Above is a comparison of snow surface halo stacked from 40 frames two different ways (click image for an animation). The photo on the right with crystal glitter is hand-stacked with Photoshop using Lighten-method, which was introduced by Piikki in the early winter ( 1 ). The other photo is stacked automatically with Registax. Because of the crystal glitter, Lighten-method provides more realistic output, though of course this is much enhanced realism.
Camera was moved between every shot some 30 cm sideways. 24° halo is well visible in 148 frame mirrored stack ( 2 ). Pyramidal crystals were observed with microscope, but unfortunately I could not get them photographed. The display was photographed on 30 January in Tampere, on Näsijärvi ice.