Astrophotography is a fancy term for photography of astronomical objects (planets, stars, nebulae, galaxies, etc.). Those incredible pictures you’ve seen of the Milky Way or the rings of Saturn, that’s astrophotography. Many amateur astronomers quickly become interested in astrophotography as a way to enhance their astronomical viewing sessions. This is because specialized astrophotography techniques actually enable you to get better views of the night sky than what is achievable just by looking through a telescope. Take a look at the two images below of the Orion Nebula (a personal favorite).
Pretty incredible…so how do you do that?
Principles of Astrophotography
The first thing to consider with astrophotography is, “what is a photograph?” In simple terms, a photograph is a recording of light particles, or photons, that form an image. Whether it’s with film or digital, the photons that make it through the aperture of the camera to the sensor or film are recorded for later display. The more photons that are recorded in any area of an image, the “brighter” that area will later be displayed. For the purpose of iAstrophotography, we’re going to focus on the digital photography world here.
There are two key terms are important to understand when it comes to capturing those photons. The first is exposure. Exposure can basically be thought of as the amount of time you allow those photons to impact your camera’s sensor. Naturally, the longer you allow photons to hit your sensor, the more photons you will capture, thus the brighter the image will appear. Long exposure images are very helpful for astrophotography, because we are trying to pickup very fine details in a low light environment. However, for long exposure images to provide crisp detail, the camera must remain very still, and we must eliminate motion in the field of view (with a tracking mount for astrophotography).
The second term to understand is ISO. ISO is essentially a measurement of your camera’s sensitivity to light. This is a setting which is typically adjustable on a digital camera or to some extent on a smartphone. Lower ISO means less light sensitivity, and vice versa. Thus, for astrophotography, we often rely on high ISO image capture. That said, if the ISO is too high, it can lead to unwanted “noise” in the image.
Astrophotography can be done with any camera, but using a telescope creates a natural advantage over regular photography. If you recall from the astronomy terminology page, one of the main functions of a telescope is to function as a light collector. All of the photons that are captured through the large aperture of the scope are then condensed and focused into the viewer using mirrors and/or lenses. In this same way, connecting a camera to a telescope will produce greater light sensitivity for astrophotography than using the camera alone.
So, using a telescope, we can take astrophotographs with great light sensitivity. However, to turn these into the magnificent astrophotographs you’re used to seeing in various publications, some extra work is required. We won’t get into the fine details here, but the high level principle is that multiple images of the same exact portion of space can be digitally combined one on top of the other to enhance the signal-to-noise ratio using some specialized software. The end result is an astrophotograph with even more detail than you perceive when looking through the telescope.
What is iAstrophotography?
iAstrophotography is just what it sounds like – astrophotography with an iPhone. Ever since I first got an iPhone, I’ve been amazed by its picture taking capabilities. While the camera may have some limitations compared to a DSLR, the form factor allows for excellent composition. Plus it’s always with you and incredibly easy to experiment with.
Rather than dole out the cash for a fancy new DSLR camera to go along with my fancy new telescope, I’ve decided to try and perfect the technique of using my iPhone for astrophotography, hence iAstrophotography. I’m still experimenting with various techniques and software, but hopefully that all will improve with time. There are a few other astrophotography sites on the web with a page or a blog post talking about iPhone Astrophotography. My goal for this site is to make it the go to resource for iAstrophotography. My hope is that the reduced barrier to entry for iAstrophotography will enable many others to become engaged in amateur astronomy and astrophotography.
Here are a few of the early results I’ve been able to get with iAstrophotography…more to come!