12mm Lenses on a K-1

Thought you might like to see a comparison of two 12mm lenses used on a K-1, both were taken from more or less the same spot. One is taken with a Samyang 12mm f2.8, the other a Sigma 12-24mm AF DG EX (at 12mm) that I have just obtained from Papa_Lazarou via the forum.
I'm not saying which is which for now, I'm just interested in any general observations and which do you reckon is taken with which lens. I'll reveal all later with my own thoughts which might prove useful if anyone else is thinking of obtaining such a lens.

1.


2.



Clue: The Samyang is a fish-eye!

My money is on 5 he bottom one being the samyang, both seem nice and sharp and nice colours.
Derek

Difficult to tell with the resolutions as uploaded, but I think the Samyang edges it.

The first one has some visible vignetting, suggesting it might be the zoom. The second one is wider and you have approached closer to the subject, changing the perspective. This is probably the prime, but it doesn't seem to have the expected bending at the edges for it to be a fish-eye.

Well yes, the first is the zoom Sigma and the second the prime Samyang.

I did tweak the Samyang image in Hemi-fisheye, though it isn't overly fish-eye without doing that. This is the un-tweaked version:


Despite both being 12mm, the Samyang has a much greater field of view and seems sharper, albeit the geometry of the Sigma shows really good rectilinearity.

Some 100% pixel crops from both.
Sigma centre


Sigma edge



De-fished Samyang centre


De-fished Samyang edge


Clearly the Samyang wins on sharpness, though stopping the Sigma down to around f11 did improve it a little, but still not as good as the Samyang.

Both lenses give really great wide images when the whole frame is used, but the Samyang has the wider field of view and its result stand cropping much better. If good geometry is required the Sigma might be the more useful lens depending on circumstances and it can be zoomed in to 24mm.
I believe the Samyang has the widest field of view of any full frame lens, period. The Sigma does compete with marques from other (non Pentax) brands with the same range and there is a newer version of it, but not in a Pentax mount.
Just one final observation, the Samyang is an 'A' type lens that requires manual focussing, but given the depth of field it would be hard not to manage to do that!

I must admit I was very surprised how good the Samyang proves to be and how well Hemi-Fisheye straightens it out.