Re: [Gimp-user] GimpLensfun database

[Leonard Evens <len math northwestern edu>]

On Sat, 2013-09-28 at 17:57 -0400, Partha Bagchi wrote:
> Here is something you can try. Copy the lens database from svn:
> http://svn.berlios.de/wsvn/lensfun/trunk/data/db/ and put it the
> appropriate location within lensfun-0.2.7. Rebuild lensfun and you
> should have the D800 with 24-70.

Thank you.  I may try that.  But I don't really understand why it should
be that hard.  Presumably, the program darktable and the gimp filter
gimplensfun are looking somewhere to find correction information.  If it
is not in /usr/share/lensfun, where in the world is it?

> Personally, I think you should fix lens distortion (if any) within
> your raw editor rather than in Gimp, but that's me. :)

I ordinarily work in darktable on NEF fiiles, but I somehow managed to
nuke a whole bunch of NEF images and had to instead work with the jpeg
images on my backup card.

> BTW, curious where did you read that the 24-70 is the "standard" lens
> for the D800? I have never heard of the D800 being sold with the 24-70
> as a kit lens (or any lens for that matter).

It is perhaps an exaggeration to call these "the" standard lenses for
the d800.  When I was contemplating laying out a fortune for my D800,  I
posted a query at Nikonians about which lenses I should consider given
my needs.  The 24-70 and 70-200 lenses were both strongly recommended by
several people.  Also, my Calumet salesman recommended those same
lenses.   I think these lenses are common choices for use with the D800.
They should definitely be in the Lensfun database, and if my reference
above makes any sense, they are, so I am perplexed about why I can't
find them.

Fortunately, my lenses have very little distortions, so I may be able to
avoid using corrections. 

The 14-24 lens was also recommended, but I didn't think I needed it, and
I had already spent enough money.  Later I got a 24 mm tilt-shift
Rokinon lens which was something of a bargain for under $1,000.

Perhaps I should explain that I have been doing view camera 4 x 5
photography with 75 mm, 90 mm, 150 mm and 300 mm lenses.   I wanted the
Nikon D800 to cover roughly that range.  24 mm is relatively short for
35 mm but not as short as 75 mm is for 4 x 5, so someday I may get a
shorter lens for my D800.   One of my interests is architectural
photography, and my 75 mm lens wasn't even short enough to photograph a
building facade from across the street.   I had to stitch two images
using hugin to capture that scene.   I think I can do the same thing
easily, if the need arises, using 24 mm on my D800,

If I feel a pressing need, I may get a shorter focal length lens for the
D800, but given that I am 80 years old, that need may never arise. 


> On Sat, Sep 28, 2013 at 12:29 PM, Alexandre Prokoudine
> <alexandre prokoudine gmail com> wrote:
>         The only update that article needs is that apparently Hugin is
>         now
>         capable of outputting XML data for LensFun.
>         
>         Alexandre
>         
>         On Sat, Sep 28, 2013 at 6:53 PM, Pat David
>         <patdavid gmail com> wrote:
>         > Alexandre had a neat write up on lgw about using Hugin to
>         generate
>         > correction parameters:
>         >
>         >
>         http://libregraphicsworld.org/blog/entry/creating-lens-distorsion-models-with-hugin-lens-calibrator
>         >
>         >
>         > --
>         > pat david
>         > http://blog.patdavid.net
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-- 
Leonard Evens len math northwestern edu
Professor Emeritus, Department of Mathematics, Northwestern University