The Grad ND Battle: Physical vs. Digital Filters

Grad ND filter used on a landscape of a sunrise and wheat field.

Capturing high dynamic range images like this can be accomplished with an ND grad filter

Recently, I wrote an article on outdoor landscape photography in the mountains.  In that article, I mentioned that I brought a graduated neutral density filter for the shoot and used it heavily.  It was mentioned in the comments of that post that a grad ND is useless because the same effect can now be accomplished in post.

So today, I thought I would respond with an explanation of why I use a physical grad ND filter instead of doing it in post.  Also, I argue against my own argument (in a totally non-schizophrenic kind of way) to help you to understand why many photographers have stopped using a physical grad ND filter.

What is a Graduated Neutral Density Filter (ND Grad)?

Grad ND is landscape photographer code for a “graduated neutral density filter.”  If you have ever seen a car’s windshield, you have seen a grad nd.  At the top of most windshields, there is dark tinting that fades to clear.  The purpose of the tinting on a windshield is to block out some of the bright sunlight coming from above while not darkening the driver’s through the windshield toward the middle of the window.

A graduated neutral density filter works in the same way.  It is simply a glass filter that has dark tinting on the top of the filter and fades to clear.

Grad ND filters are most often used by landscape photographers to hold back the bright sky without darkening the land portion of a scene.  This helps to balance the exposure and produce a dynamic range that is within the recordable range of a DSLR.

Landscape photographers use ND Grads constantly.  In fact, it is rare that I go through a landscape shoot without breaking out the Grad ND at some point.  I use Grad NDs frequently because I have recently fallen out of love with HDR.  In fact, I haven’t fired up Photomatix in several months.  Using a grad ND is a method for me to average out a dynamic range without the loss of image quality inherent in the HDR process.

Boise Foothills at Table Rock

I had to use Photoshop to apply the Grad ND filter effect on this picture. A physical filter simply wouldn’t be capable of darkening the sky without affecting the jagged rock face.

Advantages of Using a Physical Grad ND Filter

Advantage #1: The photographer can see the Grad ND effect immediately, which allows her to adjust the effect to match the scene.  This way, you can completely avoid the horrible sinking feeling of going home, loading your pictures on the computer, and seeing that you totally messed up the shoot because you can’t fix something in post.  If you make a mistake in the field, you can change it immediately.  If you realize the mistake at home, you may have to re-shoot if you can’t Photoshop it.

Advantage #2: Time.  It takes about 5 seconds to hold a graduated neutral density filter in front of the lens.  While it can also be easy to apply a grad ND effect in post-processing, it can also be somewhat time consuming if it is a tougher fix.

Advantage #3: Physical grad ND filters work somewhat better for scenes with complex shapes covering part of the sky.  Suppose you have a bright sky in front of a rocky landscape in front of you.  The rocks throw deep shadows on the land.  This scene has much too high of a dynamic range than can what can be capture in one traditional photo.  To complicate the matter, there is an aspen tree on the side of the scene that towers above the horizon.

With a physical graduated neutral density filter, the light in the sky can be held back without creating any unnatural look on the leaves of the tree.

If you tried to approach this scene by using a digital grad ND, it could become quite difficult to properly expose the tree and darken the sky without creating an unnatural ring around the tree.  In my experience, the physical grad ND filter works much more effectively in this situation.

Advantage #4:  Applying a grad ND effect in post usually requires that the photographer brackets the photos to have an underexposed version to add to the correct exposure.  This is how the digital grad ND effect is applied.  Bracketing causes problems when there are moving items in the scene, it increases the amount of photos you need to store on your computer, it complicates the workflow, etc.  It is significantly easier to manage one correct photo instead of 3 photos that need to be smashed together to produce a clean file.

 

Using Photoshop or Lightroom to Create a Grad ND Effect

Photographer uses a computer to apply effects on photos while sitting on a mountain.

If you look very carefully, you can see that this guy is applying a grad ND effect with Photoshop (totally not true).

Advantage #1: You can customize the gradiation of the ND effect to perfectly match the scene.  Most photographers only have one or two different Grad ND filters and sometimes you want more or less darkening at the top of the photo.  Applying the effect in post allows for that customization of how quickly the neutral density fades to clear.  It also allows for more complex-shaped skylines (such as when hills or mountains cover part of the sky).

Advantage #2: Cost.  Cheap grad ND filters can be purchased for as little as $20, but most of these filters cause ugly color shifts in the graduated nd part of the picture.  A quality grad ND from a company like Lee or Singh Ray (my personal choice) can cost from $80 – $150 US Dollars.

