I don't thing
that mattered. By now, it was early in the morning and I was no
longer trusting my decisions so called it a night. Here is what I know... - Dec still seems to be a problem using the C8, they might still be there with the FSQbut not visible with the FSQ. In fact, I would say the FSQ is completely usable with the current configuration - I have never touched the RA motor, and have used Pempro many times on this mount with this scope, this is definitely new behavior. I checked the play in the RA axis and there is a little bit, but I decided not adjust it until I heard back. Would appreciate any help, I would totally believe I messed up
somewhere, just need more places to look and things to try.
On 8/28/21 10:59 AM, Tom Carrico wrote:
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