In fact the photograph macrophotography is when an object (the negative or chip) to a size equal to or greater than the reality. At a time when size was the same as the negative of the picture that was synonymous with taking pictures in a size equal to or greater than the reality.

At the time of analog photography where negative 35 mm (36X24 mm) was becoming a standard began to be interpreted as the macrophotography pictures to look at them on paper have a size equal to or greater to reality. This definition is somewhat ambiguous since following the enlargement of the picture and the same picture can be seen macrophotography or not.

At present the definition remains ambiguous, since a picture is displayed larger or smaller than reality as the screen that look.

We can say that macrophotography begins where normal just focus on the goal of cameras. For a traditional analog camera 35 mm with a target of 50 mm is normal in around 40 or 50 inches. We can extend this definition to any camera with a focal length when using normal (same focal length of the diagonal chip or negative) pictures do less than 40 cm.
Photos taken in these conditions when displaying enlarged typically have a larger than actual size.

How do macrophotography

In compact cameras

Most current digital cameras allow you to focus very close so no stranger can make macrophotography device with an acceptable quality. With compact digital cameras can make macrophotography smoothly.

In digital reflex cameras

If you use a normal reflex camera then goals (not macro) does not allow us to do macrophotography, the goals will allow us to focus on short distances. To solve the problem we have several solutions

  1. Slow approach: It is a kind of filter that allows us to focus on shorter distances. Is the most bad as we are adding an objective lens is the result of many calculations and this affects the quality of the results.
  2. Extension tubes: It is interposed between the lens and the camera body tubes without any optical element in order to increase the distance between the lens and the camera. From the optical point of view is a good solution. Sold in sets DETR tubes that are between 50 to 70 mm can be used alone, in combination of two or all three at once. The increase achieved depends on the size of the camera sensor (like smaller increase) and the focal length used (as most smaller increase). With these tubes with a regular camera (sensor (24X18 mm) can photograph a fly in a way that almost takes up the whole picture. Use is nothing to prevent two or more sets of extension tubes together. They can buy at a price if they have financial connections to keep the automatic camera and more expensive to maintain connections with all automation of the camera.
  3. Macro objectives: Are objectives made to work with macro focus and allow an objective standard with extension tubes. They are very comfortable and a good solution because it is not necessary to add or remove tubes. If you want to get more gains nothing prevents use extension tubes or bellows with these objectives. It is designed to work goals short distances and therefore have superior performance in macrophotography. Its focal length ranges between 50 and 100 mm.
  4. Bellows: This solution is very similar to the extension tubes. Consists of a bellows interposed between the lens and the camera to separate the camera lens. Vary gradually allow the distance between the lens and camera from about two to 15 cm or more. As the separation distance between the camera and the target is at least 2 cm can not be used for few gains. It is the only solution for many increases. Generally not the automatic camera.

Objective invested

The objectives are designed assuming that the distance between the object and purpose of photographing is greater than the distance between the lens and the sensor or negative). In macrophotography, for large increases, as the distance between the target and the camera body is greater than the focal length of the objective this relationship is reversed. This happens a lot when using a bellows or extension tubes (more than one game) in such conditions should use in order reversed. This is achieved with a ring on one side investor who rallied to the camera body (bellows) and the other at the front of the lens with a filter.

The ratio of extension and depth of field

Call ratio to increase the ratio between the size of the object to the sensor or negative and the size of the real object. If we have a ratio of 1 increase the size of the object and the sensor size is the same. When we move with microphotography relationships expansion from 0.3 to 4 or 5 if you use a bellows.

When using extension tubes or bellows in order to focus to infinity the formula that relates the ratio of the separation of extension tubes or bellows is:

Where R is the ratio of expansion, a the separation between the lens and the camera and f the focal length of the lens.
If the target is not focused at infinity the distance between the lens and the camera is a little larger, a target of 50 mm focused at 40 cm should add about 7 mm.

The formula that relates the depth of field ratio and diaphragm expansion is:

The circle of confusion (usually take the value of 0,033 mm) diameter is a point that can have negative or sensor and consider a point. This value depends on the extension of the final picture (pixel size in the paper.)

As we can see the depth of field depend besides the diaphragm also depends on the expansion ratio, the greater the enlargement ratio smaller depth of field.

Note that the depth of field is independent of the focal length used, it just depends on the relationship of the diaphragm and expansion. This in macrophotography and photography in general.

Depth of Field Table

The following table is the depth of field for combinations of ¡Iversen and diaphragm expansion of relations:

  Depth of field (mm)
5,6 8 11 16 22 32
0,1 40,66 58,08 79,86 116,16 159,72 232,32
0,2 11,09 15,84 21,78 31,68 43,56 63,36
0,33 4,51 6,45 8,87 12,90 17,73 25,79
0,5 2,22 3,17 4,36 6,34 8,71 12,67
1 0,74 1,06 1,45 2,11 2,90 4,22
1,5 0,41 0,59 0,81 1,17 1,61 2,35
2 0,28 0,40 0,54 0,79 1,09 1,58
3 0,16 0,23 0,32 0,47 0,65 0,94
4 0,12 0,17 0,23 0,33 0,45 0,66
5 0,09 0,13 0,17 0,25 0,35 0,51
Area diffraction problems

As we can see in the table, for large expansion ratios (greater than 2) the depth of field becomes very critical, less than one mm.