After hours of playing with my new Nextar 11 I began to notice a strain on my eye. I am a professional photographer and never experienced this as it is not nessessary to consintly look through the lens. I came across Celestrons Stereo Prism Binocular #93690 eyepiece (for lack of a better word) This unit requires two of the same eye pieces to be used and fite where a single eyepiece would go. The results are amazing. It yeilds a 3D effect along with allowing you to spend hours upon end viewing with no strain, as both of your eyes are open. Any questions regarding this little seen product, feel free to email me at gman77@ix.netcom.com