Catch-42 is designed to be a simple but powerful tool to optimize image capture quality and speed on your SAC4-2 camera. The SAC4-2 is well-suited for tasks like planetary astrophotography. In general, the best planetary and lunar shots are taken by streaming large numbers of frames from the camera as fast as possible to your hard drive. When some of these frames are taken, the boiling, rolling distortions caused by atmospheric "seeing" will be calm and you will have very sharp, clear frames to stack and process. Catch-42 is designed to help you collect those frames and to get the best data out of your SAC4-2 camera. It streams raw, entirely uncompressed data from the camera as fast as possible, supporting full control over the camera (see Features, below)

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Catch-42 is distributed here as freeware. If you use Catch-42, enjoy it, and wish to make a donation to help support it, its development, and the development of similar products, you can use the button below. All donations are greatly appreciated.

Recent Updates

  • When using AVI output, file split at 2G limit into multiple files
  • Directory remembered across sessions
  • Max # frames increased to 5000
  • Directed to registration website on first use


  • Simple, clean interface. There is one main window with all basic controls at your fingertips.
  • Streams RAW data from the camera and to the disk. Color CCD and CMOS camera chips are really black and white camera chips with separate colored filters over each pixel. If you stream RAW data to the disk rather than color:
    • One third as much data comes off the camera, meaning it goes 3x as fast
    • One third as much data needs to go to your hard drive, meaning it goes 3x as fast and takes up one third as much hard disk space.
    • You can use very high quality "De-bayer" algorithms to turn that RAW data into color images. If you're streaming color images, this has to happen on the fly, meaning fast but inaccurate De-bayer algorithms must be used. If this happens after-the-fact, you can use slower but very accurate algorithms.
    • It is completely uncompressed. You are getting the purest data off the camera possible with no compression loss whatsoever.
  • Full "Region of Interest" (aka "ROI" or "subframe") capabilities. If you want the whole moon that's filling up the whole chip, stream that to disk. If you just want one crater or want to crop off the black space around Jupiter, crop it off during capture. You'll be rewarded by not only using up less disk space but you'll collect images much faster if you use an ROI.
  • High speed captures. Full-frame, entirely uncompressed shots can stream off the camera at approximately 10 FPS and small ROIs can stream off the camera at up to 50 FPS. You're generally limited by hard drive speed and by the shutter speed. If you use a 200 ms shutter speed, even if it took no time to download the image and write it to the disk, you would be running at 5 FPS (5 frames per second equals one frame every 200 ms).
  • Full control over camera exposure, gain, and color balance.
  • 10 ms - 2 s exposure duration (Note - some versions of the 4-2 are limited to 750 ms)
  • Live preview in full color (quick) or in RAW format.
  • Small preview during capture to let you monitor a region of the image being streamed to disk
  • Manual or automatic control over number of frames captured
  • Still snapshots to BMP files
  • Logging of precise time for each frame
  • Final output to a single AVI file or to a series of BMP, PNG, or TIFF files