Resolution Tests

NEX-7 Lens Imatest Results

Published April 29, 2012

For the last 3 years now, I’ve been running my mouth, basically saying something like ‘I think the NEX series is a camera that could give great resolution if there were any decent lenses for it’.  When the NEX-7 came out there was now an even better resolving sensor, and for the first time at least a few supposedly good lenses to put in front of it (if you can get them). A lot of people preferred high quality Zeiss or Leica M mount lenses on an adapter, and Sony was smart enough to put nice peaking filters and other manual focus aids in the camera.

But some of us (myself included) like to shoot native-mount lenses, or can’t afford the price of Leica glass to put in front of the camera. The NEX-7 is physically set up in a way that allows us to mount it to our Imatest set up, and we happened to have most of the new lenses in stock one day, so I thought I’d take advantage of the situation to do some resolution testing. (Because I know someone will ask, we can’t test many of the small cameras because mounting to our tripod system blocks the memory card door. It takes 10 to 20 test shots to align the test setup. But if you have to unmount from the tripod mount, you have to start over. So it’s not possible for us to test some camera systems.)

The usual “don’t read this stuff and go insane” cautions apply: this is a test of lens and sensor resolution done at a distance of 10 to 30 feet, depending on focal length. The results might be different at 4 feet or 400 feet. Focus is done manually and bracketed so it’s not a test of a camera’s autofocus ability. The tests use a controlled-lighting test-target with a hardware mounted camera and Imatest software at ISO 400, so photos taken in the dark of night or hand-held for 12 second exposures will give slightly different results. It doesn’t measure autofocus speed, lens size, manual focus feel, bokeh, color rendition or anything like that.

The Lenses

Still the results are interesting and I suspect none of you would pick one of the eventual resolution co-champions out of the lenses we tested:

Leica 50mm f/1.4 Summilux on a Fotodiox adapter (picked because it’s the highest resolution 50mm lens we’ve tested on other bodies).

Sony 18-55mm and 18-200mm E-mounts zooms both tested at 30mm because that was our original point of interest. That was probably the sweet spot for the 18-55, but may have handicapped the 18-200 a bit: it seems better around 50-90mm. But certainly it’s better at 30mm than at the long end.

Sony 16mm f/2.8; 24mm f/1.8; 30mm f/3.5 Macro and 50mm f/1.8 E mount prime lenses.

Sigma 19mm f/2.8 and 30mm f/2.8 E mount lenses.

Unfortunately we did not have a 55-210 Sony zoom in stock at the time of the tests.

Imatest Results

The values are for MTF-50 (which correlates with fine detail resolution) measured in line pairs / image height. The first (higher) number is the MTF 50 measured at the center of the lens only. The second (lower) number is the average of the MTF-50 measured at 13 points including the center, 4 corners, 4 sides, and 4 mid points.

The first graph shows the numbers for each of our lenses (zooms measured at 30mm) with the lens wide open. This test isn’t a level playing field, since some lenses are f/4 wide open (the zooms) while the primes are at anything from f/1.4 to f/3.5. But since some people tend to shoot every lens wide open, it may be useful to them. Please note: On Monday, May 7th I retested a number of Sony-Zeiss 24mm f/1.8 lenses because the initial two we tested seemed strange, and were very close in SN (it’s all we had in stock at the time). I’ve since repeated that test with different copies and the new results at f/1.8 are much better. I’ve changed the results below to reflect the better results — here’s a good example of tests of one copy of a lens, even two copies, is never enough to base your decision on. We’ve examined the copies from the original test carefully and other than the softness at f/1.8 (which is gone by f/2.2) we still haven’t figured out what problem they have.

MTF 50 at Widest Aperture

Lens Max Avg
Sony 16mm f/2.8 665 490
Sigma 19mm f/2.8 870 740
Sony-Zeiss 24mm f/1.8 740 590
Sony 18-200 f/4 855 680
Sony 18-55 20 f/4 855 640
Sony 30mm f/3.5 940 725
Sigma 30mm f/2.8 985 805
Sony 50mm f/1.8 675 602
Leica 50mm f/1.4 627 545

We can level the playing field a little bit by shooting the wide primes at f/2.8. That gives us the numbers below. It’s somewhat more meaningful: the zooms are still f/4 and the Sony 30mm Macro at f/3.5, but everything else is shot at f/2.8 here. Notice the results for the little, reasonably priced Sigma 30mm f/2.8 are in bold. While some lenses are close to as sharp in the center, nothing is nearly as good in the corners. Impressive.

