In astrophotography, the camera’s sensor is a key element which needs special attention while choosing your equipment. This rectangular component is about the size of a fingernail and can contain several million of pixels made for converting photons coming from the stars into an image. Compared to the human eye, a sensor is able to detect far fainter objects and can see their actual colors. On the market, reams of sensors are used, all of them having their own dedicated application: webcam, smartphone sensor, DSLR sensor… For instance, the Stellina smart telescope is fitted with a 6.4 MP sensor covering deep sky and lunar imaging. Why is it necessary to choose a high resolution sensor for astrophotography like the one Stellina integrates?
A resolution to fit with your devices’ screens
The most widespread sensors have pretty bad resolutions, ranging from 0.3 to 1.3 Mega pixels. Such sensors are made to equip devices where image quality is not a big deal: webcam, front camera of smartphones or tablets.
For a picture to be pin point sharp on a Full HD screen, its definition should be at least 1920 x 1080 pixels, namely around 2.07 MP. Breaking this rule, the quality of a 1.3 MP resolution image displayed on a Full HD screen will be extremely low since the celestial objects will be pixelated. A zoom in will damage even more the quality, which is not conceivable when we know that, nowadays, FHD is the minimum resolution required.
The IMX 178 Sony sensor of the Stellina telescope was chosen on purpose to display nice-looking stills on an Ipad or even on an Ipad Pro without loosing quality! Provided with a 6.4 MP resolution, equivalent to 3086 x 2076 pixels, the sensor is able to capture photos of galaxies, nebulae, star clusters and our natural satellite: the Moon. Such a comfortable number of pixels guarantees an optimized experience for viewing your own images on most of your devices, smartphones, tablets as well as TV.
Sharper details and the ability to crop
Owning a high resolution sensor allows you to increase drastically the overall details of the celestial object you captured. If the sensor you are using is more resolved than a Full HD display, a crop on that picture should give simultaneously a close-up view and an identical amount of sharpness. The example below simulates the evolution of the image quality according to four different sensor resolutions applied to an image of the North America nebula – NGC 7000.
A high-performance sensor
Stellina integrates a sensor specifically designed for astronomy, enabling a sensitivity in the near-infrared part of the electromagnetic spectrum, added to the common visible domain. Indeed, a lot of deep sky targets like the Laguna nebula, Orion nebula, Soul nebula, Heart neabula emit a pretty large amount of infrared light. This extended sensitivity increases the light collected by the sensor, rising the intensity of the signal which keeps reducing the disturbing digital noise. Another interesting feature of the sensor: its light pollution filtering or CLS filter (City Light Suppression). This optical filter installed just in front of the sensor often makes urban space enthusiasts happier since it eliminates the typical coloration of the sky caused by artificial lighting: a must have tool, especially nowadays, when the environement has never been so light polluted by human’s activities, degrading the natural darkness of the night sky.