Focus stacking – what and how?

Ok – I’ve heard talk of focus stacking; what is it – and how do I do it?

Phil Winterbourne answers:

What is it?

Focus stacking is a technique used to make a composite of several versions of the same image where a different part of each version is in focus, giving a final composite with a much greater depth of field than otherwise could be obtained.

As most photographers will know the depth of field in any image is a product of the aperture used and camera to subject distance. A small aperture gives a greater depth of field, and the further away the focus point is the depth of field becomes even bigger.

The problem happens when you want to get very close to your subject – perhaps macro or just very close-up shooting. Even with a very small aperture if you are only inches away from the subject the depth of field is unlikely to be deep enough to get the whole subject in focus.

And this is where focus stacking comes in – you take several pictures of the same thing starting with the closest part in focus, and slowly moving the focus back and back with each shot.

Then combine all the in focus parts of the images to give a final composite where everything is in focus that you want.

How to do it with Photoshop and LightRoom

My method is to open all the images in Lightroom and do any global adjustments to the exposure, white balance, contrast etc. Then open them into Photoshop as layers in the same file.

Once you have them in Photoshop there are two tools that do almost all of the work for you.

First align the layers by selecting all your layers and, using the menus select “Edit > Auto Align Layers”. I tend to go with the auto option, selecting the “Geometric distortion” checkbox.

That will take a few minutes to chug along.

Once that operation is done I blend the layer together using the “Edit > Auto Blend Layers” tool. Choose “Stack Images” and check the Seamless Tones and colours” check box

That takes even longer to work through and will leave you with a pretty good image. But you’ll probably notice that it’s a bit messy round the edges so you will probably want to just crop out the centre.

You should end up with something like this…