Orion G3 instruction manual Using the Thermoelectric Cooler TEC

than the whole frame. The exposures will display continuously. Adjust the focuser as needed to get the sharpest looking star.

8.Once the star looks sharp, hover the mouse cursor over the star and pay attention to the HFD value. Make additional adjustments to the focuser if needed to achieve the smallest HFD possible.

Be sure to uncheck the Subframe box once you are done focusing.

Note: If the G3 is grossly out of focus, no object will appear in the image, not even a blur. Increase the exposure time if needed and patiently move through the focus range of your telescope until you see the centered star come into view.

4.2. Using the Thermoelectric Cooler (TEC)

The StarShoot G3’s cooling system was designed to reduce the noise in your astro-images. All digital cameras, whether CCD or CMOS have inherent noise. Taking longer exposures at night on a target that is very faint will have little signal, so the noise will be more apparent.

Cooling the CCD camera suppresses the most prominent noise, the thermal noise. You will see bright pixels in most of the images you capture. These bright pixels, and a lot of the noise you see will be reduced by activating the thermoelectric cooler (TEC).

Just as importantly, the noise stays fairly consistent at the same temperature. You should take your dark frames (see “Dark Frames” in Section 4.3) at the same temperature as your light frames, which will remove most of the nose effectively.

The StarShoot G3 can cool the CCD to about 10°C below the ambient temperature. But remember that the ambient temperature changes and you want to have enough cooling capacity to take dark frames at the same temperature later.

To set the cooler:

1. With the G3 already connected to your computer, plug the 12V power

source into the G3’s power port. The fan will immediately power on.

CCD temperature will naturally heat up on its own. To start with, set the Target (°C) to about 7°C lower than the current CCD Temperature, to allow yourself some margin for outdoor temperature changes. (Figure 12)

5.Let the camera temperature stabilize. You can resume imaging while this takes place. It’s common for the CCD temperature to fluctuate to within about 1°C of your target temperature.

You can view the Temperature Log (Figure 13) to monitor the status of the cooling system. Go to the Camera menu, and click Temperature Log

If the cooler power remains at 100% after 20 minutes, you need to reduce the target temperature. Most of the time you can simply monitor the CCD temperature by looking at the CCD Temperature in the Camera Control tab.

Note: Being able to match the light and dark frame temperature is more important than trying to cool the CCD more than the TEC will allow. Matching the dark frame temperature to your light frames ensures a very effective calibration to remove unwanted noise from your images.

Figure 12. Monitor the CCD temperature and determine the best target temperature to set.

Figure 13. The temperature log can help you determine how much margin you have to cool the camera based on the cooler power and current CCD temperature.

2.	Click Connect in the Camera Control tab if you have not already done so.
3.	Click Cooler On, and the CCD temperature will begin to drop.
4.	Enter a target temperature for the CCD in Target (°C), and remember you
	can only cool to about 10°C cooler than the outside air temperature. The

Additionally, you will notice the CCD temperature will rise if multiple fast expo- sures are taken in succession. This is normal and the temperature will drop back to your target temperature shortly.

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