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.
Interesting pair of photos. Both have good attributes. Interesting to note, that pyramid crystal halos on snow surface can be seen “regularly”.
By blending both versions one may get a satisfying compromise.
Yes, it seems odd radii is not uncommon on snow surface. I heard rumors that the Hungarians had this winter some 5 days in a row of odd radii on snow surface.
To echo Jukka, it is really interesting to see these photos together. Both have advantages.
And yes, the rumours are true, indeed. The observer was Ákos Ujj, who noticed the odd radii on a Tuesday in the first half of January, and the halos remained there till Saturday. Who knows – they might have appeared even earlier, as the weather had been unusually cold for a couple of days then.