Brian,
Geoff is correct.
Unlike most other eyepieces, the eyecup on the Pentax really needs to be adjusted to suit each individual observer. An important thing, when using an eyepiece with long eye relief is you CAN'T get too close to the eye lens, otherwise you will suffer blackouts. Because of the longer eye relief it takes a tiny bit of getting used to putting your eye in the right place to observe and adjusting the eyecup correctly. The eyecup has a long travel range to accomodate eyeglass wearers, so if its screwed right down you will need to screw it up a fair way if you observe without glasses. Once you get the eyecup correctly adjusted, and a little practice in where to put your eye, they are extremely easy to use and very comfortable for long periods of observing.
CS-John B
PS: If you are not sure how to adjust the eyecup, this is what you do.
Hold the black section at the bottom of the eyepiece body steady. This is the stepped metal section about 10mm thick that adjoins the chromed barrell. Then turn the top 1/2 of the eyepiece body anticlockwise. The top 1/2 is the section with the rubber fingergrips and the Pentax label on it. As you turn it anticlockwise you will see the top of the eyecup move away from the eye lens of the eyepiece itself. If you don't wear glasses you will need this almost all the way up, but experiment for yourself until you get it most comfortable for you.
In addition the top of the eyecup itself unscrews. Hold the top 1/2 of the eyepiece body (where the Pentax label is) and unscrew the top of the eyecup in an anticlockwise direction. It could be really firm the 1st time you unscrew it, a couple of mine were, but when you put them back on they just need to be snug. The idea behind removing the eyecup is to make cleaning the eye lens much easier, or to fit a camera adapter directly to the top of the eyepiece for eyepiece projection photography. The top of the eyepiece where the eyecup screws is threaded for a special camera adapter.
Its sorta like driving a Ferrari for the first time when the only car you ever owned is a Morri, Gotta get the feel of it
