Am 10.03.2013 14:51, schrieb Pascal de Bruijn:
>>
>> The problem seems to be that we do a lensfun search with LF_SEARCH_LOOSE
>> when we try to find a lens. I don't know what lensfun does exactly then,
>> but I assume it will just try to find the closest match, whatever that
>> is. In this case it is:
>>
>> lens: A-Serien Linsen, maker: Carl Zeiss, model: VCL-MHG07a
>>
>> That's way off. All is still OK in the beginning, as long as the camera
>> name is not set manually. The camera is not found, because we are
>> looking for an exact camera match. If module lens correction does not
>> get an exact match in the database no correction is applied.
>>
>> As soon as the camera is manually selected, our module assumes all is
>> good and a correction is done. However, with the wrong choice of a lens  :(
>>
>> I was not involved, but we probably do the loose search in order to
>> overcome variations in writing when in comes to the lens names. Probably
>> it was found that all too often a lens was not detected although it was
>> existing in the database with a slightly different spelling.
>>
>> Not sure how we can overcome this situation. One solution could be a
>> blacklist of lens names which libexiv2 will typically report if the
>> photo was taken with a pure mechanical lens. If the lens is one of those
>> we avoid any automatic detection. I fear that the blacklist might get
>> quite long. On my system for the two incumbent files the lens is
>> reported with a German string, even if I start darktable with LANG=C.
>> Different cameras will have different strings etc.
>
> Well, the thing I find particularly strange is, that manual selection
> gets disabled as well...
>

Unfortunately, there are quite a lot of strange things in that module. 
The lens selection in populated from a list that is generated by:

   lenslist = lf_db_find_lenses_hd (dt_iop_lensfun_db, 
g->camera,NULL,NULL, 0);

g->camera is NULL until a camera has been auto-detected or manually 
selected. And with all arguments being NULL, lf_db_find_lenses_hd() 
obviously returns just nothing.

Ulrich




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