Sony a7S vs. Leica M Typ240 infinity test with 21 Leica, Zeiss, Voigtlander rangefinder lenses

The Sony a7S is the third camera in Sony’s a7 series and this write-up is the third installment in my series testing various rangefinder lenses on this platform to determine technical performance when photographing a distant, near infinity scene. While this may seem a simple task, the combination of a rangefinder lens with a short exit pupil distance and a scene at infinity is the most technically demanding combination of variables influencing technical image quality from these ‘mirrorless’ cameras. Please refer to the original a7 shootout for an explanation why infinity focus is such a ‘torture test’ for these cameras.

The previous two installments of this series can be found here for the a7 and here for the a7R.

As a bonus comparison, I photographed the same scene on the same day, with the same lenses, using the Leica M Typ240 camera.

As with the previous a7 tests, I’m making this information and the high resolution files freely available for personal, non-commercial use only. If you find this useful, please consider making a donation through the Paypal button below, or making your next purchase through B&H using the indicated links throughout the article. Any amount is appreciated!





The test scene above is basically the same view overlooking downtown Hamilton as the previous two tests and should be sufficient to give an idea of general edge-to-edge lens performance on these cameras. My interest is the left and right edges more so than the extreme corners.

The parameters:

– Tripod mounted.

– Self-timer release (2 seconds IIRC).

– a7S set to electronic first curtain shutter.

– a7S was manually focused using maximum focus assist zoom on the church spire near the center of the frame (which is under scaffolding).

– M240 was focused using the accessory EVF at maximum magnification.

– a7S vignetting correction and other in-camera corrections were turned off in case these might be baked into the RAW file.

– Some lenses tested on the M240 were not 6-bit coded. Generally this isn’t a big problem with the M240 as it seems to handle this better than the M9. If EXIF doesn’t report a focal length in the M240 files, then the lens was used uncoded.

– A Sony-Leica M adapter from Novoflex (B&H) was used for the test. While one would expect such an expensive adapter to be made to tighter tolerances, and therefore be less likely to induce uneven lens performance across the frame, it’s difficult to determine this without testing against other adapters. One concern debated in the forums is whether a significant difference between focus at the infinity hard stop and actual infinity as seen by magnified live view might adversely affect image quality from lenses with floating element systems (such as the Leica 50 Lux ASPH). I can’t really say one way or the other, but with the difference being minimal, whatever influence this had on final image quality will likely be very minor. With only one adapter, there’s no way to really know how much influence the adapter had on edge to edge sharpness inconsistencies apparent with some lenses. For a better understanding of how adapters can make a mess of things, see this great blog post by LensRentals.

– RAW files converted in Lightroom 5 with the default parameters. WB adjustments were generally a single setting for each camera, which therefore doesn’t compensate for lens to lens tint shifts, etc. I did spend some time trying to get the exposure between the two cameras to look similar, and consistent from frame to frame. No CA or distortion correction applied. Try to ignore exposure/color/light differences since the test is all about technical sharpness/focus away from the center of the frame.

– M240 images were shot after the a7S was tested with all lenses. As a result, sun position between the two cameras changed a fair amount and I was not successful in aligning the M240 composition to perfectly match the a7S. Therefore, there will be a slight shift in the scene when flipping between images from each camera.

– Jpegs exported at 100% from LR, then watermarked in Photo Mechanic and exported at 50% to keep file sizes reasonable. Should be good enough for this purpose.

Also…

– Leica M240 files were resized to Sony a7S dimensions of 4240 pixels wide.

Why did I do this? I’m primarily interested in a direct comparison between the two at identical ‘resolution’. This also revealed that the M240’s greater resolution, even when downsized, will retain better fine details and ‘truer’ detail information that is less likely to be a sensor/software aliasing aberration.

