For NexStar 4SE and for all C90 Spotting Scopes. A T-Adapter allows you to attach your 35mm SLR camera to the prime focus of your telescope or spotting scope. This arrangement is used for terrestrial photography and short exposure lunar and planetary photography. It can also be used for long exposure deep-sky photography when using a separate guidescope. Both a T-Adapter and T-Ring are required to mount a 35mm SLR camera to your instrument Specific T-Adapter for NexStar 4SE Telescope Also works with Celestron C90 Spotting Scope Must use a T-Ring for your specific camera Allows astrophotography with your 4SE telescope