Long Exposure Photography without ND Filters

Canon 7DII + Canon EF-S 17-55 f/2.8 IS USM + B+W Circular Polarizer

ISO 100, 17mm, f/10, 1/5 sec

50 light frames composited with mean by Long Exposure Stacker.

Overview

Instructions for using Long Exposure Stacker are here.

Long Exposure Stacker is a tool for combining images to blur motion and to reduce noise. It can be used to simulate very long exposures to remove the appearance of waves from the surface of water or soften the motion in water falls and clouds. Long Exposure Stacker is an alternative to dense neutral density filters such as 6- or 10-stop ND filters. It might be most appropriate for very wide lenses where there may be difficulties using filters in front of the lens. Because the images are combined, the noise in the final image is reduced. This means that split neutral-density filters may not be needed during capture. Instead, burning, dogging and gradient filters can be used in an image editor, without the risk of exposing noise. As with most long-exposure techniques, it is important that the camera be motionless throughout the all of the image captures.

Like its siblings Starry Landscape Stacker and Starry Sky Stacker, Long Exposure Stacker supports dark-frame subtraction and flat-field correction to further reduce noise and lens artifacts.

Long Exposure Stacker can be purchased from the Apple App Store. A free trial is available. If you are running MacOS Mojave (10.14) or later, Long Exposure stacker is available as part of the Image Stacker Bundle. If you have already purchased an app that is included in  a bundle, you get credit for the app[s] you have already purchased towards the purchase of the bundle. Bundles are only supported on MacOS Mojave and later. The links will not work with the older version of the App Store.

If you have any questions, suggestions or ideas, please contact the developer.

Restrictions and Requirements

Long Exposure Stacker version 1.6 requires macOS 10.14.6 or newer.  More requirements.

Stacking with Generic Image Editing Tools

Other image editing tools, such as Adobe Photoshop can be used to stack images to simulate long exposures. See for example:

From verdantvista.com  Long Exposures with no Filters

From wexphotographic.com How to Create Long Exposure Images Without an ND Filter

From expertphotography.com Photo Stacking: Awesome Daytime Long-Exposure Photography

Long Exposure Stacker is much easier to use than Photoshop and other image editing tools because it is purpose-built for this task. Also, Long Exposure Stacker completes the process in less than half the time that Photoshop requires and uses less memory in the process. Long Exposure Stacker currently shows the results of 6 different algorithms for stacking the images. Some of these are not supported by Photoshop and Photoshop only computes one result at a time. So, if you want to compare two algorithms with Photoshop it will take you (at least) 4 times as long as it would with Long Exposure Stacker. Also, Long Exposure Stacker can align images so it is possible to compensate for a tripod that is slowly sinking into the sand, or to even shoot hand-held in situations where no tripods are allowed.

Advantages of stacking with Long Exposure Stacker (compared to using Photoshop)

• Simpler for the user.

• Less memory required, can be faster.

• Choose among multiple algorithms.

• Automated dark frame subtraction and flat-field correction.

Stacking vs. Using an ND Filter 

Stacking is different from using an ND Filter and yields different (but similar) results. Some people will want or need to use ND filters. For many people stacking may be all they ever need. For the best of both worlds, using a mild ND filter (maybe 5 stops) combined with stacking may allow the most creative options.

Advantages of Stacking over using an ND filter

• No need for a filter. Less to carry. Less to keep clean and dry when working in severe weather.

• Stacking is inexpensive and adds no color cast. Filters tend to be expensive and/or have a color cast.

• The photographer can choose which images to use in a stack, e.g., only images showing reflection on the beach or only images with big splashes or just the right number of images to get the perfect softness in the waterfall without being too soft.

• The photographer can decide after-the-fact how smooth to make movement by varying the number of images that are stacked.

• There are always images to select from to replace things that may be moving in the stacked result with a selection from a single images (e.g., replace moving foliage with foliage from a single frame thus making the foliage sharp but the nearby waterfall soft). As a generalization of this, it is also possible work from a single collection of images and stack a different number of images for a waterfall and the pond below the waterfall to achieve different smoothing effects. Since the same basic images with the same exposures are in both stacks, the exposure and color will be a perfect match in the combined image.

• There is much less noise in the stacked result than in the original images making it easy to bring out detail in the dark areas.

• Stacking works well with all lenses while filters might not work well in the corners with super wide lenses.

• Stacking can completely remove objects moving through a scene while an ND filter will reduce them to ghosts.

• Image alignment can be used with stacking to compensate for accidental camera movement.

Advantages of using an ND filter over Stacking

• ND filters may generate results that look softer or smoother, especially for movement with a long period captured in bright light, for example, ocean waves breaking on a beach on a sunny day.

• There are fewer images to capture, so less storage used and there is less work in post-processing.

• If you need a really long exposure then ND-filters may still be needed. Some people will stack a 10-stop ND with a 6-stop ND, for a total of 16-stops to achieve really long exposures in bright light. Using the same aperture and ISO without the filters, you would need 65536 exposures (each an exposure duration 1/65536 as long) to get the same total exposure duration and hence the same motion blur. That is not practical for most people. So, if you are trying to achieve exposures with exposures measured in hours, in bright sunlight, you may still need filters. You might want to combine the use of filters with stacking to get the advantages of stacking while avoiding having a huge number of images to stack.

Last updated March, 2025 for version 1.6.0.