Just tried PTP mode with Pentax Native, ISO can be set, but not exposure time - I tried both Bulb modes - Start/Stop trigger pulse and constant pulse, no changes.
Nothing works in PTP mode with Pentax Legacy.
So, if we could have an exposure start pulse and an exposure stop pulse, that would make the day, It should be a feature you can activate/deactivate in case you use a camera like the KP or K-1 which is supposed to be working with the Pentax SDK.

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