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Long exposures of natural scenes
In the absence of sunlight

It is possible to obtain pictures of outdoor natural scenes in the periods that precede sunrise (dawn) or that come after its total absence, but with some simple rules for long exposures with consistent stops, in addition to knowing the method of dealing with “reciprocal failure”.

Photographers are accustomed to capturing outdoor landscapes during the day, and we talked at length about photography before and after noon, and during dusk and sunset with the beginning of sunrise and sunset, but here we want to throw photography on photographic light after the sun has completely set, or before its threads appear until ...
Many may find that this method is not available to them because their reflex cameras (SLR) will not enable them to obtain reasonable meter readings, but for the truth
We say that with a little experience, you can rely on the available meters to reach good results with the weak light conditions referred to.

Here, first, it is necessary to adopt slow-speed color films from 64 to 25 aza, with exaggerated exposure times ranging from four seconds to four minutes sometimes! .. From here and with these very long periods, we must first work with a three-legged pillar with a high degree of stability. With a wire to catch in order to avoid the slightest possible vibration.

The first step usually begins with focusing on the most important part of the scene that we want to capture, for example, focusing on the front, middle, or back of the scene, according to the requirements of each scene, and focusing on this concept, says the international photographer Brian F. Peterson.
- In a sunset scene with rocks in the foreground, I decided to adopt the exposure for the reflections on the wet sand, so I directed the camera towards the specified area, focusing on the direct front to infinity within a sharp prominence
And to get that I had to lower the aperture by the stop until f / 16 . Here, it was not permissible to go down to the required pause - F / 16 - immediately, to avoid not being able to read the scene with weak lighting. Instead, I worked to make the lens wide. As for the presence of a camera with aperture. favourites. It suffices here to note the indicated shutter speed, with the need for parity needle cameras (*) or the shutter preference for dealing with the shutter speed dial until indicating the correct exposure at this location for the wide aperture.

For more clarification about this method, the following image can be presented:
Let us consider that the meter has given us a reading of 1/4 or “a quarter of a second at f / 4, and this is what happened with the aforementioned wet sand image (but we previously decided that the need requires adopting / 16, from here we must know the exposure time that It gives us at f / 16 what is equivalent to 1/4 of a second. At f / 4 it is a simple calculation because the two stops referred to, and the two shutter speeds, are going here in double succession (*).
What the transition from F/4 to F/16 means is to give four stops less optically, because the intervals between the two stops are F5.6. F / 8 F 11 or four halves of the exposure, then we have to double the exposure time to four times, starting from the basic “quarter” second exposure, and so the first doubling leads us to 1/2 second - half a second - and the next doubling to one second, two seconds, up to four seconds and incrementally until you reach the minutes.

And for those who see that their cameras do not accommodate exposures for more than four seconds, we remind them of the possibility of adopting the location of the time exposures (B) and pressing it. With the required time expression on the wristwatch.
It also indicates that by adopting exposures longer than four seconds, we will find ourselves facing the problem of reciprocal failure (0). This means that the film will suffer from a lack of light exposure, which will affect its colors, despite the adoption of correct and accurate calculations.

Returning to Peterson, we see him saying:
- I've found that doubling the recommended exposure time works best for exposures of between four and two minutes and at sunset as the sky gets progressively darker, it actually takes up to four minutes when the timer says one minute.
We point out here that some photographers tend to use filters to compensate for any color shifts during long exposures: Brian Peterson says here that he does not do that, but rather prefers the way colors shift with different slide films.
We can add that experiments determine the best way to adopt and benefit from the filters.
Finally, we present a table of exposures equivalent to light, and this means that whenever the meter falls to a specific location, the more we have to drop the pause to the corresponding location within the table.