Help needed with focal reducer spacing on a C8

[Helen]

I've put the 6.3 reducer on my C8. The problem I've got is that because I want to use the SX filter wheel and OAG I have to add an SCT to 2inch adapter (which is a couple of inches long) after the FR, otherwise the filter wheel won't attach because of the focuser. So I'm wondering whether that is a good thing to do? or should I put the adapter on the back of the scope and attach the FR to the front of the filter wheel?

Many thanks

Helen

[Merlin66]

Helen,

The design distance for the reducer is 110mm - the more you move away from this distance, the more the reduction ratio and aberrations change.

[BlueAstra]

I have a similar setup with my C8 SCT, 0.6FR, SXOAG, SXFW, SXH16. I actually use a SCT-2" NP adapter at the mount (longer than the one shown, another AE part) that provides a clamping 2" NP interface for cameras, EP, etc, so that I can easily switch between a diagonal for visual and cameras for imaging. The focal reducer is sandwiched between the parts of a Orion prime focus adapter #5269. This has an SCT thread between the parts so you can thread the FR to it. I then use a 30mm T thread spacer to the OAG/FW. With the H16 on the FW it puts the CCD at 105mm from the FR (I use an OpticStar FR, but I had the required distance from ref, I want to use the focal reducer/corrector with an aftermarket eyepiece holder. What is the best spacing, focal length, etc?. I used the same parts for my original setup with a DSLR.

The PF adapter is 18mm and the OAG+FW is 42mm = 60mm total. In my case the CCD is 17.8mm from the mounting interface, so the space required is 105 -(60+17.8) = 27.2mm, hence the 30mm spacer.

[Helen]

Thanks guys - will doo some measuring!

Helen