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This article compares two wide-to-telephoto zoom lenses for Sony
digital cameras.
The first is the Sony 18-70mm f/3.5-5.6, often supplied as a kit lens with
the Sony Alpha A100. The second is the Sony Zeiss Vario-Sonnar T* DT 16-80mm
f/3.5-4.5, which
has a similar zoom range but is about four times as expensive.
Both of these zooms are designed for the APS-C sized sensor in the
Sony A100 (and A700).
Because their image circle is smaller than that of full frame lenses,
they cannot be used on
earlier Konica-Minolta film SLRs.
Left: Sony 18-70mm f/3.5-5.6 Right: Sony Carl Zeiss Vario-Sonnar
T* DT 16-80mm f/3.5-4
.5
The 18-70mm and the 16-80mm are fairly similar in size as shown
above, although the Zeiss 16-80 is twice as heavy (15.5oz vs. 8.3oz)
and seems sturdier. Both have a useful zoom range for general-purpose
work and yield images of good quality and contrast. However, the more
expensive 16-80 lens does have a slightly larger zoom range, keeping
in mind that 16mm provides significantly wider coverage than 18mm.
The 16-80 has the same effective coverage as a 24-120mm zoom would on
a full frame camera, while the 18-70 has the effective coverage of a
27-105mm on full frame. Lenses with this range are suitable for travel
photography and are a staple for wedding photographers, but are not
long enough for sports or wildlife.
Both lenses have a maximum magnification of obout 0.25x, which
means you can fill the frame with an object as small as 63mm x 95mm
(2.5" x 3.75"). The 16-80 has a distance scale marked in feet and
meters, while the Sony 18-70 lacks any external indication of focus
distance. In practice the lack of a distance scale is unlikely to be
of concern to most users of the 18-70. Both lenses are supplied with a
lens hood, but as you can see from the photo above, the 16-80 hood is
a deeper "petal" design and is more efficient at shading the lens from
stray light.
The A100 body recorded the 18- 70
lens identity in the image EXIF data correctly, while the 16-80 was
recorded as "unknown lens". If there are any more lenses in the Sony
line that can't be identified by the bodies, this could cause
confusion this didn't cause any problems for these tests since
I was only using two lenses, it could potentially cause confusion for
someone using multiple lenses, especially if more than one was not
identified in the EXIF data.
Image Quality
While the quality of the images from both lenses was generally quite
good, if you look closely,
you can see that the image quality of the more expensive 16-80 lens is
higher, particularly
when you look at areas away from the center of the frame. This can be
seen in the 100 percent
image crops shown below.
The areas outlined in yellow and red are shown in more detail below
for each lens set to
around 30mm and images captured wide open (f4 for the 16-80, f5 for
the 18-70) and stopped down
by about one stop.
In the center of the frame all the images look pretty good. Those
taken using the
16-80 were slightly sharper than those taken using the 18-70 kit
lens.
The differences are easier to spot closer to the edge of the
frame. Here the 16-80
shows its superiority by producing a sharper image than the 18-70,
even with the 18-70
lens wide open and stopped down to f8.
Both lenses showed visible barrel distortion at their widest
setting. Distortion was reduced at longer focal length settings,
becoming slight at 35mm (particularly for the 16-80) and negligible at
the maximum focal length. Note that barrel distortion can be
corrected with digital post-processing. Chromatic aberration was well
controlled in both lenses and would be unlikely to be a problem.
Conclusion
You get what you pay for and what you're willing to carry in terms of
weight. The more expensive and heavier lens delivers substantially
better image quality. Both lenses are too slow for use indoors in
available light, especially given the mediocre performance of Sony
digital bodies at high ISO settings.
With all due respect to the review; what's with the comment about the Sony ISO performance? And I quote, "especially given the mediocre performance of Sony digital bodies at high ISO settings." Bashing a camera system like that just isn't right especially without backing it up. Is the reviewer that biased against the Sony (Minolta) system? I guess he must be a Canon shooter since they really have their noses high up in the air (or should I say their ASS?). I'll put my photos made with my A700 up against any other camera system. You hear me Bob? If you're going to write a review then write an unbiased review. Don't slip in little comments here and there suggesting some sort of inferiority just because you do not prefer that particular camera system. Minolta (now Sony) pioneered so much for photography. Probably more than any other single camera maker. 'Nuff said.
Having a Minolta film camera with two fairly good lenses, I am interested in buying a Sony DSLR Alpha body. When shopping for a good Minolta lens to avoid buying the Sony Kit lens, I read a comment on Amazon that the Minolta AF 18-70mm DT, when used at the wide angle end of the focal length, caused significant vignetting. The sensor of the Sony Alpha is the same size as the Minolta sensor that the lens was originally designed for, so I wonder how accurate the comment was. And, after reading this article, I also wonder if the Sony Kit lens might work just fine and not be as bad as the some of the comments I have read. Is there any additional information that anyone has heard about the vignetting problem with the Minolta AF 18-70mm DT lens used on the Sony Alpha body? Is it worth shopping for a used Minolta 18-70mm AF lens to replace the Sony kit lens when you might just be exchanging identical lenses? Is there an alternative quality lens that would be a better choice than the Sony kit lens? Thanks in advance to anyone who has any ideas on these subjects.
@ Nikola, you can see that the test is made with a α100 body who is obsolete now in term of high Iso use, I think it's only a misuse from the author, the α100 was not a good example for high Iso quality.
@ Edward, the Tamron 17-50 is a very good lens, but not so sharp than the CZ when full open, I had the Tammy and sold it when I found a α700 kit with the 16-80, you can look for a Cz now because a lot of people have switched to the α900.
@Pierre Gagnaux: I'm not annoyed about what was said about the A100's ISO performance. What annoys me is that the review is about the Sony/Zeiss Vario-Sonnar DT 16-80 f3.5-4.5 ZA lens and how it performs. This review is not about the A100 and its high ISO performance. You're right, the A100 does not compare to my A700, which is way better. However, regularly dropping comments in the review that has nothing to do with the lens is just bad reviewing. If you are going to review a lens then review the lens and restrain from making negative comments or "pot shots" about the camera system.
, April 23, 2008; 09:19 A.M. 