@dh No, I didn't use a filter. It was shot in the evening, and it was quite cloudy, so the light wasn't too strong. I set the ISO as low as it would go, the shutter on 3 sec and adjusted the aperture till I ended up with this. The camera has to be still while the photo is taken so I placed my camera on the ground (though a tripod can also be used of course) and set a 5 sec delay on the shutter. It's actually quite easy.
!