The night sky is very changeable. The moon may or may not appear, there may be clouds, it may be the time of meteor showers… You will even have to take into account the tide times if you plan to photograph in coastal areas. And right now, you don’t need to know when the International Space Station will pass through your frame, but at an expert level, you’ll need to factor that in as well.
To summarize and plan all this well, we will establish four different types of night photos, depending on the sky and/or the astronomical element to be photographed. These are basic scenes, which the amateur photographer uses to familiarize himself with how to photograph at night and thus be able to gradually establish his own guidelines to deal with other more complex scenes later…
We will therefore retain four types of photos:
- The moon alone or as part of a landscape
- The fixed stars and/or the Milky Way
The moon alone or as part of a landscape
Photographing the moon in one or the other of its phases is relatively easy (with the exception perhaps of the new moon, and then again…). The difficulty lies in including it in a landscape, while bringing out the details and without using additional artificial lighting (or Photoshop).
To immortalize the moon alone, you will need a cine lens, not necessarily ultra bright. You can opt for a maximum f/8 value if you have no other choice, or even beyond. You will use a medium aperture to take advantage of the best part of the cinema lens and not have to force the ISO. As for the exposure time, it will be brief, even if you shoot from a tripod.
Between the spinning moon and the spinning Earth, you’ll need to trigger at a speed between 1/100 and 1/300 if you want to gain sharpness. As for the ISO value, you will lower it to the maximum to benefit from a correct exposure with the other parameters mentioned. Focusing can be automatic by doing it on our satellite.
The moon will largely affect your summer (or winter) nighttime photo. It brings so much light that it can illuminate an entire landscape, while erasing most of the stars from the sky. The night photographer should always be familiar with the phase of the moon, as well as its rising and setting times.
If one wants to include the moon in a landscape, one must ask the following question: how much light does the moon bring to the scene? If it is full, you can trust the exposure meter of your camera, it is even there the only time when it will be reasonable to consult it. You will be able to act as if it were a daytime photo but with the camera installed on a tripod, of course.
When the moon is not full, things change, so the most reasonable thing is to do a few tests before deciding on the most adequate exposure (this is a rule that applies to everything).
Anyway, if we want to include the moon in a landscape, we will have to keep in mind that we will obtain a white disk or something similar but devoid of details. For the details, it will be necessary to use more complex processes, which will undoubtedly be the subject of future articles.
Otherwise, you can always check where the moon passes at sunset (but this is not always possible) and find the optimal exposure.
Another option would be to expose the moon and then force the rest of the image into post to get some detail. The results are sometimes better than expected,
The fixed stars or the Milky Way
Another typical scene of the night sky is a sky full of stars, provided, of course, to move away from cities and light pollution. And if we’re lucky and know where to look, we can find a wonderful Milky Way.
Photographing the night sky with lots of fixed stars in the firmament is quite easy. We must take into account the fact that if we increase the exposure time a lot, the stars will no longer be seen as luminous points but as trails, small stripes and will lose this enchanting starry sky appearance.
To know the maximum exposure time that can be applied to the shot, one can apply the famous rule of 500, which, if not completely reliable, constitutes a good starting point.
The 500 rule is to divide this number (500) by the focal length of your cine lens (but converted to 35mm).
All these calculations, as we have said, are approximate. Because as the stars move away from the earth’s axis of rotation (in the northern hemisphere, we have the polar star which corresponds more or less), the points will stretch little by little to become small lines.
Get good star exposure
Once the maximum exposure time well defined, I will explain a simple method to check the exposure for a landscape with the starry sky.
The first thing I do is use the maximum aperture allowed by my cinema lens, to try to capture as many stars as possible. Warning: do not believe that by increasing the exposure time, you will capture more stars. You will see them brighter, at most.
Once the aperture determined, I program the highest ISO that the camera allows me (not the one previously defined as being the maximum usable ISO, but the highest possible).
And finally, I choose an exposure time of 1 second.
I do a first trigger-test and I observe the exposure obtained. I then have three options:
- There’s too much light, so I lower the ISO to half
- It lacks light, so I double the exposure time
Until I get the exposure that interests me (the histogram is also an ally here).
3. Did I get the exposure I wanted? Is the landscape more or less illuminated, like the stars? So now, it is a matter of applying the famous law of reciprocity until the ISO is left at an acceptable minimum, for an exposure time that will not exceed what has been calculated using the rule of 500 applied at the beginning.
