Using GND filters on a Digital Camera: Part 1

I have received several questions on my blog about the use of Graduated Neutral Density (GND) filters, or better what these actually are. So I decided to come up with a little series of posts in three parts, trying to explain what these actually are, and what is required and how I use them.

Why do I use them?

From the moment I started to become more seriously interested in photography I was fascinated about the technical aspect of getting a “proper” exposure. Since landscapes had been my main interest from the beginning, I quickly learned about the limitations of digital sensors. Whatever I tried to achieve, my images were never nowhere near (besides a few exceptions of course) to those images that I saw and liked in magazines, books or one the web.

It was frankly a little frustrating, but I tried to figure out the reason why my images looked so much different. Besides the amount of Photoshop, the most significant difference was that I realized that all my favorite images captured the whole, or at least a wider dynamic range of the scene than my images did. No blown out skies, dark foregrounds or just overall boring exposures.

I learned about HDR then and experimented with that for a while and came much closer to the look that I wanted to achieve. Also I learned about the possibilities to blend two or more exposures in Photoshop. Whereas these techniques are great and actually provide more flexibility it didn’t feel right for me, since the first time I could then see the final image was after the post-processing. For me it feels just better if I would get the shot right in camera first.

The more I investigated in this, it did strike me was that a lot of my favorite photographers used all kinds of filters, most notably so called Graduated Neutral Density Filters, which at least at that time felt a little old fashioned to me in this digital age. But the more I learned about the purpose, benefits and also weaknesses of these filters the more interested I became. I looked up information everywhere on the web and I decided to get some.

As easy as that may sound, it’s a little confusing if you have no store nearby where you can go an have a look at them, or check out what you actually need to start with. There are holders, slots, adaptor rings and so on. And even though I did some research, what to get first and so on, I was still a little confused by all the possibilities. Most of the time I just read a description, but I never saw an image of what I actually would get and need.

I thought that this might occur to other people as well and want to bring a little clarity into this by writing a little series of blog posts related to this.

Sounds cool, but how do they look like and what do they do?

 

On this image you see a 3 stop hard Graduated Neutral Density filter from Lee Filters. As you can see the upper part of the filter is dark, while the lower part is clear. That means the dark part is exactly three stops darker and the transition from is hard. These filters are also available with a soft graduation, where the graduation process encompasses a wider area, like you can see in the following example:

The purpose is to make one part of the image a certain amount darker than the other part in order to take away the exposure from the brighter part of the image. This usually is the sky, but can also be another part of course like bright reflections in a lake/river, snow etc. In a upcoming post I will then explain why there are hard and soft filters.

The color used on these particular filters is neutral gray, which will be invisible on the image and should not create any color cast, which are said to be created by filters which are just using a gray tone.

Assuming you attach the filter to the lens, whatever you will shoot, the top part will be three stops darker than the lower part. In other words, if the sky in your image is three stops brighter than the foreground, and you use this filter, the whole dynamic range of the scene should be correctly exposed. So the foreground wouldn’t be too dark, or the sky just a blown-out white all done in camera. Isn’t that great!

In part two of the series I will post, what you will need to have, in order to attach these filters to the lens.

If anything in here is wrong, or if you have any questions or further comments you’re welcome to leave me a comment.

5 Replies

  • Surprisingly I know all the theory behind these things, but have never taken the time to learn how to *use* them. I'm looking forward to the next post too.
    This one was a good introduction.

  • Thanks for the guide. I can't wait until the other parts come out. One question, In your example of the sky being 3 stops brighter what do you make the final exposure for? The Sky or Foreground? What are the steps? Take a reading on the sky and then the foreground, set it to the sky then slap on the filter????
    Thanks
    Rob

  • Thanks for your comments. I'm glad you enjoyed my post. This will keep me going in finding the right sentences.
    @Rob: I do not want to get into detail here now, since I don't want to spoil my own upcoming post since I will answer your question in Part 3 of this little series. But in short: meter sky/foreground, check difference and then expose for the foreground. But pssst! 😉

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