The trick to using this kind of light is to balance out the camera exposure for the scene with the flash exposure on the snow flakes. I used the flash in manual mode and determined the best exposure with some trial shots. The choice of aperture did more than determine exposure, it also defined the size of the bright snowflakes. The more open the aperture the larger the flakes appear due to the bokeh effect of a lens. For these photos I varied the aperture between f/2.8 and f/5.6, changing it to sync with the focal length I was using on the zoom. In general, f/4 gave me the best results. Anything more stopped down made the flakes too small.
I began shooting with the X-T2, but half way thorough the day I tripped and fell on the slippery snow and the camera suffered sever impact damage and ceased to work. The fall also destroy the flash and caused some scraping on the lens. Fortunately, the flash I broke was a Yongnuo and not one of my really expensive Nikon flash units.
On my next outing I switched over to an X-Pro2. I really prefer outdoor shooting with this camera except for one factor. A tilting screen would make it a lot easier to achieve some very low, off the ground angles.
|In this image I wanted to intensify the amount of snow so I opened up the 18-135mm zoom lens to maximum aperture at a focal length of 24mm, set the ISO to 640, shutter to 1/60 second, and used full power on the flash.|
Mostly I used my ISO to control the overall exposure balance. It varied between 200-800 depending upon the amount of contrast I needed between the white snow and background scene. Once I established a base exposure for each scene, I made changes based on trial and error trying to balance out the size and contrast of the falling snow against the background scene. Each time I changed by zoom focal length this balance also changed.
By the time I took the dusk photo below my exposure had fallen to 1/15 second, f/4.5 at 11mm on the Fuji 10-24mm zoom, an ISO of 800, and flash power of 1/16 on a Nikon SB-900.