Bracketing vs. Graduated ND Filters

I’d long ago answered this question, but a comment from Frank B. about this image caused me to reconsider some things.

Cocoa Beach Pier before dawnCocoa Beach Pier before dawn

Fair warning:  This post is a little deep into the weeds.  Feel free to look at the photo and move on if it isn’t your thing.  But I think it’s an appropriate subject, since part of the blog’s purpose is “… and how to photograph them.”

What are we talking about?

Bracketing means taking multiple photos of a scene, each with different camera settings (see this Wikipedia entry).  In this case, I made three photos at different exposures so I could capture the entire dynamic range from super dark under the pier to super bright above the clouds.  Making just a single exposure would’ve risked losing detail in the shadows or highlights (or both).

You can also use a Graduated Neutral Density Filter (GND) – an optical filter you add in front of your lens to reduce light in the bright part of the frame (see this Wikipedia entry).  Typically they have a 2 or 3 stop reduction that transitions into clear.

I’d long ago experimented with GNDs and decided not to use them.  I can  mostly reproduce their effect in static scenes by bracketing and then blending the resulting frames in post-processing.  For landscape images bracketing is an easier solution in the field and gives me more control and a better final result.  You can read about one example of my technique in this post (from back in 2011).

But then … Frank left a comment:

… amazing how the clouds remain sharp compared to the water given the time of exposure

And my reply:

Frank, this is a 3 frame, hi-res exposure bracket hand blended in Photoshop. The bottom portion was at f/5 for 25 seconds. The top was at f/5 for 3.2 seconds. So that and distance is why the clouds are sharp compared to the water.

The way I made this image resulted in a huge difference in shutter speed between the water at the bottom and the clouds at the top.  And using the Olympus Hi-Res mode exaggerated the shutter speed differences since it combines 8 separate captures to create each hi-res output file.

If I’d used a GND the shutter speed would be constant throughout the frame and the blur in the clouds would’ve matched the blur in the water.  In this particular case,  bracketing exposure by varying aperture instead of shutter speed would also make the motion blur consistent.  I’ve never done that since it seemed like it would lead to other issues (inconsistent focus / depth of field).  It’s something to think about and maybe try in the future for a setting where consistent motion blur is important.

Thanks for the question Frank!  Photography is fascinating.  There is so much to think about and still left to learn.

And thanks to everyone else for stopping by and reading my blog (especially if you read all the way through!). Now – go make some photos!

©2019, Ed Rosack. All rights reserved

6 thoughts on “Bracketing vs. Graduated ND Filters

  1. Thank you for explaining more in-depth about your technique.

    As you said: “Photography is fascinating.”

    Photographers use tools and experience to create images for themselves and others to enjoy. When we obtain new tools (e.g., cameras, lenses, software) we experiment to find out how best to use them. As we gain experience and education, we continue to experiment to see how our end-product is affected.

    A valuable part of my own education is discovering blogs such as yours, Ed, where your generosity in sharing experiences and techniques motivates me to try something similar with my own efforts.

    I’ll continue to try everything I can to produce something I like, whether it be new equipment (within very limited financial constraints!), different software, alternate processing techniques or combinations of all of the above.

    Your final image is wonderful!

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