wwp@yahoogroups.com:
Re: fisheye lenses : Nikkor 10.5 mm vs Sigma 15
Erik Krause 2005-Mar-31 23:55:00
On 31 Mar 2005 at 21:00, pedro_silva58 wrote:
> you're right, of course, about the difference in "full-frame-ness"
> between the two. assuming they have similar geometries, the 10.5 vs
> 15mm should have that effect. still...
> i find the sigma 8mm not too bad (considering) near the center, but
> much worse in the periphery. cropping a 15mm might give a nice
> quality image all around (and require more shots: there's no free lunch!)
> also, is a "rectilinear" 14mm or zoom necessarily better for panos
> than a 15mm fish? why?
Rectilinear images are compressed in the outer regions (resulting in
more pixels and higher sharpness) whereas fisheye images are
stretched. See Helmut Derschs article:
http://www.einem.net/~dersch/heliarVR/heliarVR0.html
> if its distortion is moustache-like (quite
> common, i hear), wouldn't that be harder to correct than a good fish?
No. As long as the distortion curve can be modelled by a fourth
degree polinomial (this is what panotools does) there is not problem
to correct it. This wavy type of distortion is the reason why we have
three lens correction parameters and not only one or two...
best regards
--
Erik Krause
Ressources, not only for panorama creation:
http://www.erik-krause.de/
Read panotools at GMane:
http://news.gmane.org/gmane.comp.graphics.panotools