Samyang 7.5mm f/3.5 Fisheye is a native Micro Four-Thirds M4/3 lens but manual focus (MF) only.  This is a much cheaper alternative to the Panasonic 8mm f/3.5 Fisheye lens, and according to the Samyang 7.5mm is sharper and handles flare better.  It comes with a built-in hood that cannot be detached.

In some parts of the world, the Samyang is marketed as Rokinon instead.  As of this writing, the Rokinon 7.5mm is available for about USD277-300 in the USA, and the Samyang 7.5mm for HKD2180-2380 in Hong Kong.

I hope to use Samyang / Rokinon 7.5mm as an ultrawide angle lens on the OM-D E-M5. So I shot these test photos in Hong Kong Science Park to compare the field of view (FOV) against 12mm and 14mm (using M.Zuiko 12-50mm), processed in Lightroom 4.1 – only some sharpening, with CA correction off. IBIS off. Handheld. Focus is on the tip of the golden egg at the center.  (The clouds were moving so the exposures were somewhat different.)

Aperture was set to f/5.6, which according to lenstip is the sharpest edge-to-edge aperture for the 7.5mm fisheye. I can confirm that f/5.6 is indeed sharper than f/4 in the corners.

(Note: any large-scale moire pattern or strange artifact that is shown in this web page is caused by downscaling of the photos present in the host server and/or web browser only.)

Olympus OM-D E-M5, Samyang 7.5mm Fisheye, ISO 200, 1/400 sec, f5.6:

Using kenw’s Rectilinear Correction Lightroom profile (free), the above picture becomes the following: (note that there’s an increase of resolution in the center but a decrease of resolution in the corners.  I don’t know if this is the best way to install it, but I unzipped the profile and placed it in my Windows 7 C:\Users\<USER_NAME>\AppData\Roaming\Adobe\CameraRaw\LensProfiles\1.0\Downloaded\ then the profile would show up as Panasonic)

As a comparison of FOV, look at the following photo at 12mm.

Olympus OM-D E-M5, M.Zuiko 12-50mm @ 12 mm, ISO 200, 1/640 sec, f5.6:

Another FOV comparison at 14mm.

Olympus OM-D E-M5, M.Zuiko 12-50mm @ 14 mm, ISO 200, 1/640 sec, f5.6:

The following is another example of before and after rectilinear correction:

In addition to the free rectilinear correction mentioned, there is a commercial Photoshop plug-in known as Fisheye-Hemi

Since this is a MF lens, here’s the MF procedure I used: (Note: for Panasonic cameras there is a setting called Shoot Without Lens which has to be turned on for this lens.)

  1. Set the camera to Aperture Priority (A) mode
  2. Set the aperture to maximum f/3.5
  3. Go into magnify mode by pressing a button on the OM-D E-M5 that has been customized to magnify
  4. Turn the MF ring to find the correct focus via the OLED or EVF
  5. Set the aperture to the desired aperture (e.g. f/5.6)

Note that since the fisheye lens has 180 degree FOV, it is easy to get your finger or foot in the photo, as in this example my left hand finger (while supporting the lens) appears in the bottom right hand corner:

The Samyang / Rokinon 7.5mm is very sharp wide open, and really sharp at f/5.6.  Offering 180 degrees of FOV, it offers exceptional image quality at a limited cost.  With free and commercial rectilinear correction / defish, I think it is a very useful lens.  As for weaknesses, other than having to use MF (instead of auto-focus), the focus scale is not precise – the actual infinity is not aligned to the infinity mark printed on the lens.  My copy is about 1-2mm off, and there are other reports of larger misalignment – but this does not affect image quality at all.  In addition, this lens does not have a depth-of-field scale.