Are graduated neutral-density filters really useful?

For a few years now I have been using various different filters. I mostly use them to reduce the overall light coming into the camera or to help control reflections. It seems though I always overlooked one type of filter: the graduated neutral-density filters (ND Grad for short)

I honestly thought that graduated neutral-density filters wouldn’t work very well in the real world. While they offer a reduction of light on selective parts of your image, they do so in horizontal lines. Sure, I can use this to cut the light out in the sky, but what about buildings, trees or other landscape elements that go “across the line” like the tree in the image above?

As you can see the sky is well-balanced, but anything else in the upper area sort of turns into a silhouette and looks unnatural. Add to that that there are many free ways to deal with high contrast scenes, and ND grads do not make sense any mode. Here are just a few options:

• Shooting multiple frames at different exposure settings
• Using built-in camera modes like HDR
• Super Fine Detail on the Sigma Quattro cameras that take seven frames at 7 stop intervals to create a high dynamic range raw file. (well, this is kind of DHR too, I guess).

While great, these options can require more time to photograph and edit. They could also have issues even if there is the slightest movement between frames.  Here is something that ios going for ND grads:: at the very least, having a way to control the light in a scene before hitting the shutter could save a lot of time.

K&F Concept graduated filters

The good people at K&F Concept, the same people that sent the variable ND filters I recently reviewed, also sent me some graduated filters to test.

The filters are made of optical glass with anti-reflection, water, oil and scratch-proof coatings which you normally find on high-end filters. They also come with nice little felt-lined magnetic pouches to keep them safe. You will need a 100mm filter holder to use these. Preferably one which allows you to rotate and adjust the area affected by the filters.

There are many types of graduated filter, the ones K&F Concept sent me were a soft 3 f-stop grad and a 3 f-stop reverse grad.

The soft grad on the left is dark at the top and becomes lighter as it travels down the filter. This is great for creating moody skies or to balance the sky when the sun is high. While the reverse grad on the right has a dark band in the middle of the frame and becomes lighter towards the top. This is better for low winter suns, sunsets or sunrises as the brightest part of the sky will be closer to the horizon.

Comparing Grad ND filters

To demonstrate the differences between both types of graduated filters along with using no filter. I took a series of images of the famously well photographed Blackrock Cottage in Glencoe with the Sigma dp0 keeping the exposure on the cottage the same in each frame.

The differences between the filters are easy to see here, the shot with no filter has lost a lot of detail and color in the sky. When I tried to balance the exposure, the ground is got underexposed.

The shots with the filters offer a much better starting point for editing.  Not only is there more information in the sky, but the foreground is better exposed.  This is because I was able to use a slightly longer exposure. This is not something I had thought about before using these filters.

I feel the reverse graduated filter gave the most natural result here with the sun was low in the sky. That said,  I actually really liked the mood the normal graduated filter gave more. I used the regular grad filter version of the image to create this final image.

Optical Performance

Optically the filters are pretty nice; there no loss in sharpness that I could see. Even using my Sigma sdQ-H with 50-100 Art lens at 100mm f5.6, I have noticed that most filters do well at wide angles but can get a little soft at longer focal lengths which is why I tested in this way.

Color shift was a little on the blue side with +9 temp and +8 tint in Adobe camera raw. While there is a tint it can be fixed in editing and didn’t seem to be an issue when shooting.

It’s always nice when you get the chance to learn new things, and I’m glad to say that my initial thoughts were wrong. Graduated filters are a useful tool to have in your bag.  They offer more control over the scene. This means that we can bring back the dark elements going into the sky by applying a +shadow gradient in post. The results create a lovely balanced image, as you can see here in this shot from Loch Ness using the Sigma dp0.

The K&F Concept filters can be purchased for $99.99 for the normal 3 f-stop graduated filter or the reverse 3 f-stop graduated filter which is pretty reasonable particularly when compared to other versions available.