Vintage Albinar-ADC Auto 2X Tele Converter P/K Pentax‎ K Mount Case Caps Manual

Brand: Albinar  Model: Albinar-ADC Auto 2X Tele-Converter P/K designed for Pentax K mount SLR cameras.  Type: 2X teleconverter that doubles the effective focal length of attached Pentax K mount lenses.  Mount: Pentax K (P/K) bayonet with metal mounting surfaces, alignment dots, and auto-aperture coupling lever.  Color: Black barrel with silver metal mounts and white engraved lettering.  Optics: Multi-element glass; glass is clean and clear, free of scratches, haze, or fungus based on visual inspection.  Exterior: Textured grip rings for secure handling and rotation; side markings read Albinar-ADC Auto 2X Tele-Converter and P/K.  Included accessories: Front and rear plastic caps (rear cap marked ASAHI OPT. CO MADE IN TAIWAN R.O.C.), black leatherette cylindrical case with red felt-style interior and snap closure, and folded paper 2X TELE CONVERTER INSTRUCTIONS leaflet printed in Japan.  Case details: Black leatherette case embossed JAPAN on the back with stitched edges and belt loop tab, fitted to hold the teleconverter snugly.  Instruction leaflet: Explains attachment, exposure adjustments, and tripod recommendations, and includes a Focal Distance Conversion Chart (Unit: mm) listing Prime Focal Lengths 50, 55, 85, 100, 135, 200, 400, 600 and corresponding values with 2X Converter 100, 110, 170, 200, 270, 400, 800, 1200.  Usage status: Teleconverter has not been tested on a camera body or lens, so operational performance is unknown.