Macrophotography is close-up photography, usually of very small subjects. Classically a macrophotograph is one in which the size of the subject on the negative is greater than life size. However in modern use it refers to a finished photograph of a subject at greater than life size. The ratio of the subject size on the film plane (or image sensor plane) to the actual subject size is known as the reproduction ratio. Likewise, a macro lens is classically one lens capable of reproduction ratios greater than 1:1, although it now refers to any lens with a large reproduction ratio, despite rarely exceeding 1:1.
Outside of technical photography and film-based processes, where the size of the image on the negative or image sensor is the subject of discussion, the finished print or on-screen image more commonly lends a photograph its macro status. For example, when producing a 6” x 4” (15cm x 10cm) print using a 135-format film or sensor, a life-size result is possible with a lens having only a 1:4 reproduction ratio. Source: Wikipaedia
Depth of field problems with macrophotography
Macrophotography always suffers (sometimes intentionally) from depth-of-field problems. The more light you can pour onto the subject, then the smaller the aperture that can be used on the lens, and the greater the depth-of-field.
The central point of focus is, ironically not in the centre of the range of the depth of field. I’ll explain what I mean by that. Take a look at this simple diagram:
We all use depth-of-field limitations to throw the background out of focus when taking a portrait, for example, out of doors. When shooting macro images depth-of-field can become critical. Halve the lens aperture and you will double the depth-of-field. And when you are shooting a subject just a few inches deep (in terms of distance from the plane of the camera), then that can still mean part of the image is out of focus.
Macrophotography is often used for producing images of small objects such as jewellery, toys, flowers, insects and confectionary. I have used a number of clockwork toys in the examples here: http://www.bdfoto.co.uk/UL/Snowmen.jpg
There are two rows of three pictures. In each row I have focused on the nearest toy, then the second pair and then the third pair. But the difference between the two rows of pictures is that in the upper row I have used powerful lighting and a small aperture whilst in the second row I have used much lower powered lighting and a wide aperture. The difference is very obvious.
The effect has been achieved by varying the light intensity. By using LED lights it is possible to have a highly controlled environment in which to work. And sometimes the use of a varying and limited depth-of-field is advantageous as it is not always desirable to have the entire subject in focus. The reason is simple. You may well want to highlight the main element of the subject whilst leaving the less important elements out of focus.
This really is a case of letting your imagination run riot. The effect you want to achieve is simple enough as long as you remember a few simple rules:
- The smaller and the closer the subject to the camera plane, then the shorter the total distance from the front to the back of the in-focus area in real terms;
- Greater light intensity allows you to close the shutter aperture to increase the depth-of-field;
- The distance from the central point of focus to the front of the in-focus range is half that of the distance to the back of the in-focus range.
Macrophotography is limited, but using those limitations to their best effect can be great fun.
Macrophotography – original article © 2011 Barney Douglas at http://www.bdfoto.co.uk and http://www.bd-shop.co.uk
Article produced for Fotogenic Photographic Equipment of 3a Averill Street, Rhodes, NSW 21380, Australia
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