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Extreme Macro

by Mike McNamee

Themes for articles sometimes build from unlikely sources. While casting about for some sure-fire, weather proof projects for a teaching course, we had occasion to rebuild and recommission a dark field illuminator. More on the technique later, but for starters it guaranteed an ability to make macro nature shots regardless of the weather outside (which turned out particularly useful as it was pouring down and not an insect in sight!).

The dark field technique was described back in May 2007 so it is timely to repeat it. For the first time ever we also include a DIY project in Professional Imagemaker in keeping with a general maxim of macro photography that what you do with the BacoFoil and Blu-Tack is often as important as the latest fancy camera or lens!

There are a number of issues to overcome in pursuit of higher magnification macro work, by which we mean from 1x magnification to about 10x:
1. The depth of field is vanishingly small, measured in fractions of a millimetre.
2. There is an extreme sensitivity to vibration.
3. The working distances in front of the lens are very small, often less a than a centimetre.

Control of the shooting environment is thus essential and, if the subject is also live, control of the subject is also essential. Subjects such as butterflies are live, wild and free, and almost impossible to image at greater than 1x magnification; you can only just cope on a very calm day with a receptive subject.

Getting higher magnifications than 1:1 becomes progressively more difficult with the problems already described but one thing that does not rocket out of control is cost. There is a thriving second-hand market and microscope accessories are less expensive than ever (and almost universally made in China these days). By way of example, a 4x microscope objective only cost £37 brand new!

Subject Control

Control of subjects becomes progressively more difficult until eventually only morbid (dead) specimens can successfully be imaged. Ultimately they may also have to be sandwiched between a microscope slide and a cover glass in order to get them flat enough to cope with the narrow depth of field.

The best starting point for small aquatic insects, imaged at between 1:2 and 2:1 is a compressorium. This gloriously named device (compressoria in the plural) is a small tank sometimes with an additional glass wall in the water to control the space in which the subject is able to move. They are easily made (hence the DIY theme in this feature) using glass microscope slides, which brings three benefits: relatively thin glass, optical quality and handy sizes. The standard microscope slide is nominally 3x1-inch but if you can also get some 3x2-inch slides the tank will be more useful.

We made our tank as shown in the accompanying images using superglue to tack the sheets in a simple jig and then we sealed around the joint edges with fast-setting Araldite. We were able to make about four tanks in an hour. The finished tanks were water tested for leaks then filled with filtered water - pond water is very mucky and even the residual detritus brought in on the subject can be something of a problem. You should observe the following precautions when making and using the tanks

1. They are delicate and sharp when broken, keep them out of the reach of small children.

2. Use the superglue sparingly (just the tiniest drop is required) and ensure that you don't glue your fingers together or to the jig-work.

3. Keep the glass spotlessly clean from start to finish; it is either difficult or impossible to clean a tank once finished and thumbprints show up spectacularly well in dark field illumination!

4. The glued surfaces have to be pressed together for 15 seconds; make sure you don't press too hard and break the glass. Safety glasses are always advisable when doing this type of work.

5. When collecting live specimens do not damage the environment, do not trespass and return the specimens to the pond within a couple of hours or they will probably die.

Lighting Control

Lighting is difficult because the working distances make for very little space in which to introduce lights. For this reason fibre optic light guides are often used; they provide, continuous light which is compact but also cool. Flash used to be a problem, especially judging the exposure but these issues are resolved today with the use of digital cameras.

Dark field illumination is shown in the diagram and gets around all the lighting issues in front of the lens because it is a transmitted light technique. The fact that it creates spectacular back-lit effects is a considerable bonus. Two flash guns are best, but you can get away with just one. The guns only need low power as they are used very close to the subject. This brings benefits in terms of flash durations (see later).

Flash - using Commander Mode

The modern system flash guns (eg Nikon and Canon) and the Sigma guns may be controlled 'off-camera' using EX Flash (for Canon) and Commander Mode (for Nikon).

On the Nikon you press the menu button, then Custom Settings, then Bracketing and Flask, then Built-in Flash to reveal the correct menu for setting up Commander Mode (you scroll down to this to reveal the options).

We used the 'built-in flash' set to do nothing ( - - ); Group A on manual flash and set to 1/4 power (initially at least) and then Channel 1. This is a default setting but your flash might have been set up differently on other jobs. Settings are completed by pushing the Enter Button. Opening the pop-up flash automatically brings commander mode into operation. The two guns are normally set to Manual and 1/4 power then put into Remote mode.

This is done by holding down the centre SEL button, then pushing once more to select the Remote controller then scrolling to the right to select the list and then scrolling down to REMOTE. Push SEL once then push the on-off button briefly. A new screen view appears on the back of the flash and you are good to go.

This procedure sounds difficult; is very difficult to write about, but is actually quite easy once you have done it a few times.

Setting Up

Test shots are fired off before the specimen is introduced to confirm the= exposure and particularly to check for any glare and reflections from the many glass interfaces that are kicking about. We usually find that 1/4 power is OK at 200ISO, f16 and around 1:1 magnification. You can fine tune the exposure (for the thickness of the insect for example) using the aperture, moving the guns nearer or further away or by going back to the flash guns and reducing the setting on the manual flash power. We rarely use TTL metering.

