Neutral density what? Neutral density filter.
The principle behind the filter is rather straight forward: Essentially, a neutral density filter is a dark piece of glass placed in front of the lens that allows less light into the camera through the lens. This means you need a longer exposure to get a properly exposed image. This is great when working in an open field on a bright, cloudless day, or when you want motion blur.
I suppose that was my reaction twelve years ago. Well, that and the idea that, once again, I needed to buy more gear. Another gadget. Another object that would live in my camera bag.
Truth be told, for a very long time now, I haven’t needed to use a filter. But, my Pentax 6×7 55-100 MM lens changed that. The face or mouth of the lens is 95 MM wide, and, given the design of the lens, light pours in. I’ve been able to “control” that by significantly under exposing – 2 or more F-stops – but there are times when that isn’t enough. Example: Photographing water. Sometimes I want that long, silky, smooth, blur. With that lens, not going to happen unless it is nearly dark or very overcast. Even then…..
Try finding a 95 MM neutral density filter, by the way. Not easy.
In the May edition of NyghtVision Magazine, we will be reviewing neutral density filters from Sirui and Irix. The Sirui is 72 MM and will fit my Pentax 645 lenses. I will use the Irix on the vintage Pentax 55-100. You can see the Irix filters here. The Sirui can be found here.