The Challenges of Astrophotography
Astrophotography is something a good portion of amateur astronomers try, as
is illustrated by the Amateur
Astronomer Survey results above. It appears that more amateur astronomers
try photography than not. And the survey shows that the most often used camera
type is the digital camera. In many cases, this is even a cell phone camera,
but it's definitely easier to use a digital camera that has some kind of
mounting method available so one can use a DIY Digital Camera
Mount or something like the Celestron
93626 Universal Digital Camera Adapter.
Even a non-SLR type of digital camera can be used to take some nice
snapshots of the moon and planets with mounts like those listed, such as the
image below. It is an image of the Lunar Straight Wall region, taken with a
simple non-SLR digital camera, mounted to my 6 inch f/5 Newtonian with a DIY Telescope Camera
Mount. Given the simplicity of the setup, it's not a bad image.
Lunar Straight Wall
The survey results also show that the web cam is the next most
popular camera for taking images of the moon and images of planets. I don't
know if most of these astronomers were using a commercially modified web cam
designed for astronomical use, or if they were using mostly DIY web cam
astro-camera equipment. But certainly, very nice moon images and planet images
can be obtained with either type of web cam conversion.
I expect that simplicity and cost are the reasons behind these two camera
choices. Most people have a digital camera of some type around anyway, and
it's natural for them to try shooting through their telescope with it. The
web cam, once converted, is even easier to use successfully, but one has
to either purchase a specially made one, or make one themselves. I suspect
that's why the web cam has a bit less use than the digital camera.
Compare the image below with the Straight Wall image shown previously.
The Copernicus crater shown below was taken with a Celestron web cam
conversion, mounted to my Meade ETX 90. It is the result of stacking some
50 frames, and shows more detail that usually obtained by the simpler
snap shot technique used to capture the Straight Wall image.
Copernicus Crater with Web Cam
Click on image to see full size
In addition, the survey results show that a few amateur astronomers still
use 35mm film rather than digital. I don't know for sure, but I suspect that
the common use for 35mm cameras is for star objects which need several seconds
to a few minutes of exposure. I know that I still use 35mm photography for that
purpose. The image below of Comet 17P/Holmes was taken in 2007 using a 35mm
camera on a DIY
Piggyback Camera Mount. Shown are the field of stars and the orb of the
35mm Image of Comet 17P/Holmes
The reason to use a 35mm camera, for me at least is that a digital camera
that can take long term exposures is quite expensive, but a 35mm camera can be
had for very little. However, taking time exposures of star objects is a
different topic altogether, and not addressed in detail in this web page.
What is addressed in this web page is how you can get inexpensively into
astrophotography, taking your own images of the moon and planets, with
either a DIY web cam conversion, or a commercial web cam astro-camera. That
kind of photography can be easily done on many amateur telescopes that
are available, in that most any kind of motorized telescope will put you
in the game. I even took some web cam images of the moon and planets with
an unguided DIY 60mm Telescope.
Read on to see how to make your own web cam astro-camera.
How To Make Your Own Web Cam Astro-camera
This page explains how I modified a Logitech Quickcam Express web cam for
astrophotography. It should be general enough to apply to just about any
inexpensive web cam. If you enjoy do-it-yourself projects, this is a fun
alternative to purchasing a ready made web cam conversion like the Orion StarShoot Solar System Color Imaging Camera IV.
All you need is the type of little web cameras mounted in a ball that sit on
your computer. Sorry, I no longer have the original housing, but hopefully you
get the idea of how to do the conversion from the description on this page.
Even should you opt to buy a ready made conversion, this page will show you
what you're basically getting.
To make a device that's great for taking lunar and planetary photographs,
you only need an inexpensive web cam version, like the Logitech Quickcam.
You'll also need a T adapter like that often used to mate a 35mm SLR camera to
an astronomical telescope.
This type of camera will not likely let you take photos of deep space
objects, because most web cameras have exposure times only in the fractions of
a second. But the moon and planets are definitely within reach with such a
device. Add an old laptop to run the camera when in use, a copy of Registax for processing avi files
or snapshots, and you'll be in business.
In the years since I made my modified web cam, which still works and gets
some use, Celestron has introduced a well priced web cam astro-camera called the
Celestron NexImage. The NexImage, now replaced by the Orion StarShoot Solar System Color Imaging Camera IV,
comes packaged with a recent version of
Registax, a program for
Windows that lets you stack images. I have a Celestron NexImage, and can verify its usefulness.
The image above is an example of what the Celestron conversions can do. I
took this image using the NexImage coupled to my ETX90. It caught the
Great Red Spot, but also shows the disappearance of the SEB in 2010. Maybe
it's my imagination, but I think I see hints of some festoons in the image. The ETX 90 is getting hard to find, but a comparable telescope at a good price is the popular Celestron NexStar 90SLT Mak Computerized Telescope (Black). I rather suspect you could get as good of photos with the Celestron, as I have with my aging Meade ETX 90.
