Version:            (using KDE 3.5.9)
OS:                Linux
Installed from:    Compiled From Sources

If I convert image from NEF to TIFF, some EXIF info is lost. Saving the image using jpg or png preserves the info. Image coverted using bibblepro has the EXIF info present.

dan@dan:~/foto/20090409Nebe> exiv2 dsc_8692.nef
Warning: Size 5303 of Exif.Nikon3.0x0091 exceeds 4096 bytes limit. Not decoded.
File name       : dsc_8692.nef
File size       : 10786603 Bytes
Camera make     : NIKON CORPORATION
Camera model    : NIKON D300
Image timestamp : 2009:04:09 18:42:25
Image number    :
Exposure time   : 1/320 s
Aperture        : F9
Exposure bias   : -1
Flash           : No flash
Flash bias      :
Focal length    : 50.0 mm (35 mm equivalent: 75.0 mm)
Subject distance:
ISO speed       : 200
Exposure mode   : Auto
Metering mode   : Multi-segment
Macro mode      :
Image quality   : RAW
Exif Resolution : 4352 x 2868
White balance   : AUTO
Thumbnail       : None
Copyright       : 2009
Exif comment    :

dan@dan:~/foto/20090409Nebe> exiv2 dsc_8692.jpg
File name       : dsc_8692.jpg
File size       : 1769328 Bytes
Camera make     : NIKON CORPORATION
Camera model    : NIKON D300
Image timestamp : 2009:04:09 18:42:25
Image number    :
Exposure time   : 1/320 s
Aperture        : F9
Exposure bias   : -1
Flash           : No flash
Flash bias      :
Focal length    : 50.0 mm (35 mm equivalent: 75.0 mm)
Subject distance:
ISO speed       : 200
Exposure mode   : Auto
Metering mode   : Multi-segment
Macro mode      :
Image quality   : RAW
Exif Resolution : 4320 x 2868
White balance   : AUTO
Thumbnail       : JPEG, 2663 Bytes
Copyright       : 2009
Exif comment    :

dan@dan:~/foto/20090409Nebe> exiv2 dsc_8692.png
File name       : dsc_8692.png
File size       : 52637141 Bytes
Camera make     : NIKON CORPORATION
Camera model    : NIKON D300
Image timestamp : 2009:04:09 18:42:25
Image number    :
Exposure time   : 1/320 s
Aperture        : F9
Exposure bias   : -1
Flash           : No flash
Flash bias      :
Focal length    : 50.0 mm (35 mm equivalent: 75.0 mm)
Subject distance:
ISO speed       : 200
Exposure mode   : Auto
Metering mode   : Multi-segment
Macro mode      :
Image quality   : RAW
Exif Resolution : 4320 x 2868
White balance   : AUTO
Thumbnail       : JPEG, 2663 Bytes
Copyright       : 2009
Exif comment    :

and now the bad version

dan@dan:~/foto/20090409Nebe> exiv2 dsc_8692.tiff
File name       : dsc_8692.tiff
File size       : 53776524 Bytes
Camera make     : NIKON CORPORATION
Camera model    : NIKON D300
Image timestamp :
Image number    :
Exposure time   :
Aperture        :
Exposure bias   :
Flash           :
Flash bias      :
Focal length    :
Subject distance:
ISO speed       :
Exposure mode   :
Metering mode   :
Macro mode      :
Image quality   :
Exif Resolution : 4320 x 2868
White balance   :
Thumbnail       : TIFF, 51100 Bytes
Copyright       : 2009
Exif comment    :

and good version from bibblepro

dan@dan:~/foto/20090409Nebe> exiv2 pano/dsc_8692.tif
Warning: Size 5303 of Exif.Nikon3.0x0091 exceeds 4096 bytes limit. Not decoded.
File name       : pano/dsc_8692.tif
File size       : 36992356 Bytes
Camera make     : NIKON CORPORATION
Camera model    : NIKON D300
Image timestamp : 2009:04:09 18:42:25
Image number    :
Exposure time   : 1/320 s
Aperture        : F9
Exposure bias   : 0
Flash           : No flash
Flash bias      :
Focal length    : 50.0 mm (35 mm equivalent: 75.0 mm)
Subject distance:
ISO speed       : 200
Exposure mode   : Auto
Metering mode   :
Macro mode      :
Image quality   : RAW
Exif Resolution : 4304 x 2860
White balance   : AUTO
Thumbnail       : TIFF, 51020 Bytes
Copyright       : 2009
Exif comment    :

Also the problem is, that tiff from digikam is not usable for hugin panorama tools, becouse hugin depends on focal length and angle info about the lens used for taking the picture. As you can see from the warning message, bibblepro transfers all the exif info from .nef to .tiff.