#168. Is the new Zeiss 35/2.8 Z better than the RX1 ?

By pascaljappy | Opinion

Oct 24

By now, it’s pretty certain the new Sonnar T* FE 35mm F2.8 ZA will be a stellar performer on the equally new Sony A7 and A7R cameras. Brilliant samples such as the one below by ijsvogel at Dyxum have shown us just how good.

Click here to access ijsvogel’s samples at Dyxum.

But the pressing question in everyone’s mind, is how good, compared to the extraordinary 35mm lens in Sony’s RX1 and RX1R cameras?

Until we have A/B comparison tests on identical targets, all we can do is assess what elements we already have in hand : official MTF curves and official sample tests.

Starting with the MTF curves, what can we see ?

The RX1's Sonnar 35mm f/2 MTF curves (10lp/mm and 30lp/mm).

The RX1’s Sonnar 35mm f/2 MTF curves (10lp/mm and 30lp/mm). (c) Sony

Above are the MTF curves at 10lp/mm and 30lp/mm for the RX1. Below are those for the new Sonnar T* FE 35mm F2.8 ZA at 10lp/mm, 20lp/mm and 40lp/mm. For comparison purposes, the 30lp/mm curves for the Sonnar T* FE 35mm F2.8 ZA would be roughly half way between the blue and green curves on the graph below.

If you are not MTF litterate, a brief intro to reading these curves is provided in a previous post.

Sonnar T* FE 35mm F2.8 ZA MTF curves

Sonnar T* FE 35mm F2.8 ZA MTF curves

What this tells me is that the image quality from both these lenses will be virtually undistinguishable at F/8.

But at full aperture, the RX1’s Sonnar seems a tad better corrected than the Sonnar T* FE 35mm F2.8 ZA, particularly in the corners, where the difference would probably be visible. Though the difference will not be that big in real life pictures, remember the RX1 is achieving these results one stop more open than the Sonnar T* FE 35mm F2.8 ZA !! That’s remarkable and, in my mind, the RX1 possibly has the best 35mm ever designed !

Still, lenses do not operate in a vacuum. Used on the 24Mpix A7, the Sonnar T* FE 35mm F2.8 ZA will not be quite as sharp as the RX1, but on the A7R things are a little different :

  • at F/8 and up to the edges, where the tangential curve falls quite low, the Sonnar T* FE 35mm F2.8 ZA will probably resolve 80lp/mm which the A7R sensor will be able to exploit. Over almost all of the frame, there should be more resolution in the A7R/Sonnar T* FE 35mm F2.8 ZA combo than in the RX1 image.
  • at F/2.8, things are different and I’m guessing the difference (in favour of the A7R) will be clearly visible in the center 20 mm and gradually less, the RX1 actually being sharper in the corners.
  • at F/2, well … there’s only one winner 😉

But there’s more to be learned from the specifications. The RX1 has 9 blades whereas the Sonnar T* FE 35mm F2.8 ZA only has 7 ! This is likely to make a difference in out of focus highlights, such as in the sample below, by dcfever.


As you can see, heptagons are present instead of the smoother shapes that would be produced by a lens with more blades. Note that the 9 blades in the RX1 have sometimes been criticised for not being as circular as hoped for but the bokeh from that camera is superb, so maybe we shouldn’t make too big a deal of it all.

Still, I cannot help feeling that Sony have deliberately held back on some aspects, probably in order to keep the RX1 at the pinnacle for a longer stretch of its life cycle.

But all this matters very little as I am just writing this to keep my mind occupied until the lens is mine 🙂 Whatever the charts and blade numbers suggest, I’m pretty confident this will be an outsanding lens (check out the nice bokeh below :)) on theA7R and cannot wait to use it !

Official Sony sample for the Sonnar T* FE 35mm F2.8

Official Sony sample for the Sonnar T* FE 35mm F2.8 (c) Sony

  • Well, it might be dreamy, but in a 35mm prime, I want f/2 or faster for low light and DOF control. It is good that Sony is doing innovative things, but I will hold onto my D800 for now.

    • pascaljappy says:

      I get you ! What 35mm do you use on the D800 ? I use a Leica-R Summicron 35/2 and that’s really nice. I sure wish I had a Zeiss 35/1.4 though 😉
      The wait for more info on how well M-mount glass works with the A7R is killing me. A summilux 35 would sure be a treat !

      • I don’t have a 35mm prime for the D800 because the Nikon 35mm f/2 AF-D is nasty. I use a 28 f/1.8 AF-S and crop if I have to. With 36 MP I can throw a few away. The Sigma 35mm f/1.4 has a good reputation, but it is awfully big. For me AF is a must because I shoot stuff that is changing fast and in light that is too weak to use f/11 and DOF to save me.

        • pascaljappy says:

          Yes, I saw the awesome pics on your blog ! Can’t imagine working these without AF ! I hear the 28/1.8 is superb. 28 is also the focal length I feel most free with. And, as you say, 36Mpix lets you crop quite a bit. Strange thing is I don’t own a 28 on my D800 even though it’s my fave fl. I just love the Summicron-R 35/2 so mcuh … I hope something nice turns up on the A7 in that 28mm fl …

        • pascaljappy says:

          You’re right, a real pro will make a great picture with any gear (not that I find this one particularly great, photographically, except for content).
          I think other commenters are just saying there are better options out there for their needs.

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  • Jared says:

    Your MTF guide was really helpful, so thank you for that. Now I get the best of both worlds – geeking out over images and MTF curves.

  • John Hagts says:

    I have found that the SIGMA 35mm F1.4 works superbly well on my D800e .You are right about the 35mm F2 an update is long overdue

    • pascaljappy says:

      Yes, hear that Sigma is a beauty. The Zeiss 35/1.4 is also rather special but what a big lens … I’d still love to try either 😉

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  • Martin says:

    Good points here and, yes, these lenses look stellar. But so, arguably, were the Zeiss E lenses for the NEX (including the very recent Touits) which are redundant for the new FE mount. And since there will be no more NEX cameras that means these lenses will eventually become dead ducks. Who knows? – maybe the new FE lenses will go the same way if this new system fails to attract sufficient interest. However, because of their new universality, the alternative lenses which can be used with different adapters on all of these mirror-less systems are set to become timeless and should therefore hold value. So, much as I fancy the AF Zeiss FE 35/2.8 I think I shall be running with one of the manually focusing equivalents, be it Leica, Zeiss or Voigtlander.

    • deveron3 says:

      Sony is simply rebranding their E-Mount still cameras to Alpha. They will surely make more aps-c E-mount cameras in the future!

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