cz-variosonnar-24-70mm-f28za

Introduction

With the acquisition of Minolta's camera business, Sony faced a major problem of tilting the user base away from the incumbent players like Canon and Nikon. After all, Minolta's of the DSLR percentage market share has been steadily declining from in 1990s, dwindling to low single digits. Besides introducing a wide range of aggressively priced, well marketed and more importantly competitively featured cameras, Sony also pursued an aggressive strategy of expanding the lens lineup for its fledgling alpha lineup. The company struck a number of partnerships to rebadge several lenses from Tamron in addition to rebadging the most popular Minolta lenses, and in late 2006 announced a partnership with Carl Zeiss to manufacture lenses designed by this venerable optics manufacturer. This certainly caught attention of many users and Sony managed to outpace all of its competitors, rapidly expanding and capturing ~13% of the total DSLR market share by 2010. The roll-out of Carl Zeiss lenses was rumored to be pretty aggressive, with 1 to 2 new lenses planned to be released every year.

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Vario-Sonnar 24-70/2.8 is a full frame lens, but can be used on any alpha mount camera, full frame or APS-C. It can also be used on NEX cameras with a special electronic adapter (manufactured by Sony), which allows retaining all electronic functions of the lens, including proper EXIF transmission and aperture control. On 1.5x crop APS-C/NEX cameras, the lens will have EFOV of 36-105mm.

 

Summary

Lens Composition 17 elements in 13 groups
Angular Field 84-34 degrees
Minimum Focus 34cm/12.7in
Focusing Action AF/MF
f-stop Scale f/2.8-f/22, electronic
Filter Size 77mm
Lens Hood Metal (included)
Weight 985g/34.74oz
Dimensions 80x111mm/3.25x4.4"
Lens Case Soft lens pouch (included)
Retail Price $1,799 (2012), $1,799 (2009)
Depreciation -$500 (2012)

 

Handling

The so called 'universal' zoom lenses have always been fairly popular among users who want to have a one lens combo for example for travel. Lens makes understand that quite well and have answered demand with a reasonable selection. However, for whatever reason, the 24-70mm zoom range has always been considered to be premium - if you look at the lens lineup from Canon or Nikon in this range, you would only see the so called 'professional' grade lenses. It is as if only 'professionals' want a 24-70/25-105 zoom and everybody else will settle for a super zoom, i.e. something like 18-200mm. Market segmentation at work... But when Sony entered the SLR market, it had to offer something respectable (read 'professional' grade) in order to be able to compete with the likes of Nikon 24-70/2.8G and Canon 24-70/2.8L. Carl Zeiss to the rescue! Who else but Zeiss can instill the image of professionalism?

To the best of my knowledge, the Vario-Sonnar 24-70/2.8 is a new design - never in its history Zeiss has had a 24-70 zoom. The closest predecessor from the past seems to be the 35-70/3.5 Vario-Sonnar. I never owned that lens myself, but from various online reviews, it seems like a fairly solid performer. But a new design does not surprise me - it has always been rumored that Sony struck some kind of an exclusivity clause in its licensign deal with Zeiss. And so we may never see 24-70/2.8 outside of the Alpha mount. It's a pity... Carl Zeiss so far has introduced only manual focus lenses in all other SLR mounts - I am not complaining as the lineup has been quite strong so far, but I will squeal like a little girl when the company decides to bring back the venerable Apo-Teletessar N 400/4 with fully electronic focusing in Canon or Nikon mount! Ok, I will squeal even if Zeiss decides to license it to Sony. But I am digressing...

The Vario-Sonnar 24-70 is a fairly bulky and heavy lens, slightly heavier than its direct competitors in Canon and Nikon mounts. When mounted on a larger a850, the combo becomes heavy enough to warrant using both hands for stabilization when shooting. The center of the weight is shifted slightly towards the tip of the lens, particularly with the inner lens tube extended when zoomed at 70mm. The lens does not have a lens collar, so when mounting on a tripod, use a quality ball-head to prevent the camea/lens combo from drifting downwards. But, with the bulk and weight also comes ruggedness - the build of the lens is quite solid. I lugged this lens across Japan and China with all the usual bumps, dings and occasional drops along the way and it withstood all of this abuse without any problems. While in Kyoto, I took a trip to Fushimi Inari Shrine one of the days, but when I got out of the JR train station, it started to rain. Not willing a light drizzle stop me, I hiked to the entrance, but by that time the drizzle turned into a pretty heavy rain. I still decided to hike through the area since I had a waterproof jacket - well my a850 and Vario-Sonnar did not and got completely drenched in water. Still, pictures came out just fine and after wiping the moisture off the camera and lens they were ready for the next adventure. My only wish here is that the lens had inner focusing and zoom so that the barrel length remained constant at all positions instead of extending towards longer end of the zoom range. But at least the tube is made of hardened plastic (or metal, I can't really tell), so it seems to be able to withstand some amount of abuse..

