Impact of PowerMate on optimal distance to imaging plane

[x6gas]

Searched SGL and t'internet but can't find an answer to this question so hoping that you fine folks can help me out!

The Celestron 11HD has an integral field corrector and there is an optimal distance from the visual back baffle and the imaging plane of 146mm.

http://www.celestron.com/c3/support3/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=2260&nav=0

Not sure what contribution to the back focus the PowerMate will add and so I am wondering how a Tele-vue PowerMate will impact on this distance. Am I correct in thinking that this will change the optimal back focus completely?

Any thoughts?

[NickK]

Hmm with the SDP (refractor with inbuilt flattener) there's no change to back focus.

[scope][50mm ext][oag][fw][cam]

[scope][powermate][50mm ext][oag][fw][cam]

The big difference is the additional weight - both in the power mate and the additional distance that the imaging gear sits at a further distance so requires a rebalance.