ToUcam Tutorial

1. Introduction

This webcam astrophotography tutorial is intended to explain my method for obtaining the planetary images found in my solar system image gallery . I hope it will be useful to those who are just starting out in astrophotography with a webcam. Below are a few of my favorite astrophotos that I have taken using my telescope and webcam. Click on thumbnails to view full size photo.

Incredible detail can be obtained with today's imaging techniques and software. I hope to demonstrate how this is done on a basic level in my webcam astrophotography instructions below. First though, I will start with the setup I use for astrophotography of planets.

2. My Astrophotography Equipment

The telescope I use is an 8" Celestron Schmidt Cassegrain Telescope (SCT). Here's the details:

Mount: CG5
Aperture: 8" (200 mm)
Focal Ratio: f/10
Focal Length: 2000 mm
Highest Useful Magnification: 450X
Resolution: .57 arc/sec
Home-built pier

Accessories include a Telrad viewfinder, JMI zero image-shift microfocuser, Celestron 6X30 viewfinder, RA and DEC motor drives, and dew shield

The camera I use for planetary astrophotography is a Philips ToUcam Pro 740K. It's basically an upper-end computer webcam. Here's the details:

Philips ToUcam Pro 740K
Max resolution: 640 x 480 pixels (1280 x 960 for stills)
Max frame rate: 60 fps
Sensor: CCD

This one is a very popular camera for astrophotography. However, Celestron and Meade have their own version as well. They are designed specifically for Astrophotography. See the "Further resources" section to the right

3. Registax Software

The method for obtaining high resolution images of the planets actually starts with a video taken with the webcam. The video is then processed in a freeware program called Registax (by Cor Berrevoets) and results in a "stacked" image of several hundred frames. This will all be explained in detail later in this article. The Registax download can be found at: http://registax.astronomy.net.

4. Finding the Planet Through the Webcam

The first step can be the most tricky part of it all! It is necessary to precisely center the planet in a relatively high power eyepiece. This must be done before switching to the webcam. Here are the steps involved:

Insert 2X barlow lens
Insert 32mm eyepiece for a low power, wide field of view. Adjust RA and DEC until the planet is as close to center as possible.
Carefully switch to the higher power eyepiece. I use a 10mm Plossl for this. This gives me about 400X magnification which is close to my highest "useful" magnification.
Center the planet and make sure it holds its position. A good polar alignment helps a lot here!
Very carefully, switch to the webcam.
Open the webcam software program. In my case, I use Spotlife which came with my Philips ToUcam Pro 740K. If the planet is not visible on the screen, it is usually due to 1 of 3 things: gain setting is too low, the planet is not centered (normally the case), or the telescope is WAY out of focus.
Gain Setting

One time I got frustrated because I could not get Saturn to show up on the screen. I was certain that it was centered well enough in the eyepiece. After quite a few minutes I decided to turn up the gain. Saturn was right there the whole time! So the best thing to try first is to turn up the gain. This is done in the webcam settings. I usually turn the gain up to about 75% to make the image bright enough to detect.

Center in Eyepiece Again

This is normally the case. If the planet is still not visible, then follow the steps above again to center the planet. Normally it's just a matter of getting the planet centered in the webcam field of view. This was difficult when I first started using a webcam, but became MUCH easier with practice!

Focus

When all else fails, check the focus. It's possible (although unusual) for the image to be so far out of focus that it's too dim to detect. When the planet is in focus through my 10mm eyepiece, then it is usually visible (although not focused) through the webcam. I can easily make the adjustments once the planet is centered on the screen. Here is a screenshot of what it looks like:

Insert 2X barlow lens
Insert 32mm eyepiece for a low power, wide field of view. Adjust RA and DEC until the planet is as close to center as possible.
Carefully switch to the higher power eyepiece. I use a 10mm Plossl for this. This gives me about 400X magnification which is close to my highest "useful" magnification.
Center the planet and make sure it holds its position. A good polar alignment helps a lot here!
Very carefully, switch to the webcam.
Open the webcam software program. In my case, I use Spotlife which came with my Philips ToUcam Pro 740K. If the planet is not visible on the screen, it is usually due to 1 of 3 things: gain setting is too low, the planet is not centered (normally the case), or the telescope is WAY out of focus.
Gain Setting

One time I got frustrated because I could not get Saturn to show up on the screen. I was certain that it was centered well enough in the eyepiece. After quite a few minutes I decided to turn up the gain. Saturn was right there the whole time! So the best thing to try first is to turn up the gain. This is done in the webcam settings. I usually turn the gain up to about 75% to make the image bright enough to detect.

