CELESTRON T-ADAPTER, (EDGEHD 8)T Adapter for 8 EdgeHD optical tube threads onto the rear cell. This T Adapter allows you to attach your 35 mm DSLR camera to the prime focus of your EdgeHD telescope. 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 DSLR camera to your instrument.