Hi,
It's always difficult to tell if there isn't any drawing how they measure the distance.
When I read here they say backfocus is 180 mm.
http://www.teleskop-express.de/shop/...-Teleskop.html
Maybe there are different models or they measure it different.
But it must be when the focuser is full racked in as you say.
When they say visual backfocus I'm not sure. They could mean with a attached 90 degress prism. But then the backfocus from the diagonal should be shorter.
This telscope also have a big 3" focuser, normally there is a reducer to 2" when visual. From which are the visual backfocus?
Now I maybe just confusing you, but this is confusing and important to have the correct distance and how they measure that. Otherwise it can be expensive mistakes.
/Lars