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As titled, how common is this problem? I tried the 102ED-R out for the first time last night and my old buddy, tilt, came along for the ride. That's 3 different scopes I've had now that have some sort of distorted stars at the edges. So trying to dial in the correct flattener spacing is difficult as you end up chasing your tail. Stars ok one side, coma on the opposite. I have a tilt adapter which fits in between flattener and camera somewhere but the problem with that is if it's in the focuser, as soon as you change orientation to frame an image any adjustments made go out the window. Example of last night, I started off with a 0.8 reducer, everything threaded connection. No good. So then I switched to the Hotech SCA and worked at F7. Still the same. Tilt on one side. I rotate the camera and flattener 90° in the drawtube, tilt moves from left side of image to top. So its definitely not the camera. Surely I'm not the only one to wrestle with this? Anyone got any tips or ideas?

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I'm in the same boat as you. Stars on the left are basically perfect but the stars on the right are slightly elongated. 

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Depends on the target of course but I find it's less trouble to aim off centre and crop the image or if there are only a few stars sort them manually one at a time in P'Shop otherwise you can waste away valuable clear skies getting nowhere.

Dave

 

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Yep, same for me.. I been chasing flex around driving myself mad.. I think mine is focuser draw tube sag... seeing my focuser has just broke im hoping that once I've replaced it , it all disappears...

Fingers and toes crossed,  just got to save up the funds

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The only thing I can think of is to put a tilt adapter onto a nosepiece and leave in the focuser. Flattener, spacers and camera threaded to flattener. Dial out tilt. Leave nosepiece untouched from that point on. Framing of an image? TS 5.5mm camera rotator to rotate camera only?

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My plan this summer is to take my moonlite focuser apart and try to eliminate any tilt by having everything central. 

What focuser do you use David? 

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3 hours ago, geordie85 said:

My plan this summer is to take my moonlite focuser apart and try to eliminate any tilt by having everything central. 

What focuser do you use David? 

The stock R&P focuser on each scope. They're pretty good to be fair. Both the same so I can just swap my autofocuser between them. It's got to be a slight misalignment between focuser and lens cell, and then another slight shift in tolerance between flattener, spacers, filterwheel, camera and also the amount of glass photons have to pass through to converge at a single point on the sensor! No wonder Taks are so expensive!

As much as I hate to say it lads, I'm glad I'm not the only one!

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That looks pretty horrendous David, is it identical in a short exposure ?

Dave

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1 hour ago, david_taurus83 said:

Don't think I can carry on with this. Going to have to take apart and try and sort it.😓

Autosave001.jpg

That's bad. Alot worse than mine in fact. Mine I could just live with mine but using a OSC camera makes them appear worse due to colour smudging

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35 minutes ago, Davey-T said:

That looks pretty horrendous David, is it identical in a short exposure ?

Dave

Yes, pretty much!

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28 minutes ago, geordie85 said:

That's bad. Alot worse than mine in fact. Mine I could just live with mine but using a OSC camera makes them appear worse due to colour smudging

When I started the other night with the reducer it wasnt this bad. I switched to the Hotech to see if it was any better but it looks worse. I'm thinking the SCA section isn't compatible with my scopes. They both have 2.5 inch drawtube but the 2" adapter isn't very deep. I had to arrange the rubber bands on the SCA to the centre, ie 3 together just so they seat within the adapter. I'm thinking this could be a reason. The focuser cant be this much out. More testing tonight I think.

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On 21/05/2019 at 11:29, david_taurus83 said:

I rotate the camera and flattener 90° in the drawtube, tilt moves from left side of image to top. So its definitely not the camera.

Hi. Not sure what 'tilt moves', means... Are the stars are elongated in a different place in the frame when you rotate the camera? The position of the bad stars depends upon the camera rotation? JTOL. Cheers.

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29 minutes ago, alacant said:

Hi. Not sure what 'tilt moves', means... Are the stars are elongated in a different place in the frame when you rotate the camera? The position of the bad stars depends upon the camera rotation? JTOL. Cheers.

Yes, when I rotated the camera the elongated stars went from the side to the top.

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Well folks, I've had a play this evening. I've removed the Hotech and put the Flat6 reducer back in. Configuration now is 2" nosepiece, tilt adapter, reducer, spacers, fw and camera. This enables me to dial in correct spacing without messing it up with an adjustment to the tilt adapter. I think I've got spacing correct. I started off by pointing at the zenith and then looking east and then west. The star elongation was pretty much the same each time so this ruled out flexure or sag in the focuser. I also tightened up a few brass screws in the drawtube before starting. It took about 4 trips out to the scope to tackle the tilt adapter with the allen keys but I think it's a huge improvement. Not perfect in the corners or edges, particularly the right hand corners but the edges get cropped out anyway after stacking. Across the middle looks loads better to my eyes. I will get things marked up tomorrow and measure the tilt adapter with some calipers and make notes! I'm going to get one of those TS t2 5.5mm camera rotators so the assembly can stay in the same position and I can frame the camera independently. The previous stack and a single sub from this evening below.

 

 

Autosave001.jpg

Light_Ha_2019-05-24_00-34-17_Bin1x1_600s__-15C.jpg

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Looks a lot better David, the remaining odd stars may just stack out with luck.

Dave

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