Eyepieces & Skywalking Skywalking is the practice of moving through a region of the sky depth-wise. First you view a larger object such as an entire Constellation, then focus on a vicinity within the constellation and then on an object within that vicinity increasing your magnification with each move until you have a large magnification the selected object itself. Pentax has zooming eyepieces like the one on the left, that can zoom through several Magnification ranges. Such lenses must trade-off lens performance at any one focal length, to be able to reach many focal lengths.  For Astrophotography, this is the ticket, for critical work, - you need PARFOCAL eyepieces.  These are single focal length eyepieces that can be interchanged without losing your focus on an object.

To move from one end of your telescope's magnification range to the opposite end will require at least 9 eyepieces.  This can be halved by the use of a 2X Barlow lens already mentioned. To keep the lenses parfocal, the best solution is to select all your focal lengths from a single series of eyepieces from any given manufacturer.  The table on the next page shows the eyepieces required for my telescope equipped with a 2" focuser.  Note:  The last eyepiece in each row is the same as the first eyepiece in the next row.