I have posted a few photos to flickr this month wherein I explain my Black Sock/Black Masking technique. Those photos have garnered a little bit of interest so I thought I’d delve into the particulars of the technique here. I guess you could consider this Amendment 1.0 to the Flash Parker Basic Filter Guide, which can be found right here, if you are interested in such things.
Let’s begin with a question: why am I placing a black sock in front of my lens in the first place?
Simple answer: to block light from exposing the image sensor. In effect, I am using the sock as a filter. Not a neutral density or a graduated filter, of course, but a full-on light blocking filter. So let’s not even call it a filter. Let’s call it a blocker. The Black Sock Light Blocker.
Why would I want to do this?
I would want to do this when I have a scene with extremely desperate exposure levels. Take, for example, this landscape image right here:
I shot this on a very bright day in the early afternoon. The light hitting the rocks and illuminating the water was fantastic but I had to do something about the sky; the sun was shining so bright that any attempt to create one exposure with my ND1000 (ten stop) neutral density filter resulted in blown out skies. To solve this problem I pulled out a black sock and held it over the top 1/3 of the lens to block any light from exposing on the sensor. I did this for roughly 12 seconds; this means that the rest of the frame exposed for a full 30 seconds while the sky and mountains had only 18 seconds to record as data.
Yes, I could have added a Neutral Density filter here, but adding more glass on top of a lens already sporting a filter is going to degrade image quality. I could have used a black card, too, but I didn’t have one handy. Thus the point of this exercise; you don’t need any gear to create interesting long exposure image. Just an itchy trigger finger and sweaty feet. This can help lighten your kit for those long haul journeys across the world.
This is a very simple trick and one that you can experiment with over and over; in some cases it can help you avoid tedious hours in post production combining exposures and will invariably lead to the satisfaction of knowing your stinky, sweaty sock helped create some beautiful imagery.
More black sock trickery: The ND1000 allows me to utilize a slow shutter speed (30 seconds in this case), creating a misty effect over the lake. The black sock blocks light from the top 1/3 of the frame and helps me expose the entire scene correctly. I could have done this with multiple exposures – one for the foreground and one for the sky – but I’d rather spend time shooting than working on Photoshop.
Below: The same scene, this frame shot without the aid of the ND1000 filter or the magical black sock. In this image I’m using a Circular Polarizer. Notice how the light isn’t mixed in quite the same way; in order to exposure the sky properly I had to leave the foreground elements (water and rock) a little darker. I could easily remedy this in post production but I enjoy shooting much more when I can get everything done in camera.
Things to consider: To avoid having the sock itself (or any stray fibers!) record on the sensor you need to be shooting long exposures of at least 30 seconds. In my opinion 30 seconds is the absolute minimum baseline for using this technique; you’re much safer doing it in the 45 second and up range. Keep in mind that the longer the exposure the more time you’ll be stuck holding a sock in front of your lens – but what would you be doing otherwise?
I’d love to see what you can come up with using this technique. Post any links to your images in the comments and share for all to see.