using dark filters i.e ND one

[valaman]

I've been reading up on ND filters after being very impressed with the long exposure pictures on this site and elsewhere and am wondering how does the camera auto focus on a subject/area if the filters are so dark?

[Nicole]

Most ND filters aren't so dark that the camera can't focus. However, for the very strong ones that are, people tend to focus first without the filter then switch to manual focus or apparently in some cases using live view and focusing manually will also work. However, for the 1, 2, and 3 stop ND filters you won't really have a problem focusing.

[OsmosisStudios]

Using a 3-stop ND filter on my camera is fine with most lenses, though the focus is slow and not always accurate. Most of the time that filter is reserved for my film kit which is manual focus anyway

I have a 10-stop filter, and it's almost opaque. No way you'll get AF through there: you cant see a thing. Its a filter you use on a tripod when youve got the time and patience to take the filter off, compose, focus, etc, then set the camera to manual focus, set your exposure, replace the filter, and so on.

My usual set up is camera on tripod, lens, wired remote, filter on and off as needed to get the shot, Me standing there with a stopwatch like an idiot because Ive got an 8minute exposure in the evening.