Extreme Macro: "Boy and Girl"
The making of a stacked macro photo
By Nass in Articles and Tips on Apr 5, 2014
Have you ever wondered how to capture extreme macro images with greater than life-size magnification? In this article, we'll be taking look at the technique that'll get the job done by walking you through an example image shot with a Pentax K-7 rig.
When my wife decided she'd had enough and went on one of her ballistic flyswatting rampages, I took this as too good an opportunity to miss out on for some extreme macro photography. And whilst one fly is good, two flies is even better, and her anti-fly mission was so devastating that I soon had a collection ready to give this challenging shot a go! Focus stacking is a niche branch of macro that actually only became possible with the advent of digital photography. Stacking is an attractive digital option because the laws of physics dictate that depth the of field at magnification will be very narrow before diffraction limits kick in, and this technique overcomes that problem. Stacking requires digital stills taken at many different focus points - because they have to be blended electronically in order to create one master "all in focus" image. Shooting the stack and combining the images are both slow processes - a typical finished stack would combine several hundred stills with subsequent overnight processing on a reasonably beefy PC.
The completed stack, after postprocessing with Noise Ninja and Topaz Detail (click to enlarge)
The challenges in this sort of photography start at the outset. Arranging and cleaning the small arthropods so that they photograph well is by itself a whole branch of entomology, the skills for which are usually the preserve of professional museum curators and college entomologists. This is a world filled with curious terms such as 'spreading' and 'relaxing' insects; a craft requiring deep reserves of patience and complete attention to detail. Preparing one specimen is itself a challenge but doing two together, trust me, made for some colourful language.
Shooting the stack involved three flashes in total: one Metz 58-af2 connected to a Pentax K-7 DSLR, using a PTTL cord on manual rear sync acting as master for two Pentax AF540s on manual settings acting as the two reliable slaves. This arrangement works very well indeed on the K-7 although you do have to fool the K-5 and onwards to make this work (you have to make it think it has an aperture-linked lens connected). The optic involved was a Componon 35/f4 on a beautifully crafted piece of vintage Pentax equipment which is just about perfect in every sense for extreme macro: Pentax-M bellows. This Componon is an old enlarger lens - a superb lens for extreme macro like this because they are optimised for flatfield performance. Great value for money as well nowadays with the decline of the darkroom - $75 gets you a really great lens to use for reverse macro on eBay.
Central to the hardware required for shots such as these is a stage to move your camera by small increments, which obtains the images with differing plains of focus. I personally prefer to move the camera rather than specimen because it means the lighting won't change, but either route works. There are all sorts of macro stages, ranging from DIY stages that cost very little to top of the range electronically controlled specialist hardware such as a Stackshot Stacker. There are really three grades: fine for 1:1-3:1, fine for 1:1 to 10:1 and fine for 1:1 to 100:1. You do get what you pay for: a Stackshot Stacker can do 1µm increments and costs 100s of dollars whereas a Velbon slider will give you up to about 3:1.
The lighting deserves a mention: these flies were heavily diffused using a cheap polystyrene chip cone diffuser. Macro diffusion falls into two categories: the ornamental 'plastic sheath over the flash head' much beloved by companies trying to make an extra buck selling an accessory, and the much more useful 'light spread over a wide area' type. The difference is very important to obtaining decent macro images.
The post-processing on this image was fairly typical of the processing I do on all my stacked shots. They were output as JPEGs and not sharpened in the camera, then on the finished stack I performed minimal cloning to remove any specks of dirt that I couldn't remove with a fine paintbrush beforehand before teasing out detail with Topaz Detail and finally treating it with NoiseNinja to remove excess noise. The full sequence of images for this stack was 121 shots, but I actually did a double stack process to be able to obtain detail in the hair. So I made 34 sub-stacks as an intermediary, then stacked those all into one master. The software that I personally use for this is Zerene Stacker which makes it very easy, but there are other alternatives on the market and you can even use Photoshop to stack!