dSLR image train & backfocus

[1CM69]

Hi all,

while the weather here isn't playing ball I thought I'd go through my setup & try out one or two things.

Anyhow, I attached my dSLR to my scope for the purpose of measuring the max slew limit & it struck me that maybe I could reduce the image train length down a bit.

At the moment to measure for the slew limit max, I have extended my MoonLite focuser drawtube to it's maximum extension, my image train is this:

MoonLite Focuser > Celestron 0.63FR > Celestron Visual Back 93653-A > Celestron T-Adapter Barlow 93640 > T-Adapter > Canon EOS 750d

Measuring from the back of my scope to flange of my camera is pretty much 300mm & my camera flange focal distance is 44mm.

I was considering swapping the combined Celestron Visual Back & Celestron T-Adapter Barlow and replacing it with http://www.modernastronomy.com/shop/accessories/adapters/low-profile-sct-to-t-thread-adapter/

This new adapter would reduce the length of my image train by 75mm.

However, I am not too sure whether I'll be able to achieve focus using it and here is where I need advice.

My focuser has got the option to have the FR inside the tall flange, thus reducing again the length of the train but I have read that using it this way with a dSLR attached for imaging is an issue. To this end I purchased another drawtube for my focuser that replaces the original and has a male 2" SCT thread on the end ready to attach the FR here.

So would I be able to use the above adapter from Modern Astronomy directly on the back of the FR with my dSLR then directly attached the adapter?

I appreciate any help.

 

Regards..,

Kirk