The STF 8300 Off Axis Guider by SBIG:
SBIG's OAG 8300 is a precision off-axis guider that is compatible with the ST and STF 8300 cameras.
A seven element internal optics system moves the guide camera to the side of the imaging camera. Incorporates a 0.7x reducer for twice the field of view than other off-axis guiders. Slim profile adds only 19 mm of back focus. Four positions for the guide camera available to help manage cord placement and allow for proper telescope movement. Guide in front of the filters, allowing you to leave your narrow band filters in place.
OPT Product Number: SB-OAG-8300