Clear Mountain Garden Treasures
 

Clear Mountain Garden TreasuresMacro Photography of Flowers and Plants

Macro Photography of Flowers and Plants

This article is on macro photography of plants and flowers using digital cameras. It is based on a talk that I have gaven to a number of orchid clubs on orchid photography, so the examples are mainly of orchid flowers. While this article is geared towards macro photography of flowers, most of what I say here also apply to photography in general.

Background: I am the awards photographer for the New Zealand Orchid Society and I also have an interest in landscape photography.


Piha Beach

Camera
Compact vs. 35mm SLR
Digital camera
Other equipment
Composition
Focus
Exposure
Speed
Aperture
ISO
Lighting
White Balance
Software

 Camera

The most important factor in photography is you, the photographer. A good photographer can make an ordinary flower look nice, and a nice flower into a great photograph. The essence is to capture the flower at its best and highlight its good parts. However, a good photographer also needs good equipment.


A Basic Camera

A camera is a light proof box with an attached lens that focuses light into a film or a photo sensitive surface. Between the lens and the film, there is a diaphragm and a shutter.

The distance between the lens and film is called the focal length of the lens. With 35mm cameras, a lens with the focal length of 50mm creates an image on the film that roughly corresponds to the field of view of the human eye. Lens with longer focal lenghts will make the image look bigger. They are known as telephoto lens. Correspondingly, lens with shorter focal lengths make the image look smaller, and are know as wide angle lens. Most modern lens are zoom lens, that is, their focal length can be changed either by sliding or rotating a ring on the lens, or otherwise is controlled by a couple of buttons on the camera.

The diaphragm controls the amount of light that enters the camera. It is like the iris of the human eye that opens and closes in response to changing light levels. The aperture of the diaphragm is measured in f-stops. The higher the f-stop, the smaller the opening, and the less light is able to enter.

The shutter captures the photograph by momentarily allowing the light to fall onto the film. The shutter speed is measured in seconds and for regular photography, it is common to use shutter speeds of 1/100 to 1/200 of a second. The faster a shutter operates, the less light enters the camera. Together with the aperture, the shutter speed regulates the amount of light that falls onto the film.

Different films are manufactured with different sensitivities. A film's sensitivity is measured in ASA units. Common ASA values are 100, 200 and 400. Films with higher the values are more sensitive and require less light to form an image

 Compact vs. 35mm SLR


An SLR Camera

Digital SLR Camera

An SLR (Single Lens Reflex) camera has a mirror that is placed between the lens and the film. This serves to reflect the light upwards towards a pentaprism that reflects the light into the viewfinder. When the camera takes a photograph, the mirror is flipped upwards before the shutter opens, allowing light to transmit to the film. The advantage of an SLR is when viewed through the viewfinder one sees exactly the same image as the film.


A Compact Camera

Compact cameras on the other hand, have a separate lens for the viewfinder. This lens is usually offset from the main lens by several cm. In normal operation, where the subject is several metres away, this small separation does not make much of a difference, and the image in the view finder approximates that on the film. However, when used for macro photography, where the subject can be only 20cm away, the image formed on the view finder will be somewhat offset from the image formed on the film. For this reason, most film compact cameras are unsuitable for macro photography.


Digital Compact Camera

Digital compact cameras, on the other hand, can display what the detector "sees" on an LCD screen. When used in macro photography mode, this screen represents an accurate image of the photography that will be taken. However, the viewfinder should still not be used for the same reasons as mentioned above. Only compact digital cameras that support a macro mode should be used for macro photography. Macro mode is a usually indicated on the screen or buttons as an icon that looks like a tulip.

 Digital camera

In a digital camera, instead of film, there is a matrix of photo-sensitive cells. When light falls on to a cell, the electronics convert it into a number, 0 means black (or no light) and 255 means white (or bright light). All other values in between represent different shades of gray.

The detector can only detect light levels, and if used as is, will only take black and white photographs. For the camera to take colour photographs, colour filters are placed in front of the detector array. Each detector has its own coloured filter, that only lets through one colour, thus the detector only "sees" the one colour. By having a matrix of red, green and blue colours, it is possible, through a software algorithm to reconstruct a colour image from the detector.

The photograph on the left is the result of a 30 x 30 detector array. Each detector creates a pixel (picture element) in the photograph. While it is not a great photograph, and even with only 900 pixels, it is possible to see that it is a picture of a flower. Obviously, with more pixels, the photograph becomes clearer. The photograph on the right was made with 36100 pixels, or 190 x 190 array.

