I'm taking pictures of a D&D miniature. I'm using an iPhone with an app called VSCO that allows me to change the focus point. I've taped a 10x jeweler's loupe over the camera. My goal is to focus stack the images. However, the images are not aligned correctly, because changing the point of focus slightly zooms out the image.
Does anyone know why this zoom occurs? The edges of the jeweler's loupe are slightly visible around the edges of the image, maybe that's causing the problem?