Voigtlander 15mm F4.5 III V3 Review (vs. Kowa Prominar 8.5mm F2.8)(English Version)

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Introduction:
This fresh ultra wide Voigtlander 15mm F4.5 Super Heliar III is not a lens with new design but modify from Super Heliar II. The first and second generation design don’t take the characteristic of digital camera body in consideration, so make the picture has some problems like color shift on fringe and smear corner. Especially on SONY A7, A7r and Leica M240. The manufacturer Cosina make a modify to resolve these problems and hope this 3rd generation lens can become the new era of full frame ultra wide.

Outlook of 2nd(left) and 3rd(right) generation

Fringe color shift:
Most of the old lens used in film camera made the same result in digital camera body. But some ultra wide lens with short flange distance(or back focus distance) could come with bad color rendering on fringe. This color shift problem is from the tilted incidence light on sensor’s surface. The micro lens on the surface of image sensor come to different efficiency with different incidence angle. The worst case is the R,G,B micro lens have different efficiency each other, so the color shift become.

Corner smear:
The problem of corner smear comes from the filter stack in front of the image sensor. This filter stack is necessary for image sensor to filter out the infrared. Because the lens used in film never take this filter stack in consider, the optimum optical design no longer optimum in front of digital camera body. Some experiment prove the thicker filter stack the worse corner smear(please reference “Sensor Stack Thickness: When Does It Matter?”). Like the Sony A7’s 2mm and Leica M9’s 0.8mm, Sony’s corner smear is worse than Leica’s.

Cosina made some modify from 2nd generation lens, wish to resolve the fringe color shift and corner smear problems while mounted on digital camera body like SONY A7 and Leica M240 etc. Here is the optical structure:

Optical:

Optical of 2nd(left) and 3rd(right) generation

Above is the optical structure of 2nd (left) and 3rd (right) generation. It is from 6 groups 8 elements to 9 groups 11 elements. This new version seems a little more complex than other M-mount wide angle lens, and more like SLR wide angle lens, like this:

Optical of Nikkor 14mm F2.8 AF ED

Anyway let’s take a look at the MTF of 1st generation lens. The contrast of 10lp/mm is very high at center, and keep 70% till to the border. The sagittal contrast of 30lp/mm is very good, but the tangential decrease to 40% at border. This MTF result is decent for an ultra wide lens.(Understanding the MTF)

Voigtlander 15mm F4.5 I 的 MTF 圖

First Impression:
This Lens is bought from the Voigtlander Taiwan Agent cost NT23100. The price at USA is US$750 and JPY82620 at Japan. The price of 3rd generation is almost 1.5 times to 2nd version. The weight and size are also much more than prior generation(weight more 100g, diameter over 5mm, length longer 15mm). Even though the overall size is still smaller than the Kowa 8.5mm F2.8. Sure the Kowa is aperture F2.8, faster than Voigtlander 1 step. The other good improvement for this new lens is the RF couple ring has oil exposed no more, clean enough to avoid damage your camera body.

Voigtlander 15mm F4.5 III(left) and Kowa 8.5mm F2.8(right)

Lens back

The distance of focus ring is short, around 90 degrees to get to the infinity focusing. Damping of the aperture ring is very good, it is between Leica(too soft) and Zeiss(too hard). The step of aperture ring is 1/2 Ev, just like the other Leica Lens. This is good for recording aperture in EXIF while mounted on Leica’s camera body. Here is the picture of Voigtlander 15mm F4.5 III with Leica M240:

Voigtlander 15mm F4.5 III with Lecia M240

Pretest:
We take a quick look to understand the color shift and corner smear. Here is the pretest result(mounted to Leica M240 and turn off the lens profile). We didn’t see any color shift on fringe.

Here are the 100% crop of center and four corners. There are some detail loss on corners but not much.

Detail Test:
This test will base on Voigtlander 15mm F4.5 III with Leica M240 and turn off the lens profile. And compare it to Kowa 8.5mm F2.8 with Olympus E-PL6. All the test results are Voigtlande on the left and Kowa on the right. The test items include resolution, vignetting, distortion, flare, chromatic, coma aberration, sun star, bokeh and detail rendering. Regarding the details of testing please reference “Basic of lens test”.

Resolution:
Here is the center resolution. Left 2(left is sagittal, right is tangential) are Voigtlander, right 2(left is sagittal, right is tangential) are Kowa. From up to down are F/2.8, F/4(Voigtlander is F/4.5), F/5.6, F/8, F/11, F/16 and F/22. The optimum resolution is at F/5.6 where the resolution is around 3300 lines. At F/22 the resolution still have 3000 lines. It’s pretty good.

F/2.8

F/4

F/5.6

F/8

F/11

F/16

F/22

Here are the sagittal(left) and tangential(right) resolution at center, 1/2 and border on aperture F/5.6. At the border the resolution still keep up to 3000 lines, that is very good for an ultra wild lens. The corner smear is no longer a problem for this Voigtlander 15mm F4.5 III 3rd generation lens.

Center of frame

1/2 of frame

Border

Vignetting:
The light loss at the corner on maximum aperture is healthy. But it don’t get much improvement while shrink aperture. Vignetting is still existence at F/16. This is not the lens problem for sure, but the digital image sensor. Because the light incident angle is too oblique at fringe.

 
F/2.8

 
F/4

 
F/5.6

 
F/8

F/11

F/16

Distortion:
Distortion is very good. Only have a very tiny barrel distortion. 

Flare:
It just has slight flare while the light source is coming to the frame.

Chromatic:
We can see slight chromatic at corner. Here are the chromatic at F/5.6 and F/11.

F/2.8

F/5.6

F/11

Coma Aberration:
Not good, but no too bed for an ultra wide lens.

Sun Star:
Here are the sun stars at center and corner at F/8. It is decent as other Leica lens. 

Center

Corner

Bokeh:
In general the wide angle lens is not easy to get the bokeh. But this one seems not bad. Here are the F/4.5(Kowa is F/5.6) and F/11.

Detail Rendering:
The detail loss are not much at F/22. Here are the F4/5(Kowa is F/5.6) and F/22(Kowa is F/16).

Conclusion:
For this test and comparison, we know that Voigtlander 15mm F4.5 III is a good ultra wide lens. Especially the resolution and distortion are out standing. Flare and sun star are in average level. Chromatic and coma are weaker than others. Even though we think this 3rd generation lens will keep at the buyer’s top choice for M-mount ultra wide lens just as the 1st and 2nd generation. We wish Cosina can keep developing faster ultra wide lens, like the Zeiss Distagon 15mm F2.8.


More about the fringe color shift:
After take a lot of sample pictures. We found this 3rd generation lens still have a little color shift on right fringe. Especially at the full aperture and in mid range of histogram. Here are some samples. You can see the right fringe has a little vine color.

 Mid range histogram

 Gray color in mid range histogram

A landscape sample

Not like the 1st and 2nd generation can’t be corrected. This 3rd generation’s little fringe color shift can be corrected with Leica M240’s lens profile code 11626 28mm. Here are the comparison for before and after correction.

 Left without lens profile, right with code 11626 28mm

Regarding the outdoor pictures of Voigtlander 15mm F4.5 III, please reference to “Voigtlander 15mm F4.5 III Sampe Pictures (with Leica M240)” .