Digital cameras are measured by the number of pixels in the detector array. This is the often quoted megapixel (MP) measurement. One megapixel equates to a million pixels.

 Other equipment

Digital cameras store photos on a flash card. A flash card is like an electronic hard drive. It is now common to get sizes of 1, 2, or 4 Gb (billions of bytes). As a general guide, a 1Gb card will hold about 280 photographs from an 8 MP camera. Different makes of cameras use different cards, and it is important to check before hand whether your camera supports the card before purchasing. Flash cards are now very cheep, and it is advisable to buy a card as big as your camera will support.


Tripod and cloth backdrop

The other piece of equipment that is essential to macro photography is the tripod. This keeps the camera steady while the photograph is being taken, and allows for slow exposure speeds to be used.

A backdrop provides a plain neutral background for the photograph. Dark coloured backdrops are suitable for most flowers, and a light grey one is often used for dark coloured flowers. Backdrops can be made of cardboard, painted wooden panels, or just plain cloth.

A light tent is another useful piece of equipment. Its main job is to diffuse the light so as to elliminate glare. Basically, a light tent is made of material that diffuses light. It is placed over the flower to be photographed and an opening in the front allows the camera to shoot the photograph.

The photograph on the left is of a very shinny flower. The photograph on the right is the same flower inside a light tent.

 Composition


The subject must be balanced

When composing the photograph, the flower should be balanced, meaning, it should either be at the centre, or if off to one side, there should be another flower to balance it out.

In the photograph on the left, the flower is off to one side. In the right photograph, the same flower is more off to one side, but is balanced out by the other flower that is side on.

In the photograph on the left, the flower is taken slightly side on. This is acceptable. In the right photograph, the same flower is balanced out by another flower that is more side on.

The flower should be taken at sufficiently close so that its details can be seen. The flower in photograph on the left is too far away. Sometimes certain features can be highlighted by taking super closeup images. The photograph on the right emphasises the pollen of the flower.


Whole spike

It is usual for the flower to be shot front on (photo on the left), or a little off to the side. Sometimes a combination is necessary to fully show the shape of the flower. The photo on the right is side on of the same flower. It shows the depth of the flower, which the photograph on the left doesn't.

If you are taking a picture of the whole plant or flower spike, it is desirable to have at least one flower that is front on, and a few others from diffrent angles.


Cluttered background

The background should be plain, of a contrasting colour and clear of distracting objects. In the photograph on the left, it is hard to see where the flower ends and the background starts.

Any props or ties should be temporarily removed or if not possible, then carefully hidden. When taking pictures in the garden or the wild, pick flowers where the background is uncluttered as possible. Sometimes, it may be necessary to change the angle of the camera to achieve this.

 Focus


Out of focus

Most modern cameras have an auto focus function, which is on by default. In most cases, this function works fine, but occasionally, the mechanism incorrectly focuses away from the subject, for example to the background. Cameras either focus in the middle of the photograph, or may pick from have a number of points away from the centre. For macro photography, it is best to set the camera to focus only on the middle. Point the middle towards the part of the flower that is to be in focus, then pan the camera to complete the composition.

 Exposure

Under exposed Correct exposure Over exposed

For an image to be registered, film have to be exposed to a certain amount of light. The precise amount is determined by the ISO rating. In a camera, the shutter speed and aperture opening regulates the amount of light that falls on the film.

A camera auto exposure control works fine if the photograph has a balance of light and dark areas. When the photograph is dominated by light or dark areas, the camera's auto balance will not be accurate. Predominantly light photograph will end up under exposed, and vice-versa. This is particularly bad for macro photography because the photograph is mostly the colour of the flower and the background.

To work around this, bracketing must be used. Bracketing is taking a number of photographs of the same subject, but with different exposure settings. With light coloured photographs, bracket by progressively over exposing the shots, and vice-versa for dark coloured photographs. One of the photographs in the bracket list will have the correct exposure.

 Speed


Blur caused by unsteady camera

A shutter regulates the amount of time a film frame is exposed to light. A longer time will allow more light to accumulate. The camera must remain stationery relative to the subject, while the shutter is open, and a long shutter opening time makes a photograph more prone to camera and subject shake. However, the faster a shutter operates, the less light falls on the film. So picking a shutter speed is a compromise between useability and exposure. In regular camera use, it is normal to use speeds of 1/100 to 1/200 of a second.

For macro photography, a tripod is usually used to keep the camera stable, allowing slower shutter speeds to be used. Even when using a tripod, slower shutter speeds will still make the photograph prone to subject shake. In particular, when the camera is close to the subject, a small shake translates to major bluring in the photograph. It is therefore important that the subject is sheltered from droughts, and even foot steps.

