#166. Are the new Zeiss / Sony lenses for the A7 camera too expensive ?

Short answer: NO. They’re a bargain. The end.

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Disclaimer : Let me state upfront that I am a fanboy, but of Voigtlander and Leica lenses. Not of Zeiss. The first lens to go when I decided to switch from my current Nikon D800e to the Sony A7R was my Zeiss Distagon ZF.2 25/2mm. It is an extremely competent lens, but too large and heavy for me. I have held on to all my Leica-R glass except for one single lens of which I have an exact copy in M-mount. So the raving below is entirely objective (pun possibly intended!)
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Onwards !

A recurring theme in the comments to the A7R launch coverage is the crazy price of the Zeiss lenses being announced at the same time. The New Sonnar 55mm f/1.8 took a particularly bad rap.

Below, I’ll examine the two that are most interesting to me from a purely technical point of view.

Sonnar T* FE 35mm F2.8 ZA

The Sonnar 35/2.8 is an important lens because it is small, high-quality and the Sonnar name promises a certain type of aesthetics that will appeal to many photographers around the world : excellent bokeh qualities.

Because of its optical formula, the Sonnar design cannot be used for most focal lengths on SLR cameras because the mirror would be too colse to the rear of the lens. In a mirrorless camera such as the Sony A7, this is no longer an issue and the Sonnar formula’s wonderful drawing qualities can now be used on wide angle lenses such as this 35mm.

Let’s examine its MTF curves to judge its optical qualities from a purely technical point of view :

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

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

In the frame below, I’ll give a quick explanation of how to read this information. If you’re familiar or not interested, just jump below 😉

Reading MTF charts (in a few seconds)

First, this is dangerous stuff 😉 You could get stuck in the 4th dimension thinking a chart is all you need to understand a lens and how it will render a scene. Ain’t so.

An MTF chart such as the one above describes how visible the separation between close details will appear on your film/sensor.

On the horizontal axis, you have the distance from the center of the image. At the 0-5mm marks, you are at the center. At the 15-18mm zone, you are approaching the wide edge of the sensor. At 21mm, you are in a corner. Ideally, curves on this chart would be horizontal, showing equal performance all over the frame (center, edges, corners).

On the vertical axis, you have contrast. The higher the curve, the more contrasty (ie, clearly visible) the separation between two details will be.

As you can tell from the two pictures above, this lens performs better at F/8 than at full aperture (what else is new), since all the curves on the right (F/8) are bunched higher up near the top.

The 5 or 10 lp/mm is indicative of how well coarse detail will be transmitted by the lens. They determine the apparent sharpness for web sized images but also the “pop” of much larger prints. At the other end of the scale, 40 or 80 lp/mm shows how well very tightly packed detail is shown. Among other things (notably, your sensor and shooting technique) this determines how much you can enlarge.

Results are traditionnally given for several spatial frequencies (usually 10 line pairs/mm, 20lp/mm and 40lp/mm). Leica often adds 5lp/mm and high end lense for medium format cameras from Rodenstock or Schneider will add 80lp/mm.

As a rule of thumb, the eyes will see 3lp/mm at a distance of 30cm. If you’re viewing your pictures at 1 meter, you’ll see 1lp/mm of resolution. If your lens and sensor can produce good contrast (above 50%) for 50lp/mm, you will be able to enlarge 50 times, giving you a print six feet wide. In real life, I would half that for a more realistic figure (*very rough* rule of thumb) !

You sometimes read that a lens has 62lp/mm resolving power. It means that this separation is rendered at 50% contrast (usually at the center of the image and optimal aperture).

What to look for ?
The shape of the curves is interesting. If they start very high and dip quickly, as in many (excellent) vintage Leica lenses, you have an extremely sharp center and fuzzy corners. This can often be a design goal, not a flaw, though it isn’t much in fashion in our pixel peeping days. But for a portrait lens, it would throw all the surrounding beutifully out of focus without paying a photoshop expert to do so in post processing.

