Indexed 2" adaptor?

[RyanParle]

Does anyone know if there are any adaptors available that have some form of indexing to ensure that the camera is always fitted in the same orientation to the telescope each time?

i was thinking of somthing such as a 2" extension tube with a location slot and a mating 2" nosepiece with a key that would locate in to the slot.

the reason i ask is to alow me to disassemble / reassemble the imaging train in the same position each time so that i do not need to shoot fresh flats every time i image, I often capture my data away from my house and after a late night imaging it would be good to be able to to acquire calibration data at home on the following morning. at the moment i have found myself leaving the whole imaging train assembled and carefully placing the scope, OAG & cameras in to the van and driving very carefully so as not to disturb the position.

[perfrej]

That really doesn't sound viable. I would suggest you shoot dithered sky flats for every session if you tear down the rig between them.

You have a few points where all alignment can be lost, some of are most likelt threaded objects, and you cannot guarantee alignment there.