10 stops of darkening is often too much for waterfalls, as was already explained here. I personally believe that they're better for blurring out motion in a seascape.
$60 for a 10-stop ND is cheap. There's no way around it - such a strong darkening effect isn't well suited for cheap filters. However, there's a gem from a company called Camdiox: http://camdiox.wix.com/camdiox#!product/prd12/2191246525/camdiox-cpro-smc-nano-nd1000-filter
They also have a variable ND, which may be more useful for you (though it is more expensive).
I'd get a filter for the lens with the biggest thread size you have, and just get cheap step-up rings for the rest. It's better to have it and not need it, than to need it but not have it. And I'd personally shoot a lot more landscapes with the 18-140 than I would with the 35.
- Fujifilm X-T223.6%
- Nikon D50025.4%
- Nikon AF-S 105mm F1.4E8.2%
- Olympus M.Zuiko 12-100mm F47.5%
- Panasonic Lumix DMC-G857.2%
- Sigma 85mm F1.4 Art6.7%
- Sigma 50-100mm F1.8 Art5.1%
- Sony a63006.4%
- Sony Cyber-shot RX10 III3.7%
- Sony Cyber-shot RX100 V6.3%
|Kingfisher by cjf2|
from An A to Z of Subjects- Week 11, K
|Bull Rider Being Launched by RBFresno|
from FX bodies and very high ISO