THE BIG PICTURE
COMBINING TWO IMAGES INTO ONE WITH LAYER MASKS
With the return of M42, the Orion Nebula, to UK skies this month, we take a look at how to image this popular target with an extended dynamic range. Unusually for a deep-sky object, the core part of M42 is bright enough for over-exposure as you attempt to record the fainter outer wisps. Using layer masks it’s possible to combine images of the core with those showing the outer nebulosity, revealing the whole dynamic range of the object in a natural-looking manner. This technique is a good tool to have in your repertoire as it can also be applied to some other bright deep-sky objects too.