other telescope accessories

This 45 degree erecting prism is great for birding or terrestrial viewing but is not suitable for star gazing (imagine if the star is right above your head). For star gazing the prism does not reflect as much light as desired so you won't be able to see dim distant objects easily, for that I recommend star diagonal with everbrite mirror ( from televue), it will cost more but a good investment for anyone who is serious about star gazing.

This is a generic Pacific-rim made prism imported by Meade, and not terribly different from similar items sold by Celestron, Orion and other popular companies catering to amateur astronomers. It's a useful accessory for nature viewing, but don't try to use it for star gazing. Because of how they're constructed, with multiple reflecting surfaces, erecting diagonals lose a lot of light, something you can't afford when looking at distant, dim images. Worse, they produce ghost images- for every star or planet, you'll see a dim twin nearby. Save it for daylight use, and you'll have no problem.

This prism is needed if you intend to use your telescope for terrestrial viewing and photograpy. If you do not use it, your image will be inverted.