Sony NEX-7 Tests, Part 3

These are my final tests (for now) of the Sony NEX-7. See also Part 1 and Part 2. To wrap this up, I rented two Sony E-mount lenses: a second 18-35mm f/3.5-5.6 and a 18-200mm f/3.5-6.3. The reason for getting a second 18-55mm was to determine whether the disappointing performance was due to my particular copy or shows up in other copies.

As for the 18-55mm, my copy of the lens is in fact slightly sharper at 55mm and f/5.6. At f/8, both mine and the rental lens were equally sharp. As mentioned in the previous tests, this is really a “keep it at f/8” lens if you want the sharpest possible results.

Comparing the 18-55mm to the 18-200mm was also interesting. At 55mm f/5.6 the longer lens was sharper in the center but noticeably softer in the corners. At 55mm f/8 they were equally sharp in the center but the longer lens was again softer in the corners. And comparing the 18-200mm to itself wide open at 55mm (f/5.6) and 200mm (f/6.3), it was quite soft at the longest focal length (center and corners) as well as showing quite a bit of chromatic aberration in the corners at 200mm.

While I still like the camera quite a bit, I’m really looking forward to some better zoom lenses. I like the 11x range of the 18-200mm, but since it’s about the same size/weight as the Nikon 18-200mm f/3.5-5.6, there’s not much advantage over just using the Nikon lens on my D7000. The Nikon body is larger, but with a big lens, the difference isn’t as significant. With the smaller 18-55mm, you take more advantage of the NEX-7’s diminutive body. For now, at least, I’m going to stick to the smaller lenses for the NEX-7 and just take my big Nikons (D700, D3s) with the superior glass when compactness doesn’t matter.

FYI: I’ve heard the Sony 50mm f/1.8 ($300) is supposedly a better lens than these zooms, and since it’s obviously much faster, I may give that one a try. I like the idea of a 75mm full-frame equivalent lens.

Sony NEX-7 Tests, Part 2

In an attempt to understand why the images from my new Sony NEX-7 w/18-55mm f/3.5-5.6 kit lens are soft, I ran some basic tests earlier today. I wasn’t satisfied with the results for a variety of reasons (wrong ISO, not enough variables and general sloppiness) so this afternoon I repeated and expanded the tests. The results are shown below. All exposures were at ISO 100. Click to see the image in full-res.


  • On the Sony NEX-7 body, the Nikon 35mm f/2D prime (via an adaptor) is sharper than the Sony 18-55mm, both at f/5.6. No surprise on this one.
  • The Sony 18-55mm has less chromatic aberration at 35mm than the Nikon 35mm prime (both at f/5.6).
  • The Nikon 35mm prime is equally sharp on the NEX-7 (24mp) and the Nikon D7000 (16mp). (The Sony’s extra megapixels don’t help, but it’s just as good as the D7000 in this regard.)
  • None of my tests at 35mm explain my soft images from Saturday’s shoot. So I tested at 55mm…
  • The Sony 18-55mm is noticeably soft at 55mm wide open (f/5.6), but stopped down one f-stop (f/8) it looks quite a bit better.
  • Not shown here, it gets soft again at f/11 and beyond. At 55mm, the Sony 18-55mm is a “keep it at f/8” lens.
  • Also not shown here is the fact that the NEX-7 underexposed this test one full f-stop. This was corrected in Lightroom 4. No other corrections (sharpness, noise reduction, CA removal) have been applied to any of these images.

To see the full test charts, click on the images below. Mouse over to see which is which. These high-res JPEGs were made 1:1 from the original RAW files using quality 80/100.

Nikon D7000 ISO 100 w/Nikkor 35mm f/2 @f/2  Sony NEX-7 ISO 100 w/Nikkor 35mm f/2 @f/2  Sony NEX-7 ISO 100 w/Sony 18-55mm f/3.5-5.6 @35mm f/5.6  Sony NEX-7 ISO 100 w/Sony 18-55mm f/3.5-5.6 @55mm f/5.6  Sony NEX-7 ISO 100 w/Sony 18-55mm f/3.5-5.6 @55mm f/8

I’m curious to know if it’s just my copy of the Sony 18-55mm that’s soft or is it common to all copies. I’m also curious to see if the Sony 18-200mm zoom is much better. I’ll have copies to test this coming weekend.

Sony NEX-7 Tests

[See Update/Part 2]

In early May I managed to get my hands on a Sony NEX-7 camera with a couple of lenses. On May 15 I recorded a video review with Frederick Van Johnson on This Week in Photo. Ultimately, I decided this would be a great small, mirrorless camera to complement my huge Nikon D3s and its lenses, so last week I ordered one from Sony. I spent half of this past Saturday shooting with the NEX-7 and its kit lens, an 18-55mm f/3.5-5.6 (about 28-85mm full-frame equivalent). But when I got home and transfered the images, I was disappointed in their sharpness, pretty much uniformly. Did I get a bad copy of the lens? Was the camera just not as good as I though when I had a review copy? I decided to run some tests.

I’m just getting started, but here are the initial results. I started with the kit lens set to 35mm and f/5.6. (Wide open at 35mm is f/4 on this lens.) For comparison, I used an adaptor to mount a Nikon prime lens to the Sony body — an AF Nikkor 35mm f/2 D. Finally, I used the same lens on my Nikon D7000, which has an APS-C sensor, the same size as in the NEX-7. I used the lowest  “normal” ISO on each body: 100 for the NEX-7 and 200 for the D7000. The results are below. Click the image to see it full-sized, 1:1.

My interpretation? The Nikon 35mm on the Sony NEX-7 body is sharper than Sony’s 18-55mm. No real surprise there. But both lenses are sharper on the NEX-7 than the prime on the Nikon D7000. Well, maybe that’s not really a surprise after all, since the D7000 is a 2+ year-old camera and uses an older Sony sensor that’s the same size as the NEX-7’s.

As for the final decision about the NEX-7, we’re not there. I still don’t have an explanation as to why this weekend’s images are so soft. Perhaps it’s because most were shot at 55mm. Or maybe it’s that I used ISO 200 most of the day. In any case, further tests are required to determine what’s going on here. Stay tuned.