 Aperture

The size of the diaphragm opening, called aperture, also affects the amount of light that falls on to the film. This size is measuerd in f-stops, with larger numbers meaning smaller openings. Larger openings allow more light in, but like shutter speed, there is a trade off.

When a camera focuses on something, there is an area to the front and the back of the focal point that will appear clear. This is called the depth of field. The bigger the opening, the smaller this area.

In the above three photographs are taken with pencils spaced at different distances from the camera. The camera was focused on the green pencil. The photograph on the left is shot with f-5, the middle f-8, and the right f-16. In the left photograph, the F and B pencils are very blur, and the 4B is marginal. Stopping the lens down to f-8 improved the depth of field. The 4B pencil is sharp, and the F pencil is sharper, just marginal. With f-16, the the B pencil becomes marginally focused. Compare this to the f-5 result.

Most lens take the best picture at around f-8. This is known as the sweet spot and produces the best photographs. Openings that are too small suffer from diffraction effect, bluring the photograph.

If a tripod is used, it is best to pick an apperure value that will result in the whole subject being in focus, but the background is still blur. The speed is then set to allow the correct exposure on the film.

 ISO

The ISO rating of a film determines its sensitivity to light. High ISO means the film requiers less light to form an image, but as you have guessed it, there is a trade off.

The protograph on the left was shot at ISO 100, and the photo on the right, 1600. Higher ISO ratings cause grain in film photography, and noise in digital photogaphy. If a tripod is available, use the lowest ISO rating and use a slow shutter setting.

 Lighting

Bright diffused daylight is best. The photography can be done indoors, next to a bright window, but out of direct sun. Direct sun causes colours to wash out, and also causes harsh shadows.

Where daylight is not available, incandescent lighting that comes from multiple sources is the next best thing. Where a tripod is unavailable, or when there is a lot of wind, and a tripod cannot be used, it may be necessary to use flash. Flash tends to also wash out colours and can cast a blue tint over the photograph.

The top-left photograph was shot using diffused daylight. Top-right was done in full sun. Bottom-left was shot using incandescent lighting. Bottom-right was shot using flash.

 White Balance

In the days of film photography, the film is formulated to reproduce correct colours when used in daylight. A daylight film when used with incandescent lighting will produce an orange cast. Florescent lighting produces a greenish cast. While it is possible to buy film with different chemical formulations for different lighting, it is more common to employ filters to correct the colours.

Daylight film will render the photograph on the left correctly. If the photograph was illuminated by incendescent lighting, it will appear like in the middle. Flourescent lighting will result in the photograph on the right.

Digital cameras on the other hand, do not have the luxury of using specifc detectors tuned to different light sources. Instead, the colour correction is done in software. The camera software is usually intelligent enough to pick the correct white balance, especially, if there are light coloured areas in the photogtraph. With macro photography, on the other hand, it is common for the photograph to be mostly one colour, the colour of the flower. This usually confuses the auto balance function of the camera.


Camera white balance setting

With most cameras, it is also possible to tell the software the sort of lighting to expect. On the left is a snapshot of the white balance of the Canon EOS 350D camera. From top to bottom, left to right, the settings are, auto, daylight, shadow, cloudy, incandescent, flourescent, flash and custom.


Camera white balance setting

Both photographs were shot using incandescent lighting. The photograph on the left was shot with the camera's shite balance set to incandescent. The photograph on the right was shot with the camera's shite balance set to auto.

Using the custom setting, you will need to first take a picture of a white paper or card in the same lighting as the subject. You then tell the camera to use that as the custom white balance.

 Software

You can also use software to perform colour balance. If your camera supports it, shoot in raw mode, using auto white balance, and then use software like Raw Shooter Essentials or Lightroom to convert the raw file to JPG. As part of the conversion process, it is possible to perform colour correction.


Raw Shooter Essentials

There is also software for photograph manipulation, for example, Photoshop and Paint Shop Pro. These software will allow you to, for example, remove an unsightly stake from the photograph.

In the photograph on the left, the flower stake is visible just under the flower. There was also a gap in the backdrop, showing the brown coloured floor. These serve only to distract from the flower. With software, it is possible to remove the stake, and crop the picture to exclude to floor, picture on the right.

The software is so powerful, that you can do pretty much anything to the photograph. For example, you could turn a yellow flower green. Why one would do this is a another matter. In my opinion however, software should only be used to enhance the photograph to make it look natural and as close as possible to the flower.


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