SBIG-OAG-8300 is a seven element optical system.
Relay Lenses move the optical system to the side.
Results in low profile.
.7 Focal Reducer will give you a greater field of view for better selection of a guiding star.
Great image quality , all the way to f/3.5
Compatable with ST-8300 as well as STF-8300
The new Low Profile Off-Axis Guider is designed with a 7-element relay lens system that places the position of the guide camera to the side of the main camera and filter wheel. This allows a minimum impact on overall backfocus. The same lens system also acts as a 0.7X focal reducer that doubles the field of view of the guide camera compared to a typical off-axis system. The OAG adds only ¾ in. (19mm) backfocus to the camera and filter wheel. The guide camera can also be rotated in 90 degree increments about the OAG to orient the guide camera and cables in a convenient
The OAG can be used on both mono can color cameras (with appropriate adapter) and is 100% backward compatible with all ST-8300 cameras.