The separation between the continuous and dashed lign (each measuring contrast for line pairs oriented towards the ceter of the image or at right angles to this, in order to simulate real world object edges which have no specific alignment) will reveal the presence of astigmatism and other nasties that can affect acutance, bokeh and other subjective attributes of a photograph as well as lateral aberations. Ideally, both should follow the same path.

Comparing lenses
There’s much more to this boring science, but these basics are enough to get an understanding of how much work has been put into the design and construction of a lens. Oh yeah : some manufacturers calculate these curves. Others, such as Zeiss, go the more honest way of measuring them on an actual lens. This takes into consideration polishing and alignment quality much more realistically. (I hope it is still the case with the Zeiss / Sony lenses)

Don’t ever sweat over a 10% difference in curve level. It simply isn’t visible in the real world.

Make sure the charts you are comparing are using the same scales (Nikon & others uses 30lp/mm in stead of 40, because it corresponds to the elargement most users will want, and is more flattering in the chart).

Look for high and tightly packed curves for better (technical) performance. Look out for strong separation between continuous and dashed lines, and for vary wavy curves possibly indicating a curved focal ‘plane’.

One important last point to keep in mind : as pixels get smaller, diffraction kicks in quicker as you stop down the lens. For the A7, you can probably use f/8 – f/11 as your limit, but the effects of diffraction will become visible almost one stop earlier on the A7R. So, ideally, you’re looking for a lens that will deliver it’s best at or before f/5.6 – f/8.

That’s it. For a far more comprehensive lesson, please read this document by Karl Zeiss.

With this science in mind, let’s compare these curves with those of competing lenses.
Two very natural competitors are the Leica Summicron-M 35mm f/2 and Leica Summarit-M 35mm f/2.5.

Leica Summarit-M 35mm f/2.5 MTF curves

Leica Summarit-M 35mm f/2.5 MTF curves (c) Leica

The comparison is unfair to the Summicron – wide open – since it is one full stop faster. Also, Zeiss shows its second set at F/8 whereas Leica’s is at F/5.6, so *might* be a bit better at F/8.

Leica Summicron-M 35mm f/2 MTF curves

Leica Summicron-M 35mm f/2 MTF curves (c) Leica

As a bonus, here’s the King of the 35mm hill, the 4000€ Leica Summilux-M 35mm f/1.4 stopped down to f/2.8

Leica Summilux-M 35mm f/1.4 MTF curves at f/2.8.

Leica Summilux-M 35mm f/1.4 MTF curves at f/2.8. (c) Leica

My point here is not to say which is better. There are many other factors to take into account (number of blades, build quality, ease of use …) But here are 3 of the best 35mm lenses the world has ever know and the Sony/Zeiss 35mm F/2.8 Sonnar is easily as good on the MTF charts.

And as final comparison, here is what I consider to be the best 35mm in the world, the Sonnar 35/2 used on Sony’s RX1 !

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

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

Both are virtually undistinguishable at F/8, but the RX1 lens seems a tad better at F/2 than the Zeiss 35mm F/2.8 FE at F/2.8. It also has 9 blades instead of 6 and a full stop more of aperture, so it’s obvious Sony has taken no risk of stealing the RX1’s thunder too early in its career. Still, the FE still looks to be a gem !

And there’s better to come !

Sonnar T* FE 55mm F1.8 ZA

Here are the charts for this slightly long standard lens, which has probably received the greatest price-related criticism.

Sonnar T* FE 55mm F1.8 ZA MTF curves

Sonnar T* FE 55mm F1.8 ZA MTF curves (c) Sony

Now,let’s compare this to a lowly newcomer that’s humbly been touted as the best 50mm lens ever designed, the Leica APO-Summicron-M 50mm F/2 ASPH.

Leica Apo-Summicron-M ASPH 50mm F/2 MTF curves at F/2.

