All input images must be either RAW files from supported cameras, or TIFF or JPEG files. TIFF files should be 16-bit with ProPhoto RGB profile. Images must be RGB (not grayscale). Note that the list of supported cameras varies depending on the version of the operating system in use. The list for Catalina (10.15) is here.
The camera should motionless during capture. You can use the optional alignment with images that are captured as a short hand-held burst with a high shutter speed but it is best to use a stable tripod.
All light frames and dark frames should have identical exposure settings (duration, aperture, ISO, focus). (Aperture and focus are irrelevant to dark frames and are ignored for dark frames).
The maximum output image size with 16-bit samples is about 500 M pixels. The maximum output image size with float samples is about 200 M pixels. Both of these limits are due to limits on the maximum size of a TIF file.
Long Exposure Stacker only runs on macOS 11 or newer. There is no Windows or Linux version.
Long Exposure Stacker should work on any Mac supporting macOS 11 or later.
Lightroom and Adobe Camera Raw (ACR) users with mirrorless cameras--as of spring 2020 Lightroom and ACR automatically apply lens distortion correction for most (possibly all) mirrorless cameras. There is no way to turn this off other than to manually strip the metadata from the RAW files. Lens distortion correction, as implemented in Lightroom and ACR (as well as many other RAW converters) adds artifacts that are enhanced by stacking. This means that neither Lightroom nor ACR can be used as a RAW converter before stacking if you have one of the affected cameras. There are other raw converters that allow lens distortion correction to be turned off for all cameras. Instead of converting your images to TIFF with Lightroom or ACR you can supply RAW files directly to Long Exposure Stacker.
Capture One users--if you are exporting very large TIFF files, e.g., 100M pixel, then specify "Tile 128" in the export format, probably "Uncompressed - Tile 128", see https://captureintegration.com/tech-tip-mitigating-black-tiffs-in-el-capitan-10-11-6/.
Luminar users--as of the spring of 2020, Luminar would occasionally change the size of images during RAW conversion. This makes Luminar unsuitable for use as a RAW converter for Long Exposure Stacker.
Last updated March 2025 for version 1.6.