The concept is quite different - my 16mm Zuiko is 180deg diagonal while
my 12mm Voigtlander Heliar is 121deg (though I don't know if that's
diag. or rect.). The whole experience is different. Fisheyes don't
vignette either as they don't 'stretch' the light at the corners to
make the image rectilinear. (I know, I know but I find it easier to
think of it in that way).
Just off to take some 8mm portraits of the missus.
AndrewF
On 11/12/2004, at 7:41 AM, Andreas Pirner wrote:
>
> Brian Swale wrote:
>> Pity the image is not rectilinear!
>> Given the curvature applied to straight lines by the 16mm,
>> it is amazing that the Samyang 18-28 lens I have manages
>> to deliver straight lines at 18mm.
>
> Don't confuse the optical design differences
> of rectilinear wide angle lenses and fish eye
> lenses. The first tries to keep lines straight.
> They are built 'down' to 15mm, even 14mm lenses
> (i.e. Sigma). Fish eye lenses project a half
> sphere with curving lines as part of the design.
> 16 mm puts the sphere 'around' the 24x36 film
> frame, roughly giving the 180? angel of view
> across the diagonal. An 8mm puts the whole
> sphere as a circle image into the 24x36 frame.
> There are 6mm fish eye lenses giving even more
> than a 180? sphere.
>
> Andreas
>
>
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