I am looking for an adapter to use my pentax lenses with samsung nx 200. The adpter must have the ability to open/close the aperture. Can you please recommend one, you have experience with and is working flawlessly? Right now I own basic adapter like this and the problem is that there is a tiny play between the adapter and the body and i'm getting lens attached/dettached messages all the time, which is annoying. Thanks for suggestions.