Sony 135mm f/1.8 Carl Zeiss Sonnar T* SAL-135F18Z

Name: Sony 135mm f/1.8 Carl Zeiss Sonnar T* SAL-135F18Z
Brand: Sony
Rating: 9.8 (9 reviews)

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Lens Review
Specifications
Description

135mm	$1,798 average price

Blur
Chromatic Aberration
Vignetting
Geometric Distortion

Blur
Chromatic Aberration
Vignetting
Geometric Distortion

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Buy the Sony 135mm f/1.8 Carl Zeiss Sonnar T* SAL-135F18Z

SLRgear Review
February 23, 2009
by Andrew Alexander

The Sony 135mm ƒ/1.8 ZA lens was introduced in October 2006, shortly after the debut of the Sony alpha system earlier that year. The lens was designed by Carl Zeiss, and is the fastest 135mm lens currently available, but only by a hair (Canon and Nikon come in with close second places, both offering a 135mm ƒ/2 lens).

The lens was an early indicator that Sony was contemplating a full-frame camera in its future, as it is designed to fill the 35mm film frame. Given the relatively quick release after Sony's adoption of Konica-Minolta's camera division, it's reasonable to assume the lens was in development by KM for some time. On a Sony reduced-frame (APS-C) digital SLR camera, the lens has an effective field of view of 203mm.

The lens takes 77mm filters, and ships with a large cylindrical-styled metal lens hood. The lens is currently available for approximately $1,400.

Sharpness
Let's start with the best part - this is one sharp lens, even wide open ƒ/1.8. It's also worth mentioning that the depth of field with this lens, used at the wider apertures is incredibly thin. On the A900, at a regular portrait distances for this lens (about 8 feet) you have only 1.3 inches of your subject in focus. Of course, that's one of the attractions of this lens. You can isolate very specific parts of your subject, and throw the rest out of focus.

Given the thin depth of field possible with this lens, it's all the more impressive that even with the aperture set wide open to ƒ/1.8, images are very sharp. On the sub-frame A700, we see on average 1.5 blur units. Performance improves as the aperture is stopped down; marginally at ƒ/2, to just over 1 blur unit at ƒ/2.8, and by ƒ/4 the image is tack-sharp across the frame. This sharpness is evident through to ƒ/8; by ƒ/11 diffraction limiting sets in, but even at ƒ/16, the lens is just shy of 2 blur units. Fully stopped-down performance is still very good at ƒ/22, with 2.5 blur units.

On the full-frame A900, the 24-megapixel taxes the resolution of the lens to the limit. Even so, at ƒ/1.8, the lens holds its own and provides excellent results - still sharp in the center, at 1.5 blur units, but now showing some very slight corner softness, at just over 2 blur units. Stopping down to even ƒ/2 solves any corner softness issues, with overall sharpness improving as the lens is stopped down to ƒ/4, but it isn't until ƒ/5.6 that we see the same tack-sharp quality across the frame. (If you're a statistical stickler there are tiny pockets of corner softness at ƒ/5.6, so according to the numbers you'd have to stop down to ƒ/8 for absolute sharpness, but I defy you to see the difference in real life.) Performance is still good at ƒ/11, and diffraction limiting affects sharpness at ƒ/16. Image sharpness is excellent at ƒ/22, at 2 blur units across the frame.

In summary, the 135mm ƒ/1.8 ZA produces excellent results for sharpness even wide open on Sony's subframe (APS-C) cameras, and quality is only marginally affected even with the mammoth 24-megapixel sensor of the A900.

Chromatic Aberration
Chromatic aberration is very well-controlled by the Sony 135mm ƒ/1.8 on both the A700 and A900 cameras. In either case, the maximum CA evident doesn't exceed 3/100ths of a percent of frame height, which we regard as excellent performance. The lens is optimized towards the wider end of the aperture spectrum, which isn't surprising: you buy this lens to shoot it wide open.

Shading (''Vignetting'')
On the sub-frame A700, corner shading only manifests with the lens used wide open at ƒ/1.8. Even then, in this case (or at ƒ/2), the corners are only 1/3 EV darker than the center.

On the full-frame A900, light falloff is a bit more of an issue. When used at ƒ/1.8 or ƒ/2, the corners are 2/3 EV darker than the center; this falloff reduces as the aperture is stopped down, with only a 1/3 EV loss at ƒ/2.8, and at smaller apertures corner shading isn't an issue.

Distortion
The 135mm ƒ/1.8 ZA produces effectively zero distortion when used on a subframe digital SLR camera; on the full-frame A900, there is statistically a small trace of pincushion distortion in the corners (just under -0.1%) but it's so small as to be unnoticeable.

