Focuser question

[The Warthog]

The focuser tube on my C6N is larger than the eyepiece holder, which is an adapter that screws into the tube. The diameter of the tube is about 1 5/8" so it doesn't correspond to any eyepiece size. Is this to accomodate photographic equipment, or is there some other reason for it?

[geppetto]

Very good question WH for which I don't have an answer.

Often wondered about these strange design happenings myself :?

[fmeireso]

Synta stuff? Mine is too. And my 2 inch focuser on my Skywatcher is also odd because it needs an adapter to hold 2 inch eyepieces, i believe it's actually 2.5 inch. Why ?, i just don't know??? On my OO a 2 inch eyepiece fits directly on the focusser. The lThe latter seems normal...to me...