Cooled or uncooled

Cooled or uncooled

Cooling of camera chips is intended to reduce their dark current and thus dark current noise. As shown in the menu item 'Basics' - 'Physical quantitites' - 'Exposure time and noise', dark current noise does not play a role in background limited capturing and cooling is not necessary. It is quite possible to capture with an uncooled astro camera or a modified DSLR in this case.
(Note on modification: Since silicon chips are more sensitive in the red wavelength range than in the blue and green, DSLR cameras have a filter that partially blocks the red light spectrum so that daylight images do not look reddish. For astrophotography, however, this filter is a disadvantage, since emission nebulae emit photons mainly in the H-alpha range (656 nm). This filter is removed during the modification.) (Source:


The following is a list of points that argue in favor of a cooled camera:

    • On very warm summer nights, dark current noise may still play a dominant role from time to time.
    • With very dark skies, it is sometimes difficult to get into background limiting, so dark current noise can become noticeable.
    • With narrow band filter exposures, almost no background limiting is achieved, and the images are exposed for a very long time, so dark stream noise becomes noticeable.
    • Dark frames should absolutely have the same temperature for calibrating the sub-frames (see menu item 'Basics' - 'Bias, Flats, Darks, Darkflats'). A fixed temperature can be well realized by using a cooling system.


The following is an example of the astronomy camera ZWO ASI294MC Pro with regard to the dark current generated. Already from 10°C the unintentionally generated electrons are very small. When cooling, it should be ensured that the cooling power is not too high. A maximum cooling power of 80% to 90% should not be exceeded.