Center in Eyepiece Again

This is normally the case. If the planet is still not visible, then follow the steps above again to center the planet. Normally it's just a matter of getting the planet centered in the webcam field of view. This was difficult when I first started using a webcam, but became MUCH easier with practice!

Focus

When all else fails, check the focus. It's possible (although unusual) for the image to be so far out of focus that it's too dim to detect. When the planet is in focus through my 10mm eyepiece, then it is usually visible (although not focused) through the webcam. I can easily make the adjustments once the planet is centered on the screen. Here is a screenshot of what it looks like:

7. Registax Processing

Next comes the fun part of processing the video. The program of choice for stacking frames is Registax. Since Registax 3 is the latest version of software as of this writing, I'll use it as an example. However, the basic principles are the same with any version of Registax.

Registax can be downloaded at http://registax.astronomy.net. Thanks to Cor Berrevoets (creator of Registax), it is available as freeware. His program is WELL appreciated!

Here is the basic procedure for converting an AVI video into a single stacked imaged.

Change screen area to 1024 by 768 pixels. In Registax 3, the entire screen is not visible with 800 by 600 resolution.
Open Registax and click on the select button at the top left of screen. Choose the video taken with webcam.
Scan the individual frames in the avi to find the best looking one. Frames will vary in quality from each other mostly due to the fluctuations in the atmosphere. It is important to select a frame that provides the sharpest detail in the group since all others will be sorted according to this frame. Frames can be previewed by using the slider bar or the framelist. See screenshot below. Click to open in separate window (for easy reference).

4. Once the best frame is found, then an alignment box must be drawn around the image or particular feature within the image. I usually draw a box around the entire image though. There are several sizes of alignment boxes to choose from. These include 32, 64, 128, and 256. I select a size that is just large enough to completely surround the image of the planet

5. Be sure to check the box "Use Colour"

6. In the Quality Estimate section, I select the Classic method and a Lowest Quality setting of 90%. This means that only those frames that are at least 90% as good as the reference frame will processed.

7. Click the Align button and the alignment process will begin.

8. At the end of the alignment process, note (at the bottom of screen) the stack size vs. the original number of frames. The lower quality frames (as compared to the reference frame) were screened out. Clicking the Limit button will eliminate the lower quality frames. Note the fewer number of frames for processing.

9. Now click on the Stack tab. Further refinement will be performed here. If the Stackgraph is not already displayed, click on the tab. Note the 2 sliders. The vertical slider is for difference cutoff. This is adjusted downward to eliminate those frames that are significantly different from the others. Here I cut off any large spikes. The horizontal slider controls the quality of the frames. The graph slopes downward from left to right. The left side being the highest quality frames (again, as compared to the originally selected reference frame) and the right side being the least quality frames. Better frames are selected as the slider is moved to the left. As this adjustment is made, the number of frames shown at the bottom of the screen will change.

10. When the best frames are selected, it is time to stack them together. Registax combines all the selected frames (that were at least 90% as good as the reference frame plus the additional manual adjustments) into a final composite image. I like to have a stack of at least 300 frames. The more frames that are stacked, the better the signal to noise ratio (more signal, less noise). Since each frame varies a bit in the amount of detail that was captured, the final stack will be a nice composite with lots of detail!

11. Now click the Wavelet tab. This is where the magic begins! Click the contrast tab and move the slider slightly to the left for both contrast and brightness. Note the wavelet sliders in the screenshot below.

12. Now it is time to adjust the wavelet sliders to bring out the detail in the composite image. I normally only adjust the sliders for layers 2-5. A lot of trial and error takes place at this stage. As the sliders are moved to the right, detail is brought out of the image. A nice balance must be struck between under-processing and over-processing the photo. If the wavelets aren't adjusted enough, then not all of the available detail will be brought out in the image. Over adjusting however will only make the photo grainy (noise). Here is a screenshot of the image above after some adjustment of the layers:

Final Image

I hope you enjoyed my webcam astrophotography tutorial for the planets and find it useful. I will make updates to it as I refine my techniques further. If you have any suggestions, questions, or comments, please feel free to contact me at ray@shoregalaxy.com . Thanks, Ray

Ray Shore and his family live in North Eastern Kansas, where he has been an amateur astronomer since 1985. He has been a member of several astronomy groups and participates in local astronomy events, such as star parties, public observatory nights, school science presentations, etc.

Like so many others, Ray began astrophotography around the time of the 2003 Mars opposition. You can find out much more at his website, http://www.astro.shoregalaxy.com/.

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Webcam Astrophotography Tutorial for Planets