Sony NEX-5N with Voigtlander and Zeiss rangefinder lenses – part 1 – ultrawides

f/11

There has been a lot of discussion about how well the new NEX cameras will work with wide and ultra-wide angle rangefinder lenses. Apparently the NEX-3 and 5 did not work well with many, resulting in color shifts and smearing in to the edges and corners.

With the release of the NEX-C3, reports trickled in of much better performance. Many naturally hope this will hold true for the 5N and the much anticipated 7. However, from early results posted by Steve Huff in his mini-shootout between the 7 and the Ricoh GXR with M module, the 7 definitely appears to have issues with some lenses, such as the Voigtlander 15mm f/4.5 Super Wide-Heliar. Coincidentally, the 15mm is also a difficult lens on the Leica M9 (B&H link – black, silver), also due to strong edge color shifts and vignetting (though much better now with the latest firmware).

So, what about the NEX-5N?

I had a 5N on loan for a few weeks and spent some time trying all of my rangefinder lenses on it.

To start off, here are results from my three super wide angles – the Voigtlander 12 (the Leica screw mount version) and 15mm and the Zeiss ZM 21mm f/2.8 Biogon.

As you will see from the images below, all work well on the 5N with no adverse color shifts and sharpness is retained into the corners (with some catches).

What surprised me though was that of the three, the Voigtlander 15mm (M mount version) trounces the other two until about f/8.

On my M9, it is the problem lens, yet not here on the 5N.

On my M9 the 12mm is pretty good, though with some edge softness/smearing. On the 5N it looks terrible along the left edge until about f/11. I should point out I’m using a Novoflex M to NEX adapter, which is probably the most expensive on the market, and one would expect, with its German manufacture, to be held to the tightest tolerances of any of the adapters currently available. However, based on these preliminary results, I’m a bit suspicious about the adapter because the 12mm looks so bad. On the M9 it is very usable even wide open, though I can detect a slight band of softness/smearing in the left third of the image. It’s possible that the 16MP 5N sensor is exaggerating this defect in the lens. FWIW, when I bought the lens in person (rather than online), I was able to test it against another one in stock, which was markedly worse with much stronger chromatic aberrations and much, much softer corners (though on the M9)… but it would seem it could still be better.

It could be possible that what works well on a full frame M9 sensor doesn’t translate exactly to the NEX APS-C sensor due to factors such as the NEX’s much higher resolution of the very central part of the lens’s image circle, as well as optical issue with the lens and misalignment with the adapter. It’s also worth stating that alignment tolerances are considerably more sensitive the more wide angle the lens.

The Zeiss 21mm f/2.8 Biogon is kind of a surprise on the 5N. I didn’t expect there to be as much sharpness issue into the corners as I see in my initial results, however, if one examines the Zeiss MTF for this lens, one will see it falls off in sharpness towards the edges at wider apertures (on full frame). And it has a fair amount of field curvature, from my experience. So this is probably coming to play against it on the NEX. Stopped down to 5.6 and higher though it’s really pretty good. And this is also my opinion of it on the M9. The Zeiss is a pretty good performer but I wouldn’t use it to photograph flat objects wide open, especially at closer distances, but past f/5.6 it’s very good across the frame.

It would be interesting to compare the Zeiss C-Biogon 21mm f/4.5. It’s technically a better performer than the f/2.8 version, however, like the Voigtlander 15mm, it’s notorious for extremely strong edge colour shifts and vignetting on the M9. In fact, the resulting characteristics are nearly identical. Given how good my 15mm is on this NEX-5N, I’m now very curious about the C-Biogon, though probably not enough so to spend about $1100 for what will be a 30mm equivalent field of view and not very usable on the M9.

UPDATE 2011.12.13

Zeiss has published an interesting piece about their wide angle lenses, which contains some relevant information explaining the poor performance of the ZM 21mm f/2.8 on the NEX on page 12 here (pdf). To quote directly:

Lenses with a very large beam tilt (from the rear element to the corner of the sensor) react in a much more sensitive manner to a change of refractive index in the image space caused by filter plates in front of the sensor (such as low pass and IR-blocking filters). If the filter plate is not considered in the design of the lens, the edge definition will suffer. The effect of the additional path through the glass grows exponentially with the beam inclination. A Distagon which never achieves more than 20° beam tilt in the corner of the image reacts more tolerantly than a symmetrical wide- angle lens, which might reach a 45° tilt. This is why filters in digital Leicas are very thin – to remain compatible with older optics.

