Flattener/Reducer for RC8?

[AstroBogan]

Hi all,

Just took the dive and upgraded to an RC8 carbon fibre.

I've used the RC6 and didn't use any flattener or reducer, but was wondering is it necessary with the RC8?

Imaging with an ASI1600mm-pro with a ZWO OAG and EFWmini.

Any advice would be very much appreciated :thumbsup:

[Marke]

You want an Astrophysics CCDT67 its a reducer / flattener that works very well with all the RC scopes.

[AstroBogan]

I thought so, I ordered it this morning, thanks for the advice.

Also, having never used one of these before, can anyone provide me with guidance on how the imaging train should look?

gear is:

RC8, ZWO ASI1600mm pro, zwo OAG, zwo efwmini.

[Marke]

I have almost the same gear the CCDT67 just screws on the end that goes into the focuser. Think from memory I use a 10mm spacer between it and the filter wheel its very tolerant of spacing but you may need to add 10-15mm after the wheel to be ideal. So you have camera - Fwheel - oag - spacer - CCD67

[DiscoDuck]

I have the same camera and scope. I found that, referring to the graph in this thread for the spacings https://www.cloudynights.com/topic/435157-coupling-of-astrophysics-ccdt67-with-stf-8300m/
a 0.75x reduction with the CCDT67 worked ok in terms of star shapes with the ASI1600 and the RC8 (which is about 60mm sensor to rear flange of CCDT67).

Any bigger reduction than that and the stars at the edges started to look a bit dodgy.


Worth noting that at 0.75x with that camera and scope, the resolution is about 0.65 arcseconds per pixel. You don't want to go much less of reduction than 0.75 then, as then you'll be risking oversampling.


Paul

[AstroBogan]

Wow, thanks for the wealth of info, much appreciated!

Now to find myself a D-style saddle for the HEQ5 pro.. I really overlooked that :lol:

[AstroBogan]

Just another question on this..

Do you remember if you had used one of the spacers that came with the scope?

[Marke]

You mean the ring that screw on the back ? I think the smallest one but just need to see how you go getting focus because I have a big Feathertouch on mine so it may differ from yours but doesnt effect the reducer spacing at all just the overall focus.