About Astronomical Photography
For us simple mortals, taking pictures of Saturn’s rings is something we’re a bit far away from. When we hear astrophotography we imagine those amazing images of nebulae of thousands of colors, we imagine solar explosions or craters on the dark side of the moon. And yes, those images would fall into this category, but to get them we need to have pockets full of money and be willing to spend it to get them, or we need to be lucky enough to be sent to the International Space Station.
Then you’ll say that what’s the point of reading, what’s the interest in something photographic that I’ve already denied you. Well, you won’t be able to photograph Neptune nebulae or rings (without previous extra investment) but if I tell you that you can get incredible images of the sky without having to invest too much, you’ll get more excited, won’t you? We see how? We see what?
- Camera with manual controls, interchangeable lenses (Reflex/Evil) and Bulb mode.
- Telephoto lens
- Remote Trigger
- Basic Concepts
- Before you start, you’ll need to be clear about the following concepts:
Diaphragm aperture: Regulates the entry of light into the target and the depth of field. Since we will generally have little light, we will most likely have to work with large apertures in order to capture it (low values of f).
Speed: The time the camera shutter is open. The longer the shutter is open, the more light enters the shutter.
Long Exposure Photography: Are you familiar with those images of night cities full of lines created by cars running at full speed with lights on? Well, that’s done with long exposure photographs, which are those taken at very low speeds so that the shutter is open long enough to capture the evolution of the movement.
ISO: Another aspect to take into account is the sensitivity of the sensor to light, which is determined by ISO. The higher the ISO, the more sensitivity (ideal for low light situations) but at the same time loss of sharpness. On the other hand, the lower the sensitivity, the higher the image quality.
Bulb: It is one of the modes of your camera, usually marked with the letter B, and allows you to keep the shutter open for an indefinite time, beyond the maximum allowed by your camera. With this system, the shutter is opened and closed manually by pressing the shutter.
Where do I start?
Although it seems to you that with what you have you can not do great tricks, the truth is that with patience, imagination and perseverance you can get fantastic images, even without a telephoto lens, although if you are encouraged by the subject, without one you will be a little left with the desire.
While it may seem that photographing stars at such a distance is not worthwhile, you can get fantastic images thanks, for example, to the rotational motion of the earth.
Since stars in the night sky are generally not very bright for our camera, in order to photograph them we work with long exposures (our shutter stays open certain seconds to be able to capture enough light).
There are two ways to photograph stars for the simple mortal: with the static camera on a tripod and with the camera placed in some artifact that imitates the movement of the earth so that it is annulled leaving the stars visually static (on top of a telescope that imitates the rotational movement of the earth, or some other system). You will most likely simply use a tripod, at least to begin with.
If you want to portray the movement, ideally you should do everything possible to work at very slow speeds. That is, lower the ISO to the maximum or close the diaphragm (high f-values).
If, on the other hand, you want to portray the stars in a static way, and you don’t have external help (telescope, rail…) you should do everything possible to reduce the shutter time as much as possible (fast speeds). You can do this by opening the diaphragm or by increasing the ISO to values such as 2000 or 4000 as long as you maintain a good image quality (this depends on each camera).
In general, these are the recommendations for shooting stars:
- Well-charged batteries (keep the shutter open for a while, check, repeat, etc., it wastes a lot of battery)
- Tripod (essential)
- Remote trigger to avoid vibrations
- Manual focus (infinity)
- Manual mode to control aperture, exposure time, and ISO
- Perform various tests. You can make the first overexposed to contemplate the landscape and choose the best frame. Then rectify the exhibition
- Checks histogram to rectify if times or opening is necessary
- Magnify the image 100% on the screen and check that you have focused and exposed correctly.
- Repeat, check, repeat and infinite patience
If darkness is not your thing, the star king can be a great photographic opportunity too, since alone or accompanying some beautiful landscape, can be a great protagonist of the image. The ideal, if you want to get the sun moderately close, is to have a telephoto lens of approximately 200mm. Or, obviously, a telescope. If you don’t have either, don’t worry, you can get wonderful images by playing with the sun and the environment, especially when it approaches the horizon line where it looks bigger.
- Always use a tripod
- Reduce vibrations with a remote trigger or with your camera’s self-timer
- Keep the mirror of your camera open if you work with a SLR that has this option, this way you will avoid the movement it generates when it opens and closes.
- Keep the ISO as low as possible to achieve the best possible sharpness.
- Focus on manual; cameras are easily lost when focusing on infinity, since you have a certain amount of time, do it yourself to ensure the focus.
- Close the diaphragm approximately in half to have a greater depth of field and good sharpness (e.g. f/11 if the maximum is f/22).
- Take your time to compose the scene.
- Predicts where the sun will rise or set, you can use applications such as Photopills
- Do different exposure tests (the best way to measure in this case is to under-expose a point to the edition obtained in point).
- Activate your camera’s Histogram to check and/or correct the image in situ.
Another great astronomical classic. In this case you will face darkness, in fact, the darker the better, the more contrast and the more the moon will stand out.
- With the moon we have more limitations when trying to integrate it into the environment because the better it looks, the darker it is. Therefore, in this case, if we want to portray the moon as a motif in itself is essential a telephoto lens.
- If the sky is clear and the moon is full, it may emit enough light to capture surrounding elements. These images are very artistic, dreamlike and suggestive.
- Tripod. Even more essential than when we photograph the sun due to the lack of light. A tripod will allow you a sharp image at low speeds and with the ISO to the minimum.
- Remote shutter (or in its defect automatic shutter of the camera)
- If your camera has this option it blocks the mirror to avoid trepidations.
- ISO as low as possible to achieve maximum image sharpness.
- Consider moon phases. If you want to photograph the lunar orography, it is best to do it in the lunar quarters because the light falls sideways increasing the contrast and textures of the surface of the moon.
- Focus on manual.
- For good depth of field and maximum sharpness, work with medium diaphragm apertures.