Photography of astronomical objects brings many difficult problems as compared to the photography as most people know. The exposure times can be very long (even tens of minutes) and the lenses, or telescopes used, typically characterize with big focal lengths (thousands of millimeters). This means that the photographed objects must be well guided during the exposure and that the noise (that increases with the exposure time) can spoil the efforts. When we add to this problems with light pollution, quality of optics (even smallest imperfections are clearly visible in case of photographing stars) and the weather, astrophotography appears to be very difficult.
What is more, there are the same problems as in the "normal" photography. One of them is the high dynamic range of the photographed objects - comets, nebulae, galaxies, or the Moon.
One of the examples is the Orion Nebula (M42). It is very difficult (top shelf class equipment is needed) to take a photo with properly exposed core as well as the outer fine detail.
The sample M42 (Orion Nebula) photos, shown below, were taken by Luke Bellani with Meade DSI Pro 2 astrophotography camera attached to Skywatcher ED80 telescope. The photos were taken at 4, 15, 60 and 340 seconds of exposure. EasyHDR directly imported the FITS image format (that is used by the camera to store image data) along with the exposure parameters, which were used to calculate the exposure values, necessary for true HDR radiance map generation.
|True-HDR method, selectivity: "normal".||Smart-Merge method.|