Why did I turn off vignetting correction for the a7S but left the M240 set to read 6-bit lens codes and make automatic vignetting/color shift corrections? Because that is how I would shoot with both cameras. This gives you and me a better idea of how bad the vignetting and color shift is with each lens… and with the a7S, it turns out the lower pixel density is a definite benefit, which considerably reduces edge color shift with problematic lenses such as many of the wides and the Voigtlander 15/4.5 in particular.

Similar to the a7R infinity test, I’ll break this down by lens and offer a few comments about each on both cameras. Order is by focal length and lens speed. Being a Photo Mechanic fan (possibly one of the most powerful, fastest image sorting, tagging, captioning apps available), I’ve color classed the images from each lens set so that viewing by color class will put the files from each camera at the same aperture side by side for easier flipping between the two. For those using other viewing apps, you’ll have to figure out something else, like renaming the files, etc.

This comparison is by no means perfect or exhaustive. I’m certain valid criticisms will be found. That said, it gives me the basic information I wanted: whether or not the a7S causes edge smearing with a given lens for near infinity scenes and how bad that smearing is compared to how the lens performs on my reference camera – the Leica M240. It also allowed me to get firsthand information to answer the question many seem to have based on forum discussions stating the a7S performs better with wide angle rangefinder lenses.

I’ll spill the beans here – it doesn’t. At least not in regard to edge smear/loss of sharpness. Where it seems to perform better is with regard to edge color shift. I didn’t see anything of concern. If there is color shift, it’s a less objectionable and noticeable blue/cyan compared to the more typical magenta tinge.. That said, edge color shift can generally be fixed later in post, whereas edge smearing cannot. Therefore, being able to generate the sharpest, best details in-camera is definitely a higher priority for any technical applications.

Many of the poor performers here will likely be much more acceptable in applications that place less demand on edge rendering and sharpness. It is precisely what I found with a few lenses I used on the a7S for day-to-day people photos. For example, the 28 Summicron looks like shooting through a Coke bottle in the test images here, but performs quite well with nearer subject distances and where edge detail/sharpness is not a priority.

Commentary below generally refers to image quality from the a7S unless otherwise stated, in part because most of these lenses performed best on the M240.

Click on the lens name/headline link to access the full-rez files hosted on Google Drive. Images are only available in complete sets including both the a7S and M240 in the form of zipped folders. To download, click on the download arrow at the top middle of the page that appears after clicking on the link (at the time of this writing – Google tends to redesign Drive from time to time, so this might change). It will take you to another page with the warning “Google Drive can’t scan this file for viruses.” Ignore this and click Download anyway (you’ll have to trust me, I guess).

The Lenses:

(image from the a7R vs. M9 review)

 

Voigtlander Ultra Wide-Heliar 12mm f5.6 Aspherical LTM

Fairly strong vignetting typical of this lens but without obvious color shift. Performance is very similar to the M240 in respect to edge sharpness, though the M240 is better wide open. The lens seems to be sharpest at f/8. Coded as the Leica 21/2.8 pre-ASPH for the M240.

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Voigtlander Super Wide-Heliar 15mm f4.5 Aspherical M

This lens was one of the most problematic for vignetting and color shift on the M9 and color shift remains a problem on the M240, too, even if used coded. But no obvious color shift with the a7S (might be slightly blue/cyan). Vignetting is fairly strong, but is typical of this type of lens. Performance is very similar to the M240 in respect to edge sharpness, especially by f/8. Like the 12mm, better than I expected Coded as the Leica 21/2.8 pre-ASPH for the M240.

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Zeiss Distagon T* 18mm f4 ZM

Color shift is not obvious, but might be slightly blue/cyan. Edge sharpness is poor compared to the M240 and might be usable at f/8 and higher, depending on the application. At f/4 the softness creeps fairly far towards the center of the frame. Central sharpness is fine from wide open. There are two sets of M240 images. One is coded as the WATE at 16mm, the other is uncoded because I wasn’t sure if the lens’s owner’s choice of coding was the best. In hindsight, color shift is evident and a different lens code might have worked better. Perhaps the 21/2.8 pre-ASPH? While there is a touch stronger vignetting in the uncoded M240 images, it seems that color shift might be slightly less problematic…

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Leica Summilux-M 21mm f1.4 ASPH.

