Hi Marc
The Vixen Reducer/Corrector (R/C) “reduces” the focal length (918mm) of my Vixen 4” F9 refractor to around 590mm making it an “faster” F5.75 system whereas the my Tak Reducer/Flattener (R/F) “reduces” the focal length (2160mm) of my Mewlon 180 to around 1728mm making it an F9.6 system.
This results in a wider field, correction of coma at the edges and shorter exposure times.
These are the opposite of eyepiece projection where you are effectively increasing the focal length, f-ratio, image scale and narrowing the field, typically the same behaviour as a Barlow lens.
I have read that some people who use bino viewers on their telescopes have to use a Barlow in order to get to focus; here again, the Barlow “extends” the focal plane further outside the optical tube.
So, a Barlow or eyepiece projection might work with your set up, but the major downsides are:
- Image is much dimmer
- Filed of view is much narrower
- The increased image scale will severely stress the capabilities of the mount and it is unlikely that you would be able to take images of longer than 2 to 5 seconds duration before you get start trailing.
Also, be careful of “cheap” T-rings for fittings DSLR’s to telescope accessories. I had a problem where my focus kept changing during an imaging run and I eventually traced it to a sloppy Pentax K T-Ring purchased cheaply!
Cheers
Dennis