CCD Imaging Primer
	Imaging Made Easy and Fun!

The camera-computer interface used by Starlight Xpress cameras has evolved significantly since the late 1990s:

• The standard parallel interface was the original interface, and it worked with cable lengths up to 15 metres. Whenever a picture is downloading through the parallel interface, the mouse pointer and keyboard are frozen. This was done to insure a proper (i.e. uninterrupted) download of the image.
   
  
• Then the parallel port accelerator module was introduced, which could run with cable lengths up to 10m (sometimes 15m if you were lucky). This was a big help with cameras like the HX516 and MX916 with their larger number of pixels (and hence longer downloads). Image download time was typically cut in half. There were two interfaces: the Mark I and Mark II. The Mark I units were larger in size and had a ribbon cable that connected the box to the parallel port.

  I liked the Port Accelerator since it decreased the download time from 20 seconds to 10 seconds on my 486DX4/100. This 10 second saving per image can become significant when you're taking a lot of frames in a night. If you take 360 images in a night (easily done at 30 seconds per image), the port accelerator will save you an hour!
   
  

• USB1.1: In 2001, Starlight Xpress introduced the USB Interface kit, which allowed both new and existing Starlight cameras to be run through a USB port instead of a parallel port. Download times for the MX5 series cameras went from around 20 seconds (10 sec with fast parallel) to 2 seconds with USB1.1! USB offers faster, "cleaner" downloads and allows all background Windows tasks to run without interruption (since USB has its own processor)!
  Cable length is 5m, but this can be extended up to an additional 25m by the use of active extension cables. Artifacts can be introduced into the images if the computer can't keep up with the download. This can be the case if the processor is slow (Windows is sluggish) or if certain programs like disk defragmenters, etc. are running. In most cases, shutting off these programs or making sure the imaging application is in the foreground while downloading will avoid this problem. On fast machines it's not a problem.
  USB also offers greater simplicity in the CCD Setup dialogs in AstroArt and MaxIm, since there is no port address, interrupt mode, speed adjustment, or interface type (i.e. standard, Mark I fast, or Mark II fast) to choose. Just choose the camera and click the button!
   
  
• USB2: This interface was introduced with the SXV-H9 in 2003. With a faster download than ever (though not anywhere near the limit of USB2 capabilities), the greatest feature is the ability to run an autoguider and extra serial ports through the single USB cable! This great SX innovation makes cable management easier than ever! It is expected that a USB2 interface kit for existing MX and HX series cameras will become available sometime in late 2003.

One trick I do is to nudge the telescope (and sometimes rotate the dome!) to compensate for field drift during the image download. You gotta be fast doing this with the speedy USB interfaces these days! This can be done by having the telescope hand control next to you, or use scope control software (e.g. AstroArt 2, ECU, MaxIm 3.x) to do it (should be on a different machine if you are using a parallel interface though!).

Camera Startup

Once all your hardware is connected and running, it's time to start up the camera. Open the camera control dialog in MaxIm or AstroArt and choose the camera you want to use (e.g. MX5, MX9, etc.). In MaxIm you push the "CCD" button (MaxIm 2.x) or "Setup button (MaxIm 3.x) or "Check CCD" button (AstroArt 2.x).

Choose your software: AstroArt 2 MaxIm 3.x MaxIm 2.x Old browsers: AstroArt 2 MaxIm 3.x MaxIm 2.x

Note that with the Starlight cameras, there are no temperature control parameters to fiddle with or worry about. As long as the camera is plugged in, the cooling system will take the chip down to 30C below ambient. That's why I like to say that the Starlight Xpress cameras are "plug and play".

At the end of your imaging session, you should return to this window and click the "Shutdown" button (MaxIm 2.x) or "Disconnect" button (MaxIm 3.x) to terminate your computer link to the camera. (If you don't MaxIm will remind you!) In AstroArt, simply close the camera dialog with the "X" button.

3. Choose the port address:
   • 378 (LPT1:)
   • 278 (LPT2:)
   • 3BC
4. If you are using the optional port accelerator, make sure the "Fast Parallel Interface" box is checked (MaxIm 1.x) or that your "Interface" selection is "Fast Parallel" (MaxIm 2.x).
5. If you want, you can try increasing the "Speed Adj." parameter. The strategy here is to choose the highest (fastest) setting that doesn't noticeably degrade the quality of your images! I typically run at 150%. The best setting will vary by camera, cable, and computer used.
6. Press the OK button.

After a second or two MaxIm should show a successful connection to the camera. The message "No camera is present" will change to "Open loop cooling" (MaxIm 1.x,2.x) or "No cooler control" (MaxIm 3.x). If the connection is not successful, MaxIm will warn you. The most common causes of failure are incorrect settings in steps three and four.