Starizona SCT Corrector IV - 0.63X Reducer / Coma Corrector

Starizona SCT Corrector IV - 0.63X Reducer / Coma Corrector

Focal Length

The exact focal length of the reducer/telescope combo depends slightly on where in the optical path the SCT Corrector lens is placed. Nominally it will be within a few mm of the rear threads on the telescope. Changing this distance should only affect the focal length, not the optical quality. Listed below are the nominal focal lengths for the various sizes of Celestron SCTs*. 

* The SCT Corrector has a reduction factor of 0.63x, but the C6 and C8 are actually closer to f/11 natively, and they have a shorter backfocus compared to the larger scopes so the reduction is a bit less.  The C14 is f/11 natively.

Camera Adapters

The SCT Corrector IV has a nominal image circle of 27mm, accommodating most popular CCDs and DSLRs. 

The nominal backfocus is 90.3mm from the base of the threads on the camera side of the SCT Corrector IV. For the largest compatible cameras, this should be kept within +/-2mm, while smaller format cameras may work fine at slightly larger tolerances. 

Telescope Adapters

The SCT Corrector IV, like the original SCT Corrector, has a 2" barrel that allows it to fit into a 2" visual back or 2" focuser.

Filters

The front (telescope side) of the SCT Corrector IV is threaded to accept standard 2" (48mm) filters.

Features

• 0.63x focal reduction factor
• 2.5x faster than SCT's native f/10
• 1.4x faster than original f/7.5 SCT Corrector design
• 27mm image circle
• 2" barrel
• Threaded for 48mm filters
• SCT Corrector Top Thread: M42 x 0.75mm T-thread
• Mechanical Backfocus (thread shelf to focal plane): 90.3mm (3.56”)
• From August 2024: including 35.3 mm long M42 spacer, which takes the back focus to 55 mm for simplified use with cameras
• Black anodized, machined aluminum housing
• Fully multi-coated optics
• 5-element optical design with extra-low dispersion (ED) glass