This is the 1st in what will be a few threads on MW issues. Spent a few hours at a close dark site shooting 4 lenses & 2 cameras of the Southern MW. Unfortunately had poor seeing due to haze - NWS reported 10 mi. visibility at a near by airport. So these are the worst MW captures I've ever done. In some of the captures, you can even see inversion layers containing more haze. But for this testing, I think it won't matter. Just don't expect any wow in these images - especially these purposely under exposed ones. First up was a test of my new Kowa 8.5mm f2.8 lens. My hope was that it would be as good as the M.Z 12mm & 17mm that I have been relying on. The short version of the results is the Prominar is certainly acceptable. I plan to use this lens for future aurora photography among other things. So for testing I used the E-M5 but difficulty focusing the short lens due to the low rez EVF gave me pause. I especially wanted to see if there was much coma in the Prominar. So I purposely under exposed by 1 EV so only the brightest stars would show thinking this would be a good test of coma. Since the lens apertures range from f1.8 to f4 & I wanted to give approximately equal exposure to each capture, I varied the ISO from 800 for the f2, 1600 for f2.8 & 3200 for f4. All lenses were shot wide open except the 17 which was at f2. Here are the captures w/ no lens adjustments or NR (RAW development was done w/ DXO w/ everything turned off). I adjusted black point & exposures by eye to be about equal. Kowa 8.5mm by tradesmith45, on Flickr M.Z 9-18 @9mm by tradesmith45, on Flickr M.Z 12mm by tradesmith45, on Flickr M.Z 17mm by tradesmith45, on Flickr Here's a 65% crop of the upper right corner of the Kowa (on the left) & 12mm (right) for comparison. Kowa 8.5mm - M.Z 12mm by tradesmith45, on Flickr Here's what I'm seeing on my iMac Retina. Prominar has about the same or less coma, a bit more CA, and about as much vignetting as the M.Z 12mm. It has less CA & coma than the 9-18 at 9mm. Not bad for a fast UWA. These dark low pixel jpgs won't allow you to see much difference. But that's really the story, the Prominar is a solid match for the fast WA Oly primes for star photography (and from other's sample images, everything else too.) And it will take filters - yeah! Kowa put 17 elements into this lens in their commitment to low geometric distortion. So far, I've failed to be able to stack images from the 12mm due to either distortion or decentering. I now have plenty of captures to try again w/ both new stacking software & all 3 primes but that will be the subject of a new thread some time later.