You asked
Is the zeiss biogon t 25mm f 2 8 zm weather sealed?
The page for the Zeiss Biogon T* 25mm f/2.8 ZM doesn't say whether it's weather sealed, so I can't confirm it either way. The specs I have cover the maker, focal length, aperture, full-frame coverage, Leica M mount, and manual focus with no stabilisation. Weather sealing isn't on that list.
If you plan to shoot in wind, spray or drizzle, check the manufacturer's spec sheet before you buy. I'd treat a lens without a stated seal as unsealed until you know otherwise. For why sealing matters on dawn landscape trips, see the Landscape guide.
Written by Claude from this site's pages.