Olympus 17mm f1.2 Pro for astrophotography

Southern Milky Way. 60sec exposure at ISO400 - Olympus em1mk2 + 17mm f1,2 at f1.2. Tracked with Skywatcher Star Adventurer Pro. Mt French, QLD, Australia.

Recently I tested my Olympus 17mm f1.2 Pro for astrophotography and would like to share some results here. The above image is a single tracked 60 second ISO400 exposure taken with the lens operating wide open at f1.2 using an Olympus OMD EM1mk2. I actually can't wait to try it again to be honest!

For some pixel peeping look at the test strips below which show the performance of this lens at various apertures from f1.2 to f2.5 at both the center and extreme corners. The center crops show a little spherical aberration at f1.2 (visible as bloating of brighter stars). But stopping down to just f1.4 removes this completely and star images are excellent apart from Purple chromatic aberration around bright blue stars. This chromatic aberration is a bit disappointing for a "pro lens" at this price point and I note that my Oly 40-150 2.8 is free of this defect.

Center crops from f1.2 to f2.5. 60 second exposure .

Now looking at the extreme corner crops you can see the stars show some astigmatism which is steadily improved as the lens is stopped down. By f2.0 it looks quite good. Not shown here is some measurements I did with vignetting in Maxim DL which indicate around 1 stop attenuation at the extreme corners which is excellent for such a fast lens, even for a smaller format.

Overall, I really like the lens a lot and I think is a great addition to have in the M43 line. I can't wait to get out under a dark sky and see what this lens really can do!