MTF 50 at f/2.8

Lens Max Avg
Sony 16mm f/2.8 665 490
Sigma 19mm f/2.8 870 740
Sony-Zeiss 24mm f/2.8 960 735
Sony 18-200 f/4 855 680
Sony 18-55 20 f/4 855 640
Sony 30mm f/3.5 940 725
Sigma 30mm f/2.8 985 805
Sony 50mm f/2.8 806 732
Leica 50mm f/2.8 920 730

We can level things out a bit more by shooting all of the lenses at f/4. Most of the lenses would get a bit sharper still at f/5.6, especially in the average number. Notice the Sony 24mm f/1.8 has gone from easily the worst resolution to among the best (at least in the center) by stopping down a bit. It really was much, much better at f/2.0 so I would consider that the real maximum aperture for that lens. (We checked a second copy and it was exactly the same – it’s possible that we had two copies that were bad at f/1.8 and not at f/2.0, but I really, really doubt it. I’ll check a couple of others when they get back from rental to be certain.) Really only the Sony 50mm and the zooms are lagging behind in the center, and the Sony 16mm pancake does, of course, still suck.

MTF 50 at f/4

Lens Max Avg
Sony 16mm f/4 915 646
Sigma 19mm f/4 920 765
Sony-Zeiss 24mm f/4 1000 795
Sony 18-200 f/4 855 680
Sony 18-55 20 f/4 855 640
Sony 30mm f/4 940 725
Sigma 30mm f/4 1040 840
Sony 50mm f/4 885 835
Leica 50mm f/4 1020 870

Comparing Lenses

Imatest is measuring the resolution of the lens-camera combination (as opposed to an optical bench, which measures the lens’ maximum using collimated laser or LED lighting). We chose the Leica 50mm f/1.4 Summilux because we’ve tested it on a lot of other camera systems and know the lens is as good as it gets from a resolution standpoint. That the Sigma 30mm, a $200 lens, is keeping pace with it is really amazing. Obviously it’s not really a wide aperture prime, with a maximum aperture of f/2.8, but it gives world-class resolution. The Sony 24mm f/1.8 is not the bargain the Sigma is, but from f/2.2 on it has amazing center resolution, although it lags behind the other two in the corners. The Sony 50mm f/1.8 appears to be tuned like the Nikon 50mm f/1.4 G: it’s not quite as sharp in the center, but keeps good resolution across the entire front of the lens. Notice it’s average resolution is up there with the 3 best lenes, although the center isn’t quite as sharp as the other primes.

The Sony 30mm Macro may be better at Macro distances (should be actually), but the Imatest setup requires us testing it at about 15 feet distance. Very decent also describes the Sigma 19mm f/2.8 which is clearly far better than Sony’s 16mm pancake. The zooms, well, they’re about what we thought: OK lenses for when you need a zoom.

Comparing Systems

It’s always a little complex to compare Imatest resolution between cameras with different sensor sizes, since the numbers we generate are measured in line pairs / image height, and image height differs.  I hesitated to do it at all, because it will inevitably lead to 716 posts about whether it’s most appropriate to multiply the resolution of the crop sensor of divide the resolution of the full frame, and by what amount. But my thought is to keep it simple. If I take a picture of a building with whatever camera I’m shooting so that it is the same size on the image I print, then image height of the sensor doesn’t matter.

In other words the printer doesn’t care what size the sensor that took the picture was if the pictures were the same. Given this ‘Roger Rule’ the results with the NEX – 7 and good lenses are about what we’d expect: resolution at f/4 with a good lens is about what we see with a Canon 5DII or III (1050 / 800 or so LP/IH) with a good lens, not quite as good as a Nikon D800 (1200 / 1000 LP / IH). So shooting with one of the better lenses  listed above you can certainly get all the resolution you should ever need.

