4 replies to this topic

[Suphys]

I just bought an ONTC 8" with a 3" focuser from TS. And I am consider to add a coma corrector for the imaging. 

 

However, the length of drawer is only 3.5cm which seems not support to TV Big paracorr because it will shift focus length 73mm outwards. 

 

May I can only use 1.0x Riccardi Design or TS-Optics NEWTON Coma Corrector 0.85x Reducer. 

 

Is there any comparsion of them or some solution to use Big paracorr?

 

Thanks

 

Su

[Dan_I]

Can't you move the  mirror cell down to bring the focal plane closer to the optical axis?

[Suphys]

Can't you move the  mirror cell down to bring the focal plane closer to the optical axis?

There are 3 position on the tube.

 

However, the shortest focus position is 154mm above the tube. +73mm will shift it to 227mm, the height of focuser is 83mm, +35mm drawer and 73mm working distance cannot satisfiy the requirement. 

[a__l]

I just bought an ONTC 8" with a 3" focuser from TS. And I am consider to add a coma corrector for the imaging. 

 

However, the length of drawer is only 3.5cm which seems not support to TV Big paracorr because it will shift focus length 73mm outwards. 

 

May I can only use 1.0x Riccardi Design or TS-Optics NEWTON Coma Corrector 0.85x Reducer. 

 

Is there any comparsion of them or some solution to use Big paracorr?

 

Thanks

 

Su

I don't think you need Big paracorr. This will significantly ruin your wallet and reduce the f ratio of your device.
If your corrector is a SharpStar 3" 0.85x (I know TS likes to rename Chinese brands) then this is a good corrector.

https://www.flickr.c...in/52758136953/

https://www.flickr.c...in/52757560731/

Table from SharpStar. I hope this helps you.

 

Ps Yes, I wanted to add. That the telescope on the link is not Chinese. If that and not USA. The photo was taken 40 kilometers from the metropolis.

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Edited by a__l, 22 March 2023 - 05:33 PM.

[Suphys]

I don't think you need Big paracorr. This will significantly ruin your wallet and reduce the f ratio of your device.
If your corrector is a SharpStar 3" 0.85x (I know TS likes to rename Chinese brands) then this is a good corrector.

https://www.flickr.c...in/52758136953/

https://www.flickr.c...in/52757560731/

Table from SharpStar. I hope this helps you.

 

Ps Yes, I wanted to add. That the telescope on the link is not Chinese. If that and not USA. The photo was taken 40 kilometers from the metropolis.

Thank you for the interesting information. 

It is the first time I know TS 0.85x is made by Sharpstar. 

 

I still have an epsilon-160ed, if I use the 0.85x cc the focus length will be too near to that. 

So I think it may better for me to use 1.0x Riccardi designed. Do you know anything about it?

 

Best regard, 

 

Su