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The lens sports all the usual features of an Alpha mount lens - you will find an AF/MF switch on the side of the barrel along with the focus lock button. The distance scale window is also present with markings in meters and feet (and unlike with the NEX lenses, where the lack of the distance scale is an endless cause of my frustrations during testing). The Vario-Sonnar supports manual focusing as well as manual focus overdrive - basically after the lens auto-focuses on something, you can nudge the focusing ring to adjust the focus position without refocusing the lens anew. But the manual focusing is kind of an afterthought on this lens (like pretty much on all modern AF lenses these days) - the focusing ring travels ~90 degreed from the MFD to infinity and thus does not leave enough precision on the longer end of the zoom range. But the AF is quite good - it's pretty fast and reasonably accurate. It does tend to hunt quite extensively at the MFD and longer end of the zoom as well as in dim or low contrast environments, but this is not unique to Sony lenses. Both focusing and zoom rings are nicely damped and have tight tolerances. The focusing ring is decoupled and does not rotate during AF operation. The lens does not have a zoom lock but there is no creep even when the lens is pointed down.

One area where Sony holds a dubious lead over its main competitors is in nickeling and diming poor users who need to replace lens accessories. For example, if you lost or broke your petal shaped lens hood, it's gonna cost you a whopping $130 to buy a new one. Canon's costs $70, while Nikon's costs $41. Yea... that's for the piece of plastic that costs 10c to manufacture (fine, Sony's aluminium hood costs 20c to manufacture).

 


 Resolution

Most wide-to-normal(ish) zooms like Vario-Sonnar 24-70/2.8 ZA are fairly good performers. Canon's 24-105/4L is one of my favorite lenses when I travel light and choose to drag along a Canon body. Vario-Sonnar fills in a similar role for situations when I use Sony camera. But the word 'good' is obviously relative here - good compared to what? My reference here is other zoom lenses in similar focal range, but not fixed focals. Because of much more complex optical designs that manufacturers have to employ in zooms, comparing say Vario-Sonnar to Distagon 24/2 is not gonna be very fair. Take a look for example at the Imatest MTF plot below. If we try to make our decision about resolving capabilities of this lens solely based on this test chart, we might conclude that the lens is not particularly good. and if we compare the said lens at 24mm to the Distagon 24/2, we would simply render a verdict that this lens sucks plain and simple (at least @ 24mm). The Imatest chart claims that the lens performs quite well in the center across all focal ranges, but under-performs around borders. 24mm is particularly challenging where resolution seems to be the lowest and does not seem to improve much with stopped down apertures. 35mm to 70mm results are better, but still exibit lower relative resolution compared to the center. Stopping down to f/4 starts to produce good results everywhere except @ 24mm borders, which require another stop-down to get to more or less decent, per Imatest, results. But Imatest's numbers describe only one dimension - how well (or poorly in this case) the image performs with a slanted edge discrete MTF algorithm and completely ignores any visual aspects.

 

24mm (Sony a850)

a850-mtf-24mm-cz-variosonnar-24-70mm-f28za

35mm (Sony a850)

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50mm (Sony a850)

a850-mtf-50mm-cz-variosonnar-24-70mm-f28za

70mm (Sony a850)

a850-mtf-70mm-cz-variosonnar-24-70mm-f28za

The crops of the imaging target below compare image quality around corners at f/2.8 and f/8. The shots here were taken at the focusing distance of 3m for 24-35mm and 6m for 50-70mm. This is what was fed into Imatest - note that as Imatest claims, f/2.8 corners are indeed softer pretty much across the zoom range. But visually, 35mm, 50mm and 70mm borders at f/2.8 are not too bad, even if you compare them side by side with f/8. It's the 24mm borders that are quite noticeably worse off. Ok, so what does this mean for a user?

