The Opticstar OS-SCT is a versatile photographic adapter for SCT type telescopes. The adapter will attach on the back of an SCT telescope. It has an SCT (48mm) thread on one side and T-thread (M42 x 0.75) on the other. The adapter can be split offering a variety of lengths i.e. 5mm, 20mm, 35mm and 60mm. Typically the SCT side will screw into the back of an SCT telescope. Accessories like filter wheels and DSLR cameras with an appropriate T-ring can be attached on the other side.