In article <4s9c16$aeb@decaxp.HARVARD.EDU>, kkobayas@fas.HARVARD.EDU says...

>I just got several rolls of slides from my recent trip. The horizon is
>tilted on every picture. (well, every picture that has a horizon in it,
>which is about half of them). The tilt is about one or two degrees in
>the same direction. Am I right to assume that the fault is with the
>mounting of the slides, not the camera? (the camera is a Nikon FM2
>with a newly installed grid screen, which I used to align the horizon)
>And is it safe to grasp the film with a microfiber cloth and manually
>rotate the slide within the mount? I tried it on a couple and it seemed
>to work fine without requuiring much force, but I'm wondering if there
>is a better way. The mounts are plastic but it's the kind that is glued
>together so if I opne one it won't close again.

Ah, the dread Tilted Horizon syndrome.......
Kodalux was, for several years, hollering on my part notwithstanding,
committed to delivering ALL slides slightly rotated in the mounts, and
the film itself was glued to the mount.....;-( Plastic mounts do allow
some rotation/shifting of the image after mounting (plus they have cleaner
edges and sharper corners than paper mounts, though they don't hold the
film as flat during projection, alas....). I have seen cameras with
slightly rotated viewfinder masks, though - it is worth shooting one
frame with the horizon carefully lined-up with the frame edge, then
removing the slide from the mount to check (negative film may be handier
for this). Keep in mind that the VF has pincushion distortion which makes exact alignment of a horizon line with the frame edge difficult (almost all cameras have this problem), and a grid screen may be installed with a slight rotation.
Hope This Helps