Wide-angle macro part 1. PHD

The ‘wide view’ for close-ups offers maximum information about a subject by setting a plant or animal in the foreground, yet allowing you to include the surroundings. The background does not have to be pin sharp – a slightly blurred set of mountains or trees in the background tells you all you need to know about a habitat because you can still see what they are. In fact, a slight background blur might even accentuate subject sharpness.

Whereas a telephoto lens ‘condenses’ perspective, a wide angle produces distortion through perspective foreshortening, since elements of a subject closest to the lens are enlarged. This works amazingly well with flowers – perhaps because a flower is a ‘beacon’ for us (and its insect visitors) so we tend to notice that first. I have long thought that this bit of exaggeration mirrors the view we have of a flower and my  landscape shots use it constantly. It has to be used carefully with animal subjects – have you noticed how some ‘wicked’ press photographers take photos of politicians with facial features thus exaggerated…and they are often unprepossessing individuals to begin with? Then, when they are on the slippery downward path these are the ones that get published!

I must admit that I did not feel comfortable for a long time with distortion of animal ‘faces’ and then I saw some of the superb pictures of chameleons by Frans Lanting (http://www.lanting.com/) . The technique with insects has been developed by Solvin Zankl (http://solvinzankl.com/blog/) and also employed brilliantly by Piotr Nasrecki (http://www.insectphotography.com) with invertebrates, lizards, frogs…By the way, Piotr is a top entomologist with a passion for insects (and small things) and a deep understanding of their world that shines through his pictures. So, if  you want a superb Christmas present for yourself or a naturalist friend/family member then I can wholeheartedly recommend his book The Smaller Majority (ISBN 0-674-01915-6)

The conventional fixed focus lenses:  28mm, 24mm and 20mm wideangles

As close-up photographers, what we really need is a generous length of thread in a focusing mechanism that lets the lens get close. Fixed focus lenses were much better in this respect and only a few AF lenses take you in as close as they might. An aged 28mm f/2.8 AIS Nikkor is still one of my favourites – giving reproduction ratio of 1:3.9 unaided and just over half life-size (0.55x) with the PK11A tube. ) It is also exceptional reversed, as a ‘true’ macro lens, on a bellows (a future post)

Sigma are often in tune with the needs of close-up and macro enthusiasts and produce 28mm, 24mm and 20mm objectives that focus much closer than most… and all offer a maximum f/1.8 maximum aperture. They are very sharp indeed – one or two comments I have seen on-line suggest they are not bitingly sharp at open aperture but for goodness sake who uses them for that (and they had probably never used them either…)

For those who like data I have assembled two tables below:

Table 1

LENS (Sigma)	Closest focus (from sensor/film plane)	Reproduction ratio unaided
20mm f/1.8 EX DG ASPHERICAL	20cm	1:4 (0.25x)
24mm f/1.8 EX DG ASPHERICAL MACRO	18cm	1:2.7 (0.37x)
28mm f/1.8 EX DG ASPHERICAL MACRO	20cm	1:2.9 (0.34x)

Using Extension tubes

If you want to get closer than an internal thread allows, the traditional way is to fit an extension tube. The only problem is that very few thin extension tubes are made – Canon once made a manual 5mm tube for their FD lenses and Nikon’s thinnest, the PK11A, gives 8mm of extension.

Table 2

reproduction ratios and close-focus limits for lenses with extension tubes

Nikon lens	lens unaided	PK11A (8mm)	PK12 (14mm)	PK13 (27.5mm)
AF 20mm f/2.8	1:8 25cm	1/2.6 – 1/2 13.7-12.7cm	1/1.5 -1/1.2 12.1-11.8cm	1.3 – 1.5 11.9 -12.1cm
AF 24mm f/2.8	1/8.8 30cm	1/3.0 – 1/2.3 16.4 -14.8cm	1/1.7 – 1/1.5 13.8 – 13.4cm	1.1 – 1.2 13.1 – 13.2
AF 28mm f/2.8	1:7.6 30cm	1/3.6 – 1/2.4 19-16cm	1/1.7 – 1/1.5 13.8 – 13.4cm	1.0 – 1.1 13.6 – 13.5cm

