Ripe frost conditions in the Alaska Interior
Even though a snowpack settled in early this year, with its arrival on October 6th in Fairbanks, we've experienced a relatively mild autumn, at least through November, as we approach the Winter Solstice. The temperature in this area was over 10°F above the 1991-2020 average. November’s lowest temperature at the airport dipped to -10°F, and living north of town in the hills, we didn't feel the bite of subzero Fahrenheit temperatures until recently. Two nights ago, on November 2, the mercury at my home dropped to -5°F (a notable shift from the -32°F and -41°F of my first winters here in 2010 and 2011).
The colder nights, high humidity, and little to no wind provide the perfect conditions for frost to form. Over the weekend, I observed some incredible frost crystals around my home. While hoarfrost cups and spikes often grow several centimeters long, sometimes reaching up to a meter, it's quite rare to see hexagonal crystals reach the size I saw recently. Many of the crystals on my truck's windows were between 5 and 15 mm across.
All the photos here were taken with my Nikon D850 and Laowa 25 mm f/2.8 Ultra Macro lens (Lens Rentals affiliate links). I wanted this macro lens specifically for the D850 because it is such a high-resolution camera that it would allow for much additional cropping. However, no cropping was necessary for these large crystals. Due to their three-dimensional nature, extensive focus-stacking was essential.
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The limited depth of field of the lens means each photo captures only a thin plane of focus, typically around 1 mm or less. I had to take multiple photos at different focus points to bring a substantial portion of each crystal into focus. These were then merged through a process known as focus-stacking, resulting in one comprehensive final image.
Yesterday, I spent nearly an hour outside taking some of these photos. When I came back in, Cat asked if I had captured any good shots. I replied that I believed I had four good crystals, and then I had to explain why it took so long for just four shots. Each crystal required multiple photos, necessitating the use of a tripod to prevent any movement relative to the subject. My tripod is equipped with a macro focusing rail, enabling minute adjustments to the camera's position by sliding it slightly forward or backward to change the focal plane.
This lens functions almost like a microscope for the camera, requiring positioning just a few centimeters away from the subject. Setting up the tripod near the car to position the camera in front of the crystal can be tricky. It involves a continuous process of tiny adjustments from the tripod legs, ball head, and focusing rail to target the chosen crystal accurately. With limited available light, exposures typically exceed one second each, necessitating a timer or remote to avoid vibrations caused by pressing the shutter button.
Each shot demands adjusting the focusing rail to capture different parts of the ice crystal using the LCD to achieve the desired focus for the final image. Capturing the necessary shots for each final photo easily took about 10 minutes. Then there was the editing. Before focus-stacking, each photo needed color and exposure adjustments. Fortunately, the stacking process is almost entirely automated; masking and blending manually would be incredibly time-consuming. While the computer processes one set, I can start working on the next.
Finally, I made edits to the completed photo. This usually involves some clean-up and sharpening. Specifically, sensor spots from dust on the camera sensor appear as odd spots and artifacts, especially noticeable due to the stacking process, and these need to be removed. However, I leave all other artifacts, like blemishes on the glass, to maintain the authenticity of the scene.
If anyone is interested more in the details of the process of taking these photos or editing, give me a shout and I may start writing up a tutorial.
This exploration of frost and ice crystals in microcosm wraps up here. You can see these photos and others in my Macro Gallery, where they're also available as prints and wall art. Additionally, I'll be selecting some of these images for my Water and Ice project, which you can read more about here.
P.S. I've previously mentioned ice spikes growing up to a meter in length. Here's a glimpse of nearly a meter-long spikes captured deep within a glacier cave at Castner Glacier three years ago.
If you want to read more about that, check out my article, Ice Crystals in R-Channels.