This little vibrant gem hits on a few features that we also rarely see in snowflakes: purple colours from interference patterns, and a much less common form of inward crystal growth – the closing canopy. View large!
I think I just coined the term “closing canopy” in that last sentence, as I don’t recall this ever being described before. This is where a thick ridge on a snowflake flattens out like an anvil-shaped Cumulonimbus cloud or an “I” beam, growing a new plate off the top of the ridge. This ridge is both growing inside and out – you can see a tiny little “wing” at the bottom that is casting a shadow on the underlying plate.
These shadows can also be seen around the center area of the crystal, showing that it is distinctly above the coloured area and growing in towards the center, an example of three layers of ice overlapping: two created by the bubble inside the main plate, and the third growing over from the thicker ridge. This might be the first snowflake I feature here that has this kind of growth in such a visible formation… it’s great to see new things when you think you’ve seen it all in a snowflake!
The Stag Beetle jaws in the middle of the image, being darker than the surrounding area, are solid ice. The coloured areas are caused by a layer of air trapped inside the ice being just the right thickness. As it’s thickness shifts, so too does the colour, and we see some subtle shifts towards blue along the outer edges. Thin film interference colours are usually fluid and rainbow-like, but in snowflakes they almost always take on static colours. If you’d like to read more about these seemingly impossible colours trapped in the ice (actually created BY the ice itself), further reading is here: http://skycrystals.ca/pages/optical-interference-pages.jpg
These snowflakes are tiny, and photographed at 12:1 magnification. This is achieved using the Canon MP-E 65mm macro lens which natively gets up to 5:1 magnification, and adding a set of extension tubes to push that further to 6:1. Using the Canon Lifesize Converter EF, which is basically a telephoto extender for macro purposes (a regular TC will work too, often coupled with extension tubes to cover the protruding element), I double that magnification to 12:1. At these scales, even when the camera is dialed to the widest aperture of F/2.8, my effective aperture is somewhere in the realm of F/180 and diffraction grossly limits the resolution. I have shot some of these snowflakes with microscope objectives and I plan on doing a little more of that this coming year as well – higher resolution but less depth of field per image.
These thin film interference colours only show up with reflected light – they’d be invisible to you if you were lighting the snowflake from behind. This means that the tiny snowflake needs to be photographed on a slight angle (otherwise the source of the light would need to be coming from inside the lens) and roughly 20-30 images are used to put these small plate crystals together with extensive focus stacking efforts. Larger snowflakes average around 40 frames, with my record for a snowflake being 70 shots to get everything in focus from tip to tip.
If you’d like to know more about the science of snowflakes with an exhaustive and comprehensive tutorial on how to photograph and edit these little gems, check out my book Sky Crystals:
Other things you might be interested in:
2018 Ice Crystals Coin from the Royal Canadian Mint featuring my snowflakes: http://www.mint.ca/store/coins/coin-prod3040427
“The Snowflake” print, taking 2500 hours to create: http://skycrystals.ca/product/poster-proof/
Photo Geek Weekly, my new podcast: http://www.photogeekweekly.com/