Takahashi FS-60CB back focus advice

[Dean Hale]

Don't laugh i've just spent a small fortune on adaptors and i need some advice lots most likely. This is my first attempt with using a flattener and a Takahashi FS-60CB. I'm realistic and know more suitable scopes are out there for astrophotography but i'd like to give it a go. I'm easily pleased.

So, has anyone any idea if this looks correct? I've pointed it at a windmill a few hundred metres away, the only structure in my line of sight and it seems ok (at least i can get focus - lots of sea fret around so not the clearest image) however i'm unsure what to look for to see if anything is amiss and not even sure if it is possible to do a daytime test? 

The adaptors are Tak Multi Flattener, Tak CA ring, Tak Reducer/Corrector to T Adaptor, ZWO M48 to M42 Adapter Ring, ZWO M42-M48 Extender 16.5mm and ZWO M42-M42 Extender 21mm then the ASIAIR 486MC.

Any pointers appreciated 

Many thanks

[fireballxl5]

This configuration doesn't look right.  I think that the sensor should be 56mm from the metal back of the flattener.  I have the same scope but usually use the reducer so *maybe* the back space is different with the flattener but unlikely.  But maybe these adaptors give the required back focus distance?

Edited December 18, 2021 by fireballxl5
Added maybe

[Stuart1971]

As said above, that is not correct, the flattened should be 56mm in front of the camera sensor, yours is much more, also there was no need to spend all rat on adapters, I have this same scope and the flattened just replaces one of the adapters that comes with the scope…

Here is mine as it came with all the adapters fitted as it was supplied with, the one I marked in red, is removed, and the flattener goes in it’s place….job done…

 

Edited December 18, 2021 by Stuart1971

[Dean Hale]

Cheers @fireballxl5. I can remove the CA ring which knocks a chunk off and when i find my tape measure i can check how close to 56mm i am or not. Thanks @Stuart1971 I should have asked first. The intention is two sets of adapters one for visual and one for imaging so no need for me to fiddle unscrewing bits in the dark apart from attaching to the tube. Madness maybe.

[Stuart1971]

6 minutes ago, Dean Hale said:

Cheers @fireballxl5. I can remove the CA ring which knocks a chunk off and when i find my tape measure i can check how close to 56mm i am or not. Thanks @Stuart1971 I should have asked first. The intention is two sets of adapters one for visual and one for imaging so no need for me to fiddle unscrewing bits in the dark apart from attaching to the tube. Madness maybe.

Well, that’s not really possible, to have a one fits all really, but with my set up I can just swap out the camera for an eyepiece, but leave the flattener in position…

[Dean Hale]

18 minutes ago, Stuart1971 said:

Well, that’s not really possible, to have a one fits all really, but with my set up I can just swap out the camera for an eyepiece, but leave the flattener in position…

I should have said a filter drawer is also being added to the mix which is why I wish to have the two sets 'once i take note of the distance as mentioned' and prefer the ease of unscrewing whole rather than odd bits hopefully that makes sense? 

[Stuart1971]

2 minutes ago, Dean Hale said:

I should have said a filter drawer is also being added to the mix which is why I wish to have the two sets 'once i take note of the distance as mentioned' and prefer the ease of unscrewing whole rather than odd bits hopefully that makes sense? 

Well, yes it does….I think…, but you still need to get the correct distance or 56mm between flattener and camera sensor…

[Dean Hale]

Indeed. The next ordeal. 

[Stuart1971]

Just now, Dean Hale said:

Indeed. The next ordeal. 

And that 56mm needs to include your filter slide too..

[fireballxl5]

2 hours ago, Dean Hale said:

Indeed. The next ordeal. 

 

2 hours ago, Stuart1971 said:

And that 56mm needs to include your filter slide too..

@Dean Hale lucky that you don't have the added complication of wanting to also squeeze in an OAG...🤣

PS or just get the x1.7 Q-Extender, imaging at f10 but no flattener needed 

Edited December 18, 2021 by fireballxl5
added PS