This one is interesting. My lens might not be properly infinity optimized at the hard stop for the M240. On the a7S, the central area looks good at f/1.4, though the edges definitely smear compared to the M240 and take until at least f/8 to be comparable. As I pointed out in my 21mm lens shootout, the Lux has a mid-zone drop in sharpness apparent with the M9 (also evident with the M240), but interestingly, not so much an issue with the a7 series, which makes a wider central area more usable with this lens. But the tradeoff is the edges, where on Leica digital M cameras, the wavy plane of focus recovers with quite good sharpness already from wide open. Vignetting is quite strong and remains so on both cameras all the way through f/11. There has been discussion about how much the compact hood design affects vignetting, and at least one test I’ve seen indicated that it was a factor on Leica cameras. Having casually tested this, vignetting does seem to decrease if the hood is removed. This lens has very strong CA… a design trade off, but does clean up well in post. It also tends to purple fringe in high contrast transitions areas at wider apertures.

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Zeiss Biogon T* 21mm f2.8 ZM

Some vignetting and color shift doesn’t seem bad, though might be slightly blue/cyan. The problem is more so poor edge sharpness performance that never catches up to how the lens performs on the M240. Might be usable at f/8 and higher and likely is better when there is greater subject/background separation that places no emphasis on edge performance. Coded as the 21/2.8 pre-ASPH for the M240.

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Leica Super-Elmar-M 21mm f3.4 ASPH.

Possibly some slight blue/cyan color shift (difficult to tell from this scene). Edges are disappointing on the a7S, which doesn’t really come close until f/11, and who wants to buy a $3000 lens to shoot at f/11? The potential of this lens is best exploited by the M240 which confirms Leica’s statement that this lens can be shot already from wide open with excellent results. Stopping down only provides increased depth of field, if needed.

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Zeiss Biogon T* 25mm f2.8 ZM

Second time I’ve used this lens. Some mild vignetting and possibly also slight blue/cyan color shift on the a7S. On the M240, from f/4, it’s blazing sharp across the frame. Wow! Unfortunately, it’s the usual story on the Sony… poor edge sharpness that never matches the M9 through the tested aperture range, though from f/8 and higher, it’s probably acceptable, depending on the application. Coded as the Leica 24/2.8 ASPH for the M9.

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Leica Summicron-M 28mm f2 ASPH.

Vignetting is evident on the a7S, but this lens is known for fairly strong vignetting. Color shift, like many of the earlier lenses, seems to be slightly blue/cyan. Continuing with the theme, edge performance is poor on the a7S but might be acceptable at f/8 and smaller. In this respect, it never catches up to the M240… where it needs until about f/4 for quite good edge performance. While this lens looks bad on the a7S at infinity, I got some quite nice people photos with it at much nearer distances in the 2-4m range. But, unlike on the M240 where the lens is a great all-rounder, it won’t be a satisfactory landscape/infinity scene lens on the Sony.

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Voigtlander Nokton 35mm f1.2 Aspherical VM II

Vignetting is pretty strong until around f/2 and never really improves much beyond, but isn’t so bad. Doesn’t seem to be a noticeable color shift problem, though might be slightly blue/cyan. It’s the first lens in this comparison that appears to work equally well on both cameras, with the a7S showing slightly better edge performance from f/2.8 and beyond.

The lens is surprisingly decent wide open at this subject distance. Central sharpness is certainly usable wide open and stopping down slightly to f/1.4 does show some improvement in contrast. Even greater improvement is achieved at f/2.

Coded as the 35 Lux ASPH pre-FLE for the M240.

