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Kowa Prominar 12mm f/1.8 MFT Lens Review

John Riley reviews the wide-angle Kowa Prominar 12mm f/1.8 Micro Four Thirds lens, a lens that features both f/ stops and T stops.

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Handling and Features

Kowa Prominar 12mm f/1.8 MFT Lens Review: Kowa Prominar 12mm F1,8 Front Oblique View

Kowa is indeed a venerable name in the world of photography, having produced many cameras and lenses from 1954 to 1978, plus more recently spotting scopes and even a range of ultra-telephoto lenses. The Prominar lens name has been used extensively and now we see it reappear in a series of three compact prime lenses for MFT format. Having looked at the Prominar 8.5mm f/2.8 (T3.0) lens, we now follow up with a review of the 12mm f/1.8 T1.9) – the 25mm f/1.8 (T1.9) will follow in due course. The 12mm looks the part, just as the previously reviewed 8.5mm did, and balances well on the Panasonic Lumix G6 used for this review. Let's see how this one fares compared to the first.

Kowa Prominar 12mm f/1.8 Handling and Features

Kowa Prominar 12mm f/1.8 MFT Lens Review: Kowa Prominar 12mm F1,8 Top View With F Stops

The lens itself is quite compact but moderately heavy for its size, weighing in at a solid 475g. The front element and its surrounding rim are large compared to the general feel of the lens, with the push on lens hood dwarfing the whole. As before, the hood is held in place by a locking screw rather than the usual bayonet fit. This is simple and effective, albeit looking slightly strange with the bright chrome screw jutting out from the rim of the hood. As the hood just pushes into place we do need to align the marks carefully to avoid vignetting. There is ample room to insert filters into the 72mm thread, without having to remove the hood every time.

The focusing ring has very sculpted and hard ribbing to ensure a good grip, helping to maintain the vintage look of the lens as a whole. The lens is manual focus only, down to 0.2m, just under 8 inches. This represents a maximum magnification of 0.1x, or 1:10. This is conventionally close for a lens of this focal length. There is no depth of field scale, although there are ample distances marked in feet and metres to make this a useful possibility. 12mm on MFT format equates with a “35mm format equivalent” of 24mm, a classic focal length that is suitable for a wide range of wide-angle applications, including landscape, architecture and street photography. It is much easier to focus than the 8.5mm and the focusing aids on the G6 make a useful difference to the accuracy. The focusing and aperture rings move in the direction of Canon cameras, rather than Nikon/Pentax which move in the opposite way.

Finally, we have the aperture ring, with a design that is very intelligent indeed. The review setting used was f/stops, which are provided with firm, positive click stops at full stop intervals, although one-third stops are quite easy to approximate. Pressing a small button enables the whole ring to be rotated through 180 degrees to bring into play the T stop settings. The T stops, usually used for movie shooting, are clickless. The whole idea is highly inventive and works beautifully.

Kowa Prominar 12mm f/1.8 MFT Lens Review: Kowa Prominar 12mm F1,8 With Hood On Lumix G6

Lens construction is 12 elements in 10 groups, a relatively complex formula no doubt necessitated by the unusually wide maximum aperture. The aperture comprises 9 circular blades, a feature used to enhance the bokeh of the lens.

A 24mm-equivalent lens is a powerful choice, very versatile as mentioned. The f/1.8 bright aperture is a huge bonus, that being something that for a full frame camera could be a very large and very costly lens.

Kowa Prominar 12mm f/1.8 MFT Lens Review: Kowa Prominar 12mm F1,8 Rear Oblique View

Kowa Prominar 12mm f/1.8 Performance

Centrally, sharpness is excellent at f/1.8 and remains excellent all the way through to f/11. It is still very good at f/16.

The edges are very good from f/1.8 through to f/11, remaining good at f/16. This is a very satisfactory performance and makes all the apertures very usable, perhaps avoiding f/16 at the edges if sharpness there is critical.

Kowa Prominar 12mm f/1.8 MTF Charts

How to read our MTF charts

The blue column represents readings from the centre of the picture frame at the various apertures and the green is from the edges.

