Panasonic 100-300 a good lens?

that requres 1600mm effective focal lenght!

So what exactly is it that you are trying to do?

The only thing I can think of that is legal is wildlife and I can't think of any wildlife videographer that used lenses that long.

Most of the famous ones use blinds, allow the animals to acclimate thenselves, etc.

but don't use lenses over about 300-400mm.

If you tell us exactly what you are doing maybe we can give you some reasonable options.

Tedolph