If the filter is significantly thicker, the contrast transfer for the image edge becomes worse for tangential structures. In the graph of the curves, this looks like the old retrofocus lenses but is caused by astigmatism rather than lateral chromatic aberration. The focus is shifted to greater distances for tangential structures by the additional path through the glass. If the best edge definition is to be achieved, then all that can be done is to stop down further.

Advantages of nearly symmetrical wide- angle lenses (such as the ZM 21mm f/2.8):
• Small size and low weight
• Very good, uniform definition despite
moderately high effort required
• Usually excellent freedom from ghost
images
Disadvantages of nearly symmetrical wide- angle lenses:
• Cannot be used with every camera
• Require specially matched digital
sensors
• More sensitive to the change of optical
parameters in the image space
• Greater natural fall-off of brightness
toward the edge of the image

Based on samples in various photo forum discussions the ZM21mm f/4.5 seems to perform better on the 5N than the 2.8 version. Why it does, and the f/2.8 doesn’t, yet both are highly symmetrical lens designs, is a mystery to me. But one conclusion drawn by many is that the ZM 18mm f/4 Distagon is a better option than both 21s, though it is somewhat larger.

Below are sample images. Clicking on the image will point you to the full size, straight from camera JPEG file. The camera was set to the default settings – Standard color profile – and high ISO noise reduction was set to low (you can’t turn it off in-camera), though these were mostly done on a tripod at ISO 100. White balance was on auto, so some of the sequences show variations in white balance as a result.

Planar object (building) with the Voigtlander 12mm, 15mm and Zeiss ZM 21mm f/2.8, focus was set with magnified view, dead center:

12mm at f/5.6, 8 and 11:
f/5.6

f/8 f/11

|

15mm at f/4.5, 5.6, 8 and 11:
f/4.5

f/5.6 f/8 f/11

|

Zeiss ZM 21mm at f/2.8 through f/11 in one stop steps:
f/2.8

f/4 f/5.6 f/8 f/11

|

The same building from the side with the Zeiss ZM 21mm f/2.8 Biogon, again f/2.8 through f/11 in one stop steps:
f/2.8

f/4 f/5.6 f/8 f/11

Forest scene. The focus was on the near tree trunks at the left side of the frame.

12mm, f/5.6 through f/11:
f/5.6

f/8 f/11

|

15mm, f/4.5, 5.6 through f/11:

f/4.5

f/5.6 f/8 f/11

|

Zeiss ZM 21 from f/2.8 through f/11:

f/2.8

f/4 f/5.6 f/8 f/11

I should note that all images were focused wide open using the magnified view, without focus peaking to get the best visual idea of correct focus.

If you’re looking to buy any of this equipment, please consider using the following links to help support this site:

For all Zeiss lenses (ZM, ZE, ZF, etc.), please contact Rob Skeoch at Big Camera Workshops or his sister site the Rangefinder Store. Rob has been the source for most of my Zeiss ZM purchases and is a great guy to deal with. Free shipping within Canada is included, as is a B+W UV filter with each Zeiss lens purchase, and Rob will ship outside Canada. Due to the scarcity of many Zeiss lenses at this time, it is best to contact Rob for availability and please mention this site as a referral.

Otherwise, please consider using these B&H links:

Voigtlander 12mm f/5.6
Voigtlander 15mm f/4.5
Zeiss ZM 21mm f/2.8 black silver
Zeiss ZM 21mm f/4.5 black silver
Zeiss ZM 18mm f/4 black silver
Novoflex NEX-Leica M adapter
Sony NEX-5N camera only (black only) or kit with 18-55 in black or silver
Electronic viewfinder (EVF) for NEX-5N

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9 Responses to “Sony NEX-5N with Voigtlander and Zeiss rangefinder lenses – part 1 – ultrawides”

  1. Sam Waldron Says:

    Ron – fantastic work here – informative and appreciated.

