2009年3月25日

Macro Photography for Beginners - Part 1

The advent of digital photography swept away one of the most challenging problems in image capture: how to shoot macro without a pile of specialised gear. Now you can get down, dirty and close in the image capture business and make macro the digital way with a 100 per cent success rate.

Image by ~jjjohn~

Image by ~jjjohn~

I know I’m not alone when I say that macro photography is an absorbing activity: to be able to reach into ‘near space’ and record an image that is not easily visible to the naked eye is an attractive option. There is nothing more satisfying than to make a huge print of an insect, mineral specimen or any small object that is normally so tiny to the naked eye and captured with the technique of macro photography.

To shoot macro in the days of film — aside from the requirement of using an SLR camera — you needed a few add-ons to take highly magnified images of extremely small subjects. You could begin by slipping a dioptre lens to the front of the existing standard lens … this would impart a degree of magnification; you could also install extension tubes between your normal lens and the camera body; you could also acquire a set of macro bellows and place them between lens and body; and finally, you could invest in a fairly expensive — and optically superb — macro lens that was dedicated to macro shooting; another option was to fit a reversing ring that allowed you to fit the lens on backwards … this improved the lens close up resolution and allowed to you to focus much more closely. But to be honest, it was a hassle — although you can still use these methods if using a DSLR to shoot macro.

These days, digital does it with a dash! With a digital camera — compact or DSLR — even newbies are surprised by how easy it is capture really, really big shots of tiny subjects.

In truth, you can make digital macro photography as basic or as complex as you wish it to be: even with a budget, $200-special digicam you can capture images of the tiny world before you, subjects as small as a matchbox, a match-head or even tinier. The higher-priced compact digicams can do it even better, some offering macro shooting with a powerful zoom lens, so you can stand back a bit.

The other approach is to use a DSLR; it is surprising how powerful a macro camera a circa-$1200 DSLR can become.

Image by macropoulos

Image by macropoulos

What is Macro Photography?

First, an explanatory note for all those with a modicum of photo history and tech basics: the term macro used to refer to the capture of an insect or whatever, that resulted in an image on the 35mm film frame (24×36mm) 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 3×4mm, 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-to-sensor 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!

Image by macropoulos

Image by macropoulos

Tips for Macro Photography Beginners

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 and the system adjusts the lens elements to re-arrange 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 aperture 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 favourable setting; nor can you slow the shutter speed to permit the use of a smaller lens aperture.

For the keen macro makers I’ve discovered a few digicams that do allow the use of macro mode and lens and shutter speed adjustment (see Chosen Few).

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.

Read the Second part to this series at Mcro Photography for Beginners Part 2.

Image by ecstaticist

Image by ecstaticist



Macro Photography for Beginners - Part 2

Today we continue to look at some tips for beginners wanting to explore the world of Macro Photography. Check out part 1 of this article at Macro Photography for Beginners Part 1.

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.

Image by ecstaticist

Image by ecstaticist

There is one more thing to be taken into account: you must keep the subject still and the camera must be locked off.

For macro shots you need a steady camera and subject, a small lens aperture and a slow shutter speed. Then you need more light to cope with the slower shutter speed.

Keep Your Distance

In macro shooting the optimum camera-to-subject distance is a long one. Place the camera too close to the subject and there’s a good chance you’ll throw a camera shadow onto it; at too close a distance you may distort the subject.

Using the macro mode on a compact or DSLR and wanting to capture a very, very close detail of your subject, it’s most likely you’ll move the lens to the widest angle/shortest focal length setting. This also presents the possibility of optical distortion.

Macro lenses for DSLRs are best chosen in the longer focal lengths: many lens makers market a 100mm macro — ideal for the task.

Canon and others make stabilised macro lenses. The idea is sound in principle: if you have to handhold the camera/lens combo while you snare close shots of a bug, a stabilised lens would seem to be the answer to the need for a steady camera.

The truth is that there are too many variables in the equation: moving camera, moving focus, moving subject. And then you have to frame the shot properly.

The best approach is to keep the camera steady.

image by macropoulos

image by macropoulos

Chosen Few

There are some cameras that offer lens/shutter speed adjustment in macro mode.

The Canon PowerShot S5 IS has a long 12x optical zoom lens along with 8.0 million pixels of image capture.

And it has a terrific macro mode: unlike most others digicams this camera’s macro button is a separate control placed on the lens barrel and not on the mode dial. With this arrangement you can select shutter or aperture priority and macro simultaneously.

Now you can reduce the lens aperture to a minimum setting and attain the optimum depth of field when the camera is close to the subject.

Another macro-friendly model is the Canon PowerShot SX100IS. It is unusually well set up for macro shooting: with the SX100IS you can engage macro mode along with aperture priority, allowing selection of a small aperture for depth. This camera has a 10x zoom and 8.0 megapixels of image capture.

Another contender in the maxi macro stakes is the Olympus’ SP-5500UZ. There are others that have the same benefit. Aside from an extraordinary 18x optical zoom lens it has 7.1 megapixels on its CCD. When selecting macro the camera still allows you to use the zoom, so you can back off and yet still take big closeups.

In a slightly different fashion, the Ricoh Caplio R6 helps you light subjects in macro mode, an often difficult chore with the camera positioned so close to the subject. The Ricoh’s Auto Soft Flash function dampens the output of the camera’s flash. This avoids ‘washing out’ the subject at close range.

image by macropoulos

image by macropoulos

Viewing

When shooting macro with a digicam always use the LCD screen for viewing — never use the optical viewfinder. Use the optical finder and you will encounter parallax error … what you see in the finder is not what the camera will photograph.

Distortion

Digital compact camera optics are a compromise between size and price. With budget cameras you will probably encounter spherical distortion: shots taken at the wide end (even in macro!) of the zoom will barrel out at the edges; shots taken with the zoom set to tele may show distortion which forces the picture edges to bow inwards, like a pincushion.

Try shooting a square subject — like a stamp — and you’ll see what I mean. The solution is to use the Spherize filter in Photoshop to straighten the barrel distortion on the affected image.

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.

image by jerryhsu2k

image by jerryhsu2k

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 centimetres 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.

Image by Matthew Fang

Image by Matthew Fan