24mm (Sony a850)

cares-a850-24mm-cz-24-70mm-f28za

35mm (Sony a850)

cares-a850-35mm-cz-24-70mm-f28za

50mm (Sony a850)

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70mm (Sony a850)

cares-a850-70mm-cz-24-70mm-f28za

 

Well, the image quality of Vario-Sonnar 25-70/2.8 ZA in real life applications is quite good actually. Throughout the years of using this lens, I have yet to discard an image from Vario-Sonnar 24-70/2.8 because of its quality, specifically sharpness. Yes, borders are softer - we a;ready determined that, particularly at wider apertures, where distortion claims its toll (you can observe that in the crops below, even without peeking at the images at high magnification). But guess what  - image quality, most notably at 24mm, is somewhat better when the lens is shot at longer focusing ranges (infinity in the examples below), than what we're led to believe by Imatest. Also, remember that I mentioned that comparison should be made in the appropriate scope, that is we should be comparing Vario-Sonnar to other 24-70mm lenses? Well, I own Nikon's 24-70/2.8G and used Canon's 24-70/2.8L in the past, and while comparing these three lenses is not strictly speaking possible because of the variance in cameras, processors, sensors etc., subjectively speaking, Vario-Sonnar does not produce results that are much off compared to the above mentioned competition. Nikon seems to have better resolution at 24mm, but that gets lost when you use these lenses at long focusing distances.The biggest issue with Vario-Sonnar's 24mm is the somewhat higher distortion and field curvature, which wreck chaos at close focusing distances. This is where Distagon 24/2 clearly bests Vario-Sonnar 24-70/2.8 - it's sharper, has less distortion and less field curvature, but again, that's not a fair comparison. And that's is - if we were to focus only on the Imatest's results, we would not have managed to piece together a complete picture (pardon the pun) - Vario-Sonnar's Achilles heel, the 24mm at wide apertures, is mitigated to some degree at longer focusing distances, and Imatest misses that completely.

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24mm (Sony a850)

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35mm (Sony a850)

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a850-res-ll-35mm-cz-vson-24-70mm-f28za
a850-res-ur-35mm-cz-vson-24-70mm-f28za

50mm (Sony a850)

a850-res-center-50mm-cz-vson-24-70mm-f28za
a850-res-ll-50mm-cz-vson-24-70mm-f28za
a850-res-ur-50mm-cz-vson-24-70mm-f28za

70mm (Sony a850)

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a850-res-ll-70mm-cz-vson-24-70mm-f28za
a850-res-ur-70mm-cz-vson-24-70mm-f28za

 

On the final note, take a look at the graphs below, which acerage MTF results for various focusing distances and aperture settings. Note that the 24-35mm were tested only in 1m to 5m focusing distances, while 50 -70mm ranges were tested in 1m to 8m distances.

 

a850-res-dist-cz-variosonnar-24-70mm-f28za 

Color & Rendering

Overall, color reproduction of the Vario-Sonnar 24-70/2.8 is pretty good. The color gamut is shifted slightly towards reds, highlighting warmer tones better - this is a third Sony mount Carl Zeiss lens I have tested and all three had somewhat higher emphasis on warmer colors - Planar 85/1.4 ZA was the warmest and Sonnar 135/1.8 ZA and Vario-Sonnar 24-70/2.8 have more or less similar characteristics. I don't really understand why that is the case, considering that all carry the T* coating designation (arguably all same) and considering that most original Zeiss primes emphasize blues over reds, which in turn gives images a cooler feel to them. Just o be clear, Vario-Sonnar 24-70/2.8 does not have Canon's 'over the board reds', but it is also not as neutral as Nikon.

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The lens  underexpose images at wider apertures quite consistently, mostly because of the pretty heavy vignetting at wider apertures. If you're like me, and have a habitual preference to underexpose images slightly, to capture more tonality in shadows and mid-tones, than you should be fine, otherwise you'd probably need to try fiddling with the exposure compensation a bit, setting it to +0.5/+1. Just don't forget to reset it when shooting in the 50-70mm range, where the underexposure is not that pronounces.

