Kase 4 in 1 Clip-in Filter Kit (MCUV/ND8/ND64/ND1000),Neutral Density ND & UV Protection Filters for Sony Alpha Camera A7/A7II/A7III/A7R/A7RII/A7RIII/A7RIV/A7S/A7SII/A7SIII/A9/A9II/FX3

I’m an old person—as in, I still have a refrigerator full of film and a darkroom… so I’m no stranger to filters… but filters that are inserted directly over the sensor IS NEW TO ME… I’ve used just about every brand of camera that has ever existed and lately I’ve been using Sony’s and other than their overly complicated menu system and the lack of “native” glass available they are great little cameras—especially for the money they’re an incredible value.The problem is that on some Sony lenses they do not permit the attachment of threaded filters… the 14mm, the 400mm f/2.8 and the 600mm f/4 for instance… they have a filter system that I still haven’t bothered to figure out how to use that appears to be a little “drawer” that one can place a filter in… in some cases a traditional round shaped glass filter… in some cases they appear to be sheets of plastic… more like what one would be accustomed to seeing as a gel filter on a strobe (except very small)Anyway I bought this set and I am still surprised at how well they work and even more pleased that one can “stack” filters (much like humans have been doing for decades on cameras).I highlight this feature because there is a company that makes astrophotography filters that cover the sensor much the same way as these do…. But they are designed in a way such that stacking is literally physically impossible. But not these Kase filters—the Kase filters can be stacked and again I continue to be surprised at how well they work.Attached is a photo I took using only one of the Kase filters… 25 seconds ISO 4000 single exposure from my driveway… Sony GM 600 with the doubler on it wide open… far from perfect but it was only my second time using this particular equatorial mount… and I’d never used that particular lens for Astro previously. BTW the Sony 400 f/2.8 is *amazing* and if I had a Time Machine I’d have just gotten the 400 and the doubler and the 1.7x magnifier or whatever that other one is in my bag I seldom use… but f2.8 at 400mm it’s really something… and when I bought them, it only cost about half what the 600mm cost, and it’s (in my opinion) a better piece of kit than the 600…