There is little light, I have opened the aperture fully and the shutter speed is very slow. What can I do to prevent my photos from being blurred? [3/8]
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There is little light, I have opened the diaphragm completely and the shutter speed is very slow. What can I do to avoid blurry photos?
This is the classic situation where a very bright lens makes a difference. Only if our lens is of high quality will we be able to take a photograph in extreme situations.
Unfortunately, not everyone can afford the luxury of spending astronomical sums to buy a lens with f:1.4 aperture, but you can try to control the problem by increasing the sensitivity, i.e. increasing the ability to register images on film or capture them with the sensor even in the dark, at the expense, however, of quality.
Sensitivity
The sensitivity is also called the “speed” of the film, because with very sensitive emulsions one can shoot with very fast speeds, while with low-sensitivity emulsions one must use much slower speeds.
The sensitivity was measured using the arithmetic system of Asa (American Standards Association) or the logarithmic system of Din (Deutsche Industrie Norm). The difference between the two methods is that with Asa, when you double or halve the film sensitivity, the Asa value also doubles or halves, while for Din the increment occurs in increments of 1/3, meaning every three Din corresponds to an increase of one EV.
Today, with the standardization of measurements, the acronym Iso (International Standards Organization) is used, which combines the two values separated by a “/” (100/21°), where the first of the two measurements is the same as what was used for Asa.
Before continuing to talk about sensitivity, it is useful to remember what EV is. The acronym stands for Exposure Value, and it indicates how much light reaches the film plane using a specific shutter speed/aperture combination or all equivalent value combinations (for example 1/30-f:8, 1/60-f:5.6, 1/125-f:4.0), all at a standard sensitivity of 100 Iso.
The starting value EV=0 corresponds to a shutter speed of 1 second and an aperture of f:1.0. Each value different from zero, such as EV1, EV2, EV3, etc., indicates an increase or decrease in shutter speed or aperture by one stop. If an object has a brightness of 12 EV, it can be photographed by using either 1/60-f:8.0, 1/125-f:5.6, or 1/250-f:4.0, etc., because the result, in terms of exposure, will always be the same.
If the EV of a blue sky is 14, it drops to 11 if there are many dark clouds, while the interior of a house lit by an incandescent bulb has an EV value of 5. Too complicated? Don’t worry, your camera’s light meter will do everything itself, or almost, because, as we will see shortly, this tool is calibrated to correctly expose an object that has a reflective power equal to that of an 18% gray card (
in the photo above B/W grain).
But let’s get back to talking about sensitivity. We mentioned that by increasing its value, you can photograph even with very little light. Old films were produced with different sensitivities, each had its own characteristics and was suitable for a certain situation. If the light conditions changed, the film had to be changed or a second camera body with the right film loaded had to be used. To get images taken almost in the dark, they also intervened in the darkroom by increasing the temperature of the acid or the development time of the negative. Today, with digital technology, sensitivity is simply adjusted by increasing the “electronic gain”, i.e., activating a series of circuits that amplify the light signal received by the sensor.
Nice and easy, right? Too bad that, as always, there is another side of the coin to deal with: the sharpness and quality of the image. When analog photography was used, one had to pay attention to the grain, i.e., those “balls” that appeared when using high-sensitivity films and that gave a very “reportage photo” look. In digital, instead, there is “noise”, annoying artifacts that make our photo “grainy”, with low contrast and no detail. A problem particularly evident when using cameras with small sensors.
Complete Photography Course
- Photography Course: Which Camera to Choose?
- Photography Course: The Beginning: Useful Tips
- Photography Course: Sensitivity
- Photography Course: Out of Focus or Blurred?
- Photography Course: The Circle of Confusion
- Photography Course: Apertures
- Photography Course: Battery
- Photography course: how to hold the camera
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