365DaysDate: May 3, 2009

Title: Webcam Astrophotography


Podcaster: Alexander Hobson

Organization: Discovery Space

Links: Astrosnap:
K3 CCD Tools:
Mogg Adapters:
Webcam Astroimaging on DVD:

Description: In this podcast, Alexander Hobson talks about webcam astrophotography and how easy it is to get started imaging with a simple webcam, some free software and a Goto telescope.

Bio: Alexander W. Hobson is a 49 year old manager, who works for a radio and television company in Toronto , Ontario , Canada . He is married and has twin 14 year old boys who love the night sky.

Alexander has been interested in astronomy since the age of 10. He owns a small telescope and imaging equipment, reads astronomy related books, and listens to astronomy podcasts on a regular basis including Astronomy Cast, Slacker Astronomy and of course 365 Days of Astronomy.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by Dave Mosher.

Transcript: Welcome to this podcast for 365 days of Astronomy, I’m Alexander Hobson , an astronomy enthusiast from Oakville Ontario Canada . Today I’ll be talking about Webcam Astrophotography.

No doubt many of you listening to these podcasts have leafed through astronomy related magazines and marveled at the amateur photos. You may have even looked at articles about astrophotography on websites, but never thought you could do this type of imaging.

Most of these photos and much of this work can be attributed to the introduction of relatively inexpensive webcams and photo stacking and processing software, much of which is available free on the internet. This, coupled with the introduction of inexpensive Goto or automated telescopes started the amateur revolution in webcam astrophotography.

If you’ve already purchased a telescope, and are familiar with its operation, then you should get ready to take the next step with astrophotography. In addition to your scope, all it takes is a webcam, some software, and a computer. A laptop is best, but if need be, a computer cable leading out to your scope should do the trick.

Just about any webcam can be converted into a camera for astrophotography. Whatever webcam you use, you must remove the existing lens. Most just unscrew. The telescope then becomes the lens. All you need to do, is somehow attach the camera to the end of your telescope where your eye piece should go, and you can get started. Several companies make adapters specifically for webcams. They consist of a metal tube which threads onto your webcam, allowing it to be attached in place of an eyepiece. Adapters are available on the internet if you’re not a ‘do it yourselfer’, simply search the net for ‘astrophotography webcam adapter’.

If you want to save money, and are a ‘do it yourselfer’, make your own tube and epoxy it onto the webcam. Of course this would void the webcam’s warranty, so unless you are using gaffers or duct tape to attach your adapter, you’re going to have to dedicate this unit to your astro work.

Many people use an old 35mm film canister and cut the bottom off, then they use 5 minute epoxy to attach it onto the webcam. In most cases, this is the correct size to put into the eyepiece holder, but try it on your scope to make sure it fits, otherwise, find something the correct diameter to allow you to insert it carefully into your telescope and connect it to your webcam.

Once you have your webcam and some sort of adaptor, you might want to also get a focusing ring for the eye piece you are going to use to do rough searching and focusing with. You can purchase these rings from your local astronomy shop, called parfocal rings or again do it yourself by putting tape or some sort of mark on the shaft of the eyepiece so you can focus and direct the scope with both the eyepiece and the camera every time. I’ll come back to this in a minute, but first…

Many of the computer programs which come with goto telescopes also have camera controls. If not, you’ll want to download camera software on your computer. Go to the net and download a program like Astrosnap or something similar. You’ll also need some processing software. There’s a great free program called Registacks which allows you to stack multiple image frames one on top of another to build up the image. More about that once we get things ready….

Once your telescope is set up, aligned and working, which is best to do during the daytime, of course making sure not to point the scope at the sun as blindness can occur instantly, we want to put your webcam in your scope, and start your image capture software. You’ll see a live image to start fine focusing. Once the software is on and something is appearing on the computer screen, you’ll need to move the focus knob in and out until the image becomes clear. Try focusing on something as far away as possible. A tree or building in the far distance would be good because you get good contrast between the sky and the object. If you can’t achieve focus, you may have to move the webcam tube in and out of the opening a little and try focusing again. This is why it’s best to try this process during the day, so you can see what you are doing and move things around without groping in the dark.

