Behind the Shot
With Heather Angel
Focus stacking is a great technique for gaining maximum depth of field for three-dimensional macro subjects. Essentially, a series of focus slices are blended together using a software program.
During the last three years, I have taken many hundreds of focus stacks of flowers for a book I have just completed on pollination for London’s Kew Gardens. Here, the pitcher plant flower failed to make the cut, simply because I did not get the pollinator in action.
The essential factors for a tack sharp stack are:
- a static subject
- a constant light source with a consistent intensity. It can be natural light, an LED light, or flash or a mix of these. It needs to be in a fixed position, otherwise the shadows will vary between one shot and another.
- manual focus
- a focusing rail to move the camera forward in equal increments
My preferred light for flower portraits inside is indirect window light, with maybe a reflector fill or fill-flash (or both). For this shot, I used our conservatory with an outer glass wall. A Nikon SB-800 Speedlight supported on a high level Benbo tripod that extends to 2.56m (almost 8½ feet), enhanced the back-lighting softened with a Honl Photo Traveller 8 Softbox and a cheap reflector provided the fill light.
The simple set-up above shows the flower secured in a milk bottle with Magitape, and aluminum foil wrapped around a card held in place with a Wimberley Plamp. Proof you don’t always need expensive props to tweak the light for the shot you visualize.
The camera is mounted on a RRS L-plate on a B150-B macro-focusing rail – surely the Rolls Royce of focus rails – which is attached to a BH-55-LR ballhead.
Self-adhesive tape is fixed to the knob used to advance the camera, marked with a black line (visible) and a red line (180º below) to speedily advance the rail a full turn (black to black or red to red) or a half turn (red to black, then black to red).
After the camera was manually focused on the nearest part of the flower, 35 images were taken by advancing the camera one full turn for each shot, the final image was stacked using Zerene Stacker software, which can be downloaded for a 30 day free trial.
The original was composed as a vertical format with negative space for type above the flower. Here it is cropped to square.
Soft window light with back flash from Nikon SB-800 Speedlight fitted with a Honl Photo Traveller 8 Softbox and a reflector fill.