Thanks Thomas

And to answer your private question publicly, yes, we will publish the
results of our lens calibration tests.

But it may not be soon, as there is a lot of work to do, and we
haven't yet even a clear idea of what form the results should take.

Of course one way will be in terms of the "format, a, b, c" model that
PT now uses; but that only allows two lens projections: rectilinear
and equal-angle (spherical) fisheye.  We are pretty sure that lens
correction will work better if the equal-area fisheye type is added
(indeed PTGui now uses that in place of the equal-angle); and there
are a couple of new fisheyes that follow the stereographic curve,
too.  So we may try all three prototype fisheye functions, to see
which gives the best fit (smallest a,b,c values).  An even more
ambitious goal is to fit the lens responses to an adjustable prototype
that can match all 4 functions (yes, rectilinear and fisheye in one
model) and anything in between; if successful, that should make the
needed a,b,c very small indeed, which is how they must be for really
stable optimization.

If you, or anyone else, can suggest a good way of evaluating the
"residual error" of a fitted lens projection, please let us know.

Regards, Tom



On Jul 28, 4:42 pm, Thomas Steiner <[email protected]> wrote:
> > We need photos taken with as many different lenses as possible
>
> I uploaded some toftp://tksharpless.net/lenscal/thomas/
> Some info about the lenses is in this directory.
> Let me know if you need/want more. All lenses are of course
> demountable. Do you want the shots at differnt aperatures or just the
> widest open or what? (I did them at f/8.0)
> Thomas
>
> the textfile:
> The Camera was always my Canon EOS 350D, the crop factor is something
> like 1.6, but you see this in the exif data.
> The following lenses were used:
> * Canon EF 75-300mm 1:4-5.6 IS
> * Canon EF 50mm 1.8 II
> * Sigma 24-70mm F2.8 (not sure which one exactly - do you need this?)
>
> The zoom lenes I took with different focal lengths (3 steps), all are
> taken with aperature f/8.
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