I shoot a lot of nature and have been using my long Nikon glass with a converter. Unfortunately, I have to manually focus and set exposure, and sometimes I'm just to slow for a quick moving subject. I'm told the Lumix 100-400 will focus and set exposure with the LS300, but I wonder if there is a way to get auto focus and exposure for a longer length. I'd certainly consider teleextenders and even a custom mount if that would get me greater focal length and auto focus and auto exposure.

I have several Nikon lenses I use with my LS-300 and would love to have auto focus and camera controlled aperture. But I have not heard of an active F Mount to MFT converter. I believe they exist for Canon lenses and possibly others. As far as I can tell Nikon glass users are stuck with manual focus and aperture.

Autofocus is hit or miss with the LS300 and the Metabones adapter for EF lenses. Mostly miss...

I wonder if there is a way to get auto focus and exposure for a longer length. I'd certainly consider teleextenders and even a custom mount if that would get me greater focal length and auto focus and auto exposure.
Nope, not gonna happen. Neither Panasonic nor Nikon will divulge the proprietary trade secrets engineered into their lenses. JVC's hit-or-miss problems with reverse engineering MFT electronic lens protocols is evidence of how difficult a challenge it can be.