Difficult to plump on either Alan. I only ever try and produce shots like this when the mood takes me and that tends to be in great light with indifferent details. With the 200mm shots of approx 1/5s I have little control but know what I want. If I use a 3stop ND filter and have a slightly longer shutter speed then I can control things. The 200mm shots are usually done into the light and I use a deep lens hood to stop flare so can't use my Lee filters. I still find it a matter of luck whether it works or not with my success rate is probably about 1 in 20 although sometimes it just doesn't work. I have booked a 1 day workshop with a well known ICM photographer Andy Gray I am happy with my best shots but only use 1 technique either swing side to side or up and down. He produces images totally different from me and it will be interesting to see how he does it even if I never use his techniques. http://andrewsgray.photography/ Ken
