Hi,
A quick tip FYI on the 70-300..... the result of some experimentation. I sometimes use close-up lenses on tele-zooms. They increase magnification without seeming to lose as much light as the TC or tubes, and without gaining quite as much extra length and forward balance. The trade-off is working distance.
I prefer multi-element CU lenses to single element ones. They're relatively expensive and not made in all filter thread diameters. (Eg the Canon 500D and 250D's are not available in 67mm.) So, I thought I'd see whether I could use my existing CU lenses on step-down rings without them vignetting. The answer is : the 70-300 will work perfectly well at all FLs, all apertures and all relevant focusing distances when fitted with 62, 58, and 52mm close up lenses. That's tested with CU lenses with values ranging from +1.5 to +4. All were two element lenses, so quite thick. I didn't try 49mm and smaller. So, no need to buy another CU lens in 67mm if you already have any of these,
This came as a bit of a surprise. I'm quite used to Fuji lenses working well with a filter one size smaller than the lens' own thread. I think that's because most Fuji lenses have broad nomenclature rings, so there's plenty of capacity to take a smaller filter. It was a bit of a surprise that the 70-300 would work with a 52mm CU lens without vignetting.
Cheers, Rod