Conclusion

There are a few good reasons to use a physical graduated neutral density filter rather than a digital grad nd filter effect.  If you are a serious landscape photographer, then purchasing a physical grad ND filter would be the recommendation of 90% of landscape photographers.  If you only rarely shoot landscapes or you just love pushing pixels in Photoshop, then purchasing a graduated neutral density filter may be an unnecessary expense.

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Comments from the I.P. Community

  1. says

    The two biggest reasons for me are
    1. (sort of) increases the dynamic range you can capture in one photo (your point 4 above).

    2. I have a day job where I work in front of a computer. If there’s any way I can avoid having to work in front of my computer with my hobby, I’m going to take it!

  2. says

    Thanks for this post. I’ve recently been researching grad NDs. I want the control when I take the pic. One question I have is about holding the filter in front of my lens. I’ve seen some people do this and you mention it above but it seems like if I move during the exposure, that will show up on the image. Is that not really a problem? Are you really good at holding it still? Is a filter holder a good idea? Are there different kinds and does one tend to work better than another? And so on.

    Many thanks!

  3. says

    I’m definitely in the digital camp:

    1. I already have the software. Why purchase additional equipment for the same results?

    2. There is less to go wrong in the field. Another 3+ items (you need multiple GNDs for different situations) to keep dust-free, scratch-free and fingerprint-free? No thanks.

    3. Digital gives you more gradient control. What about that tree protruding into the bright sky? If it’s in the middle of your frame good luck keeping detail in it while also bringing down the sky.

    4. Digital gives you more exposure control. I am really picky about my exposure and only working in the 1-stop intervals GND’s come in is annoying.

  4. says

    I guess I’ll weigh in on this one since I was one of the nay-sayers over on the original post.

    I’m not going to make a blanket statement and say that grad ND’s are absolutely no good for anybody. I know a guy who uses the Cokin system quite effectively to get his shots to look great SOOC. He makes some decent money that way.

    But that setup just doesn’t work for me. It’s not how I roll. What’s more, I’m beginning to resent some of the bloggers out there showing me their mediocre images and saying, “You absolutely cannot get this shot unless you have this filter.” Or, “Having that warming filter really saved the day for me.” What, you can’t move a white balance slider in Lightroom?

    Oh wait a minute, I see what’s happening. These same bloggers also conveniently place affiliate links on their site so you can buy these filters and they can get a cut of the action. Never mind.

  5. says

    @Rick – I certainly agree that there is nothing wrong with doing the filter digitally. There are times that having the physical filter can really be helpful for the way I shoot, but there isn’t anything wrong with doing it in post.

    About the affiliate links on many sites, I agree that there are times when they become strictly advertisements; however, remember that 99% of all photography blogs would either disappear or need to charge for the content without them. Also, bloggers can mention ANY product and get the same percentage off an affiliate link to Amazon, so I really don’t see how it impacts the recommendations. I guess I kind of see the “you’re just saying this because it’s an affiliate link” thing as being a bit of a cheap shot.

  6. says

    I hope that comment didn’t come out wrong. I don’t mean to seem annoyed at all. Your comment was totally appropriate. I’m just speaking in general terms.

  7. says

    I don’t mean it as a cheap shot, and I certainly understand the need for revenue. Especially if you’ve got a blog that’s getting hits in the tens of thousands. I just see a bit of a disconnect, and a potential conflict of interest when I see a post about some great camera product, then I see a link to somewhere that lets me buy that product. It happens all the time, I know, but I just have to wonder about how quickly a blogger is going to write something negative when there is potential money to be made.

    And looking back on my original comment…it came across as pretty sarcastic, and that’s not usually how I roll. Must have just been a bad day or something. Sorry.

  8. says

    @Rick – I didn’t see your original comment as being sarcastic. I think it was perfectly reasonable. I just wanted to make sure there wasn’t an understanding about the affiliate links. I can see from your comments that you clearly understand how it works and the purpose of them.

    I totally agree with you. There are times that I read articles that are written only to get to the top of Google for “Whatever Widget” Review. Then, they write a glowing review and grab a portion of the sales of that product. You’re right. I see that constantly. It is certainly a temptation, but I always remind myself that the real value of this site is in the readers, not the clicks.

    Thank you for the comment. I think we see eye to eye on this one.

  9. says

    @Bill gorton: Absolutely agree. As someone who started out in film photography and learned the proper way to use filters to get great prints SOOC, I have a certain affinity for them still.

    However, having said that, I am also a huge fan of digital tools that allow you to do things with a much greater level of pixel-level control than you can do in the field.

    Let’s face it, the majority of photographers these days are not just picture-takers…they’re picture-Makers.

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