[MF3D.FORUM:288] Vertical alignment question

["Menzel, Greg" <Greg.Menzel@xxxxxxxxxxxxx>]

In efforts to improve the mounting of my Sputnik slides, I have been paying
more attention to reducing vertical alignment errors. This has raised a
question.

When shooting with the Sputnik, I always use a tripod and make sure the
camera is level via a bubble level mounted on the Sputnik itself. My old
technique for mounting a slide was to score a horizontal line across the
bottom of the cardboard mount (parallel with the mount) and then mount the
film chips such that the bottom edge of the film chips just touched this
line. My reasoning was that if the camera was level when the picture was
taken, then the film chips should be exactly vertically aligned when
mounted.

However, if I used this mounting technique, I found that rocks, blades of
grass, etc. in the foreground of the left and right sides were not
necessarily the same distance from the bottom edge of the mount window. This
difference is considered a mounting error in the Ferwada book, and appears
to be when viewing the slides as well.

I have subsequently replaced this evidently naive mounting technique with
one involving a mounting guide and precise measurement of objects in the
foreground of the scene to ensure that the left and right chips place them a
uniform distance from the bottom edge of the mount window. This has resulted
in the left and right film chips generally not vertically aligned with each
other, but much better results when viewing the slides.

My question is this:

1) Is it correct to assume that given an ideal camera placed level on a
tripod, that vertically aligning the film chips against a horizontal line
scored on the cardboard mount should work?

2) If so, then could my Sputnik be introducing a difference between the left
and right images (e.g. vertically cropping one side differently than the
other) that makes my old technique insufficient?



Thanks...
Greg Menzel