HELP! Coma Corrector Issue

[david_taurus83]

14 minutes ago, Anthony RS said:

I've tried it more than 5 times. I followed the same tutorial.

If it was me, I'd be getting a new focuser. I wouldn't recommend anything from Celestron/Skywatcher. Baader Diamond Steeltrack or Moonlight.

[Anthony RS]

1 hour ago, david_taurus83 said:

I think you've pretty much figured out the issue. A small tilt shouldn't put you that far off centre. I know you've said you've centred and collimated the optical path but something is clearly not right. I think you need to remove the focuser and start again from scratch. I followed the below tutorial and it got me pretty close, as much as my patience would allow!

 

 

Can you tell from the image if the problem is with the secondary tilt or is it with the primary? 

[david_taurus83]

32 minutes ago, Anthony RS said:

Can you tell from the image if the problem is with the secondary tilt or is it with the primary? 

I don't know. Have you tried a collimation cap to centre the secondary? They are supposed to be better than a Chesire as you can see more of the primary.

[alacant]

14 hours ago, Anthony RS said:

I could only find this compression ring https://www.amazon.co.uk/TS-Optics-compression-Skywatcher-TSM54-2/dp/B00EE2CJ86 on amazon.

That's m54; too small. You need m60x1. A m54 female to m60 male ring would do it...  

[Anthony RS]

4 hours ago, david_taurus83 said:

I don't know. Have you tried a collimation cap to centre the secondary? They are supposed to be better than a Chesire as you can see more of the primary.

No I haven't tried it yet. I've focused mainly on checking the primary since the secondary looks fine. But i'll try a collimation cap.

[Anthony RS]

1 hour ago, alacant said:

That's m54; too small. You need m60x1. A m54 female to m60 male ring would do it...  

Good idea but I couldn't find such an adapter ? would appreciate it if you know where I can order one. Thank you so much david_taurus83, you've been really helpful!

[david_taurus83]

Ah! Try adjusting the secondary again. This is the one that can cause most headaches. The primary can't move much but the secondary can be tilted at all sorts of angles. If you get it right once though it usually doesn't need much further tweaking.

[Anthony RS]

11 minutes ago, david_taurus83 said:

Ah! Try adjusting the secondary again. This is the one that can cause most headaches. The primary can't move much but the secondary can be tilted at all sorts of angles. If you get it right once though it usually doesn't need much further tweaking.

Here's an image of the seconday. All clips are visible and the tiny white circle in the middle is right at the center of the reticle (not shown here). It could use probably some more fine tuning but could a tiny error give me such a huge problem? this is why I'm doubting more the primary mirror.

[Anthony RS]

Just now, Anthony RS said:

Here's an image of the seconday. All clips are visible and the tiny white circle in the middle is right at the center of the reticle (not shown here). It could use probably some more fine tuning but could a tiny error give me such a huge problem? this is why I'm doubting more the primary mirror.

Here's another image 

[Anthony RS]

1 hour ago, Anthony RS said:

Good idea but I couldn't find such an adapter ? would appreciate it if you know where I can order one. Thank you so much david_taurus83, you've been really helpful!

Unfortunately I don't think this kind of adapter exists :((

[alacant]

10 minutes ago, Anthony RS said:

 Unfortunately I don't think this kind of adapter exists :((

??

It exists here.

HTH

[Anthony RS]

3 minutes ago, alacant said:

??

It exists here.

HTH

I meant the  m54 female to m60 male ring adapter. Isn't the one in the link a M60/68 to 2 inch ring?  

[alacant]

1 hour ago, Anthony RS said:

Isn't the one in the link a M60/68 to 2 inch ring?  

Yes. It's the one you need. Trying to find a 54 to 60 is going to be difficult. 

Another alternative is to tale your existing m60 adaptor and get them to thread it m54. Why not ask ScopeStuff if they'll ship if it's at your own risk? 

[Anthony RS]

2 minutes ago, alacant said:

Yes. It's the one you need. Trying to find a 54 to 60 is going to be difficult. 

Another alternative is to tale your existing m60 adaptor and get them to thread it m54. Why not ask ScopeStuff if they'll ship if it's at your own risk? 

I'll try that. Hopefully this will fix the issue I'm having. This is really frustrating

[Anthony RS]

1 hour ago, Anthony RS said:

I'll try that. Hopefully this will fix the issue I'm having. This is really frustrating

After some thought, I think going for a M60 to M48 adapter https://www.teleskop-express.de/shop/product_info.php/language/en/info/p5818_TS-Optics-Adaptor-M60-to-M48---2--Filterthread---low-profile-adapter-for-photography.html is the best way. That way I'll be able to thread the Coma corrector which is already threaded to the spacer/DSLR and by that I'll get rid of any tilt issues caused by the image train. I'll be able to get some more inward focus also which would allow me to get the primary back to it's original position! Let me know if I'm doing it correctly or if I've missed something.

