Help with spacing or maybe something else?

[steviemac500]

HI, I've been trying to get the spacing right on my CCD equipment. I have  an ED80 with the 0.85 FR/FF which is attached to my Moravian G2-8300. I believe the correct spacing for the reducer is 55mm from chip to shoulder of the reducer. I have measured the distance to 56mm with some verniers and I added the extra 1mm because of the 1.25" filters in the internal wheel. 

I still think the stars are still eggy in the top left and right corner. Is my spacing still wrong or is this something else OR am i being too picky?

Please ignore the quality of the sub, it's not been properly calibrated, it's just for testing the spacing. Any advice and or comments are greatly appreciated as this is starting to wind me up!!!

 

[RichLD]

Looks like it might be tilt to me. Does your ED80 have the stock focusser?

[steviemac500]

1 hour ago, RichLD said:

Looks like it might be tilt to me. Does your ED80 have the stock focusser?

No it's a new moon lite.  The problem was there and worse when the stock focuser was in though and my spacing was way out. 

[ronin]

Wouldn't a 3mm filter take 1mm off the distance not add it on ?? Meaning 54mm not 56mm ?

[Oddsocks]

The problem in the posted image is predominantly tilt, whether this is a tilted objective, tilted focuser or a poor coupling of camera, flattener and camera can't be determined by looking at the resulting image.

How are you attaching the camera and flattener to the focuser?

If using one clamping screw to act on the compression ring to secure the flattener in the draw tube then any slop in the fit will tend to push the camera and flattener to one side and induce tilt, if three clamp screws are provided they all need to be tightened equally. If the flattener is a sloppy fit then consider adding some kind of shim material wrapped around the body of the flattener to force it into alignment, thin polycarbonate from packaging can be used, a strip of aluminium cut from a drinks can is another. 

It is not unknown for the optical element of the flattener to be misaligned so the starting off point is to test image without the flattener fitted, if the camera, focuser and objective are all in perfect alignment then the "eggy" stars due to coma should be perfectly symmetrical around the periphery of the image, if not then something else is misaligned in the image chain and this should be determined and rectified before the flattener is put back into the mix.

Check your new focuser is collimated properly to match the OTA, they are adjustable and need to be matched to the telescope.

To test, make a pair of vee blocks from timber and rest the body of the ED80 without rings into the vee blocks, fit a collimated laser in the focuser, ensure it is a snug fit, if necessary wrap paper around the body of the laser to make it a tight fit in the draw tube, turn on the laser and project the laser spot through the OTA and objective onto a wall as far away as possible but that you can still see the spot easily, mark the spots position on the wall and rotate the whole OTA in the vee blocks, if the focuser is correctly collimated then the spot should remain stationary, if it drifts away when the OTA is rotated then the focuser has to be adjusted for tilt until the spot remains stationary when the OTA is rotated. Once this is done most likely the issue will be solved.

CCD inspector can help determine the amount and direction of tilt so make use of the free trial period to help identify the source of misalignment.

HTH.

William.

[RichLD]

+1 for CCD Inspector, it's a fantastic tool and helped me sort out a tilt issue I had on my QHY9 on which the faceplate has three screws that secure it and can be adjusted. I got my sensor orthogonal to the focal plane under the stars in around 10 minutes.

[steviemac500]

Well I fixed it. Turned out I had cross threaded the lens when i screwed it back on after cleaning. Expensive mistake after buying the Moonlite. Still, my wife doesn't know yet!  

Thanks for all your help, just lad it wasn't anything more sinister,

Steve

[RichLD]

Great news Steve, glad you got it sorted