Tumbleweed Observatory's

Astronomy Hints




How to Modify a Web Cam for Astrophotography

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The Challenges of Astrophotography

Astrophotography Survey

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 Photo

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

Copernicus crate through ETX 90

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 comet.

Holmes 17P Comet Image

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.

Jupiter And GRS Through ETX90

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

Linux Survey

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 adapter.

I also fabricated a simple cover over the back of the circuit card, and hurray, I had a CCD camera for astrophotography.

Astrocam Parts

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.

Assembled 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 web cam.

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 learning).

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 camera.

Final Comments

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.