Deep Sky Objects

M42 - The Orion Nebula
M42 – The Orion Nebula

There is a lot that could be said about observing and photographing Deep Sky Objects (DSOs), so I’ll try to keep it simple. But before you go observing you have to ask yourself a few important questions:

What type of deep sky objects do you want to observe or photograph?

Star clusters, nebulae, galaxies… There are lots of them out there. Some are fairly bright, but most of them not so much. This leads us to the next question.

What equipment are you going to use?

This alone could put big constraints on the targets’ visibility. When it comes to faint and fuzzy objects, the size (aperture) of your telescope does matter.

Observation or astrophotography?

In both case you would want (if you have a choice, that is) a light bucket – a telescope with large aperture and low f-number. However, this may not be the case for piggyback photography where you use the telescope for guiding. The camera (plus lens/smaller telescope) is mounted on the guiding telescope or attached as a counter weight depending on your system.

Before you continue you may want to check some observing tips.

Galaxies in Virgo
Galaxies in Virgo

Equipment

Your equipment plays very important role in the Deep Sky Objects hunting. The first thing you’ll have to do is find your target. If you have a Go-to system, then it will be easier. If you don’t… you’re skills will be put to a test. But don’t worry! They’ll improve with time. I’d recommend that beginners do not use (or at least not always) a Go-to system. Why? How else will you learn? A situation may come that you won’t have the luxury of it, and then what will you do?

For astrophotography you must have very sturdy, equatorial, power driven mount. There is no way around it. When you use a longer focal length lenses, you’ll have to do very precise guiding. And that’s another skill set you’ll have to acquire. Unless of course you have an auto guider.

Lenses

Start with something simple, like 135 mm, or even 80 mm. There are plenty of targets, and it’ll do you good to practice guiding. Moreover, these are short enough focal lengths, so that it’ll be easier for you to keep the stars point-like even if the star in the crosshairs does wander slightely. After you get some experience move to 200-300 mm. Most photos on this page are taken with 300-500 mm lenses. M16, M22 and M27 are shot using a 10/1000 telescope as a lens. Stick to 80-300 mm lenses at the beginning. There is a lot you can do with them, so don’t be tempted to go straight to shooting through the main focus of your telescope. Besides,telescopes have drawbacks. The longer focal length comes with a price – larger f-number, which means much longer exposure times, and smaller fields of view.

About the photos on this page

I thought for a long time what images to use here. Since this website is oriented toward beginners, I decided to use some of my “early” attempts on photographing Deep Sky Objects. And though I say “early”, it still took me a lot of time to get there. Yes, they may not wow you, but these are realistic results. They show what to expect when you start your first astrophotography sessions. All astrophotos here are done using low-end equipment. And because these are some of my first photos, most of them are done using film camera, which means ve-e-ery long exposures, at times.

IC 434 - The Horse Head Nebula
IC 434 – The Horse Head Nebula
M17 - Omega Nebula
M17 – Omega Nebula

The term “nebula” comprises different astronomical objects – supernova remnants, gas clouds, planetary nebulae, etc. One of most famous nebulae is M42 – The Orion Nebula (on the very top of this page), which is giant gas cloud where millions of stars are forming as we speak. The Orion Nebula can be seen with naked eye on the winter sky.

Unfortunately, most nebulae are not that bright. For some, such as M17 (see left) – The Omega Nebula (also known as The Swan Nebula and The Horseshoe Nebula), and M27 – The Dumbbell Nebula (see below), you’ll need a telescope to find them. And they won’t look nowhere near as good as M42 in the eyepiece. Nor you’ll see any colors.

M27 - Dumbbell NebulaThere are even fainter nebulae, such as IC434 – The Horsehead Nebula (see further above on this page) that could not be seen in a telescope. They could only be captured photographically.

All in all, to capture such Deep Sky Objects it would take large exposure times, skills and patience. The result, however, would justify your invested time.

Galaxies

M31 - The Andromeda Galaxy
M31 – The Andromeda Galaxy
M33 - Triangulum Galaxy
M33 – Triangulum Galaxy

Galaxies are another well know example of Deep Sky Objects. Like the nebulae, bright galaxies are hard to find. Nevertheless, there are several that are bright enough to provide nice details. Among them is M31 – The Andromeda Galaxy (see above) and M33 – The Triangulum Galaxy (see left).

Most galaxies are not that bright. And when their brightness decreases, so does their size. Often all you’ll get in your camera is a small spot with fuzzy outskirts. See the three galaxies in Virgo near the top of the page as an example. Not that spectacular indeed.

Only if you shoot through the telescope, you can get more details from a small galaxy. And to do that you’ll need higher quality telescope, mount and camera.

Star clusters

Another subset of Deep Sky Objects are the star clusters. There are two types of star clusters – open and globular.

In open clusters as the Pleiades (see below) the stars are, as the type name suggests, loosely bound and not as clumped. Sometimes they could be so sparse that you’d have a hard time recognizing them from the background star field. In other cases they could have a nebular emission around (such that could only be seen in photographs).

Pleiades Open Cluster
Pleiades Open Cluster
M22 - Globular Cluster
M22 – Globular Cluster

Globular clusters, like M22 (see right), are gravitationally bound and spherical – hence the name globular. They all look the pretty much the same, and are not that different to photograph than smaller galaxies.

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