Astrocam Assembly Diagram
Above is a diagram of the web cam modifications.
Inside the web cam housing is usually a single circuit card, hosting the CCD
array in the center of the card.
If you have machining equipment, you can make a really nifty astro-camera.
Not being a machinist, I had to find a simpler way.
I had a simple camera T-mount adapter, like the Celestron
93625 Universal 1.25-inch Camera T-Adapter, which is great for mounting a 35mm SLR camera to a
standard 1.25" focuser. This adapter is just a 1.25" barrel that has
a T thread for a mounting.
With a T adapter for one's particular 35mm camera, this snout allows easy
prime focus photography.
I was able to find an old soft-plastic pill bottle that was the right
diameter to snugly fit over the T thread. I cut off the bottom inch or so of
the plastic bottle (discarding the top), cut a 1/2" hole in it to allow
light to reach the CCD array, and screwed the pill bottle end onto my T thread
I also fabricated a simple cover over the back of the circuit card, and
hurray, I had a CCD camera for astrophotography.
This image will help clarify my diagram and description.
On the left you see the modified web cam astro-camera. The white part
(blackened inside) is the plastic pill bottle end. You can see the hole cut in
the bottom to expose the CCD array (the square).
The pill bottle is just the right diameter to tightly fit over the T-threads of the camera to focuser adapter, shown on the right of the picture.
You can see that with electrical tape and some thin cardboard (like poster board), I fabricated a simple cover over the rear of the astro-camera.
At left you can see the assembled astro-camera. The snout slides exactly
into a 1.25" focuser.
The USB cable is plugged into a computer during use, and I run the vendor
supplied web cam software to make the exposures.
My camera is only suitable for the moon and planets, in that it doesn't
have the capacity for long time exposures.
Astro-camera on Telescope
This is a image of the web cam astro-camera mounted to my Meade ETX90. As you
can see, it simply slides into the focuser instead of an eyepiece.
If I need more magnification, I insert a Barlow lens first, then the
Individual pictures can be taken with the web cam, and is the technique I
used for most of the images displayed on my photography pages (I was still
However, I've found that what works better is to use the astro-camera
to take movies (avi files). Small clips of 2 to 4 seconds.
Since the camera takes about 10 images per second, a few seconds gives me
plenty of images to work with.
Then I use an image selection and averaging program to combine the frames
of a film clip into a single image. This technique helps reduce atmospheric
turbulence and pixel gain errors of the camera.
Note, this technique can't really overcome a bad seeing night, but can
certainly help reduce the residual turbulence on a good night.
Web Cam Astro-camera Result
At left is my best Mars image, taken during the 2003 opposition with
my Meade ETX90 and the modified web cam astro-camera.
I believe it to be a rather remarkable photo with such a modest instrument. It is a stack of 48 frames taken from an avi file. For this image I used
the Image Stacker program.
I used to use the Image
Stacker or the RegiStax
program for stacking frames from an avi file. Now I use a Yorick script of my
own design, and some ImageMagick tools in Linux.
I've taken a number of pictures with my ETX 90/web cam setup. You can see
the gallery at ETX
Astrophotos. I've also taken some images through a 60mm refractor, and the
detail obtained surprised me. Check them out at 60mm Astrophotos.
Web cams have a small CCD, so the field of view it encompasses is also
small. Getting moon images is easy. If I see the moon in the finder, some
portion of the moon is also in the camera. I use my handy added slow motion
control on the Meade ETX90 to move to the part of the moon I want.
Planets are tougher. I may have the planet in the finder, but I often can't
find it in the camera. I've gotten around this with the Meade ETX90 by removing
the rear plug and putting in another eyepiece. Using the flip mirror, I can
look through the auxiliary eyepiece to center the planet, then flip back to the
If you are interested in constructing such a device, I suggest you try with an inexpensive web cam. I paid (a few years ago) about $30 for mine. I figured if it lasted long enough to give me a bout 3 rolls of film worth of pictures, it was worth the expenditure.
I've been lucky. My little web cam is still working.
To get the most out of your photographs, it helps to keep track of
upcoming targets. The moon is one of my favorites. Best moon photos are
obtained when your targets of choice are near the terminator. A good
planning tool for lunar photography as well as lunar observing is the
software package Xephem, shown in some detail at my Xephem Review page.
Jupiter is one of the best targets for planetary photography.
It is bright enough (Saturn is kind of dim) and big enough (Mars is kind of
small) to make a good target. Some prior planning here is also helpful in
order to get a shot of the Great Red Spot, or some transiting Jovian
satellite. For my Jupiter observing and photographing guide, I again use
the Xephem software package.