I've owned a few rectilinear wide-angles, my favorite being the Sigma 8-16 which offers a FOV of a little bit less than 120 degrees at the wide end. I've sold the Sigma to fund other things and got this Samyang as a cheap 200$ substitute for a couple projects I have in mind and to have that extreme wide-angle option in my bag. I was hoping to get acceptable "defished" results out of the Samyang using Photoshop trickery. I found the results are so interesting I thought I'd post them.
I tried three different solutions for defishing. DXO Optics, PTlens and Fisheye Hemi, the later two being Photoshop plugins. I did not include the sample from DXO Optics as it is very similar to the results from PTlens. Note that none of these applications/plugins have specific profiles for the Samyang. The Fisheye Hemi-plugin do not however operate with specific camera/lens profiles, rather with generic ones whose result can be further tweaked by increasing canvas size. The test image is not at all interesting or good in any technical or artsy meaning of the word (just a quick one out the window), but I think it shows what is possible. The "test" was conducted on a D7000 body.
The original image is of course distorted with bent lines, but it's really not that bad for a fisheye, there's somewhat less bulging than I expected. It might be down to the slight controversy over this lens' projection, some claim it's more or less stereographic. Lenstip attempts to explain it in their review of the lens. The image modified with PTlens offers a classic rectilinear kind of projection where the corners are stretched but lines straight. This is similar to how for instance the Sigma 8-16 would draw, although not quite as extreme. Also quite a bit of FOV is lost due to cropping. The last sample is from the Fisheye Hemi-plugin that uses mapping algorithms.
I'd say that the results achieved with the Fisheye Hemi-plugin are impressive and interesting and shows that a fisheye lens can be more "practical" than you'd think. An important thing to notice though, that the Hemi-plugin only seem to straighten vertical lines unlike other solutions that attempt to straighten them all. Of course there's a lot of fake pixels, and resolution in the corners isn't the best, but with careful post processing large prints can definitely be made and you who have experience with wide angle lenses know that corners will inevitably suffer from field curvature, vignetting and distortion while the center portion of the frame often remains extremely sharp. I do not however find the Hemi'd results from the Samyang any worse than the rectilinear wide-angles I've worked with!
Generally speaking the overall IQ of the Samyang is exceptional considering the price and I've started to think it actually rivals the comparable offerings from Nikon and Sigma. It is also a small, light yet very, very well built lens (as good as classic MF Nikkors) and although it has no chip, thus not super accurate exposure even on the bodies that can meter with it, it works well. Achieving what one deem an acceptable exposure is always a challenge with extreme wide-angles due to the tendency to capture scenes with a large dynamic range. Color and contrast is not extremely punchy, but it's no slouch and so far I can't see any heavy color casts. Manual focus is a moot point on a lens this wide and the extreme DOF achieved even at largest aperture. The best results seem to be around F/5.6-8.0 (as expected).
Edited by M4cr0s, 18 November 2011 - 16:01 .