I have my 14" EdgeHD for over 2 years now. It originally had a problem with not holding it's collimation and had to be sent back to "C" where they "span" it - much better after that. I use it mostly for DS imaging with 0.7X focal reducer and Moonlite focuser. Everything seems to be very tight and sturdy. I focus it first crudely, lock the mirror then use Moonlite to tweak it. It all works fine even for long slews, until I do the Meridian Flip. After that focus is gone, collimation too is worse (though still usable). It usually is off by 100 steps or so.

Any idea what can cause such a shift?

Thank you for any thoughts.

Ian

Are you saying you have a Moonlight focuser on the rear, a crayford style focuser? Something does not sound right here. Once the mirror is locked down you cannot focuse it (tweak) it. Locked is locked.. If you crank on that screw focuse after you lock it down you will slant the primary.

If you are using a rear focuser after your focal reducer like a Starlight instruments or Moonlight it should be set to its mid point. All other spacers etc. should now have you mechanicay at the back focus distance. You would then use your built in screw focuser to attain the best focus you can. When this is done you lock the mirror down and forget about it. Now all subsequent focusing will be done with the crayford style on the back. I might add with regards to collimation. You must take care when collimating that your mirror focuser moves the mirror up towards the sky against gravity when you come to focus prior to your collimation efforts. When you are done collimating do a focus with the mirror always ending up pulling the mirror up. This is the same way you did it prior to collimation. Now lock the mirror and start using the crayford. Do not mess with the mirror again..

The way you stated it in your querry you implied that you tweaked the mirror after locking it down which can be disastrous.

If it just came back from the factory it is highly unlikely that something is loose in the telescope so this leaves only two possibilites.

1. You are doing something wrong.
2. Somethig is loose at the rear of the scope.

If you are using the Celestron focal reducer it is a monster. I have one and it is solid as a rock so as stated above it is you or something is loose beyound the focal reducer.

Garu

Carpe Noctem

Sent from my space ship via my LG V10 Phone
On Nov 22, 2015 12:23 PM, "cosmoimager@... [C14_EdgeHD]" <C14_EdgeHD@...> wrote:
>
> ?
>
> I have my 14" EdgeHD for over 2 years now. It originally had a problem with not holding it's collimation and had to be sent back to "C" where they "span" it - much better after that. I use it mostly for DS imaging with 0.7X focal reducer and Moonlite focuser. Everything seems to be very tight and sturdy. I focus it first crudely, lock the mirror then use Moonlite to tweak it. It all works fine even for long slews, until I do the Meridian Flip. After that focus is gone, collimation too is worse (though still usable). It usually is off by 100 steps or so.
>
> Any idea what can cause such a shift?
>
> Thank you for any thoughts.
>
> Ian
>
>

I feel your frustration. I too am experiencing a problem that I cannot seem to get my head around. After shutting my Observatory down for better then six months and then start imaging again I just cannot seem to guide quite as good as I did last year. When I started up my pointing was still dead on with The Sky x. Guiding with Maxim always yielded under .300 RMS, usually around
.200 or? better RMS. Now I have trouble getting under .400 RMS with Maxim. I have tried every conceivable setting combination, new T-Point model, new PEC curve etc. So I know what frustration is. I hope someone comes up with a suggestion for you. I tried direct guide still not better.

Good luck.

Gary

Carpe Noctem

Sent from my space ship via my LG V10 Phone

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