External mic puzzle with K70


Aero

Link Posted 09/07/2020 - 11:13
Hi, guys. I'm hoping to get some advice from any of you who are into video. I'd never bothered with the video function on my K70 but took a short clip at a music gig and was quite impressed. Bought a relatively cheap mono shotgun mic to explore things a bit further but now read in the K70 manual: "A monaural microphone cannot be used with this camera." I find this odd because the mic is fitted with a stereo plug and I assume it just sends the same mono signal to both input channels. I would try it it anyway but the manual warns that using a microphone outside of spec could "cause the camera to malfunction". Don't want that. Any comments? Thanks in advance.

R o b

Link Posted 18/07/2020 - 12:33
This is purely speculation, but here are two possible reasons for the warning about not using mono microphones

1. Having just had a look at the manual, the microphone socket can also be used to connect a cable switch. This probably shorts between two of the connections to take a picture, and perhaps a mono jack would continuously short and confuse the camera into continuously taking pictures? Having looked up the cable switch it seems to have a four pole jack plug, so I don't know where that leaves this theory.

2. The camera provides 2 volts to power an external camera. Perhaps a mono jack plug would short this voltage? Having looked at wikipedia, it seems as though a mono plug would short the righthand microphone power supply to earth:

https://en.wikipedia.org/wiki/Phone_connector_(audio)#/media/File:Jackplug-wiring.svg

That's probably why your mono microphone comes with a stereo jack plug.

So would I try plugging in your microphone into the K70? I'm not sure...

Anyone else got a better answer, or indeed tried plugging a mono microphone with a stereo plug into a K70?

Robert.

Aero

Link Posted 19/07/2020 - 12:51
Thanks for your thoughts, Rob. I think I'll leave it alone until I can contact Pentax directly, although the answer will probably be "Follow the instructions". Oddly, the microphone came with an extra cable to connect smartphones, tablets and Macs. The jack has four contacts, like the K70 remote shutter release. Beats me.
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