Pentax K to Q-mount Adapter

Features

The genuine Pentax adapter differs from third-party adapters in three ways.  First, it offers a leaf shutter, which lets you shoot and sync flash at up to 1/1000s.  The leaf shutter will also enable you to use slow shutter speeds (the Q is limited to 1/30s and the Q10 is limited to 1/13s in electronic shutter mode), including bulb mode.  When using this adapter, you will hear the leaf shutter opening and closing; it is controlled by the camera using the electrical contacts on the back of the adapter.  Adapters without the leaf shutter (i.e. all other adapters) will not allow you to shoot in bulb mode at all, and the minimum shutter speed will be restricted as stated above.

Second, it supports a tripod foot, which is absolutely essential if the lens you're adapting doesn't have one.  It's no fun to hand-hold this setup, and you can't rely on the camera's tripod socket as the center of gravity will be way off.

Finally, it offers a stepless aperture ring which turns smoothly and is clearly labeled.  Other adapters may or may not include aperture rings (if they do not, then whatever lens you choose adapt needs to have one), and even if they do, they're not going allow you to control the diaphragm as well.  Most only have labels at the extremes.

Because the lens diaphragm operates manually with this adapter, the Q can be used in both Av and M mode: in other words, the camera can always select the appropriate shutter speed for the current aperture setting without any additional user inputs.