Provided camera has a 2.5mm remote cable jack:
You can just buy a 3 pole plug adapter for $6 or under. You can find them in 3.5mm to 2.5mm or 2.5mm to 3.5mm depending on which remote you have. Yes, you can use any of the compatible 2.5mm cable remotes on the K-70 with an adapter. A 4 pole adapter isn't need because the K-70 remote/mic only uses the 3 poles.
If you have the remote for the K-70 you want a 3.5mm female to 2.5mm male adapter. If you have the remote for any of the other Pentax you want a 2.5mm female to 3.5mm male adapter. 3 pole works fine but you can find the 2.5 to 3.5 with a 4 pole male plug if you want. Doesn't seem to matter.
There are several threads on this.
https://www.pentaxforums.com/forums/193-pentax-k-70/323526-about-wired-remot...ml#post3828745
Eventually the cheap "universal" cable remotes that come with various plug adapters will include a 3.5mm plug.
Last edited by Not a Number; 11-01-2017 at 06:05 AM.