I have a few of the Kolari Vision products. If the name sounds familiar, they are well know for Infrared cameras and conversions, but they do a lot more than that!
Over the past few years Kolari Vision have moved into the photo filters market and now while browsing Instagram I found this! https://www.instagram.com/p/CSNFthGnJ76/
It is a device that appears to look like a tele-extender. Fitting between the camera and the lens it houses a drop in filter.
Whats so great about this? Well first of all this makes one set of filters compatible with ALL your lenses regardless of the front diameter. It also lets you use a filter on lenses that bubble on the front like my Sony 12-24. (the filter system for that is complicated and SUPER EXPENSIVE) Thats why I don't have one.
As of right now it appears that Canon users will benefit from this first but I hope to see other major brand adapters soon!
Joe Pellicone