Once you’ve achieved focus with the camera, mark the place on the tube where you inserted it in your scope so you can use the same position every time. Now comes the eyepiece. Put your eyepiece into the eyepiece holder of your scope with the parfocal ring around it. If you don’t have a ring, don’t worry, we can use something else to mark the tube later. Move the eyepiece in and out without touching the focusing knob, until the image is in focus. Once you have the position, tighten the screw to hold the eyepiece in that place and either tighten your parfocal ring or mark the tube with a marker or tape so you can put the eyepiece in that exact position every time.

Now you know where your camera and eyepiece are in focus at exactly the same place. This helps when you want to quickly locate an object to image. Simply insert your eyepiece, move to the location looking through the eyepiece, once you are there, slip out the eyepiece and insert the webcam , a little tweaking of the focus might be needed and you are ready to start shooting!

OK, so lets’ say you are set to go and the sky is getting dark and we are ready to start imaging. Slew over to the moon to start, and get things in focus. Once it is in focus, start your telescope auto slewing and hit the record button on the camera.

The camera will store the frames for you as a movie, made up of tens or hundreds of individual frames, depending on what it’s set for, like a motion picture camera does. These frames will be manipulated later with a program, or if you have software for capturing and processing at the same time, all the better. Basically what will happen is that you’ll get many images per second of recording, some of which will be sharp and some of which will be blurry because of the atmosphere.

The atmosphere is not friendly to astrophotography. It boils away up there and causes the light coming from objects to move around and distort, sort of like a desert mirage. Moving causes blurring in photos as most of us remember from taking pictures with film cameras, where someone moves and the image comes out blurry. Not all the frames will be blurry though. Some will be sharp. It’s those frames we’re looking for. We’ll use those sharp frames to build up the brightness, contrast, and sharpness of the final image we are going to create.

There are several programs to stack these good clear image frames, some do the work for you of sorting out which images are sharp and which are blurry and some programs allow you to do this manually. Either way, you can start stacking the frames to create a single clear image. If you have photoshop or a similar image processing software, you can further enhance the image, or add many images to form a sharp mosaic of a larger area of the sky or object.

Here are some tips for you…If you put in your webcam and can’t seem to get it to focus or the screen stays unclear, most times it’s because the gain setting is too low in the software, try turning that up first. Other times the image may be out of focus or out of frame. Just try refocusing and moving the scope around a bit and eventually you’ll find things get clear.

Be forewarned though, webcam astrophotography is very addictive and after the first night or two you may never sleep on a clear night again.

OK, so now you’re simi-hooked and want more. It’s on to planets! To really make this work though you should have a high quality 2X converter or greater. Some scopes come with one but if not, purchasing a converter will allow you to use it with your visual observing as well. The converter is installed before the lens or webcam, and magnifies the image by the amount indicated. Then you follow the camera setup in the same way as before. Just remember, the larger the converter the greater the magnification and the better your scope’s tracking capabilities has to be. It’s also harder to keep the frames aligned in the view screen.

The only limiting thing about a webcam is heat from long exposures when you start trying to image things which are really dim. Once you start dealing with very faint deep sky objects, you start to need long exposures. Long exposures cause the camera chip itself to heat up, which creates thermal noise on the chip. The chip thinks this heat is photons and eventually the heat from the chip itself overpowers the heat from the distant photons and you get a snowy screen. Unless you start cooling the camera manually or with a cooling chip, you are going to get snow, which makes it almost impossible to focus and locate objects.

Once you are at the limits of what you can do with your un-cooled webcam, you may want to modify it with a fan or some type of cooling or move on to Cooled CCD cameras. They get rid of most of the noise problem, but then you have to start spending some significant dollars, and that’s the subject of a whole other podcast!

There are lots of great websites and books to walk you through the webcam astrophotography process, just search the net for ‘webcam astrophotography’ to get started. Do it today!

For the 365 Days of Astronomy podcast, I’m Alexander Hobson , wishing you clear skies and snow free imaging!

End of podcast:

365 Days of Astronomy
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