Reviewing Samyang 12mm F2.0 Lens

I am actually disappointed with the Samyang Lens. I bought one for my Sony Alpha 5100 camera. I bought it mostly for the perceived better resolution compared to the kit 16mm-50mm lens that comes with the A5100 camera. It turned out that their resolutions are the same. The only advantage is the F2.0 aperture and 98 degree hfov of the lens. However since it is a manual lens without OSS, it is much harder to use so only useful for special functions. The 16mm lens with an hfov of around 90 degree is sufficient for most of my uses. The Sony SELP1650 is very small as well.

Camera	Lens	Aperture	Pixel/V	P Mpixel
Sony A5100	16-50mm F3.5-5.6, ISO100,50mm	8	3000	13.5
Sony A5100	12mm F2.0,ISO100	2	2400	8.64
Sony A5100	12mm F2.0,ISO100	5.6	3000	13.5
Sony A5100	12mm F2.0,ISO100	8	3000	13.5
Sony A5100	12mm F2.0,ISO100	4	2700	10.935
Sony A5100	12mm F2.0,ISO2000	5.6	2700	10.935

Of special note is the lower resolution at the F2.0 aperture setting. It can be compensated by sensitivity of ISO 2000 with an aperture of F5.6 which has a 4 stop more sensitive comaprable to F1.4 at senstivity of ISO 100. http://www.digitalcameraworld.com/2014/02/19/what-is-iso-camera-sensitivity-settings-and-the-best-ways-to-use-them/

Of course, the depth of field at F5.6 is much larger than at F2.0. It has the advantage of tolerating focussing imperfections. At F2.0, the depth of field is very low so it is useful for special effects such as the Bokeh effects where the background image is blurred.