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Canon 35mm f2.0 LTM

A lens from Canon’s rangefinder era, vintage is probably early 60s. Vignetting improves after f/2.8 and I can’t really see any obvious color shift. Performance is very, very similar on both cameras. Compared to modern glass, this lens has a smaller central sweet spot wide open and is lower in contrast with more veiling flare at wider apertures, but stopped down around f/5.6 and it’s quite good across the frame. It just needs some contrast and saturation boost in post. With specular light sources just outside the frame, it can exhibit some interesting/funky flare shapes. Coded for the M240 as one of the 35 Cron pre-ASPH flavors.

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Zeiss Biogon T* 35mm f2 ZM

This one was shot uncoded on the M240, which reveals similar vignetting characteristics between the two camera. Color shift doesn’t appear to be obvious but may be slightly blue/cyan.

Slightly glowy/hazy wide open, this clears by f/2.8 where the central area jumps in contrast and sharpness, expanding outwards as the lens is stopped down. On the M240 most of the frame is great by f/4. On the a7S the edges lag until around f/8, and even then never seem to quite match the Leica, though this will depend on each person’s expectations.

A great landscape consideration on a Leica M camera, but for the a7R, the Voigtlander above seems to be the better across-frame performer at wider apertures.

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Zeiss C Biogon T* 35mm f2.8 ZM

A decent, compact 35mm lens on the M240. Edges suffer on the a7S and never quite catch up to the Leica, though could be usable by f/8 depending on individual expectations. Coded as the 35 Summarit for the M240.

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Voigtlander Nokton classic 40mm f1.4

Vignetting is comparable on both cameras and quite strong wide open, as this copy was uncoded for the M240 and I didn’t set a correction for it manually (there isn’t a 40mm option anyway).

A quirky lens not really intended for this kind of scene, but I thought I’d include it anyway. First of all, it has very strong field curvature. Secondly, it has considerable focus shift, which required live view re-focus at maximum magnification on both cameras.

At wider apertures, the central area is very much the sweet spot, with considerable improvement already at f/2. The mid-zone and edges looking terrible until well stopped down, at least on the M240, due to the massive field curvature. Surprisingly, the lens performs much more ‘normally’ on the a7S with good across-frame performance at f/4 and very good by f/5.6.

I like this lens a lot for people photos in part due to it’s somewhat softer rendering (though background bokeh can be harsh), and this kind of field curvature tends to better blur background details the image periphery.

The results on the a7S are very, very surprising!!

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Leica Summilux-M 50mm f1.4 ASPH.

A lens many want to love on the a7 series… It’s probably fine for nearer distance work where the subject is separated from the background and peripheral details don’t require perfect focus.

For this kind of landscape application, unfortunately it falls flat on the a7S compared to what it can deliver on the M240. The problem is the edges, again. While not as bad as the wider lenses, distinct detail smearing detracts from the lens’s rendering, as correctly seen in the M240 files.

I’ve read and been told numerous times that one shouldn’t expect to shoot landscapes at f/1.4 and get sharp results across the frame… yet the 50 Lux ASPH does just that… on a digital Leica. Yes, it benefits from stopping down, but is already surprisingly great wide open. But, as indicated by the lens’s MTF values, it suffers from a mid-zone drop in sharpness through the wider aperture range. Whereas with the M240 this mid-zone drop just looks softer than other areas, the a7S’s images look softer and more nervous (what I also saw with the a7R). Vertical lines have a distracting, jittery, double image effect.

What makes this lens appeal to me is its versatility on a digital Leica M. I use it for everything, including landscapes and distant subjects if I keep in mind the mid-zone dip limitation. But even at such distances, it’s still very usable wide open, if needed. At nearer distances it has a fairly unique, smooth rendering that many other 50s can’t match, yet is still very sharp with excellent contrast and color. f/1.4 also adds to the versatility, being fast enough without making the lens too large. Maybe the closest competitors are the new Zeiss Otus 55/1.4 (B&H) and the Sony-Zeiss 55/1.8?

