Alternative to a hard edge graduated ND filter

[owen]

Hey guys I was just thinking. I don't have a ND filter, but since it reduces the amount of light reaching the sensor wouldn't another way to achieve this be to just place a black card along the top half of the image (or the bit you want to affect) and then whip it away halfway through the exposure? Of course this would only work with longer exposures, but is there a problem with this idea?

Cheers,
Owen.

[Aussie Dave]

you could perhaps accidentally bump the camera and introduce camera shake into the photo, by holding something in front of the lens, then moving it.

Depending on the situation, you could always bracket your exposures, one for the dark areas, one for the bright areas.

[gecko]

I'm not sure about your idea Owen, but I would be interested in hearing of others experience with a ND filters. I am considering getting a cokin P series graduated filter for landscapes.... any advice?

Cheers
Gecko

[Dug]

Have you seen the multi exposure thing on PSCS 2?

take 5 to 7 exposures of the same scene and it will automatically mask and average the exposure into a single image.

great for shooting interiors with a view in full sunlight.

just a personal thing I hate cokin filters way to fiddily all I ever use is a polarizer.

[redline]

instead of holding the card steady in front of the camera why not try using a dodge/buring technique and move it up and down the area you wanted held back? works better for long exp scenes of course

[DaveB]

instead of holding the card steady in front of the camera why not try using a dodge/buring technique and move it up and down the area you wanted held back? works better for long exp scenes of course

I've seen this done successfully (so Owen there's an answer to your question).

But it's not a technique I use myself - I take bracketed frames and then blend in-computer where I can take my own time at defining the appropriate borders.
Like Dug the only filters I use in the field are polarisers (except I don't spell it like an American ).