Have you ever really seen the night sky? You’d think so. But if you’ve seen it from a dark site, away from the city lights, you’re aware that things look very different. The constellations become more difficult to pick out of the bright expanse of stars. The Milky way becomes visible, as do some of the brighter galaxies and clusters. Viewing from a dark site makes it clear that there is more out there than what is visible with your naked eye. This becomes even more evident with larger apertures, faster optics and longer exposures. But astrophotography is not only for the night sky. Photographing celestial objects, can be done day or night. In this series of blog articles we will be covering the basics of astrophotography, in the day and at night. We will be examining shots with very minimal equipment as well as more advanced topics like shooting long exposure deep sky astrophotos on an equatorial mount or similar tracking device.
So let’s get started with an overview of shooting when the sky is not dark. In this segment, we’re going to do astrophotography in the daylight, afternoon and evening hours. How’s that possible, you ask? Well, it turns out that the simplest technique for of astrophotography is to shoot scenics, the Moon and planets. These subjects are typically bright enough to be captured with out the need for long exposures and sometimes can be captured throughout the day. The simplest of shots can be had, just with a little knowledge of the late afternoon or evening sky. Websites like Spaceweather.com, or Skyandtelescope.com are great resources for upcoming celestial events (planet groupings, eclipses, meteor showers, etc). There are other similar websites that also provide email alerts for certain upcoming celestial events (Calsky.com). The key to anything related to the sky, is knowing what to shoot and when to shoot it. Having information on planetary groupings, comets or meteor showers is helpful. However, even without these resources, just keeping an eye the morning and evening skies will usually present many good photographic opportunities. Below is a shot of the Moon and Venus, just after sunset. It’s interesting how the dark side of the Moon is illuminated by the light reflecting off the Earth. This was a simple fixed tripod shot with a stock, unmodified Canon 30D and a EF70-200 f/2.8 lens.
There are other opportunities that have the potential for interesting astrophotos. Shooting these in the daylight hours presents some challenges. But the results can be quite unique. The author lives in the desert Southwest. The emergence of Spring brings fairly frequent and sometimes severe dust storms. As it turns out, for those brave enough to venture out with photographic equipment, these dust storms present a unique opportunity for photographing objects like the Sun. Below is a photo, shot in a heavy dust storm, about an hour or so before sunset. It was shot with a stock Canon 7D, an EF70-200mm f/2.8 mounted on a tripod. The level of dust attenuation, on this occasion, was so high that a large Sunspot (AR1429) was easily viewable with the naked eye. It can also be seen in the photo at the 2 o’clock position.
Important: When shooting into the Sun, always use extra caution. Be certain of what equipment that you need to be safe. If the Sun is low in the sky, the intensity levels can be low enough to be safely photographed (sunrise and sunset, for example). Even during these times the intensity can sometimes still be fairly high. In these cases, a neutral density filter can be use to reduce the intensity to a safe level. Shooting in the bright midday Sun is more challenging and requires a considerably higher degree of caution. Solar filters are almost always needed, in these circumstances. Never point the camera toward the Sun, without a filter installed. A lot of damage can be done to both equipment and your eyes. Don’t attempt this unless you’re completely confident in this shooting situation and you understand the risks.
Another unique opportunity for daylight astrophotography is photographing the Moon and planets. How is it possible to photograph the planets in the daytime? It turns out that several planets are readily visible in the daylight, if you know where to look. Venus and Jupiter are two of the brightest planets and are the easiest daylight targets. Even with their high brightness, they can still be nearly impossible to locate unless the precise location is known. Even knowing exactly where to look, they can remain practically invisible. It’s usually easiest to spot these planets, when they are located near to the Moon, which can be used as a reference point. When you finally locate your target, including terrestrial object like a trees, a mountain or a passing plane (if you’re lucky enough) will a little interest to the frame. This is a daylight shot of Venus (below and to the left of the Moon). This was also shot with a stock 7D and the same 70-200mm lens, on a tripod.
A celestial event that occurs less frequently, but is equally as interesting to photograph, is an eclipse. These can be either solar or lunar. Since we’re discussing daylight astrophotography, we’ll look at a solar eclipse. This pccurrs when the moon passes between the Earth and Sun, blocking out part, or in some cases, all of the Sun. These events can occur at any time of the day. So be prepared with a proper solar filter. The simplest of this type of filter is film, sold by companies like Thousand Oaks Optical (www.thousandoaksoptical.com). These simply cover the end of the lens and are affixed there. However, there are also glass and other specialty filters that are available. Whichever filter is used, it must be securely mounted so it won’t accidentally fall off. This would allow the Sun’s full energy into the camera, and possibly your eye. Just to reiterate. Always use caution when shooting photos of the Sun.
On a recent eclipse, the event was underway during Sunset. The intensity levels were low enough to allow direct photography. So no filter was required. For this image, only a high shutter speed was required to capture the images of the setting eclipsed Sun. Once again, this was captured with my trusty 7D. Although this time, the “lens” was my Takahashi wide-field imaging telescope (530mm focal length f/5). It made a perfect platform for this eclipse, although any telephoto lens could have been used with similar success.
With eclipses, you can shoot interesting photos, without even looking at the Sun. Turn your back to the Sun and watch at the effects of the eclipse. What’s happening on the opposite side of the eclipse can be equally as interesting. For example, any small opening will easily project the image of the eclipsed Sun. This is akin to an image formed by a pinhole camera. Look at the light falling through the leaves of a tree or even crossed fingers. The crescent shape of the Sun will be clearly evident (as in the photo below).
Another simple technique to view and photograph an eclipse is to use a pair of binoculars to project an image of the eclipsed Sun. Point the binoculars toward the Sun while holding a white card near the eyepiece end. When the Sun’s light is projected through the binoculars, and image will be projected. This is also a great technique for viewing & photographing Sunspots. The photo below was shot as a projection through one side of a tripod-mounted pair of binoculars. It’s safe and provides a crisp view. Just be aware that as the Sun transits across the sky, you have to manually follow with the tripod mounted projection device. In the photo below, the moon is in front of the Sun blocking nearly all it’s light. This was an annular eclipse, where a ring of sunlight remains around the perimeter of the Moon. This is different than a total eclipse, where the Moon completely blocks the light from the Sun.
Finally, lets look at an event that won’t happen again during any of our lifetimes, the 2012 Venus transit. The next occurrence isn’t until 2117, sorry. This transit occurred when Venus moved between the Earth and Sun. Since Venus is fairly far from the earth, what is seen is a small dark circle traveling across the face of the Sun. This dark circle is the actually the silhouette of the planet. It essentially is a Venus eclipse. Although in the Astronomy community, it’s known as a transit.
With this type of event, generally a telescope or long telephoto lens is used (with proper solar protection). This event was highly anticipated by many folks and there was a bit of a run on solar filters. The author procrastinated and was without a solar filter for the event. So in order to view the transit, the binocular projection technique was again used. But this time it was projected onto a sheet of vellum, crudely mounted on a cardboard frame. This allowed the transit to be easily captured. Venus is the small circle at about the 9 o’clock position.
Hopefully what was presented here will provide a little incentive to head out and do a little daylight astrophotography. In this brief overview, a couple examples were presented of what is possible and what is out there to shoot. All this is required is a little knowledge of the sky and knowing where and when to shoot. In the upcoming blogs, we’ll transition from shooting in the daylight, to photographing at night, with more and more advanced topics.