Stack ‘em high

As one focusses closer to a lens the depth of field gets shallower, making tighter apertures a temptation. This paradoxically introduces softness thanks to diffraction, something that all lenses suffer from, due to the physics of light effectively bending it at the aperture. For static subjects there’s an excellent alternative method for high depth of field, brought to us by digital photography; stacking.

By taking a sequence of images where the focus is moved from the front of the subject to the back, it’s possible to combine them on a computer into a single image with a much deeper depth of field, giving the kind of sharpness that’s tricky in one macro capture.

Common Earthball – a pale mushroom with a purple centre – stack of 50 images

Personally I bring my images into Capture One, figure out the look I want, then export them all to a folder. I then import them into a stack of layers in Photoshop. Although it can focus stack images by itself, I only use Photoshop to align the layers to account for slight differences in image size caused by focus breathing.

Box Moth on Blue – stack of around 30 images

The automatic stacking in Photoshop is a one click option with no real settings to tweak. I found this often produced soft edges where sharp imagery was available. Instead I use Helicon Focus, a Ukrainian software featuring alarming speed and great options for retouching; ie fixing any blurry bits or seams. I highly recommend downloading the trial!

I wouldn’t choose to stack for everything macro as it demands a lot of images and post work on the computer but sometimes the results are worth it. I’m lucky my camera can shoot stacks of images itself, hundreds of desired, but manually moving the focus back through frame would work just as well.

Not a long blog post this. Every now and then I get ideas for a new post and this just happened to be one of them. Also I’m always convinced I’ve recently written a post, even if it’s been 6 months since the last was published!


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