Ok, so you ask, how do I get
started taking those incredible pictures of the planets, moon and other
celestial objects?
At first I wasn't
sure how to get started in this endeavor either but a search on the
web turned up a number of groups who's members , I figured, could
provide information to a novice on how to get started.
Eventually I connected with QCUIAG. This group specializes in unconventional imaging
techniques using among other things, webcams.
So what do you need to
get started? Obviously you need a halfway decent
telescope A GO-TO ( computer controlled Azimuth/Elevation mount)
option is helpful to find your target and track it. A webcam to
capture the images. A PC to talk to the webcam and to
process the images. You will also want to get a capture and
processing program.
When looking for a telescope keep in mind that the telescope's power is in how much light it can
gather ( see
telescope basics for more
detailed information) not its magnification capabilities. The bigger the opening (Objective) the
better. If you happen to live in the country where there is little
light pollution go for the biggest aperture scope your budget can
afford. Telescope prices vary on the type and the aperture size
and can go from around $200 for a starter scope to thousands of
dollars for a high end scope and mount.
If you are reluctant to spend a lot of
cash on a new hobby, not knowing if it's for you or not,
you may want to start out with a 114mm (4.5")
Newtonian ( reflector) telescope. It's relatively inexpensive.
I have a Meade DS114 (114mm f/8) reflector and so far it hasn't
disappointed me. WEBCAMS:
To capture the images
some use digital SLR cameras such as the Canon digital Rebel to
mention just one. Others like myself use webcams that have CCD
(charge-coupled
device) elements instead of CMOS (Complementary Metal Oxide
Semiconductor) devices (The
DALSA web has a good comparison of
CMOS vs. CCD).
I purchased a Philips SPC900NC (Toucam Pro III ) webcam
locally. In order to use the camera on my telescope I needed an 1.25" adaptor. Steve
Mogg at
web caddy has them available for the
SPC900NC
webcam and many others.
To install the adaptor simply pry off the ring around the
lens and unscrew the lens from the webcam. The adaptor screws right
in place . I also purchased a F-WIN accessory which is a clear coated
window mounted in a filter thread enclosure to protect the CCD from
dust, etc. This has threads on it to allow you to add other
filters.
IMAGING:
Now that you have a
telescope, and a webcam, you need a program that will allow you
some control over the webcam and capture and process the images.
Typically you would take a video exposure of your subject
and process that AVI file to combine the video
frames into one clear still image.
Though most Webcams come with some sort of software
that will capture images as movie files (AVI ) It is best to
get a program that is specifically designed for the
task at hand. One very popular program is called
K3CCD This program
allows allows you to set up your camera and capture
the AVI file. It will also process that AVI and produce a single
stacked picture with all the frames aligned.
Unmodified (out of the box) webcams are sufficient for
imaging the Moon, Sun and Planets, To get good pictures of deep
space objects (DSO's) such as nebulae, star clusters and
galaxies . however, requires a camera that can takes long
exposures ( in the 15 or 30 second range or longer). Most amateur
astronomers modify their webcams to allow for long exposure .
Steve Chambers has developed
modifications for various webcams.
If you have a Philips SPC900NC
webcam you can go to
Matthias Meijer's site where he
describes the long exposure modification for that specific camera.
Along with a long exposure (LX) modified camera your
telescope needs to be on a decent mount preferably an equatorial
mount. An Azimuth/Elevation mount will work in a pinch. Get the
best mount your budget will allow. An equatorial mount, when properly
set up, will track your target as it move across the sky , east to
west, without introducing field rotation. An AZ/EL type of a mount
suffers from that phenomenon. However, if all you have
is an AZ/EL mount, don't despair. K3CCD has a feature that
nullifies the field rotation effect for the most part.
Above I mentioned K3CCD as a program used to capture and
process images. Another popular program for processing is
REGISTAX.
REGISTAX allows you to align and stack AVI frames
and also manipulate individual pictures. One extremely useful tool it
has is what's called wavelets. It allows you to eek out all
kinds of details in the image. The program is a must have and it's
free.
Additional software in my arsenal is
WcCtrl which allows you to adjust the camera properties
such as shutter speed, frames per second, brightness and a
host of other parameters.
If you want to take picture in the RAW mode,
you need
WcRmac. This program runs a macro the reprograms you camera to
send the picture information back on the LUMINANCE channel and requires
that you set up the colors using one of the
above tool. Many say that the algorithm in the camera could
mess up the true image by compressing some data.
Both WcCtrl and WcRmac are free.
As a final touch, many use programs such as PhotoShop to
finish processing the final image to correct the color or
sharpen the picture.
(More to come ) |