[alacant]

1 hour ago, Anthony RS said:

M60 to M48 adapter 

Hi. It will not work; the coma correctly cannot be inserted into the focus tube as the m48 female is smaller than the 2" corrector.

[Anthony RS]

1 minute ago, alacant said:

Hi. It will not work; the coma correctly cannot be inserted into the focus tube as the m48 female is smaller than the 2" corrector.

but won't I be able to thread the coma corrector to the m48 female? The CC has a 2 inch female thread on it's nose. I might have linked you the wrong one. Here it is again: https://www.teleskop-express.de/shop/product_info.php/info/p9682_TS-Optics-Adapter-from-M60-thread-to-M48x0-75-2--filter-thread.html

[Anthony RS]

Just now, Anthony RS said:

but won't I be able to thread the coma corrector to the m48 female? The CC has a 2 inch female thread on it's nose. I might have linked you the wrong one. Here it is again: https://www.teleskop-express.de/shop/product_info.php/info/p9682_TS-Optics-Adapter-from-M60-thread-to-M48x0-75-2--filter-thread.html

m48 male*

[alacant]

6 minutes ago, Anthony RS said:

won't I be able to thread the coma corrector to the m48 female

Yes, but the you'll not be able to reach focus as the camera will be too far away from the tube. The whole assembly will become unstable as the camera will be too far away from the tube.

[Anthony RS]

1 minute ago, alacant said:

Yes, but the you'll not be able to reach focus as the camera will be too far away from the tube. The whole assembly will become unstable as the camera will be too far away from the tube.

Ah yes I understand, which is why I'm considering also getting this https://www.teleskop-express.de/shop/product_info.php/info/p2839_TS-Optics-Adaptor-with-female-T2-thread-and-male-M48--2--filter--thread---short.html which will allow me to actually put the CC inside the drawtube and thread the camera to the M60/M48 adapter. Hopefully this would work. I really appreciate your help alacant!  You are really patient

 

[Anthony RS]

7 minutes ago, Anthony RS said:

Ah yes I understand, which is why I'm considering also getting this https://www.teleskop-express.de/shop/product_info.php/info/p2839_TS-Optics-Adaptor-with-female-T2-thread-and-male-M48--2--filter--thread---short.html which will allow me to actually put the CC inside the drawtube and thread the camera to the M60/M48 adapter. Hopefully this would work. I really appreciate your help alacant!  You are really patient

 

I think I messed up the links I posted. I'll check everything again.

[Anthony RS]

1 minute ago, Anthony RS said:

I think I messed up the links I posted. I'll check everything again.

Hyg, It's this adapter https://www.teleskop-express.de/shop/product_info.php/info/p5818_TS-Optics-Adaptor-M60-to-M48---2--Filterthread---low-profile-adapter-for-photography.html combined with this one https://www.teleskop-express.de/shop/product_info.php/info/p2839_TS-Optics-Adaptor-with-female-T2-thread-and-male-M48--2--filter--thread---short.html. According to the site, "Newtonian Telescopes with f/5 or shorter focal ratios need a coma corrector for best photographical results. The standard adaptations of many telescopes (including the ones mentioned above) have no provision for attaching such a coma corrector and still being able to reach focus with the telescope. This adaptor is the solution for this problem. A normal coma corrector has a T2 male thread on the camera side. From this thread we have an adaptation to the 2" filter thread. With this extra part you can screw the coma corrector into this adaptor. The corrector will disappear entirely in the inside of the focuser drawtube. As a result it will not add extra length to the optical train."

[alacant]

Still no good. The GSO's coma corrector has a 2" (50mm) barrel. It will not fit through a m48 thread.

Two solutions:

1. Message ScopeStuff -new pics to send them- with the picture I posted and ask them to send you the correct part (about €20).

2. Get the TS part (over €60): https://www.teleskop-express.de/shop/product_info.php/info/p3588_Baader-Adapter-M68x1-und-M60x1-auf-2--Steckhuelse---kurzbauend.html

HTH

 

[Anthony RS]

1 hour ago, alacant said:

Still no good. The GSO's coma corrector has a 2" (50mm) barrel. It will not fit through a m48 thread.

Two solutions:

1. Message ScopeStuff -new pics to send them- with the picture I posted and ask them to send you the correct part (about €20).

2. Get the TS part (over €60): https://www.teleskop-express.de/shop/product_info.php/info/p3588_Baader-Adapter-M68x1-und-M60x1-auf-2--Steckhuelse---kurzbauend.html

HTH

 

Ok thank you so much for your help!

[Anthony RS]

Ok so I bought the compression ring, everything seems tight, I collimated perfectly and took a test shot. Nothing happened... Still having the same issue. I'm just posting this in case someone is checking for reviews about the GSO CC. DO NO BUY IT. It has caused me more problems than anything I've encountered in this hobby, not to mention the time and money I've wasted trying to fix the issue. Just spend a bit more money and buy a better CC.

Cheers and good luck!