I'm researching the world of photography outside of the visible spectrum and I'm really curious to get my hands on some filters, the Baader-U for example, to try shooting in these spectra. However, I noticed there's a problem -- these filters completely obscure visible light, making the viewfinder and liveview useless. Moreover, it's not simply possible to focus the image then apply the filter, since IR/UV converges at a different distance than visible light. The image will go out of focus when the filter is applied.
How then, do people get tack sharp images if they can't see before they shoot? For example, this or even this video