What is Macro Photography?
First, an explanatory note for all those with a modicum of photo history and tech basics: the term macro is
used to refer to the capture of an insect or whatever, that resulted in an image on the 35mm film frame
(24x36mm) that ranged from 1:10 to 1:1 the size of the original subject. For its part, the term micro
referred to a film image that was larger than 1:1 life size; micro photography could easily give you a
35mm film image of an ant that was itself larger than the original ant.
A CCD or CMOS sensor can be as tiny as 3x4mm, so any definition term that applied in the film days is
now obsolete. But the rules that apply in accomplishing successful and satisfying macro photography still
stand.
Normal photography works in using a camera to record a sharp image by adjusting the lens-to-sensor
distance to attain precise focus: for distant subjects at infinity, like landscapes, the lens is positioned at a
minimum lens-to-sensor distance; to capture sharp images of closer subjects, like people, the lens-tosensor is increased.
In macro photography, a sharp image of a tiny object requires the lens to be positioned much closer still,
with the lens moved even further out than for normal photography.
As far as my investigations go, just about all compact digicams and most DSLRs have a selectable macro
mode. In some cameras you can select macro mode via an external control, while in others you must
access the viewfinder menu.
Think about it: no extra lenses, no macro tubes or bellows, no special lenses. What a wonderful world in
which to shoot macro!
Being curious about how digital cameras can capture macro so easily I investigated the subject. Here are
my findings, gained by chatting to the tech expert at a major camera company.
Engage macro mode on a digicam( Digital Camera) and the system adjusts the lens elements to rearrange them into an array that best suits close focusing. Quite a feat, as even simple camera lenses have a
surprising number of lens elements to juggle.
Unfortunately, by engaging macro mode with the vast majority of cameras you lose control of both the
lens aperture (f-stop) and shutter speed.
Why is this so important?
The best macro photography — regardless of camera — requires that you use the smallest lens aperture to
gain optimum image sharpness and depth of field. Using a small lens means you need more light, so you
need to extend the exposure time to make a correctly exposed photograph.
So you can’t reduce the lens aperture to a smaller, more favorable setting; nor can you slow the shutter
speed to permit the use of a smaller lens aperture
With DSLR cameras the macro operation is somewhat different. Select macro and you activate a different
chain of events: with any lens fixed to the camera, engaging macro mode on the camera commands the
lens aperture to close to its minimum, so extending the depth of field and allowing you to move closer to
the subject.
Shooting macro with a compact digicam is easy but you have to forgo a fair bit of control and you need to
understand that the demands of an amateur as far as resolution and colour quality are less stringent than
the pros.
The pro approach would be to use a purpose-built macro lens on a DSLR. Dedicated macro lenses are not
cheap but they are optimised to operate at closer than normal distances. With macro lenses you are
unlikely to experience problems such as colour fringing and optical distortion; many macro lenses also
compensate for the additional exposure necessary when racking out the lens to distances very different to
those used in normal photography.
In macro photography you should aim to capture a sharp image of your tiny subject with all — or nearly
all — of the subject in sharp focus. Using a macro lens on a DSLR is the optimum way to travel.
There is one more thing to be taken into account: you must keep the subject still and the camera must be
locked off.
Depth of Field
This is possibly the core factor in successful macro shooting. When you focus, the depth of field includes
the plane you focus on plus an area in front of and behind that plane. Half of the sharpest area will be in
front of the plane and half will be behind it.
Depth of field varies with the lens aperture, focal length and the camera-to-subject distance. Competent
use of it will give you a subject in pin-sharp focus with the background in soft focus: a soft focus
background isolates a subject, making it stand out sharply.
No Confusion
Take care to position your macro subject against an appropriate background: no confusing fuzz, no bright
spots; dark backgrounds for light subjects and vice versa.
Lighting
You’ve probably set up the camera only centimeters from the subject. Flash is useless at a close working
distance — it would overexpose the shot. If you’re working in filtered daylight (my ideal) you can help
by scattering small reflectors around the subject. But in most cases you’ll have to live with the existing
ambient light level.
Arguably the optimum light for macro work is to set up a scrim of translucent material (like rice paper)
over the subject. In this fashion you can shoot in bright sunlight, with the subject illuminated by soft light.
Light Loss
If you’re working with a DSLR you might like to use extension tubes or close up bellows to shoot macro.
If you do, you will encounter one problem: the further the lens is extended from the image sensor the
more you will encounter light loss, requiring the camera to use a larger lens aperture.
Focus
In macro photography it is advantageous to have full charge over focusing — especially when you want
to have control over that part of the subject you want in focus. If your camera allows manual focusing,
use it and manually focus on the part of our subject that is the main point of interest.