HandyAvi® - How to Capture Meteor Trails Tutorial
What you need to get started
1. A sensitive camera
A highly sensitive camera is recommended. Camera sensitivity is rated in "lux". We use cameras that claim to be .0001 lux cameras. They are black and white cameras. The "Watec 902H2 Ultimate 1/2" CCD Camera" is an example. These cameras are more expensive than regular webcams. These cameras are usually sold without a lens. These cameras typically output NTSC or PAL signals so a USB/Video adapter of some sort (or a suitable video board) will be necessary.
2. A wide-angle lens
You will need a wide-angle lens for the camera. The Watec camera takes a "CS" lens which will need to be bought separately. Search the internet for "CS Lens." We have been using a Computar 2.6mm 1/2" lens with our Watec camera to capture the meteors we show on our examples pages.
3. A USB/Video adapter (or suitable video board)
HandyAvi can see cameras connected via USB. A USB/Video adapter plugs into your computer's USB port. The other end of the adapter plugs into your camera.
HandyAvi can also see various video boards installed on your machine and the camera could be connected to a video board input port. You should test this though to be sure that HandyAvi can see your particular board. (We think it will but we can't afford to buy and test all of them. It has worked fine for the WinTV boards we have here.)
4. A copy of HandyAvi
Download and install HandyAvi. Use the 10-day free trial period to begin working with handyAvi.
After the 10-day free trial period expires, you will need to purchase a HandyAvi license. Install the registration key by running HandyAvi and choosing the Help menu item "Install Registration Key". (The "trial version" is the actual version of HandyAvi so no additional download will be necessary. Simply install the key.)
Capturing Meteors
1. Turn on your PC
2. Plug your camera in
Either to a video adapter that is plugged into one of your computer's USB ports, or to a video board installed on your machine that HandyAvi can see and control.
3. Start HandyAvi if you have not already done so
4. Select the menu item "Capture" and then the sub-menu item "Meteor Trail Images...".
This will bring up the "Meteor Trail Detect and Capture" window:
Depending on how many cameras you have, you might need to select your "Capture Device" (webcam) from the pull-down item. (We selected the Logitech QuickCam Pro 4000 Camera for this example.)
Use "Video Format" to set the image size for your camera. (We selected 640x480 for this example.) The camera's "Frame Rate" can be selected in this panel. (We selected 30 frames per second for this example.)
The "Live Video Preview" window will be showing the night sky assuming you have the camera pointed at the night sky. If your camera is sensitive enough you should be able to see at least some of the brighter stars in the sky.
Use "Video Settings" to access the camera's Brightness, Contrast, Saturation, etc. controls. You should set brightness so that you get good contrast between the stars and the background sky. The camera's frame rate can sometimes be selected from the Settings" panel in addition to its being selected in the "Video Format" panel. You should adjust the video settings so that you see the best possible images in the "Live Video Preview window. You can click "Enlarge" and adjust the image size so you can see in detail the quality of the images. When images are captured (using the Start button which will be described below) you want the best possible images to be captured.
Note that we bring up the camera vendor's "Video Format" and "Video Settings" windows. HandyAvi does not have its own settings windows for these because each camera is different and each camera generally comes with drivers that allow us to display the vendor's settings that are appropriate for their particular camera.
Be sure to focus the camera using the stars visible in the frame. You might want to "Enlarge" the video preview window and set it to "Size/True Image Size" to make it easier to focus the camera.
5. Set up for making your movie
First choose the name of your output file by entering a full path name such as the one shown in the example above. The Browse button will bring up a file selection window if you would prefer to use it.
Then choose your compression scheme or "CODEC" from the CODECs that exist on your machine (HandyAvi "enumerates" them and lists them in the pull-down.) A CODEC will "compress" each of your images, i.e., make them smaller. There is a trade-off between compression and fidelity. High compression makes an image fuzzier typically. However, you can achieve good compression without noticably affecting the image. Some amateur astronomers we know use "Microsoft MPEG-4 Video Codec", MP42. (We usually avoid "Cinepak Codec by Radius" because we have seen it behave badly.) More CODECs can be obtained and downloaded from the internet. Check out: http://www.fourcc.org.
We usually use one of the MJPG compressors which compresses each image using JPG compression. You have to buy the MJPG CODECs via the internet though.
If you want images with NO compression you can use "Uncompressed". Your files will be very large if you use "Uncompressed" however.
Set "Sensitivity." If "Start" has not yet been pressed (or if "Stop" has been pressed) then the "Frame number" counter will count up if the sensitivity is set too high. You want to set it as high as you can without it counting up just because of camera noise in the image. You want to make it sensitive enough to record meteors but not record simple image noise. (Our "Philips SPC 900NC" can work with a sensitivity setting of 80 or so without triggering on noise. Your results may vary.) Pressing "Stop" will reset the counter to zero and display one frame.
Set Pre-Frames and Post-Frames
Pre-Frames is the number of frames you would like to capture BEFORE the meteor trigger event. When a meteor goes across the sky, its trail is often dim, then brightens, then dims. The capture system triggers when the meteor is bright enough. In order to not miss the beginning of the trail, you can set Pre-Frames to some number of frames to capture BEFORE the trigger event occurs.
Similarly, Post-Frames are the number of frames to capture after the meteor has dimmed below the detection criteria so that you can capture the end of the meteor trail without missing anything.
The default values for Pre-Frames and Post-Frames is 5 which often is sufficient. Higher or lower settings can be set of course. Higher settings require more memory for internal image buffers.
HandyAvi uses a sophisticated buffering system to allow images, pre-frames, and post-frames to be captured without slowing down or missing frames.
Choose your "Playback frame rate".
This will tell your movie how many frames per second to display if you choose to run your movie.
Create a new output file for each trail
When this is checked, a new file will be created for every meteor trail detected.
Create a JPG file for each composite image
Whenever a meteor is detected, each frame of the captured data will appear in real-time in the "Last Captured - Composite" window. After the last captured image of a trail is displayed, the system will display a "composite" image which contains the entire meteor trail. Each of the images of the meteor trail are combined into a "composite" image showing the whole trail. This image will appear in the "Last Captured - Composite" window.
You can save each composite window as a JPG file by checking the "Create a JPG file for each composite image" checkbox. This can be of value when you are wondering if your movie contains any particularly interesting meteor trails. You can look at each composite image to see each trail that was captured in your movie file.
6. Advanced button
This will bring up an "Advanced Meteor Detect Settings" window which will allow you to place circles and rectangles of sensitive regions. For example, if you have a camera with a wide-angle lens pointed straight up into the sky, then you might want to create a circle about the center of the sky. Everything within the circle that moves will trigger recording but things outside of the circle will not. So objects on the horizon that are moving (car lights, flashlights, etc.) will not trigger recording.
7. Press "Start" to begin making your movie(s).
This will begin making your movie(s).
8. Press "Stop" to stop making your movie(s).
If a file was open and images were being added, it will be closed. All other generated files will already have been closed.
9. View your movie
Use File/Open to open and view your new movie. Note that the slider will allow you to move immediately to any frame in the movie so you can rapidly scan what is in your file.
