I have a new lens! The Canon pancake 40mm f/2.8. I purchased the lens for everything except atsrophotography – but of course you know I will try it for astrophotography anyway! As reviews like this one show, the lens is amazingly sharp for general use, even compared to many canon L lenses. However, as I was to find out, the old rule applies – good for landscape doesn’t necessarily mean good for astrophotography! (so often the case). For astrophotography this lens exhibits severe distortion in the corners at f/2.8 and only becomes pinpoint to the edge at f/5.6. This did really surprise me as I’ve been very much enjoying using the lens for every-day photography and landscape photography, with those photographs coming out looking spectacularly sharp. I must get to the bottom of understanding that difference one day.
This photograph is a stack of 3 x 120 second exposures using my Canon 6D at 3200ISO from my suburban backyard (light polluted).