[ptx] Hugin: strange behavior of focal length <-> FOV arithmetic

[jeffrey-wilson at cinci.rr.com]

My problem might be related to a post Dec 21, 2004 by Stanislav Brabec with the above subject. http://www.email-lists.org/pipermail/ptx/2004-December/002942.html

 The focal length of Sony Cybershot DSC-P1 and V1 are technically about 7-21mm.  According to a Sony webpage for a Mavica, 7mm is about equivalent to 34mm in conventional 35mm film.
 When Hugin loads the EXIF information from these images, it sets the focal length at 7 and consequentially blows up the degrees of view(v) to 137.5.  After running an optimize there are large deviations (maximum 157).  After a lot of fiddling, sometimes the v drops to 50.6 and focal length adjusts to 38.1 (crop stays at 1)...reasonable values.  Alternately, adjusting the crop factor to 5.443 will keep the focal length at 7mm and give me a appropriate view of 50.6.  I assume the crop factor is missing from my EXIF data and causes the problem in the first place, right?
 I imagine Hugin might have similar problems with many consumer/pro-sumer digital cameras...at least the Sonys.  Thankfully 0.4beta has the Lens management feature to work around this issue, and I have saved my Lens Project File.  Maybe there should be a checkbox/feature for translating these focal lengths?  Is this only a Sony issue?  That Minolta DiMAGE A1 also sets the focal length at ~7mm, but seems to have a crop factor set in the images.

Jeff