Hallöchen!

Owen Mays writes:

> [...]
>
> I have a lens (Nikon AF-S DX 16-80 mm zoom) that is not supported
> by lensfun, and I thought this is the perfect opportunity to give
> back to the project by contributing calibration data! [...]

We have distortion data for this lens for a couple of weeks now.
Feedback of its quality is greatly appreciated.

> [...]
>
> For Vignetting correction, I read Torsten's instructions here:
> http://wilson.bronger.org/lens_calibration_tutorial/
>
> How even does the even illumination need to be? If I have a
> suitable diffuser, could I aim at the sky for the vignetting
> images?

Yes.

> I am concerned that if I point a standard floor lamp at the
> ceiling it will have a distinct circular illumination pattern.

Nevertheless, this will work, too.

> For TCA correction: I haven't found a good target for TCA. Does
> this calibration need a regular geometry (like the buildings used
> for distortion?)

The geometry is unimportant.  Sharp high-contrast edges with
different distance from the image centre count.

> Or are trees against an overcast sky ok?

No, because this is often dominated by longitudinal CA and blown-out
highlights.

Tschö,
Torsten.

-- 
Torsten Bronger    Jabber ID: [email protected]


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