Hi Jen, wondering your scope is skywatcher and would like to know what ind of focuser (Standard Crayford or RP). My 12" DOB has a standard crayford focuser and can swap out a 1.25 and 2" eyepiece adaptor.
My 1.25" adaptor can unscrew to expose a "T" Thread and can fit a "T" to EOS Adaptor directly to it giving me an extra 1" of extra focuser travel. I purchace a "T" to EOS Adaptor -
https://www.bintelshop.com.au/Product.aspx?ID=5551 which is all I need for the Skywatcher 1.25" attachment.
I also bought 2" "T" adaptor -
https://www.bintelshop.com.au/Product.aspx?ID=7403 which i use with my 2" 3 x Barlow.
I can't take any photos of my stuff as the camera I have is the only one. Can't take a phot of the itself
.
(ADDED) Seeing it is late I decided to add some images knowing few people are watching this late.
In order is the sequence of placing my EOS adaptor to my SW Crayforf focuser. Could be handy for others if you do not have this type of focuser.
- Standard 1.25" SW adaptor for the crayford
- Unscrew the 1.25" barrel
- The "T" Thread is exposed (Outer Thread)
- Screw on the EOS to "T" Adaptor
- Complete assembly
This method gave me a full 1 1/2" of extra focuser travel inwards which I needed as for the moon shot I have taken even with this configuration I only have about 1mm of inward focuser travel left.
You may expereince the same issue as me with the standard Crayford Focuser. The 2" - "T" adaptor (not shown) is used for Barlow use.