If you want to shoot a zoom, though, things aren’t so pretty. For example, a Nikon 24-70 f/2.8 shot at f/2.8 gives around 890/830 jumping up to 940 / 875 at f/4. A Canon 70-200 f/4 resolves at 920 / 845 at f/4. The Sony zooms are both about 855 / 660, which means the corners of a good Canon or Nikon zoom are about as sharp as the center on the Sony E zooms. Those are more expensive zooms, no question. I’m not trying to compare apples and oranges. Simply stating that the NEX system doesn’t offer a high quality zoom and giving some examples of what a high-quality zoom’s numbers would be like.

But for prime lenses, at least, we’re now getting some good quality, native mount lenses to put on NEX cameras without an adapter. My hat is off to Sigma for making a couple of really good lenses at amazingly good prices. Well done! Hopefully as the user base of E mount cameras increases we’ll start to see more third party options.


Roger Cicala

April 2012


Author: Roger Cicala

I’m Roger and I am the founder of Hailed as one of the optic nerds here, I enjoy shooting collimated light through 30X microscope objectives in my spare time. When I do take real pictures I like using something different: a Medium format, or Pentax K1, or a Sony RX1R.

Posted in Resolution Tests
  • Sofia Koutsouveli Lucifairy

    The Sigma 30mm f/2.8 really shines! I wonder how it compares to the Sony 35mm f/1.8 OSS though.

  • Fred

    Teresa K,

    AFAIK the Contax RTS has a Contax/Yashica mount. There are some simple adapters (without optics) advertised on Ebay. Search for “sony nex contax converter”.

    I use a 70’s era Canon FD 100mm f2.8 SCC at full aperture with a NEX 5R and a simple adapter. Sharpness is very good across the frame, with vibrant colors. You should get good results too. The only issue is my adapter is too short by about 0.2 mm, which results in the focus ring showing a slightly shorter distance than the actual.

  • Roger Cicala


    It’s possible in theory but I don’t know of a way to do it without something clumsy (two adapters, but that just has a huge chance of introducing some tilt or infinity focus issue). There might be a direct adapter way that I’m not aware of, though.


  • Teresa K

    Roger: Could you tell me if there is an adapter that would work with the NEX 6 or 7 for my old Zeiss glass made for a Contax RTS film camera?? My favorite is the Planar 1.4/85 … I love that lens. I also have a Distagon 1.4/3.5 and aTeleTessar 3.5/200. Interested in lightweight now because of neck problem. Or are there other digital cameras that have some way to adapt. I discovered your site and itrust your opinion. Going to Yellowstone at the end of July. Will contact LensRental to get a recommendation for the trip.

    thanks for your good site!

  • Any chance of throwing in some results with the metabones “speed booster” adapter?

  • wansai

    I got my hands on a zeis 24 f1.8 recently on a Nex7 and it consistently outperforms the kit lense in my shots by quite a large margin (wide open). The corners are a tad soft but not nearly as bad as the 18-55 and the 16. Otherwise the zeis is pretty consistently sharp; though not overly sharp.

    I know some people base a good lense entirely on how super sharp it is, but I’m perfectly happy with the clarity of the zeis. Also, it renders very pleasantly, colours pop, and everything i point it at comes out so smooth and buttery. And just as importantly, pictures shot with the zeis have a 3D quality that none of the kit lenses can produce (generally flat images in comparison).

    It’s a quality lense that’s not well represented by this data alone.

  • Lee

    I am very surprised by the poor maximum aperture performance of the Summilux, I’d really have expected more for the $3 billion price tag.

  • Roger Cicala


    There definitely are some issues with the edge and corner microlenses on NEX7s when shot with certain wide angle lenses. I don’t know if “problem with the sensor” is the right description because Sony certainly didn’t design it so it would work with rangefinder lenses. But it is an issue for some folks.

  • franz

    hi, i’ve been thinking about getting a nex 7. i was doing some research and read a lot of complaints about images having very soft edges, some were saying it was a problem with the sensor. i konw that sharpness in the center will always be better than sharpness on the edges but from what i read it seems that on a nex 7 the edges are a lot worse than what is expected.

    is there really a problem with the sensor? or is the problem with the lenses?

    thank you

  • Roger Cicala

    BF – they’re definitely better by f/5.6, maybe a tiny bit better than that at f/8. It’s certainly decent at that point, although the corners are still a bit soft.

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