4 replies to this topic

[The Cat]

So, I have a new Celestron 9.25" Edge, which I'm using on a new iOptron CEM70 mount. My experience to date has been with a simple, 100 mm refractor on a Meade GEM mount. I have never owned a reflector before. 

 

Out of the box, there have been issues with focusing. The star or planet would reduce almost to the point of being sharp but then enlarge again when I turned the focuser. So, I checked collimation by blowing out the focus on a bright star. Sure enough, the circle in the center was not centered. It was off to the left. Following the instructions, I used a screwdriver to adjust the screws, just a little, but, very quickly, the object became extremely dim. I don't know whether the circle in the center moved at all -- the object just grayed out! So I slewed to the moon and even that was very dim. I have no clue what happened. Any suggestions? I hope I haven't totally knocked the secondary mirror off-center. 

 

Help!!  

Thanks,

Felix

[Xeroid]

Just a suggestion:

 

- Obtain a small ball bearing to use as an artificial star in direct sun light.

 

- Get and read: Ed's Guide to SCT Collimation

Edited by Xeroid, 26 November 2020 - 10:23 PM.

[jrcrilly]

Don't know where you are, but if it is like here (Ohio) your eyepiece and/or corrector probably dewed up.

[Daniel Mounsey]

So, I have a new Celestron 9.25" Edge, which I'm using on a new iOptron CEM70 mount. My experience to date has been with a simple, 100 mm refractor on a Meade GEM mount. I have never owned a reflector before. 

 

Out of the box, there have been issues with focusing. The star or planet would reduce almost to the point of being sharp but then enlarge again when I turned the focuser. So, I checked collimation by blowing out the focus on a bright star. Sure enough, the circle in the center was not centered. It was off to the left. Following the instructions, I used a screwdriver to adjust the screws, just a little, but, very quickly, the object became extremely dim. I don't know whether the circle in the center moved at all -- the object just grayed out! So I slewed to the moon and even that was very dim. I have no clue what happened. Any suggestions? I hope I haven't totally knocked the secondary mirror off-center. 

 

Help!!  

Thanks,

Felix

You don’t have to have a camera but just watch this.  Ultimately it’s best to have the telescope positioned upward at a star but look at this first. https://youtu.be/hqRVIDj4aZA

[The Cat]

Okay — thanks foe the great feedback. I read the article and also watched the video and a couple others. It’s not sunny enough for the ball bearing approach and it won’t be clear enough tonight to target a star, so I guess I’m in a holding pattern.

I think I may have tightened all three screws way too much. Would that cause the image to go very dim? I mean, by the end of my efforts last night, it appeared that I was observing the shadow of a star not a bright starry/Airie disc.

Edited by The Cat, 27 November 2020 - 03:46 PM.