Sunday, 9 March 2014

In search of the equilibrium

In the last entry I spoke about "natural light" vs "flash" and depth of field in macrophotography. Aperture modifies the amount of light and the depth of field, so these two concepts are related.

Then, I was concerned about the loss of natural ambient light. I'm going to show a  crab spider with a correct equilibrium "natural - artificial light" and with a strong flash.

In both cases the flash was shot, but in one of them the parameters were set in search of equilibrium, and in the other, we've lost the natural ambient light. When we lose the natural ambient light, we have more aseptic images. Maybe we can view better some details in this case, but we lost "sensations" associated to natural light (e.g., the warmth of the light on the morning, with its weak shadows). When we lost natural light, we can lose "context" too.

What is the problem? My flash is a "TTL dedicated". I can't to use my flash in a manual way. The light is controlled by the camera sensors. I only can modify the EV flash compensation, but my camera decides how many time is working my flash. When I change the aperture, the ISO, or the exposure time, I don't change the exposure of the main subject, but I change how the natural ambient light is captured. Then, when you try to rescue the natural light, you have several options:

i) To increase the ISO speed

With higher ISO, the sensor is then more sensible to light in exterior.

The problem now is the noise. When we increase the ISO speed, the noise grows too, so the ratio "signal-noise" is worst. This changes affect to image quality. However, you can view that the ambient light with ISO 800 is much more important that when the ISO value is 100.

ii) To increase the exposition time

When we increase the exposition time, we are capturing a bigger amount of ambient light.

However, large exposure times produce blurred photos when there are tiny vibrations. This changes affect to image sharpness.

iii) To use wider apertures

If we use wide apertures we have more light, but we also have less depth of field. This changes affect to image composition.

To shoot with a strong flash is easier for me, but I'm in search of equilibrium, looking for all these lost sensations of the natural ambient light.

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