Capture
Split ND filters ... what was old is new.
Wednesday, October 7, 2009
For many years I have discounted the use of Graduated Neutral Density filters (often referred to as Split ND filters) as old fashioned and unnecessary. After all, a couple of bracketed exposures in Photoshop with a gradient mask and you have the same thing. Interestingly enough, despite that philosophy I realize now that I have very few images where I have applied this technique. Usually it’s more a case of complicated masking, not always successful, instead of a simple gradient mask.
A few months ago a friend of mine told me to check out the work of Patrick Smith .. something I highly recommend. Even though the ocean waves hitting the shore are one of my favorite things to shoot, I have always struggled trying to capture it in an artistic and pleasing way. His images are absolutely stunning. His technique relies heavily on ... you guessed it ... Split ND filters. I decided it was time I actually tried them to see what they offered, so I purchased an inexpensive set of 3 Cokin filters and my next trip to San Diego gave them a try. This image was one of those that resulted from that first experiment ...

“Seaweed”
PhaseOne with P65+ back
Mamiya AF 55-110 f/4.5 at 55mm
ISO 50, f/22, 4 seconds, 0.6 and 0.9 SplitND filters
What I found surprised me. First I realized why my attempts using Photoshop really didn’t work the same. Using Photoshop I almost always used a gradient mask with a very narrow transition area ... I tried to nail the transition area exactly. This means on anything but water it wouldn’t work at all. A Split ND filter has a much softer and wider area of transition. In Lightroom and Adobe Camera Raw it is actually much easier to simulate a Split ND filter than it is with Photoshop ... the gradient tool works very well to adjust the amount plus the transition. Unfortunately most of the time when needing a Split ND filter, a single capture adjusted in the RAW editor won’t cut it - the dynamic range is just too extreme. Add to that the challenge in Photoshop is adjusting the gradient or transition, you just have to do it again - and again, and again, trying various positions of the gradation as well as width of the transition. No handles to drag it around or resize the transition (mmmm ... nice feature for CS5. Wonder if Adobe has thought of that?). Anyway, it’s a pain and slow. So much for “just doing it in Photoshop”.

“Golden Rays”
PhaseOne P65+ system, AF 55-100 f/4.5
ISO 50, f/32, 2 seconds with 0.6 and 0.9 SplitND filters
The second thing I found was the ability to “see” what I was getting as I was shooting. I could adjust the various filters and their placement. Very often using two filters is necessary anyway, and thus you actually have two transition areas to blend. This leaves you with a lot of creative possibilities when using the split ND filters. I still have a lot to learn, but all of the images on this page look pretty much like they did on the camera when I took them. Other than a few minor adjustments, there isn’t any post-processing.
Could this have been done using Photoshop and multiple captures? Most likely so, and in fact that will be my next experiment ... how to exactly duplicate the effect of a split ND filter using multiple exposures and Photoshop. Split ND filters are a terrific tool to achieve some remarkable images. No philosophical motives here at all ... doing things at capture is just a different way than doing these things in post processing. For my skill and workflow however, the Split ND filters will always be in the bag from now on. As a good friend put it “what was old is new”. After that first experiment I purchased a set of Lee Split ND filters, 5 in all as well as adaptor rings for my various lenses. The sunrise and sunset images on this page were taken with those. The Cokins had a slight color cast, the Lee’s, while more expensive, are very neutral and optically very clear.
“Tuscan Sunrise”
Canon 5D Mark 2 with EF 70-300mm DO at 90mm
ISO 100, f/10, 1.3 seconds with 0.6 and 0.9 SplitND filters