Autofocus Operation
The Sony 135mm ƒ/1.8 ZA uses an older focusing system, employing a body-based mechanism to focus the lens. Consequently the lens produces a slight whirring noise while focusing. Even with the screw design the lens focuses very quickly, at under one second for a full focus cycle. During autofocus operations the focus ring doesn't move, and neither does the front element.

Macro
The lens isn't rated as a macro lens, but considering the focal length, its magnification rating of 0.25x (1:4 reproduction size) isn't too bad. The minimum close-focusing distance is just over 60 cm (24 inches, or just over two feet). The specifications for this lens suggest the minimum focus distance is 2.4 feet - 28 inches - but we found we could focus slightly closer.

Build Quality and Handling
The 135mm ƒ/1.8 ZA is a solidly built lens. For a prime lens, it is very large - and heavy. Considering the maximum aperture of which the lens is capable, it's no surprise that the majority of the weight of the lens rests towards the front. However, with the larger size and heft of the A900, the camera/body combination is fairly well-balanced. On the A700 it's still a bit front-heavy.

The lens constructed with both plastic and metal, with a black smooth finish. The focus ring is mounted near the front of the lens, composed of a hard plastic focus ring with a thin ridged pattern that is easy to grip. The lens mount is metal and the filter ring is plastic.

A distance scale is provided, recessed and windowed, marked in feet and meters. A depth-of-field marking is provided, but set for ƒ/22 only. There is no infrared index marker. The only other ornamentation is the focus hold button, which overrides autofocus commands from the camera when it is pressed, and effectively locks the focus to the current setting. The button can also be programed by the camera to activate depth-of-field preview.

The focus ring is a generous 1 3/8 inches in width, composed of a hard plastic with thin ribs to provide excellent traction for manual focusing. The camera body must be set to focus manually, which then activates the focusing ring. The ring turns about 120 degrees to pull focus through its entire range, and focuses very slightly past infinity. The lens uses hard stops to signal you're at the end of the focus limits.

The lens ships with the SH0003 lens hood, which when attached to the lens adds 2 5/8 inches to the overall length. It attaches via a bayonet mount and reverses for storage on the lens. The interior is nicely fitted with a flocked black finish to cut down any stray light that may enter the lens. The hood is made of aluminium, though as our technician Rob commented, "with a replacement cost of $149, it should be made of platinum."

Alternatives

The 135mm ƒ/1.8 ZA is very much a niche lens, so there really aren't many direct alternatives. If you can live with a slightly smaller maximum aperture size, you have some options.

Sony 135mm ƒ/2.8 (T4.5) STF SAL-135F28 ~$1,200
The Sony 135mm ƒ/2.8 STF has a long history as a near-legendary Minolta lens. The STF (Smooth Transition Focus) system allows the photographer absolute control over the bokeh (out-of-focus) elements in the photograph. We'll look forward to testing this lens.

Sigma 105mm ƒ/2.8 EX DG Macro ~$375
It's not the same focal length and doesn't sport the same maximum aperture setting - but it's a fairly capable portrait lens in its own right with the bonus of a macro functionality (full 1:1 reproduction, no less). The Sony lens is handily sharper, but both lenses offer good resistance to CA, corner shading and offer virtually no distortion.

Sony 85mm ƒ/1.4 Carl Zeiss Planar T* SAL-85F14Z ~$1,300
If 135mm is too long a focal length, you could always opt for the 135mm ƒ/1.8's cousin, the 85mm ƒ/1.4. It's also a Zeiss lens with very large maximum aperture. We haven't yet tested it, and you won't save much money buying it instead of the 135mm, so it really comes down to which focal length you're more comfortable with.

Sony 100mm ƒ/2.8 Macro SAL-100M28 ~$640
The Sony 100mm ƒ/2.8 macro isn't exactly a portrait lens, but with its respectably-wide maximum aperture of ƒ/2.8 it could serve the purpose. It isn't as sharp as the 135mm ƒ/1.8 - and the A900 punishes it a bit more - but it does well on the A700. On either camera CA, distortion and corner shading are handled well.

Conclusion
As is the case for most special-application lenses, it comes down to whether or not you know you need it. Optically, we're impressed - it's pretty much as sharp as you can get, even wide open, and steps up to the demanding power of the 24-megapixel A900. Other aspects are equally impressive - low CA, light falloff and no distortion. However, there isn't much else in the way of options in this category. If you're a Sony shooter, have the space in your budget and portraits are your thing, you'll be well-served by this lens.

Sample Photos

The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.

Still Life shot

VFA target

As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.