Page 66 - BBC Sky at Night Beginners Guide to Astronomy - 2017 UK

WHAT TO USE

CREATE THE PERFECT SNAP
Your webcam movie fi le of a analyses the movie fi le from stacking. These stacked frames
planet or the Moon will most your webcam. It ignores each may still be subtly different
likely be in a format called an frame that is too badly from one another, so the
AVI fi le. All it takes is a little affected by wind shake, program will apply rotations,
computer wizardry to get a your mount’s tracking errors shifts, colour balances and
good-looking image or two or too much turbulence in other tweaks until it ends up
from it. the atmosphere. with a brand-new, single,
For this, you’ll need some After dismissing the cleaned-up image. Stacking
software to process your movie unsuitable shots, it’s left with means the images you end up
fi le, and a good program to the best frames from the movie, with are brighter and sharper.
do this is called RegiStax. This which it then puts on top of Indeed, it can sharpen your
great bit of software (free to one another to improve the image so much that the fi nal
download from www. detail, quality and colour in result is far better than the best
astronomie.be/registax), them – what’s known as original frame in the stack.

Sift the wheat from the chaff from an AVI fi le of Saturn with stacking software such as RegiStax

images. But there are fl eeting moments when the
atmosphere is calm, and since a webcam records TOP WEBCAM TIPS
many frames per second, it captures these calm
To get great images with your webcam,
moments when the view is perfect and the Moon take a video that’s around a minute long.
and stars are at their best. Your stacking software can create a sharp
You can leave it at that, or you can then use fi nal image from this. Also choose an
several of these good frames from the movie to observing site that doesn’t have too many
trees or houses. These give off heat, as can
make your fi nal image. You can do this, and more
patios, creating swirling air currents that
besides, with the help of a computer program to
can cause your image to wobble. Setting
enhance your picture. See ‘Create the perfect snap’ up in the middle of a big fi eld or by the
above to fi nd out how. sea is ideal.
Accurately focusing a webcam can
SHOOTING THE STARS be tricky. There are two ways to do this,
depending on what you’re imaging. For
Webcams are designed to sit by a computer, so
the Moon, frame the terminator in the
how do you attach one to a telescope? Well, fi rst
webcam and use the contrasting features
you have to remove the webcam’s front lens and to gain focus. For planets, you can use a
add an adaptor barrel in its place. You can buy nearby bright star to focus the webcam
special adaptor barrels from telescope suppliers, or before moving the scope’s view back
you could use an old 35mm fi lm canister, or even a to the planet.
bottle top with the end cut off – anything that’s the
right size to fi t into the eyepiece slot.
The new adaptor barrel is then taped or glued under £20. There are many other computer
to the webcam and the webcam is slotted into the webcams available for a similar price too, such
telescope so that its light sensor chip is sitting as the Logitech QuickCam and the Microsoft
WILL GATER X 7, STEVE MARSH X 2 Captured with a webcam, from through your scope. You can see where the webcam lenses adapting. If you don’t fancy having a go
LifeCam. All of these webcams need their
where your eye would be to get a magnifi ed view
yourself, some astronomy shops will offer a
sits in the photo on the previous page.
The Philips Toucam is often cited as a good
modifi cation service.
top to bottom: mountains on the
Finally, regardless of what telescope and
webcam for astronomy but, sadly, Philips doesn’t
Moon, Saturn pops out from
make it any longer. It’s been replaced by newer
webcam you have, you’ll need to connect it to a
behind the Moon, the crescent of
Venus, Saturn and lunar craters
66 skyatnightmagazine.com 2012 models like the SPC230, which you can buy for laptop computer to grab images of the night sky.