Tonality reproduction with the lens is quite good overall, but does vary slightly across the zoom range. 24-35mm range produces slightly higher contrast and does compress shadows more than the longer end of the zoom. 50mm is well balanced, while 70mm has longer mid-tone tail, at some expense of highlights and shadows. Global contrast is also lower at 70mm, particularly at close focusing distance, but not completely trashed - those of you who like contrastier images would find it easy to add a little bit of contrast to your images, without flattaning shadows too much.

Chromatic aberration is reasonably well controlled in this lens. While Imatest clocks ~1.1px of lateral CA at f/2.8 and 24mm, and much lower at longer focal ranges, in real life I have yet to see a picture taken with the Vario-Sonnar where CA is easily noticeable under normal shooting conditions. If you eyeball pictures hard enough at 100% magnification, you will probably notice some fringing around borders, but it is doubtful that CA would have any major impact on overall image feel. Longitudinal CA is also well controlled - there are minor traces that I have seen once in a while at 24mm and wider apertures, but disappear at longer end of the zoom.

CA Borders Sony a850 (24Mp)

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DOF & Bokeh

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DOF and bokeh testing on zoom lenses is a brutal exercise. Not only beccause the number of possible test combinations proliferates very quickly, but mostly because the rendering characteristics  change often quite drastically across different zoom levels. The wide to medium zooms like Vario-Sonnar 24-70/2.8 ZA are the biggest troublemakers - at wide angles DOF is not particularly shallow and in many cases bokeh rendering is rather harsh, while longer end of the zoom range behaves much better and opens up a world of creative possibilities. Having owned this lens for ~2 years now, I do find muself gravitating away from 24mm whenever I am trying to create a clear isolation between the subject and the background - there is simply too much DOF at 24mm. 35mm is slightly better, but 70mm is what I use most often, even if it means stepping away from a subject a little bit in order to fit it into the frame.

Let me be clear here - I don't see anything wrong in the bokeh at 24mm (or as a matter of fact at any of the other focal ranges). There are no easily observable artifacts, and rendering of out of focus backgrounds is fairly neutral as there are not signs of spherical aberration throughout the zoom range. It's just shorter focal lengths leave too much definition even with wide open apertures. Examples of that are below - as is customary in the reviews these days, here are series of shots iterating over different zoom and aperture levels. All shots were made at close to MFD (~50cm). The distance to the farthest building in the background is over 50m. 

DOF @ 24mm

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DOF @ 35mm

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DOF @ 50mm

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DOF @ 70mm

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 As one would expect, at equal focusing distances, the bokeh feels much smoother at longer zoom ranges, giving us nice fade-in/fade-out transitions from foregrounds into backgrounds. At close focusing distances the lens produces slightly lower contrast, characteristic to most lenses, not just this particular one. Combined with muted backgrounds this gives a very nice feel  to images. Background highlights are rendered in neutral way, even at 24mm, although as mentioned above, the bokeh feels cluttered because of the longer DOF and higher definition it brings to backgrounds.

 

35mm

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50mm

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70mm

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Flare

This lens flares, but than again, every lens flares. There is no hiding from it in this lens - you get flare at all apertures and all focal ranges if you're not careful enough. Samples below show what you would get with the sun positioned right near the corner of the frame - probably the worst possible option for any lens, not just Carl Zariss Vario-Sonnar 24-70/2.8. In these situations you would get ghosting, low contrast, blown out highlights, color shifts, basically you name the artifact and it will be there. Hood helps a bit, but does not block all stray light in the worst possible case and you still end up with flare. Just don't point the lens directly into the sun and you should be fine. 

 

24mm

thumb-flare1-cz-vs-24-70mm-f28za-iso100-s1250-f28-24mm thumb-flare2-cz-variosonnar-24-70mm-f28za-iso100-s160-f8-24mm

70mm

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Vignetting

Carl Zeiss Vario-Sonnar 24-70mm f/2.8 ZA shows variable levels of light falloff across the zoom range. As one would expect, vignetting is higher at wider apertures and is worst at 24mm, where it reached ~2.3EV at f/2.8. At ~1.6EV, vignetting is still fairly high even when you stop down the aperture to f/4. Beyond that vignetting gets more or less manageable. 35mm is a bit of transitional point with Imatest registering ~1.3EV of light falloff at f/2.8 and ~1EV at f/4. Longer focal ranges also show vignetting at wide apertures, but not as pronounced.

