I finally managed to take another image of Jupiter, using my junk scope and webcam. The planet is finally climbing up high enough over the tree line here to see it. Last night there were only a few clouds, so I got out into the yard, where I could see it in a small gap between the houses. A bright street light also makes this a less-than ideal setup.

Scope has no motors, or fine controls worth speaking of. But the finder was pretty close so I was able to get the planet in view quickly without too much hunting. Focusing is always a haphazard affair. I look at either side of where I think the best focus is, by making small adjustments one way then the other, looking at it carefully each time.

By the time the scope settles from adjusting the all plastic rack-and-pinion focuser, I get about ten seconds to look at the image. Then, start hunting for it back and forth again. A very gentle touch is required! And it doesn't stay where you leave it. Not for the impatient...

But Jupiter would not be ignored. Unlike other nights recently where it was so elusive, disappearing behind clouds at the moment I finally get it in view last night it almost seemed to insist on being looked at, and to be photographed! Everything just seemed to go well from the very start, and the sky remained fairly clear and still. No wind. Even the bugs seemed to behave themselves, in deference to the King...

Despite all that, this is probably the best I can expect to achieve with this inferior equipment. Its certainly better than my first attempt. I've added an IR Filter. The webcam had an IR filter in the original lens, and this had to be removed. The image of Jupiter was too bright in the centre of the disk, and I thought this might have been the cause. Since Jupiter emits IR from its own internal heating process, the camera would pick this up without a filter installed. That caused the limb darkening to be too severe. I think that the color also improved as result of the filter.

This is just with a cheap webcam (CMOS) installed at prime focus:

Scope is a 3-inch Newtonian. Magnification was around 300x. I used a 3x barlow. Reason the mag is set so high, I wanted to get the most pixels I could across the planet disk for imaging purposes. I also magnified it another 2x digitally, so that I could see it better.

For image processing I adjusted the contrast and brightness, slight adjustments to gamma and then histogram. Lastly I used a very slight gaussian blur to remove the some of the noise from camera pixellation.

Nice shot given the scope and mounting, better than some made using tracking mounts. Sounds like you do have an abundance patience.

Robert

How does one image with a webcam?  Is this something I can accomplish with a Dobsonian? 

Cool picture, by the way.  Much better than I had expected.

Your image came out really nice.  I would not have expect that from a CMOS sensor.  The color looks really good and there is ample detail.   

Clear Skyz, LA

Thanks all for your encouragement! :) To image with a webcam you make a short movie of the planet.You connect a webcam to your scope with an adapter, just as if it was an eyepiece. Some cams are much better than others for making these kind of images. Naturally with a webcam you need some kind of laptop computer to take outside with you to record the images. You record the video preferably in AVI format, so that the frames are uncompressed. Keep recording until the planet drifts out of view. Then you use software to stack the AVI frames one-on top of the other, which produces a more detailed image than a single frame alone. Atmospheric turbulence is cancelled out. The best frames in the video file are stacked and averaged to produce the final image. Part of it is learning how to extract the best information from your AVI file, using free software such as Registax. And how to process it further with a program like photoshop. I myself use PaintShop Pro to finish the image.

I think a Dobsonian would be absolutely perfect for doing this. You will see even more detail than you can using eyes alone, because of the digital processing thats possible with stacking software. There are some excellent resources online to give you the details, just google "webcam astrophotography" and you'll find alot of info explaining whats involved. The kind folks on this site are also very good at explaining, and theres some earlier threads too if you snoop around the forum.

Great, thanks TeleNoob!

You're welcome Megawatt, check it out. Lots to explore in this cool hobby!

About the CMOS chip vs. CCD's, I believe that the Meade Lunar/ Planetary Imager (LPI) is in fact a CMOS camera. But I'm not using that one, I have just an ordinary Logitech CMOS Webcam. CCD Webcams are better but harder to find. Not sure if there are any in current production, but still some older models around.

CMOS is ok however for bright objects like planets. There has to be enough light to activate the chip within the normal frame rate for AVI's. Anything where long exposures are needed, CMOS is not a good choice. With the CCD as you know you can sit there and accumulate photons over a period of time, so it has better low-light sensitivity. I think that can also only be done with tracking scopes. Again whereas, in this method with the webcam a tracking scope isn't necessarily needed, so long as the exposure time is fast.

This is taken from the same video loop on July 21 2008. I discovered the moons were captured but I did not have the right settings in Registax to bring them out. Sometimes there is more data there than you realize. Its a matter of using the tools properly to get the best results.

I am still learning registax and am baffled by its behavour sometimes. In this case I increased the size of the processing area to 2048. I understand why this is, it allows it to process a wider image while it moves across the field of view, in this case revealing the moons. I had to apply a different contrast to bring out the moons than I did with the planet, so this is kind of cheating. The dynamic range of the camera does not match the human eye.

Not bad at all!   In fact, it's terrific for a non-tracking scope.   Did you have any help or did you do the capturing all by yourself?

I also use Paint Shop Pro.   I use Photo Shop Elements for DSO's, but still use Paint Shop Pro for moon and planet photos.....and even some DSO's.   It's a good, easy to use program.....simple, intuitive, yet effective.   I am using a 4" Maksutof-Cassegrain on a tracking (poor tracking) mount.

One of these nights I am going to try the webcam [Phillips ToUcam) on my 12" Dob.    I was thinking that it might be easier to have one person manually guiding the scope while a second person runs the laptop.......for focus and exposure settings.

I did this by myself. In my case I do not move the scope while imaging. I try to get the planet on the left side of the viewing window, then start the camera, and watch as the planet moves across the screen until its out of view. Its visible for maybe 10 seconds, enough to create a short AVI of 150-300 frames. Theres no motion of the scope while imaging which means no vibrations, maybe that helps a bit.

The other thing is that as the object moves across the field of view, each frame in the video is from a different point along the mirror. The resulting stack of images is the average of images taken from all these different points, and I think this newtonian has a different focus at different positions on its mirror. I'm not sure if thats a collimation problem, or just something inherent to newtonians.

 Sounds logical to me.  :)    Still, a fine image.   I would give it an "A" based on the difficulty factor if nothing else.   Nice work.