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A Beginner's Guide to |
Macro Photography |
by Robert Stephens
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Background |
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Consider this a beginner’s guide to macro photography. It is meant to be intuitive rather than
mathematical, though certainly the mathematics of this subject can be quite rigorous. My use of numbers
in this guide will be solely for the purpose of providing examples and will, therefore, be illustrative rather
than precise.
For the sake of my discussion, I will assume the use of a single lens reflex camera. Macro photography is the fancy term for close-up photography. It is the technique that photographers use to convert small subjects into large images. Macro photographs often consist of still life images of inanimate objects or nature photographs of living creatures such as insects and flowers. But really, there is no limit to the choice of macro subjects. The basic tools of the trade in macro photography include hardware and technique. The common hardware tools include macro lenses, extension tubes, a tripod, a flash, mechanical clamps for stabilizing subjects, and perhaps, too, a tilt-angle macro lens. The benefits of each of these tools will be explained as we go. I’ll cover hardware first and then later, discuss technique. |
Focusing Distance
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But before we cover hardware, let’s review a few fundamental technical aspects of photography,
particularly as they apply to macro photography. Let’s consider first, the issue of “depth of focus”.
Depth of focus refers to the range of distance from nearest to furthest away from the lens that objects
are in focus. Typically, for any given focal length of lens, the nearer one focuses the lens, the less
depth of focus is obtained. As that lens is focused to greater and greater distances, the ‘deeper’ the
depth of focus becomes. Let’s provide a couple of examples. A 105mm macro lens can focus on objects to
within about 15 inches. When using this lens at f/11 all objects in the range from 14.95 inches to 15.05
inches away are focused. Any object nearer than 14.95 inches is out of focus, as is any object further
than 15.05 inches from the lens. In this case, we have a depth of focus of 0.10 inches. If I now focus
this same lens, still using f/11 at an object that is 100 feet from the camera lens, all objects between
about 80 feet and 125 feet are in focus. We now have a depth of focus of 45 feet. The rule of thumb: as
the focal distance decreases, the depth of focus decreases. In macro photography, we focus close, so the
depth of focus is typically low. |
F-Stop and
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Let’s also consider another fundamental technical aspect of photography. Let’s consider the
consequences of operating our same 105mm lens at f/45 rather than f/11. At f/45 objects that are between
5 feet from the camera and an infinite distance from the camera can be in focus. This is a significant
increase in the depth of focus of this lens relative to when it is operated at f/11. The rule of thumb:
as the lens f-number increases, the depth of focus increases. These examples illustrate two of the major problems posed with macro photography – depth of focus and exposure. First, let’s consider depth of focus. Obviously, focusing is much more critical as the camera moves closer and closer to the subject because our depth of focus decreases. Also, as the camera moves closer to the subject, less of the subject remains in focus unless the entirety of the subject is at the focal plane. How do we solve this problem in macro photography? One solution is to use very large f-stop settings on the lens because our rule says that as the f-number increases, the depth of field increases. By operating our macro lens at, for example, f/45 rather than f/2.8, we increase the depth of focus of the lens and more of our macro photo subject is in focus. We can also use a tilt-angle macro lens, which I’ll describe later. |
Shutter Speed |
The use of a high lens f-number poses another problem, doesn’t it? Obviously, as the lens f-number increases,
the lens aperture becomes smaller and the light reaching our film or digital sensor decreases. Consequently, to
obtain a properly exposed image with a large f-number, it’s necessary to use longer exposure times – or, it
becomes necessary to use a flash – or both. With natural lighting, high f-number lens settings, and the long
exposure times this requires, the slightest movement of the camera will yield a blurry image. If you consider
that the macro photographer might be trying to record an image that is perhaps as narrow as 1/8” from edge-to-edge,
it is easy to imagine that it takes only a very little movement of the camera to produce unacceptable motion blur
in the final image. Even with today’s image stabilization lenses, there is only one reliable solution to this
problem and that is the use of a tripod. The use of a tripod helps to prevent camera shake from generating motion
blur in the final image, but this doesn’t always solve the problem of motion blur in the final image. If you’re
photographing insects, sometimes they will move on their own. Or, the wind might move your subject – whether your
subject is a flower or an insect on a flower. There are a couple of possible solutions to subject movement. One possible solution is to use a higher shutter speed so that the subject doesn’t move far during the duration of the open shutter. Using a higher shutter speed definitely helps, but this conflicts with our desire for high depth of focus, doesn’t it, since higher shutter speeds usually require lower lens f-number (i.e. aperture open wider)? But there is another way to increase shutter speed without changing our f-number. We can maintain our high lens f-number (and depth of focus) and still increase our shutter speed to freeze the motion of our subject by increasing the ASA of our film or digital sensor. But this increase in shutter speed does not come for free. Invariably, higher ASA films or digital sensor settings yield grainier or noisier results than lower ASA. Often, however, this is essential in capturing a macro image. Another solution to a moving subject, if that movement is caused by the wind, is to use clamps and/or wind screens around the subject. |
