I used a Nikon D800 with the Nikkor 16-35mm f/4G ED lens. On the lens I used a Nisi 3-Stop Soft Graduated ND filter and a CPL (circular polarising filter) with the Nisi V5 100mm Filter Holder.
Inspiration & Process
Prior to leaving on our 6 month trip, I picked up a great pair of (for lack of a better description) gum boots. They weren't your typical gum boots as they were made from a wetsuit material and had a fantastic grip on the soles. Anyway, I thought that this would be a great opportunity to try them out. My idea was that if I waded out into the water away from the shallow bank, it would allow me to get closer to the trees and have them fill the frame in my shot.
The boots worked perfectly until I felt my toes starting to get wet and I realised that I had gone out a little too deep. This wouldn't have been such a problem if not for the fact that this was the middle of winter and the water was freezing :) After trying a couple of different compositions with the trees in the immediate vicinity, I decided that simplicity was the best way to go and I targeted just one tree. This tree's shape was perfect and when viewed with its reflection, created a great composition.
I knew that to get an almost mirror image at the bottom I would need to slow my shutter speed to take the ripples out of the water. My exposure couldn't be too long though because it would smudge the reflection. The other trick was to stand perfectly still in the water to minimise water movement. After experimenting with the shutter speed, I decided that an exposure of 1.6 seconds gave me the look I was after.
Lens Filters & Editing
For this image I used a 3-stop graduated ND filter by Nisi. The graduated ND filter darkened my sky slightly, while allowing me to extend my shutter speed. This gave me a nice, even exposure at the top and bottom of the image. I also used a Nisi CPL (circular polarising filter) to adjust the shot to get just the right amount of reflection.
By using a graduated filter it meant that I didn't have to bracket my exposures and I was able to capture the scene in just one shot. All basic editing was done inside of Adobe Lightroom with final colour adjustments made in Color Efex Pro 2 from the Nik Collection by Google.
Tips for Capturing a Similar Shot
My advice would be - don't limit yourself to only shooting when conditions are favourable and the skies look dramatic. The truth is that 80-90% of the time, the sky can look quite uninspiring and conditions are often unfavourable. If we only went shooting during these small windows of opportunity, we wouldn't be taking all that many pictures. The trick is to be creative with what you have to work with.
Unfortunately I am really bad at following my own advice. For me I find that it helps to go shooting with a friend. A fellow photographer can help keep you motivated when nature isn't co-operating. Especially when you have to get up for sunrise and you don't feel like getting out of bed!