Sony a7 torture test with Leica, Zeiss, Voigtlander rangefinder lenses
UPDATE – January 26, 2014
I was finally able to run the test I originally wanted to back in October. Please click the link to read the Sony a7R vs. Leica M9 shootout with 20+ Leica, Zeiss and Voigtlander rangefinder lenses.
Continue reading below for the Sony a7 with various rangefinder lenses. Note, if you’d rather access images one by one instead of a large zip file download for each lens, please see the images posted on my Flickr page.
I was able to briefly borrow and test a preproduction Sony a7 camera along with the new Carl Zeiss Sonnar T* 35mm f/2.8, Carl Zeiss Sonnar T* 55mm F1.8 and Sony 28-70mm f/3.5–5.6 OSS FE lenses. Unfortunately it wasn’t the a7R, in which I am more interested for the purposes of adapting rangefinder lenses. But this provided a good opportunity nonetheless to generate some images to help me (and hopefully also you) determine whether or not the a7 is a possible platform for rangefinder lenses.
First off, the images presented here are in no way intended to be examples of creative photography. Given I had 1.5 hours with the camera on a gloomy morning, and the burning question in the minds of many is how well this new Sony camera will work with adapted rangefinder lenses, an infinity focus test was in order. Why an infinity focus test? Because when a lens is focused at infinity, the rear element of the lens is typically closest to the sensor, meaning for certain lens designs, the light rays traveling to the sensor arrive at a strongly non-perpendicular angle, rather than straight at the sensor, which results in image quality degradation if the sensor isn’t well optimized for such types of lenses. The results tend to be edge color shifts and/or edge/corner smearing of the image.
This generally isn’t a problem with lenses adapted from SLR systems because such lenses must be design with the mirror box in mind, meaning the lens sits farther away from the image plane and the light rays arrive at a more perpendicular, and preferred, angle. Rangefinder systems never had the mirror box and the lenses were made to sit much closer to the image plane. Not such a big problem with film (other than perhaps light falloff into the corners), but definitely not desirable with digital sensors due to the many sensor ‘toppings’ that contribute to image degradation when light rays arrive at a strong angle.
Anyway, there are much better technical explanations available online, particularly in this PDF from Zeiss. See page 12, points 2 and 3.
I’m required by Sony to state that the camera and Sony lenses used to create the images presented here were all preproduction models and the image results are therefore not necessarily indicative of results that will be obtained from production units once they become available.
However, unless Sony makes major revisions to the sensor package itself, I doubt results with the rangefinder lenses tested here will improve considerably once production units are available.
The lenses tested, in order of focal length and maximum aperture:
Voigtlander Ultra Wide-Heliar 12mm f5.6 Aspherical (LTM version which is identical to the current M mount version) (referred to as CV12)
Voigtlander Super Wide-Heliar 15mm f4.5 Aspherical M (referred to as CV15)
Leica Summilux-M 21mm f1.4 ASPH. (referred to as 21 Lux)
Zeiss Biogon T* 21mm f2.8 ZM (referred to as ZM21)
Leica Super-Elmar-M 21mm f3.4 ASPH. (referred to as 21 SEM)
Leica Summicron-M 28mm f2 ASPH. (referred to as 28 Cron)
Voigtlander Nokton 35mm f1.2 Aspherical VM II (referred to as CV35)
Canon 35mm f2.0 LTM (a lens from the late 50s-early 60s)
Zeiss C Biogon T* 35mm f2.8 ZM (referred to as ZM35C)
Sony Carl Zeiss Sonnar T* 35mm f2.8 (newly announced with the a7/a7R)
Voigtlander Nokton classic 40mm f1.4 (referred to as CV40)
Leica Summilux-M 50mm f1.4 ASPH. (referred to as 50 Lux ASPH)
Canon 50mm f1.4 LTM (a lens from the late 50s-early 60s)
Voigtlander Nokton 50mm f1.5 Aspherical LTM (optically identical to the current M mount model, though apparently there may be some coating differences) (referred to as CV50)
Zeiss C Sonnar T* 50mm f1.5 ZM (referred to as ZM50C)
Zeiss Planar T* 50mm f2 ZM (referred to as ZM50P)
Sony Carl Zeiss Sonnar T* 55mm f1.8 (newly announced with the a7/a7R)
Sony 28-70mm f3.5–5.6 OSS (newly announced with the a7/a7R)
Leica Summarit-M 90mm f2.5 (referred to as 90 Summarit)
Test scenes include one view overlooking downtown Hamilton, Ontario, from the escarpment brow, one intended to show ‘bokeh’ differences between the 35mm and ~50mm lenses, and one ‘brick wall’ test of foliage with the wides and up to ~50mm lenses (though not including the LTM 50s, CV40 and Sony zoom due to time and weather constraints).
I had also intended to shoot the exact same scenes with the same lenses on the Leica M9 (though obviously not including the new Sony lenses), but I ran out of time, and it started to rain. This would have provided a ‘control’ reference against which to compare the results from the a7. I’ll spill the beans now – none of the rangefinder lenses performed as well on the a7 as they do on the M9, specifically referring to image smearing into the edges/corners. Some are not so bad and are good enough when stopped down sufficiently, but some are outright horrible (ZM21, 28 Cron), to the point where one would think the lens was defective.
Naturally there were some variable that couldn’t be tested, such as whether the Novoflex NEX-Leica M adapter I used was perfect. I had a Kipon adapter as well, but no time to run a duplicate set of test images to see if, or how much, the adapter influenced the results. Therefore, take these results for what they are and weigh them against other tests that will certainly soon appear online.
Everything was shot on a tripod with the two second timer at ISO 400. While perhaps not optimal, I wanted to keep shutter speeds somewhat reasonable considering the gloomy weather (even though a tripod was used). Images presented here were taken directly and uncorrected from in-camera Jpegs. I also shot RAW, but don’t have a way to convert those yet. While it certainly would be possible to improve color and tonality, nothing could possibly improve image rendering into the edges/corners with some of the lens combinations. In-camera lens corrections (vignetting, chromatic aberration, distortion) were disabled, in case some or all of these might also apply to non-native lenses. ISO noise reduction was also disabled, though I suspect it never entirely turns off. The camera was set to manual focus and each lens was focused on the steeple in the center of the frame using 11.7x magnification. No attempt was made to correct for focus shift, which was certainly a problem with at least the ZM50C.
Canon 35mm f2.0 LTM
Sony Carl Zeiss Sonnar T* 35mm f2.8
50 Lux ASPH
Canon 50mm f1.4 LTM
Sony Carl Zeiss Sonnar T* 55mm f1.8
Sony 28-70mm f3.5–5.6 OSS
Leica Summarit-M 90mm f2.5
Note, the download links will take you to zipped files hosted on Google Drive. These are quite large, and at full resolution (though compressed somewhat more after applying the watermark shooting information, than what came out of the camera). The full set of links is several GB, so be warned.
My take on the results: I’m hoping these lenses will fare better on the a7R. Results on the a7 are for the most part disappointing. All I can surmise at the moment is that the toppings on the a7′s sensor work against achieving optimal (or in some cases, good enough) results with the rangefinder lenses I had available for this test.
What may also be the case with this new system from Sony, as was with the Nex cameras, is that compatibility with adapted lenses will be model specific. Future cameras may work better, but some may be even be worse…
Those looking to adapt SLR lenses will probably achieve much better results with the a7 and the new Zeiss lenses look to be quite good, especially the 55. Sure, it’s pricy for an f/1.8 lens, but it looks great right from wide open.
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Equipment mentioned in this article: