I'm late joining this discussion but my guess is the problem is caused by digitally induced reactionary technology. This problem is seldom seen if one's lens is not stopped down below f/8.0.
Dave Hartman
In this case, Erik has the correct answer (again). After talking to my contact at LEE Filters I’ve now gotten six new filters, because I found these red stripes on 6 of my GND’s. LEE Filters said that their technician had seen some familiar issues after they released the very first batch of the Field Pouch. The technician said the pouch insert had some color contamination that could color the filters.. I don’t think this is the issue here though.. Because the stripes were going not only vertical but also horizontal.
On my landscape shots I use f14 and 16 mostly, it works without too much diffraction on the 14-24 2.8.
About the light leaks;
On my 17-35 2.8 I had to cover the entire lens, as the focal window let so much light in, we have to remember that most (or all) lenses are NOT made particularly for LE photography, so a (f.i.) five minute exposure WILL without covering the lens (and of course the viewfinder), will be totally ruined by light leaks. That said, I don’t cover the 14-24 2.8 (Nikon, of course..), it just don’t leak, but then again, my longest exposure until now with the 14-24 are around 15 minutes in dim light..
In one of my next posts I’ll show you our new Reversed GND filters. And the new IRND PRO Glass series, which needs absolutely no color correction. One of these are 15 Stops, and I can’t wait to try them out myself.
Here’s a “teaser” for you; If the camera meter says 1/2000, with the 15 Stop filter it’ll be 15 seconds!!! 1/30 in camera = 16 minutes, 1 sec= 8hours, 32 mins, 2 sec= 17 hours, 4 mins!!! (And I got two 15 Stop filters, wonder how that will turn out...🤪😊😉