As I thumbed through the pages of the Backyard Astronomers
handbook each image exploded off the pages with a brilliant flavor. I read about
how the Hubble Space Telescope changed our view of the universe and I gazed at images
that were clear and crisp and bright. I have also watched various video
programs about visually exploring the wonders of the universe and how magical
and exotic those parts of creation can be. These views were taken with
expensive instruments so sensitive that the most distant reaches and faintest
measures of light can be imaged. They are incredible and inspiring.
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| Orion Nebula - Where stars are born |
Amateur astronomers have available today a myriad of small
but powerful telescopes that removes much of the mystery behind navigating the
night sky. Many of these are affordable, some maybe not so affordable except to
the most die hard. They are capable of revealing and tracking a tremendous
array of night sky objects using their computerized tracking software and
drives. For those of us who must live on a tighter budget, well about all we
can do is to sigh with envy and appreciate the contribution these amateur level
instruments provide. But all is not lost.
The past year or so I began photographing the night sky and
following the work of others who produce amazing images. I’ve also read about
and followed several amateur astronomers who photograph deep sky object using
their sophisticated computer tracking telescopes. Some of the results they
obtain are truly amazing. This season, I began to explore how to capture some
of the more easily found deep sky objects. What I discovered is that even
without an high dollar computerized astronomical instrument, you can capture some incredible images
using simple homebuilt tracking equipment and basic photographic cameras and
lenses.
In a previous blog entry, I wrote about building a manually
operated barndoor tracker. For wider area photographs, this manually operated
device worked very well, but in order to photograph deep sky objects, you need
to have a motorized version that tracks the sky more smoothly. The previous
image shown above and the one below illustrate the results that can be obtained by adding a simple 1 RPM motor to the tracker. Using this
setup and with some careful identification, I’ve been able to track and
photograph a few deep sky objects. The easiest of these is Orion’s Nebula in
the constellation Orion.
In the northern hemisphere Orion is primarily a winter
constellation and the nebula located in Sword of the Orion’s belt is easily
seen even with the naked eye or with a pair of binoculars. Last winter I attached my 500mm lens to the tracker and pointed it toward
the nebula to see what would happen. Once I had the tracker properly aligned as
discussed in that previous blog post, I experimented with the exposures and the
tracking. What resulted far exceeded what I expected.
One of the techniques more serious photographers use to
capture deep sky objects is what is called stacking. This technique involves
taking a series of images (several hundred in some cases) using relatively
short exposure times and then building the image one layer/stack at a time
using software written for such techniques. If you know how to do it and are a
whiz kid in Photoshop, you can indeed create some amazing images. The images I
took were the result of a single image that was slightly tweaked in Photoshop.
The result obtained were pretty good and much easier to do.
First I setup the camera at 3200 ISO and opened the aperture all
the way, in this instance f/6.3 at 500mm. I took a short test shot to verify I
had the nebula located in the view finder then I turned on the motor drive and
allowed it to run for a few seconds to dampen any startup vibrations. Using a
cable release I fired off a series of exposures ranging from a few seconds
upwards to 30 seconds and over a minute. What I discovered was that the 20 second shot
provided the best combination of detail, color, and depth. With a bit of
cropping, a little tweak in Photoshop to boost the saturation, dampen the star
glare hovering inside the nebula, and making sure the sky was black, the image
materialized into one where the lacy wisps of glowing gases and starlight
became visible with good definition and clarity.
The clarity of the image proved just how accurately the
motorized barn door tracker worked. Total out of pocket cost to build it was
less than $40.00 using materials already on hand, the largest expense being the
1rpm motor that cost about $25.00. Not everyone has a 500mm lens laying around
to use, but many people do have 70 – 200 or 75 – 300 lenses. These will work
almost as well, but may not crop as tightly.
Another deep sky object that is relatively easy to find is the nearby galaxy Andromeda, also known as M31. Andromeda is the closest next galaxy to our own Milky Way Galaxy, but it is considerably larger, at least twice the size, but is shaped similar to our own as a magnificent spiral. Andromeda is actually moving rapidly toward us and in a few billion or so years it will collide with the Milky Way and forever change the shape of both of them. Andromeda is visible by mid-summer above the northeastern horizon and continues to rise higher into the night sky as the summer progresses and if you are willing to stay out until the wee-hours of the morning you will be able to find it hovering high enough in the sky to get above the horizon light polution glare. It is located oddly enough in the constellation Andromeda and by using a star chart and some experimenting, you should be able to find it by late June or early July around midnight about 30 degrees or so above the horizon in the middle latitudes of North America. It is surprisingly quite a large object in the night sky and is just visible as a dim smudge to the naked eye on a clear dark evening. The light gathering ability of the camera will capture the dim light rather nicely.
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| Andromeda hovers in the summer sky |
The photographing techniques are the same as mentioned above and it can become one of the most exciting objects to photograph. I'm still working on obtaining a really clear image, but I have managed to capture a few decent images. It is much dimmer than the Orion Nebula and this requires a little longer exposure, and the dictates a much tighter tolerance on the alignment of the tracker.
Capturing deep sky objects are well within the capabilities of the average photographer and certainly is worth the effort. Give it a try, and along the way you might discover something exciting about the night sky.
Keith
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