The lower powers also give faster recycling times for the flash. At 1/16 you may shoot at 6fps for 8 frames; at 1/128 for 40 frames. Very short flash durations are a boon in macro photography; conversely vibration is an ever-present problem. The mirror slap of an SLR is very detrimental but at magnifications greater than 5x, the focal plane shutter is also a problem. The modern SLR shutter with a fastest speed of 1/8000s is moving at just short of the speed of sound at the end of its travel.

Small wonder then that stopping it produces vibration. At higher magnifications only leaf shutters are used on microscopes and sometimes the only way to control vibration is to work in a darkened room with the shutter already open and then to expose by triggering the flash, or turning the lights on and off for the required duration. It is not an issue for the type of work described in this feature but even the building foundations of microscope rooms have to be isolated from the rest of the laboratory if another room contains moving machinery. However, for our purposes mirror lock-up, fast flash and an electronic cable release are about all that is needed, but don't move about during the exposure!

On the modern camera, using Live View has brought benefits. Live view is present on most of today's modern DSLRs (see list) and when activated the mirror is locked up and the image is focused on either the camera screen or with a satellite monitor connected to the camera. It is an excellent way to work although there is a certain delay in shutter activation.

Lenses

Sadly the macro lens as a species has seen a population decline for quite a few years. Both Nikon and Canon madespecific lenses for use on bellows. They were usually simple 6-element Gauss designs which performed optimally at higher magnifications but lacked any of today's sophistication such as automatic diaphragms and exposure through-the-lens assistance. Without digging too far down memory lane the Nikon PB-4 bellows unit cost £96 in 1978; a good quality PB-6 unit today may be purchased second hand for around £500!

Nikon made lenses for their 5x4 Multiphot (1970s and 1980s) system at 19mm, 35mm, 65mm and 120mm, the smaller of which were fitted with RMS threads (Royal Microscopical Society), the two larger ones with M39 screw threads. The 105mm f4.0 bellows Nikkor (1969) had a standard F-mount. The only source for such gems today is the second-hand market and eBay. The Canon EF MP-E 65mm f2.8 1-5x macro lens is an interesting optic. It is capable of imaging from 1x to 5x magnification without any accessories and costs around £900 new. It effectively replaces the previous range of Canon macro lenses.

Olympus once made one of the most comprehensive and sophisticated range of macro imaging lenses and accessories. These too may be obtained via the second-hand market and adaptors will fix them to more modern

The least expensive way to start higher-power macro is probably by using a bellows or extension tubes, along with an enlarging lens. To do this you will need a 39mm screw adaptor (for the enlarger lens) with suitable adaptor for your camera or bellows fitting on the other end. Then you will need an enlarging lens. These are easily come by via the secondhand market. The upside of an enlarging lens is that they are computed for close working distances and will often out-perform a normal macro lens (on the optical bench our 75mm F4 El-Nikkor consistently out-performed our other lenses). The down side is the lack of auto aperture close down. However, for static systems this is not an issue.

Many lenses will perform better if they are reversed. This is logical if you think about it. When working normally a lens has a nominal rear working distance equal to its focal length (ie 50mm for a 50mm lens set at infinity). If it is reversed, then used with the subject a short distance away, it is working close to its optimised parameters - light does not care which way it is passing through a lens! There are a number of other technical considerations which change the working distance from the nominal 50mm; for instance at 1:1 magnification the working distance will be 100mm both sides of the optic.

This is a reason why you might not see the benefits of reversing a lens until it is used at greater than 1:1. Many adaptors are available for both reversing and re-introducing aperture auto-shut-down of lenses. The Nikon PB-6 bellows may have its front standard reversed for example and the double cable release will still operate the aperture close-down. As with all things digital, complex exposure calculations are no longer needed; you find the exposure by trial and error using the camera histogram.

Using Microscope Objectives

Providing you can cope without aperture control, the humble microscope objective lens makes an excellent high-power macro lens. Normally a microscope objective lens is corrected with the intention of creating an aerial image 160mm (or sometimes 210mm) back from the lens. This is known as the tube length. The image that is created at this distance is magnified by the stated value on the barrel.

In the compound microscope the eye-piece further magnifies the image and often corrects any residual optical aberrations. Microscope objective lenses are reasonably standardised including the nomenclature on the barrel which

will be something like this:

PL 4/0.10 160/-

where PL stands for Planar (the flatness of the created image), 4 is the 4x magnification, the 0.10 value is the Numerical Aperture (a derivative of the more familiar f-stop), the 160 is the tube length and the /- tells us that the lens does not need a correction for a microscope cover glass. A lens intended for biological work might have a value, such as 0.17, after the back slash to indicate an optimum correction for an 0.17mm cover glass. Sometimes the word APO is added to the title which indicates that the lens is apochromatically corrected. If you are unfamiliar with microscopes you are better off taking advice and we found Brunel Microscopes to be most helpful and knowledgeable. The good news is that the 4x plan lens we purchased was £37.

This has a numerical aperture of 0.10, equivalent to an f-stop of around f4.5, a working distance of approximately 15mm and a field of view of 5.5mm x 3.0mm. The measured focal length is 40mm. It is not possible to successfully stop down a lens of this type (even if it had a diaphragm - some do) without introducing serious diffraction limitations and so people have resorted to stacking software. There are two main contenders, ZCombine and Helicon Focus and they have been used to spectacular effect. In use, you make a succession of shots incrementing the camera/lens combination forward fractions of a millimetre at a time.



Updated 27/04/2026 16:44:22 Last Modified: Monday, 27 April 2026