Leica Apo-Summicron-M ASPH 50mm F/2 MTF curves at F/2. (c) Leica

Here the Leica has the slight advantage of a f/2 aperture vs the Zeiss’s f/1.8, but let’s not quibble. Here, the center performance is all but identical and the Leica shows just enough of an advantage (in the extreme corners only) that you’d probably notice (but whith greater separation between continuous & dashed).

At f/8 (f/5.6 for the Leica), both are so close to actual perfection that you really couldn’t tell one from the other (on sharpness alone).

Remember we’re comparing the 3 bottom pairs in the Leica charts to the 3 in the Zeiss charts.

Leica Apo-Summicron-M 50mm F/2 ASPH MTF curves at F/5.6.

Leica Apo-Summicron-M 50mm F/2 ASPH MTF curves at F/5.6. (c) Leica.

Is the Zeiss better ? Nope. But that it’s even comparable at 1/6 of the price is simply amazing.

Let’s continue with another recent masterpiece : Zeiss’s Otus APO-Distagon 55mm f/1.4. Here are the charts for this world shaking lens :

Zeiss Otus APO-Distagon 55mm f/1.5 MTF curvers at f/1.4 (top) and f/4 (bottom).

Zeiss Otus APO-Distagon 55mm f/1.5 MTF curvers at f/1.4 (top) and f/4 (bottom). (c) Zeiss

Here again, the Otus is at a disadvantage, being measured at f1.4 and f/4 instead of f/1.8 and f/8, but still, it’s uite obvious the two Zeiss lenses are in the same ballpark.

For a comparable price tag (only 2-3 times the price of the Zeiss Sonnar 55/1.8) here’s the standard Summicron-M 50 charts (note that this is a lens I use constantly on my D800e in its almost equivalent R-mount guise and it is brilliant).

Leica Summicron-M 50mm F/2 MTF curves.

Leica Summicron-M 50mm F/2 MTF curves. (c) Leica

On charts, the Zeiss beats it easily. And let’s repeat: this really is an excellent lens ! See a 100% shot made *at full aperture F/2* with the R-mount version on a Nikon D800e.

Place aux huiles, Marseilles. Nikon D800e & Leica Summircon-R 35/2 @ F/2

Place aux huiles, Marseilles. Nikon D800e & Leica Summircon-R 35/2 @ F/2

This is 1/16th of the full image. On screen you’re looking at an extract from a 7 foot picture. Maximum aperture. Sharp enough ? 😉 The Zeiss is better still.

One final comparison, with the new Nikkon 58mm f/1.4 G (MTF curves for 10 & 30 lp/mm @ f/1.4)

Nikkor 58mm f/1.4 G MTF curves @f/1.4 (10 lp/mm & 30 lp/mm)

Nikkor 58mm f/1.4 G MTF curves @f/1.4 (10 lp/mm & 30 lp/mm) (c) Nikon

The Zeiss is clearly better at full aperture (f/1.8) than the Nikkor at f/1.4

Real life conclusions

So ! Here we have two lenses priced half-way between entry level plastic kit lenses and the best money can buy with image quality directly comparable to the ultimate side of the scale. Seems more than fair to me.

More importantly, Sony’s RX1 showed us the benefits of matching a lens to a sensor. And, even though the A7 and A7R are interchangeable lens cameras imposing more constraints on the design, I believe Sony / Zeiss have gone even further down the same lane. And that this goes a long way towards explaining the extraordinary image quality reported by pro users such as Brian Smith.

In brief : Zeiss have really done their homework with these lenses and produced some of the sharpest / most contrasty ever produced for the 24×36 format, then thrown in very decent build and autofocus for a tiny fraction of the price of lenses of competing technical excellence from other stables.

Make your own judgement on whether you like how these lenses draw and, if you buy, do so with the assurance that you are getting an excellent deal with glass that will work equally well on future 50 Mpix sensors (should you ever wish for more resolution).