Hardware
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Alright, we have reviewed a few fundamental technical issues associated with macro photography. Let’s now return
to hardware. At the beginning of this article, I mentioned the tools of the trade in macro photography. The first
and foremost of these is a good macro lens. One might ask: what distinguishes a macro lens from any other lens? The
answer is simple – first, their close focusing ability. Macro lenses are designed to be sharp at close focus. And
macro lenses also are designed for operation to high f-numbers, offering the potential for greater depth of
focus when focusing close. Clearly, the closer a lens will focus to a subject, the larger the image on the film plane or on the digital sensor. This minimum focusing distance works in conjunction with the focal length of the lens to determine the size of the image on the film plane or digital sensor. The rules of thumb here are intuitive: for a given focal length of lens, the closer it will focus, the larger the image. Alternatively, for a given minimum focusing distance, the longer the focal length of the lens, the larger the image. |
Lens focal length
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Technically, macro photography strives for making the subject’s image on the film or digital sensor plane large
relative to the actual subject size - up to a ratio as high as 1:1. When the image size at the sensor is larger
than the actual subject, then we’re in the realm of “microphotography”. It is not unusual for a macro lens to
have a combination of focal length and nearest focal distance such that the ratio of image size to subject size is
1:4 or sometimes even 1:2. And yet, macro photography can be done with lenses where the ratio of image size to
subject size is much larger than these values. |
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The minimum focusing distance of any lens can be easily reduced, and thereby, an increase in image size can easily
be obtained. This is most simply done by using extension tubes. Extension tubes are just what the name implies.
They are tubes with no optics inside. Their purpose is to move the camera lens away from the camera itself, so
extension tubes are placed between the camera and the camera’s lens. Using extension tubes has the effect of
reducing the minimum focusing distance of a lens. Remember, if you can get closer to a subject and still focus on
it, its image will be larger on the film or digital sensor. This “magnification” of the subject doesn’t come free.
As you extend the lens from the camera to greater and greater distances, i.e. as you use longer and longer extension
tubes, the ‘effective’ f-number of the lens increases. I say ‘effective’ because you might have the lens set at
f/11 but the amount of light reaching the film or sensor might be equivalent to f/22. Consequently, exposures
must be compensated with either a longer shutter speed or a brighter flash. |
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Some photographers also use optical macro attachments to non-macro lenses to give them the ability to
focus closer to a subject. These are attachments that screw-on to the front of a lens and typically provide a
1.5X or 2.0X diopter adjustment to the lens, much as reading glasses do for old folks such as myself. These can
sometimes yield acceptable macro images, but such screw-on lens attachments generally not only have their own
optical flaws, but also magnify the flaws of the lens to which they are attached. Consequently, my suggestion
to someone getting started in macro photography is to buy extension tubes. Since extension tubes are not optics,
per se, they are relatively economical. They usually come in sets of 3, with each tube in the set being a different
length. Extension tubes can be stacked, so a set of three provide six different combinations of tube lengths. |
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Since we now know that high f-numbers are often useful in macro photography, and since we know that this
places demands on available light and shutter speeds, the need for a good flash is part of the macro photographers
hardware arsenal. On-camera flash is quite often inadequate, either for aesthetic or practical reasons. If you’re
using a long focal length lens, an on-camera flash is often shaded on the subject by the lens itself, making the
flash useless. If extension tubes are being used, this possibility is even more likely. From aesthetic standpoints,
better lighting – the secret to all great photography – is better accomplished by a remote flash. These can be hand
held and oriented to give lighting from any desired orientation. |
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Next on the list of hardware is the tripod. Its function is obvious – to hold the camera steady during
exposure. Don't fool yourself into believing you can do good macro photography with a camera that's hand-held.
It's virtually impossible to do good macro photography without a tripod. It's a crucial piece of equipment
for good macro photography. Critical considerations are stability, flexibility in orientation, ease of operation,
weight, and the
type of mechanism used for holding and aiming the camera. With tripods, as with many things, one gets what one
pays for. The tripod must be built to easily secure the weight of whatever camera/lens combination you’re likely
to choose. If you’ve invested in expensive camera gear for macro photography, don’t cut corners with a cheap tripod.
Having an expensive camera fall to the ground from an inadequate tripod mount is the last thing you want. The
tripod should be able to lower the camera to near ground level to enable photography on ground level subjects.