If shooting a lot of landscape type images with the a7 series where across-frame consistency and sharpness is important to you, then consider other options. This lens likely will be a reasonable paring on the a7 series for nearer distance, three dimensional work where there is subject to background separation without the need for edge detail sharpness. But even here, it’s closely matched or beaten by the new 55/1.8 at 1/4 the price…

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Canon 50mm f1.4 LTM

A lens from the same era as the Canon 35/2 above, it shares many characteristics with it, including a lot of softness/glow/veiling flare wide open and improves as it is stopped down. In fact, at f/2 it sharpens up quite well centrally. At wider apertures the a7S seems a bit more glowy towards the edges, but otherwise, the lens is very comparable on both cameras.

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Voigtlander Nokton Aspherical 50mm f1.5 LTM

This is the LTM version of the M mount lens currently available from Voigtlander. Unfortunately Cosina, the manufacturer of the Voigtlander line, is very stingy with product information and therefore it’s difficult to pin down definitive information about the optical differences, if any, between the two models. From what I have read from various sources, the optical formula is supposed to be the same, but changes/improvements were made to the coatings that result in somewhat higher contrast and color saturation, particularly with backlighting.

Apparently it’s designed to mimic the 50 Lux pre-ASPH. Unfortunately I have very limited experience with that lens and can’t offer a subjective comparison.

Performance on both cameras seems pretty much in lockstep, with the M240 slightly edging out the a7S through around f/2.8-4. The lens has a central sweet spot and needs stopping down to around f/5.6 for good across-frame performance.

Uncoded on the M240.

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Zeiss C Sonnar T* 50mm f1.5 ZM

A ‘character’ lens that really is more at home with people/portrait situations. Like the Voigtlander 40, it has field curvature and focus shift, which necessitated refocusing for each aperture value. While the lens eventually cleans up on the M240, it takes until around f/8-11 for good across-frame performance. The a7S, in contrast, looks quite smeary at every equivalent aperture, especially at the wider open values. But, it’s probably quite nice for portraits on the Sony, as pretty much any Sonnar will be… Uncoded on the M240.

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Zeiss Planar T* 50mm f2 ZM

Results from both cameras are very similar. Central detail/sharpness very much the same. At the edges the M240 seems to be slightly better until around f/4. This lens has always been a solid performer on digital Ms and appears to be a good option for the a7S too… Coded as the latest 50 Cron pre-AA for the M240.

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Voigtlander Heliar classic 75mm f1.8

A lens I don’t use much, especially for infinity scenes, but threw into the mix anyway. The ‘classic’ designation should serve as a warning that this lens is not intended to be a resolution monster. It has a rather gentle, moderate contrast rendering and is never blazingly sharp. Also has focus shift, necessitating refocus for each aperture value. Very similar performance on both cameras. Uncoded on the M240.

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Leica APO-Summicron-M 90mm f2 ASPH.

Very similar results on both cameras, thought the a7S looks slightly softer at the edges wide open.

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Leica Summarit-M 90mm f2.5

Very similar results on both cameras.

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Cameras:

Leica M Typ 240 silver or black at B&H
Leica M-E at B&H (the M9’s ‘replament’)
Sony a7S at B&H
Sony a7R at B&H
Sony a7 II at B&H

Conclusions:

Thanks to Sony Canada for lending me an a7S to test. The results, frankly, are not a surprise to me. Most rangefinder wide angle lenses do not perform well on the a7S, precisely as is also the case with the a7 and a7R. And with the a7 II coming soon, there will likely once again be some hope for a compatible non-Leica digital camera to take full advantage of what these lenses have to offer… But for now, if you have a collection of prized wide angle rangefinder lenses and want to extract their full potential, the best digital solution remains a Leica digital M body.

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