To help you with this I suggest you take a look at the following pages :
Official page for the Sonnar T* FE 35mm F2.8 ZA on Sony’s website
Official page for the Sonnar T* FE 55mm F1.8 ZA on Sony’s website (have you ever seen more pleasing bokeh ?)
Brian Smith’s field test in Haïti. Vividly recommended !! These are the first 35mm format pictures I’ve ever seen that convey the same sense of tonal finesse as larger format cameras do.

Probably a combination of Brian’s post-processing genius, subject matter and other technical factors. Yet the fact remains : with the same talent, you can produce this look for under 4k€ (Sony A7R + 35/2.8 + 55/1.8) !!

Call that overpriced ?

17 thoughts on “#166. Are the new Zeiss / Sony lenses for the A7 camera too expensive ?

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  3. Sony does not take difraction into the MTF curves. Leica on the other hand does! So u cant really compare this. But never thel less the mtf of the 55 looks stunning!!!

  4. Your assessment of the Nikon 58/1.4 lens is flawed. The MTF graph doesn’t show the lens at f4, but at wide open, f/1.4, one-point-four. It even says so on the picture, at the bottom right. And objectively, it would be a lie and a farce to say that the Zeiss 55/1.8 is anything but better than the $7000 APO-Leica, and at 1/3 stop faster as well. The MTF curves show a superior IQ over a much much bigger portion of the image, where contrast and fine detail is higher than the Leica 50/2 APO-summicron (again, at 1/3 higher F stop, stop it down 1/3 stop to F2 and the difference would be even higher). Also, Zeiss 55/1.8 will show noticeably less astigmatism and such. The objective facts from the MTF curves says this. Other than that, great article, thank you.

    • Ooops ! Thanks for the aperture mistake on the 58mm Nikkor (it did seem weird …) Updated.

      As for the AA Leica, I’m not saying it is inferior to the Zeiss. It isn’t. It is quite close though anf that’s praise enough for a lens of this price. My only aim with this article is to stop the “overpriced” rage against the two new Zeiss / Sony ZA offerings. They are high end lenses at medium prices and that should be seen as a great opportunity.

  5. I would like to add a comment to what Pascal writes so wonderfully simply. It is not uncommon for a product to perform “almost” as well as the state-of-the-art one, but at a fraction of the cost. One could, and should, extol the virtues of the entry-level 50mm primes from Nikon or Canon, usually 50mm f:1.8 (sounds familiar?), cheaply built, and sold for only just above 100€ new. Similarly, those lucky enough to own a now discontinued Contax C/Y 50mm f:1.7 can enjoy its great performance except wide open. These three lenses are so good, relative to price, that they were nicknamed “plastic fantastic” because of their all-plastic, lightweight construction. They are the ones to buy for anyone who wants to dip a toe into the world of prime lenses, and find out if there is any difference with zooms, be it kit zooms (also plastic) or the very expensive f:2.8 ones.
    So, how does the Zeiss 55 stack up against such similarly-specced pocket rockets?
    MTF curves tell you about contrast, resolution, bokeh, field curvature, some forms of distortion That is a lot of info, but lens performance is very complex indeed. I have listed 5 sets of performance factors that one can identify from MTF curves, but what about astigmatism? And coma? And the various forms of color aberrations? And the transition from in-focus to out-of-focus? And I could go on…
    What makes these primes “cheap and cheerful” is that they use a simple and good design of many years ago, the fabled Zeiss “planar” construction, and outfit the lenses with all-platic optical elements (no glass). These elements, while sufferening from no major issues, cannot match the performance of more sophisticated (and costlier, and heavier) glass. Look for descriptions that include “aspherical”, “low dispersion”, “fluorite”, and of sophisticated coatings as well. There is a reason why the new and extraordinay Zeiss 55mm f:1.4 Otus incorporates 12 optical elements in 10 groups (weight: 1kg), and the Canon 50mm f:1.8 only 6 elements in 5 groups (weight:130g).
    Basically, the better you want to correct a lens, the more elements you need. But more elements means more transmission losses, so one has to resort to very high quality materials to compensate for that. