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Focus Breathing is one of those things that I knew about, but never really paid attention to since it never really impacted my images, which generally shot with a single focus point. But with my recent foray into shooting using focus bracketing, then combining several images together in post, made me experience the effects of focus breathing first hand.
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Fortunately, Photoshop has the capability to take these image, all with slightly different focal lengths, and normalize them so as to allow them to be stacked. But if you looks at this short video, I step through a series of images taken with my 85mm f/2 lens at f/5.6. No settings changed and the camera is on a tripod and not moved. No other setting changed from shot to shot other than the focus point on the coin.

What is Focus Breathing in a Camera Lens?
An introduction to focus breathing (or lens breathing) in camera lenses, from what it is to how you can avoid it in your photos and videos.
Fortunately, Photoshop has the capability to take these image, all with slightly different focal lengths, and normalize them so as to allow them to be stacked. But if you looks at this short video, I step through a series of images taken with my 85mm f/2 lens at f/5.6. No settings changed and the camera is on a tripod and not moved. No other setting changed from shot to shot other than the focus point on the coin.