The magnification ‘gap’

With a 20mm f/2.8 Nikkor wide angle and the 8mm PK11A  tube the table shows the reproduction range is 1/2.6 – 1/2 whereas, unaided, the maximum was 1/8  (o.125x) which means that there is a definite ‘gap’ in the reproduction range attainable with and without a tube attached.  There is simply not the continuous reproduction range achieved with a macro lens and time and, annoyingly,  I find time and again  that this ‘missing chunk’ is where I need to go. With a Sigma 20mm f/1.8 lens there is still a ‘gap’ in the range but it is much smaller.

When needed we can easily work out the magnification an extension tube produces from a formula:

M = d/f

Here ‘d’ is the added extension (tube length)  and ‘f’ the focal length. This reveals that the smaller the focal length of a lens the bigger the effect an extension tube has.

As an example: an extension tube of 8 mm used with a 20mm lens produces a magnification of 8/20 or 0.4x (which is 1:2.5) or just under half life size.

NB this formula works for the lens set on the infinity mark – you’ll get a bit more than this from the extension provided by the focus mechanism. If you want to work this out … then look at what the manufacturers says the maximum reproduction is, work backwards to see what internal extension produced this…now add this to the tube length and work out the new magnification…(or just use a piece of graph paper and count squares…)

Sorry about that but I know some folk like to know – others don’t : it’s there anyway.

Too close for comfort.

If you go to half life-size with a 20mm lens and a 28mm lens and compare results there is a noticeable difference in the amount of background you cram in the 20mm is wider and wilder, but you are much closer to the subject. There are two hurdles to leap (or knock over) when working so close:

1. subject sensitivity: bugs and beetles might let you get that close but butterflies not – unless you set up your camera near a suitable flower and wait with a shutter release of some sort (or a phototrap). If you try to hold the camera manually and move in then that well-known fear /flight (literally) reaction takes over. To do it with lizards or salamanders (see Clay Bolt http://naturalimagery.blogspot.com/2009/04/wide-angled-salamanders.html) takes patience and good stalking technique – you might get one shot and then…

1. lighting: if the sun is anywhere behind you then you will cast a shadow and will have to manoeuvre position or try to use flash. I have used my SB900 flash gun off camera with a diffuser and it works well and so does the Nikon R1C1 set with diffusers on the SU200 units. You have to experiment a bit to get a good balance between foreground and background light. I tend to use ‘manual’ mode where I can watch background exposure from the indicator line in the viewfinder and then adjust shutter speed and aperture to keep this at a stop or so below. The flash then gives the subject exposure: at close distances you often have to experiment to see if here, too, you need compensation (it might be too bright – or with diffusers a little dull). Digital is wonderful for this since the LCD becomes your visual exposure meter.

Tilt and Shift Lenses

User of large format bellows cameras and even those who used medium format would be aware of the way a tilt mechanism could extend apparent depth of field. A T/S lens designed for 35mm would give a wider view than stated – a 35mm TS seems like a 28mm in coverage. I had the chance to try out the Nikon 24mm T/S from Nikon courtesy of my good friend Pier Luigi Pacetti – we wanted to use a PK11A extension tube but this does not afford the right electrical connections – we did not expect AF because the tube was not designed for that but it would not allow manual exposure either because the lens does not have an aperture ring. What an omission. Toni Kowal at Grays of Westminster (www.graysofwestminster.co.uk/welcome.php), an inexhaustible mine of Nikon information, suggested using Kenko tubes that offer full electrical contact including AF – as yet, we have not tried but that might be a future posting.

From the specs I have read for other T/S lenses the maximum reproduction ratio unaided is not as much as I would want for the price! Canon make a superb range of these lenses and with extension tubes – friends tell me they are superb.

coming shortly….Part 2, will deal with using ultra-wide zooms and my current passion, the rectilinear fish-eye. Watch this space….

© Paul Harcourt Davies 2009