Pentax O-RC1 Remote Control
A simple item that didn’t come with the 645D camera was a remote control. The Pentax O-RC1 is a simple device that allows you to fire the shutter without pushing the shutter release button. This is great for self portraits and family photos as it avoids the self-timer dash. More importantly for me, it means I can eliminate any micro wobble that may occur when pressing the shutter release button on a tripod mounted camera. As a bonus the remote control is waterproof, which in rain soaked Okinawa is probably a good idea.
The remote control also works with other 2010 Pentax cameras including the Optio W90 
TRAVEL 67 : Chris Willson Photography 
Don’t you have the two-second timer on the 645D? You press the shutter and the camera locks up the mirror, waits two seconds, then takes the shot. On small-format cameras it also explicitly disables the antishake system. It’s a one-button long-exposure function, basically. Of course, a remote is still useful, but you don’t need it specifically to avoid camera shake.
Interesting…
Not sure if the camera has a two second timer. Will have a look at the (Japanese) manual and see. I did find out that the remote does allows you to start and stop the bulb setting which is really useful. Hoping to try some star trails sometime soon.
Indeed, I too use the 2 seconds timer on my K20D and MZ-S for my long exposure shots as it eliminates possible camera shake of the mirror-up. I’m sure it is on the 645D, on my K20D it is accessible via the Fn button, up arrow (some of these menus seem to be common among the later Pentax Digital cameras.)
I found that I can set the camera so when I press the remote control it raises the mirror and then 3 seconds later fires the shutter. Clever stuff.
Handy that remote, and you should be able to use with the varius options.
The 2s timer is great, however, if you are interested in bracketing, or anything requiring multi-exposures, there is a problem with this timer: the first shot is delayed by 2s, which is good, but all shots after the first one are also delayed by 2s, which is not convenient (at least not in all cases). I tried to use the 2s timer for a series of shots to build up a 360°x180° picture, in HDR mode, this requires roughly 24 series of 5 exposures. Using the timer would have resulted in excessive delays for the bracketing to be successful (people moving around for example), plus useless time waste. I think the 2s timer should operate only for the first shot of a bracket, and the mirror should stay up between all shots of the bracket. Just my 2 cents…
You can just use the “Mirror Up”, switch, and the mirror will stay up for all of the shots in a bracket series.
I have also confirmed that you need to have the “One Push Bracketing” enabled (disabled by default) for the above to work. But is does work.
hey im kinda new with this camera and i got the remote y dont know how to synchronize the remote to the camera! need some help plis
Hello….I want to know that what is the main power for the Pentax O-RC1 Remote control??
Lithium battery I think.
What is the model number of that battery??