Hi Jorge,
Good stuff.
Here is some info, apparently the backyard eos 5x feature is the way to go on the T3.
http://www.astropix.com/HTML/I_ASTRO...Resolution.HTM
I always thought vonTom (haven't seen him on the forum for a long time) did amazing work with his canon cameras on planetary eg
https://www.flickr.com/photos/vontom/6374746577/
I have the same scope as you and agree the focus is a long way out on the f4 scopes. it isn't as bad on my f5 12" SW dob.
btw what type of filter wheel is that?
Cheers
Russ