Digital SLR cameras evolved from conventional film Single Lens Reflex (SLR) cameras. The film emulsion was replaced with a CMOS or CCD electronic sensor, and electronics were added to read the sensor and store the images. As such their features and capabilities are very similar to film SLR cameras. This is as it should be, because these features and capabilities are familiar to photographers, and because they are very suited to conventional daylight photography.
Unfortunately for astrophotographers, some of these design choices are not ideal for low light level imaging.
Unlike manual film SLR cameras, DSLR cameras require electrical power. Typically this is provided by battery power.
For longer sessions, the battery charge may not be sufficient, especially under cold wintertime conditions. Also many cameras automatically power down if they have not been used for a few minutes. This can result in unexpected disconnection from the computer control. Therefore if running on batteries it is best to turn off the automatic shutoff feature through the camera's built-in menus.
If at all possible the camera should be powered from an AC or DC external power adapter. This will allow for continuous use with no risk of the battery discharging, and for most cameras this will disable the automatic power off feature. An alternative is to use an external battery pack, which are often available as optional accessories.
DSLR Auto Shutdown
Many cameras have an option, usually defaulted on, which turns off the camera after a period of time. This generally causes the software driving the camera to lock up! It is highly recommended that you turn this option off, though the camera's built-in menus.
DSLR RAW Frames
For best quality, it is always best to use RAW frames, which include Bayer pattern color encoding. In order to view these as color images, they require interpolation, also known as color conversion or de-bayering. However it is always best to perform dark frame subtraction first, because otherwise the interpolation function spreads them around to adjacent pixels.
When RAW frames are viewed as monochrome images with the Bayer pattern present, you will get strange effects on the screen, especially when the image is zoomed in and out. To better present RAW images, MaxIm DL has a "Quick Color" option. For information on setting this up, please see Quick Color.