Terence Galuszka Astrophotography
astronomypix.com
Wide Angle Astrophotography
Most of us have taken photos on a 35mm film camera or its digital
counterpart. These same cameras with stock standard 28~55mm lenses can
be used to take wonderful wide angle astrophotos. You don't need to
spend a a lot of money to take great wide angle shots. A Canon digital
Rebel, 300D or any old SLR camera will do. Combine that with a tripod
and a bulb timer and you're set for Star Trails.
Star Trails
Star trails are the easiest type of astrophotos. Just set the camera
up on a tripod, point it towards the night sky, set the ISO rating to
ISO200~400, place a hat over the lenses, set the bulb exposure then open
the shutter. Remove the hat and start imaging. Very old school,
but it works a treat. A 15 minute exposure will gather a lot of light.
If you have a fancy digital with a bulb timer and a shutter delay
, the hat becomes optional.
So Here's how to take star-trails:
• Use a sturdy tripod that won't move, as movement will show squiggles
and we want arcs!
• For best results, use a 18-28mm f2-f4 lenses.
• Use a 400 speed film or set the ISO to 200~400 for digital. This will
reduce noise.
• Select a dark location away from city lights as this will ruin the
photo with "Sky glow".
• Set the camera to manual focus, near to infinity or just a little turn
back. Experiment to get sharp pinpoint stars.
• Make sure the camera batteries are well charged.
• If your DSLR has auto dark frame; leave it turned on.
You're now see to take star trails.
Things to consider
Include something in the foreground such as the trees. This will show the stars path over the earth, its apparent rotation as well as provide image scale. Star-trail images can be spectacular with the right foreground image.
Fixed Star Images
This is when you counter the earth's rotation using an astrograph.
Look closely in the banner or the about me page and you'll see me, the
red torch and camera's mounted on an astrograph. Since the earth rotates
at approximately 0.5 degree per minute, the stars appear to rotate.
for long exposure with nice round star's we need a way to counter this
rotation. The answer is an Polar aligned Byres drive or equatorial mount
like the one driving my telescope.
Equatorial mounts for imaging get expensive... quickly! So the best
option is to make a little wooden mount for tracking called a "Barn
Door". Basically a couple of bits of plywood , a hinge and a few bolts
that you adjust to track the stars. I'm not going to get into the
details of building a barn door mount, however the designs can be as
simple or complex as you want; costing $20-$1000. Point is, it'll let
you track the stars for a limited period of time so you can create
stunning wide field astro photos.
So if you want to make a barn door mount or astrograph, just on eBay and
have a search or an Ed Byres drive or Barn door; you'll be amazed at
what you can purchase.
Once you've got that tracking mount sorted, next step imaging.
Again, choose a nice wide-angle lenses as mentioned above, check your
focus is set to manual. At 28mm F1.8 or 2.8 you should be able to image
for around 40~50 seconds without too much guide error showing.
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The Southern Cross |
The Galactic Centre |
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