One of the amazing things about Photoshop is the ability to combine or composite multiple different exposures that result in a much more detailed photograph that cannot be captured in a single frame. In some cases, the images being composited need to be in perfect registration or alignment for this process to work, so you must keep your camera steady and do not move it while capturing all the frames needed for the final image. Once open in Photoshop, the layers need to be stacked in a manner that maintains that alignment and this video demonstrates a simple way to do that. While there are many ways to stack layers in Photoshop, this simple technique is one of several methods. -Charlie Borland
Charlie Teaches:
How to be a Professional Outdoor & Nature Photographer
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The Ultimate Guide to Landscape & Nature Photography