The Opening To Be Used, Then It Is Equal To


The Opening To Be Used, Then It Is Equal To

Opening actual X = f (M + 1)

Where M is the magnification ratio that we use, and f is the opening in use. In the case for example of f / 16 and a magnification of 1X, the effective aperture is therefore equal to 16x2 = 32. If we're using a full frame sensor, no problem. If we are equipped with an APS sensor, we have "passed" the limiting aperture (equal to 16, as mentioned before) and then, most likely, our final image will be affected by diffraction problems: to solve the problem you need to open the diaphragm of a couple of stops. Obviously open the aperture means sacrificing depth of field: the mediation between the two problems is a "deal" of the photographer.

Attention to the camera that obviously employed: if the sensor is an APS, for example, Nikon, the circle is smaller by a factor of 1.5. Then the radius of the circle of confusion is 0.3 / 1.5 = 0.2mm.


We have seen in previous articles such as lenses suffer from various aberrations: the presence of more lenses, the addition of tubes or teleconverters does nothing but increase this problem because the light must make a longer or more cross surfaces path It is precisely for these reasons, the most important distortion within the macro photography is the diffraction.

In short, I remember that the diffraction is the phenomenon that occurs when a light beam, hitting a not perfectly transparent lens inside (even a speck of dust can cause it) splits into its primary colors giving rise to a kind the "rainbow" that will go to impress on the sensor. The problem of diffraction is much more stringent, the higher the zoom and will be different from target to target, at different apertures: always do tests with your goal of finding the optimal situation and be prepared, if necessary, to sacrifice bit 'of the depth of field.

To make our photograph does not have the diffraction problems, the best solution is to keep the opening at the bottom of that relative to the diffraction limit. L ' "limiting aperture" is indicatively equal to f / 32 in the case of a full frame sensor and equal to f / 16 in the case of an APS sensor.


The Bokeh and blurring

We have already seen extensively on Bokeh and how to apply it in a creative way: in macro photography is often used because it allows you to isolate details of persons who would otherwise be unlikely esaltabili.
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