Ricoh recommended as follows for the K5/II/s which applies for all Pentax bodies:
(use wayback machine)
http://support.us.ricoh-imaging.com/node/1342
: The following specifications are recommended:
- Format: Stereo electret condenser
- Plug-in Power Method
- Impedance: 2.2 kΩ
- Power: Guarantee of proper operation at 2.0 V
- Plug: Stereo mini plug (3.5 mm)
This means there is a supplied power of 2V overlaying the input which can seriously damage dynamic microphones.
The problem for an external microphone is that
1. if not decoupled it will pick up noice stemming from the camera (antishake etc)
2. it is to far from the source.
A good solution:
Rode Smartlav into smartphone and this connected with your Pentax via adapter
or a good external portable digital recorder.
And yet, not too long recording with any Pentax because of sensor overheating (don't know about the K1 though!)