----- Original Message ----- 
From: "John C. O'Connell"
Subject: RE: Large Format vs. Digital/Stitching


> If you pan the camera to take the sequence of photos
> to be stitched later, isnt the fact that the camera
> back is panning going to give you a curved "plane"
> of focus or in the case of vertical as well as
> horizontal panning, give you a spherical "plane"
> of focus?
>
> I would think this could be masked with small apertures
> to gain depth of field, but what about geometry?
> I don't see how you could do architecture via stitching.
> Another thing, in order to get correct geometric
> projection, wouldn't you need to mount the camera
> such that the panning axis is at the nodal point
> of the lens instead of the usual tripod mount which
> is further back near the focal plane?

Depth of field isn't going to be much of a problem, in fact it may
well be less of a problem than with the view camera, since you can
refocus for each exposure, rather than depending on camera movements
or lens depth of field primarily.
I can't really see too much of a problem shooting architecture, but I
also haven't tried this technique for it, so I don't know if anything
unsurmountable would crop up.
Obvioulsly, one would be doing some work in Photoshop to correct the
perspective.
Not ideal, but certainly doable, and I expect easier with a view
camera, all else being equal.
Sometimes all else isn't equal......
I was hired once to shoot an office building. The AD wanted some
street detail, but also wanted the building to look "strong" (her
descriptive, not mine).
What I settled on was to overcorrect the verticals, so that the
building would actually be "leaning in".
My test shots (not of the building in question, it was in a different
city, so I picked a local office building of similar height to test
my idea) were accepted as a good idea, and I was hired.

Unfortunately, there wasn't any way to do the shot in camera. In
order to get wide enough to fit the entire building in, the bellows
was so short that I couldn't fully correct the vertical, much less
overcorrect it.
Today, I would "fix it in Photoshop".
My option in 1986 was to do some massive whacky easle adjustments in
the darkroom.
Having the pivot point at the nodal point is technically the best way
to do it, but I think with digital stitching it will be less of an
issue.
It really depends on scene type, most scenes are very forgiving, some
are not.
The typical methods for gaining depth of field with a view camera
have potential for causing massive amounts of image distortion, but
ususally it doesn't seem to matter all that much.

William Robb


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