By Paul Harcourt Davies
Backlighting: – Adding a Bit of Magic:
A single gun behind and to the side of a subject creates a rim light that accentuates hairs on flower stems or on insects – it is a little bit of magic that raises the game and your pictures go to a different level.
With radio controlled systems it is easy – a manual gun with a photoelectric trigger works, too, since the lighting is not critical but avoid placing it too close to the subject if it does not have a power-ratio control that lets you control its output. A flash gun used behind a subject (and just out of view) can enhance the translucency of the subject.
Backlighting with natural light depends on the camera position relative to the subject and the art is to avoid getting the sun in the frame (unless you want to do that deliberately) which sets up reflections on the surfaces of the internal lens elements and can also promote flare. The latter is reduced with a suitable lens hood and whilst looking through the viewfinder (or at an LCD screen) you can see the extent of the backlighting.
Ghosting- good and bad:
When balancing daylight and flash you have to watch out for ghosting where the flash freezes the subject but the camera shutter remains open long enough to expose movement and create a ghost. Sometimes you will not see it until the image is in Lightroom or Photoshop. Remedies include making sure you use a fast enough shutter speed (1/200th or less) making sure you press the shutter in a lull in the breeze. At high magnifications (dealt with in a later post) some cameras really do create blur thanks to shutter bounce – rear curtain synch helps.
There are occasions when ghosting adds something to an image by suggesting movement. You can choose to use this as part of your composition by setting a camera’s flash mode to synchronise with the second shutter curtain…the ghost image appears behind the main image and makes the movement look much more apart of the image than merely accidental.
Darkfield (dark ground) Illumination:
This is a dramatic form of lighting borrowed from microscopy where a dark disk of card/flock paper forms the background to your subject and light comes in from behind and to the side of the disk – the result is a backlit subject on a black background. I’ll cover this when I deal with larger than life shots and show some simple ways of achieving the effect.
Ultra close – larger than life-size imagery:
Many of my ‘true macro’ shots are just taken with a single small, handheld gun operated from the camera’s DTTL with a small white card on the opposite side of the subject as a reflector. At close quarters, a small flash acts like a ‘broad source’ – like employing a flash with diffuser or umbrella. You can think of an umbrella as comprised of numerous light sources, very close to one another so that light from one area fills shadows generated by another which produces a ‘diffuse’ light. Light clouds on a sunny day have the same effect, reducing the strong directionality of sunlight. In practice, a small flash is held to create a pool of light on the subject and a white card is placed on the opposite side to fill shadows (if any) – moving the card slightly helps get the balance you want and this is viewed on the camera’s LCD. If you use DTTL systems the time to control the pulse is very short (nanoseconds and less), so cable length matters and affects the response time – you might have to experiment with the compensation buttons to get perfect exposure but this is one of the boons of being able to use your LCD as a visual exposure meter,
Specular Reflections – avoiding mirror reflections on insect bodies
Many insects, beetles in particular, have hard surface coatings that reflect light an create ‘specular (mirror) reflections’. It is essential to use a diffuser to minimise these or to rid yourself of them build a sort of portable lighting tent that is placed over a beetle on a forest floor and lit from outside. The background is restricted though! I find that a sheet of flyweight, the translucent envelope stiffener, held above the subject with flash above that makes a good start and you can experiment with flower beetles or ladybirds that have highly reflective elytra.
Where specular reflections have intruded then a degree of work in post-production to eliminate them with the clone tool might be the answer provided those areas are not too large. One answer is to use a small lighting tent, such as those used for product photography – or larger diffusers made of lightweight envelope stiffening material, though in both cases you have to make sure they do not enter the background in the viewfinder. It is surprisingly easy to overlook them when dealing with an active subject that takes your attention. Macroflash units can cause twin highlights that become evident in raindrops or eyes – I tend to eliminate the most obvious of these with speedy use of the clone tool or healing brushy in Lightroom or Photoshop
Too Many legs:
Using two flash guns of similar power with insects creates multiple shadows and beasts with more than six legs…it’s a question of angling the second flash and/or reducing the power of this fill-in
Ring lights produce a flat lighting that works great for the interiors of cavities dentists use them (no pun intended) for imaging the interior of the mouth. Macroflash units such as the Nikon SB 28s and 29s and the Sigma Macrolight are sometimes described as ring flashes in magazines and advertising but they are not for they have twin-tubes where different power ratios are possible so that one side is the main light and the other the fill-in. At close range these work very well and create a degree of ‘relief’ in the lighting. Relief lighting is a form of off-axis (from the side) illumination that creates tiny shadows where there are irregularities (ridges, hairs, scales…) which help define details on a surface. This is a very important factor in macro photography where we are trying to create the sensation of sharpness and a lot more will be said on the perception of sharpness in future posts
With longer focus macro lenses the small flash units used can prove both to be underpowered at lower ISO ratings and also to give little in the way of relief since the angle between flash tube and subject is reduced. In the past, with ring flashes, I have always used black electrical tape to create ‘windows’ of different sizes on either side.
Macroflash Units- a Personal Assessment:
Read a full assessment of the value of macroflash units and of two commercially available units from Nikon and from Sigma.The main benefit is convenience of use and consistency of exposure.
© Paul Harcourt Davies 2014 NB No part of this blog may be used in any way without the express permission of the author concerned: all commercial use of images must be accompanied by a fee (rates on request)