[ptx] panosifter problems & questions

[Pablo d'Angelo]

On Thu, 12 Feb 2004, Terje Mathisen wrote:

> scholnik at radar.nrl.navy.mil wrote:
> >   While I'm complaining about free software :) I thought I'd mention
> >some other things I noticed:
> >
> >1. panosifter tries to read focal length and sensor size from the exif
> >   data, but when it can't find the sensor size it throws an error and
> >   assumes 24mm x 36mm.  My camera stores the true focal length but it
> >   has a cropping factor of about 5, so assuming 24mm x 36mm is really
> >   wrong.  I do use the -v parameter but I think it is being ignored.

Yes, the default 24x36 assumption is quite stupid. ;)

> Instead of depending upon having both real and effective focal length in 
> EXIF (or real + crop factor), otherwise require an override parameter on 
> the command line, a useful fallback would have been to combine the focal 
> length field with a command line supplied crop factor:
> 
>  -crop 4.8
> 
> would turn my Olympus D40Z at 7.5 mm into a 36 mm equivalent lens, with 
> HFOV (in portrait mode) of just under 40 degrees.

Actually, I'm not completely sure what the crop factor really is.
the ratio of the diagonals? Or the ratio of width, or height? Have seem
different interpretations on the web.

ciao
  Pablo
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