This is particularly useful for nature photography to capture images of flowers, insects, lizards, etc. Quick
release locks on leg extensions and smooth movement of the legs are important considerations. They will make
the use of your tripod easier and reduce the time for setting up a shot. Typically the heavier the tripod, the
more stable it is, but weight savings are accomplished by tripod manufacturers with the use of aluminum, titanium,
or carbon-fiber construction. If you plan to do much hiking with your camera gear, you’ll want a lightweight tripod.
Many photographers prefer to use ballheads for quick set-up, however these are also typically quite expensive.
They’re not essential to making great images. |
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The final assurance against camera movement during a macro exposure is the use of a remote shutter release. All
high end SLR cameras provide a way to release the shutter without actually pressing the shutter release button on the camera
itself, which sometimes does cause camera movement even when using a good tripod. I never shoot macro without a cable
release. |
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I promised a few words about tilt-angle macro lenses. These are sophisticated macro lenses that allow the
photographer to have a variable focal plane. That is, the portion of an image that is in focus can be different
distances from the camera, either left to right or up and down or any combination. And so, if you have a subject
oriented such that it is further from the camera at one end than another, this can be compensated for by adjustment
of the tilt angle lens. Very clever. |
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Technique
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Depth of Focus Preview |
A single lens reflex camera utilizes an internal, movable mirror to direct the image from the camera’s lens
to the viewfinder. The default position of this mirror at all times except when the shutter is released is “down”,
i.e. directing the image to the viewfinder. To make the viewfinder image as bright and visible as possible, the
aperture within the camera lens is fully open at this time. Upon release of the camera’s shutter, two things happen.
The mirror moves out of the path of the image being projected through the lens, allowing the image from the lens to
pass to the film plane or the digital sensor. In addition, when the shutter is released, the lens aperture closes
to the f-stop set for the shot. So, until the shutter is released, the lens aperture is not at the setting used for
the recording of the image, unless that aperture is set for maximum (i.e. the lowest f-number). Consequently, an
SLR camera does not provide a “what you see is what you get” photograph, unless you’ve set your lens to operate at
its lowest possible f-stop of operation, e.g. an f/2.8 lens set to photograph at f/2.8. That is, the viewfinder of
an SLR camera with an f/2.8 lens will provide an accurate view of the image photographed at an f/2.8 f-stop. For
any other f-stop setting, the photographed image will have a different depth of focus than exists when viewing the
image through the viewfinder. Most SLR cameras are equipped with a “preview” button. This button, when depressed, closes the aperture in the lens to its current setting. For example, if an f/2.8 lens is set to photograph at f/8.0, depressing the preview button will close the lens aperture to f/8.0. This will provide the photographer with an accurate (albeit darker) view of the depth of focus of the image at the f/8.0 lens setting. Given the importance of depth of focus in macro photography, this feature can provide the photographer with important feedback on image composition even when using rather high f-stop settings – as long as adequate levels of ambient lighting are available. |
Background clutter |
As with all photography, subject backgrounds are critical. If nature photography is the aim and macro
photographic subjects are flowers or insects, the position of the subject is frequently the difference between an
amazing photograph and one that is merely interesting. Careful selection of camera angle and f-stop will determine
how “busy” your photograph is with background distractions. Consequently, sometimes a critical choice to limit the
depth of focus is the right one. When there is a choice in subjects, one that is available without background clutter
is preferred and then f-stop can be chosen to provide the depth of focus desired to highlight the desired feature of
the subject itself, rather than the minimization of background. |
Mirror Lockup |
As I’ve discussed, camera motion must be eliminated. Sometimes this means it is best to use “mirror lockup”
when shooting macro. Check with your camera manual to determine if your camera has this capability. In short, mirror
lock up allows for the retraction of the viewfinder mirror before the actual image is recorded. This provides the
potential for a sharper image by eliminating any camera vibrations associated with the movement of the mirror during
shutter release. |
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Lighting is always critical. Natural light, when adequate to freeze subject motion, often yields striking
results. However, the presence of shadows are often distracting. The use of reflectors when shooting with any
light source – natural or flash – is often helpful. But also, light angle is key. Often, particularly when shooting
flowers, backlight can yield remarkable results. The bottom line for any photographer, after solving the problems associated with hardware and technique, is to determine your own artistic preference and to perfect it. I believe in trusting one’s own instincts and making images that fulfill those instincts. No photographer will ever make images that please everyone. But if you continually make images that please your own artistic instincts, and perfect this approach, you will find that others will find your images pleasing too. If you're interested, read my article entitled A Macro View of My Garden. |
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Macro Photo Galleries:TheWorldinLight Photographic Gallery Sterling Heights, MI 48310 |
| All photographs are the property of Robert Stephens and TheWorldinLight Photographic Gallery. Unauthorized use or reproduction is prohibited by US copyright law. |