    Looks like the CV 15 and the 5N are very well suited indeed!

  2. Ron Says:

    Thanks Sam. Yes, I think the CV15 is fantastic on the 5N. I wouldn’t rule out the CV12 either strictly based on my results as I think my copy is not in perfect optical condition. The CV15 is a very small lens that is well suited to the small size of the 5N.

  3. Sean Esopenko Says:

    Those shots with the Biogon 21mm aren’t resolving as sharp as what I get with the Voigtlander 21mm F4 Color Skopar I’ve been using with my Nex-5N. But I can see the shadows aren’t pushed as deep as the 12mm Voigtlander pushes them.

  4. Ron Says:

    Thanks Sean. I haven’t tried the 21 Voigtlander, but from what I’ve read on some forums, it seems to be a good lens. The Zeiss ZM21 f/2.8 is pretty disappointing on the NEX, well at least my copy is, though I doubt it’s just my copy, but it’s a pretty good lens on full frame. Not great into the corners wide open, but much better than the NEX images would lead one to believe. The Voigtlander 12mm can be a bit deceptive because it is so wide and can capture a lot of bright areas, such as sky. As a result I find cameras tend to underexpose most scenes, and combined with its high amount of vignetting, will result in darker images. Compared to the ZM21, I don’t feel the Voigtlander is a higher contrast lens. It should also be pointed out that in the forest scene, the lighting changed between the time I did the 12mm, 15mm and 21mm sequences, which will have an influence on the apparent degree of contrast seen from each lens.

  5. DanielT74 Says:

    My copy of Zeiss 2.8/21 ZM seems to be very sharp on the NEX-5N. I’ve just done a quick test close to the MFD of a blank sheet and white wall to test for the colour shift and my whiteboard to test sharpness and to my eyes it appears to be absolutely first rate – have a look for yourselves. Shots are taken from wide-open, then stopped down towards f8.

    https://picasaweb.google.com/103430830473331312618/Zeiss21mmF28QuickTest?authkey=Gv1sRgCJzMh-fEoo7cgQE

  6. Ron Says:

    Hi Daniel,

    Thanks for the comment. That’s very interesting. The only thing I can think to suggest is running the same test but on something farther away, like a wall or some buildings 20-30 feet away. The reason I suggest this is because when the lens is focused on something very close, the rear element is positioned farther away from the sensor and the angle of incidence of the light rays will be less steep, which might reduce the edge sharpness degradation I saw in my photos, which were all done at greater distances. I will receive a Ricoh GXR with the M mount module in a few days and will re-test the ZM21 on it to see if the results are any better. It’s still possible that my lens is a dud, though it has worked fine on my M9, and the poor 5N results were predicted specifically for this lens by Dr. Nasse in the Zeiss paper…

  7. DanielT74 Says:

    Hi Ron and folks

    So I took a few shots with the 21/2.8ZM out of my office window and I think they are pretty good. I front focused especially on the first shot so look for sharpness at the bottom of the image (added to the album above).

    I also took some test shots with the 21/4.5ZM which shows visible colour cast around the border. The sharpness is superb but unless you know a quick way to correct the colour cast, this may be a deal breaker for the NEX users.

    Here are the pics (see aperture values in the file names):

    https://picasaweb.google.com/103430830473331312618/Zeiss21mmF45ZmTest?authkey=Gv1sRgCKXMuNSvlMaQzAE#

  8. DanielT74 Says:

    To update on my earlier comment, I would not recommend either Zeiss 21mm for the use with NEX-5N.

    The 21/2.8 is beautiful close up but becomes soft at infinity focus.

    The 21/4.5 has pronounced colour cast on the edges at infinity which would need correction.

    Sigma is apparently putting out a Sony E-mount 19/2.8 (source: dpreview) for those who can wait and hope that it’s a winner.

  9. Leica M-Mount an Sonys NEX - Seite 194 - Systemkamera Forum Says:

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