Sony a850 (24Mp)

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From practitioners' perspective, vignetting would actually be quite visible at 24mm, which can reduce overall quality of image (in the periphery) if not taken care of either within the camera or during post-processing. If you're using Adobe Photoshop, try setting Vignetting correction to +20/+25 for 24mm/f.28 and +15/+18 for 24mm/f/4. 35mm is a bit better, but you might still want to get rid of vignetting here as well - try +10/+12 for 24mm/f.28 and +5/+8 for 35mm/f4. 50mm-70mm should not be a problem for you and should not require meddling with vignetting

 

Vignetting @ 24mm

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Vignetting @ 35mm

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Vignetting @ 50mm

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Vignetting @ 70mm

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Distortion

As hinted on earlier, distortion is the major Achilles heel of Carl Zeiss Vario Sonnar T* 24-70mm f/2.8 ZA lens. Most notably at 24mm, where barrel distortion reaches ~2.8%, which would be noticeably in real life. While it is possible to correct distortion during post-processing, the image does not recover quite completely and the residual artifacts of the correction would still persist. Post 35mm, distortion is much more manageable, even mild I'd say - at 35mm we still see barrel distortion of ~1.1%, at 50mm barrel distortion almost disappears, clocking a mere ~0.5% and at 70mm barrel distortion turns into slight pincushion distortion of ~0.4%.

24mm

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35mm

dist-a850-35mm--12

50mm

dist-a850-50mm--06

70mm

dist-a850-70mm-+05

 


Macro Performance

Considering that the Vario-Sonnar 24-70/2.8 ZA is not really a dedicated macro lens, my expectations of its macro capabilities were muted from day one. At the MFD of  34cm, the lens offers max magnification of 0.25x. You can probably try shooting still life in a studio or outisde, but the lens is not suitable for true macro photography, particularly for anything that does not stay still, i.e. insects - getting that close to them is basically out of question. Still, for a zoom lens with a moderately fast aperture, the lens performed quite well and kept a reasonably high resolution in the center throughout the zoom range. You will find 100% center image crops below - all taken at 34cm distance and wide open aperture.

24mm (Sony a850)

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35mm (Sony a850)

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50mm (Sony a850)

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70mm (Sony a850)

a850-macro-70mm-cz-variosonnar-24-70mm-f28za

 

Coma

Coma in the Vario-Sonnar is controlled fairly well. Extreme border crops of a pin-light, that you can see below were taken at the focusing of 3m and 1sec exposure. If you zoom in on these crops at 200%, you will see very minor purple fringing around the highlights, but for the vast majority of users of this lens, coma is not going to be a problem.

 

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Coma @ f/2.8 - 24mm vs 70mm (Sony a850)


 

Alternatives

Almost a decate after the initial launch of Sony Alpha system, there are still not that many lens options available for us. In the 24-70mm zoom range, Sony's own 28-75/2.8 comes to mind as a first alternative. Technically speaking, this is a rebadged Tamron 28-75/2.8, so you can choose either of those, as well as Minolta's old 28-75/2.8 and expect similar performance. Sigma makes 24-70/2.8 DG IF HSM, which is available in Sony mount, and that's pretty much it. If you're using APS-C type camera, you're slightly better off as there are a couple of additional choices available to you from both Sony as well as Tamron and Sigma, but all those lenses are a bit more 'consumerish', with variable max apertures and cheaper build quality. That's pretty much it - kind of paltry choice. Finally, Tokina recently (early 2012) announced a new, optically stabilized 24-70mm lens for full frame cameras, which certainly looks quite promising if you can wait for its release.

 

Recommendation

Sony Vario-Sonnar 24-70 f/2.8 ZA is a solid choice for anyone looking for a zoom lens in this focal range. But, the lens is pretty darn expensive, which has been a major head-scratcher for me personally, when I was considering to buy this lens. I ended up buying it used and don't regret it - I would recommend you buying it used as well to save ~$500 off the sticker retail prices. Depreciation on this lens has been quite steady over the years and I do not expect it to fall beyond this point any time soon. One major issue that you need to consider is the distortion and field curvature that this lens produces at wide apertures. If you're a purist and intend to use this lens for landscape mostly in the 24-35mm range and just occasionally switch to longer focal ranges, than you might be disappointed. Other artifacts like vignetting and CA can be easily corrected in post-processing and so do not count as major roadblocks in my books. 

 

Sample Images

 


 

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