I have a number of those adapters to fit different cameras to EOS lenses, C/CS - EOS and SBIG (T)- EOS. To date, what mimimal time I have had to trial them they seem OK (You can either blame the weather or that I have too many other astronomy things to play with
). However don't expect them to work successfully if you are using a mono camera with a filter wheel, the lens may not come to focus as it is too far from the chip.