Don’t have a neutral density filter on hand? Then use your hand!
posted Saturday, February 6, 2016 at 8:34 AM EDT
Rutherford doesn't own a hard-edged graduated ND filter as he's often relied on post-processing to achieve a similar effect, but he found that simply using his hand to cover up the brightest areas of the image (the sky in this case) during a long exposure allowed him to get the desired results out in the field.
At first, he leaves his hand in front of his lens for roughly one-third of the exposure and then he goes from there. He uses this technique during exposures that are longer than thirty seconds, although he says that it can work for shorter exposures as well. One thing that you would have to worry about in brighter conditions is your hand being lit up enough to be exposed, but if it twilight, that shouldn't be an issue.
One way to achieve the same effect without the risk of exposing your hand would be to use a piece of black construction paper or dark cardboard material. This would provide you with a straighter edge too. Of course, part of the appeal of Rutherford's approach is that you don't have to bring anything extra with you out into the field.
If you're looking for an affordable solid neutral density filter and you don't mind packing along something extra, check out this article at Instructables about how to make a 10-stop neutral density filter using welder's glass ($10) and a few other items you might already have on hand.
(Seen via PetaPixel)