Originally Posted by EukerVoorn

This is true, the closer you get to your subject (either fysically or by zooming) the shallower your depth of field. You can solve this by using a lot of light so that you can shoot with f8 or smaller @ ISO200. At f8 your DOF is "usable". Holding focus is easy when using a mechanical follow focus. Or use the Panasonic GH2 which has great "push focus".

I've been shooting porn using DSLRs for one year now and yes at first I had a lot of out of focus shots (what you call soft-focus) but now after the endurance I come home with great shots.