Features:

    ▪    Color:  Black Satin exterior; Black Matte interior
    ▪    Magnification:  0.50x
    ▪    Crop Factor for Pentax Q, Q10:  2.8x
    ▪    Crop Factor for Pentax Q7, Q-S1:  2.3x
    ▪    Maximum Output Aperture:  f/0.666 (with f/1.2 lens attached)
    ▪    Rectilinear Distortion:  < 0.666%
    ▪    Lens Elements/Groups:  6/4
    ▪    Length Reduction:  10.1 mm
    ▪    Supported Cameras:  Pentax Q, Q10, Q7, Q-S1
    ▪    Camera Mount:  Pentax Q-mount
    ▪    Image Format:  7.44 mm x 5.58 mm (1/1.7”)
    ▪    Lens Mounts:  Nikon F/G (include non-AI & AI lens mounts)
    ▪    Lens Compatibility:  Any full-frame (36 mm x 24 mm format) or DX format (APS-C) lens with the appropriate mount can be used.
    ▪    Special Features:  Long-throw clickless aperture ring on Nikon F/G version. Industry's best aperture ring covers a 8-stop range markings, clearly indicating actual number of f-stops. No more guesswork! (Patent pending).
    ▪    The tripod foot is detachable and compatible with Arca Swiss, Markins, Photo Clam ball heads.
 
Tips: Before mounting your lens to the adaptor, please make sure that the f-stop of aperture ring on the adaptor is turned to "7" (i.e. mounting your lens to the adaptor while only the aperture ring in the adaptor is full closed.).

Remark: This mount is manual aperture control. It does NOT support electronic aperture control.

Disclaimer: we are NOT licensed, approved or endorsed by Pentax or Nikon

List of incompatible lenses

Nikkor 2.1cm f/4
Nikkor AI-S 20mm f/2.8
Nikkor E series lens (the diaphragm blades are not operated by mechanical linkage levers, such as  Nikkor 105mm f/1.4E, PC-E 24mm, 45mm, 85mm T/S, and Nikkor AF-S 16-80mm f/2.8-4E ED DX VR)

Description

“The Devil’s Speed Booster”, exclusively for Pentax Q series cameras.  With its 0.5x magnification and world-record f/0.666 maximum speed it is crazy wicked fast.  So make a deal with the devil today and turn your Pentax Q with its back-illuminated sensor into a monster low-light machine unlike anything ever seen in photography.  Attach an f/1.2 lens and stop down a little to see how Stanley Kubrick made do with f/0.7 for filming those famous candle-lit scenes in “Barry Lyndon”.  Or open up all the way to f/0.666 and probe the darkness in a way that no photographer has ever been able to do until now.

With an advanced 6-element optical design, the Q666 packs lots of optical horsepower in a small package.  Sharpness is excellent even at f/0.666, and is downright superb if you stop down to f/1.0.  Distortion is very low, with a maximum value of, naturally, 0.666%.  And thanks to the back-illuminated sensor used in Pentax Q cameras, the full f/0.666 maximum aperture can be utilized with minimal pixel vignetting effects commonly seen in other cameras used with high-speed lenses.