Pentax ist - Manual (Page 152)

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Remote control Infrared remote control. Starts after approx. 3 sec. by pressing the
shutter release button on the remote control. The operating distance of
the remote control is approx. 5 m from the front of the camera.
Power source One 3V lithium battery (CR1620)
About 30,000 commands can be issued using the remote control. If the
battery is exhausted, please have it replaced at your local Pentax
Service center (there is a charge for this service).
Dimention 22mm {W) x 53mm(H) x 6.5mm(D)
Weight 7g
Specification for Remote Control (Optional)
SPECIFICATIONS TABLE