The Pentax PF-CA35 allows photography using Pentax K-mount 35mm & digital SLR cameras with the fabulous line of 65mm, 80mm & 100mm spotting scopes. It is not used in conjunction with an eyepiece, but rather you remove the eyepiece and attach this device where the eyepiece would normally attach to the spotting scope. You then attach your K-mount camera to the side of this device which is not screwed into the spotting scope & you're ready to shoot.
All ventures in the world of telescope photography require the use of a sturdy tripod, first and foremost. Logical choices for a tripod/head combination are indicated here as accessories, with an ascending order in price & support. You must take great care to keep vibrations during exposure to an absolute minimum. Employing a cable release, electronic release or remote control for tripping the shutter is absolutely necessary. And while it is not necessary per se, a mounting bracket will do wonders to reduce vibrations of your rig.
Your camera will need to be in fully manual exposure mode, although some Pentax cameras may also work in aperture-priority autoexposure mode. Additionally, the switch on the camera which chooses the focus mode must indicate manual focusing.
Push-On Front & Rear Caps
Pentax PF-CA35 K-Mount SLR Camera Adapter