The scale on the left side is an indication of actual image resolution as LW/PH and is described in detail above. The taller the column, the better the lens performance.

For this review, the lens was tested on a Panasonic Lumix G6 using Imatest.

CA (Chromatic Aberration) is very well controlled at the centre, the edges showing slight fringing that for many subjects may well not be noticed. Branches against bright sky and similar subjects may show some fringing, but this can always be corrected in software.


Kowa Prominar 12mm f/1.8 Chromatic Aberration Charts

How to read our CA charts

Chromatic aberration (CA) is the lens' inability to focus on the sensor or film all colours of visible light at the same point. Severe chromatic aberration gives a noticeable fringing or a halo effect around sharp edges within the picture. It can be cured in software.

Apochromatic lenses have special lens elements (aspheric, extra-low dispersion etc) to minimize the problem, hence they usually cost more.

For this review, the lens was tested on a Panasonic Lumix G6 using Imatest.


Interestingly, Kowa provides a distortion figure and they quote -0.59% barrel distortion. The measured figure is -1.42%, which is still very good for a wide angle lens. A zoom in this range would likely show much more distortion. If necessary, this can be tackled in software, although it may not be necessary for most of the subject matter that is likely to be covered by this lens.

Flare resistance is excellent even under the most arduous conditions, so will not be an issue.

Bokeh, the quality of the out of focus areas, is also hardly an issue as the gradation here is smooth and pleasing. There is much more possibility of getting those out of focus backgrounds with the 12mm, especially considering the f/1.8 bright aperture. There is still plenty of depth of field when stopped down, but at wider apertures, there is the potential for good differential focus when needed.

Overall, a very impressive performance that should result in excellent images with plenty of “character”, that indefinable aesthetic quality that separates out the lenses that become our favourites.

Kowa Prominar 12mm f/1.8 Sample Photos


Kowa Prominar 12mm f/1.8 Aperture range


Value For Money

The Kowa Prominar 12mm f/1.8 lens is priced at £669. There are a handful of 12mm prime lenses that could be competitors, such as:

Samyang 12mm f/2 NCS CS, £305
Samyang 12mm T2.2 Video Lens, £359
Olympus M.Zuiko Digital ED 12mm f/2, £549
SLR Magic 12mm T1.6 HyperPrime Cine Lens, £630
Meike 12mm f/2.8, £194

We might also consider:

Voigtlander 10.5mm f/0.95, £949
SLR Magic 10mm T2.1 HyperPrime Cine Lens, £894

Considering its quality of manufacture, the Prominar could be a strong contender for our cash. For more options have a look at the Top 35 Best Micro Four Thirds Lenses.


Kowa Prominar 12mm f/1.8 Verdict

The Kowa Prominar 12mm f/1.8 is a classy looking lens. It's beautifully made and the results are excellent. AF could be a useful addition, but on the other hand we have an easy to focus lens here that presents none of the focusing difficulties of its 8.5mm sibling.

It's expensive perhaps compared to some, but looks excellent value against the Voigtlander 10.5mm f/0.95, unless that extra bit of speed is needed.

It's a very compelling lens to use, very much the traditional 24mm (in full frame terms) with all its inherent versatility.

Kowa Prominar 12mm f/1.8 Pros

  • Excellent sharpness
  • Low distortion
  • Low CA
  • No flare
  • High quality of manufacture
  • Pleasant bokeh
  • Fast bright f/1.8 aperture

Kowa Prominar 12mm f/1.8 Cons

  • Manual focusing not for everyone
  • No weather resistance
  • No depth of field scale

Overall Verdict

Kowa Prominar 12mm f/1.8 Specifications

Lens Mounts
  • Panasonic Micro Four Thirds
  • Olympus Micro Four Thirds
Focal Length12mm
Angle of View86.8
Max Aperturef/1.8
Min Aperturef/16
Filter Size72mm
35mm equivalent24mm
Internal focusingNo Data
Maximum magnification0.1x
Min Focus20cm
Box Contents
Box ContentsNo Data

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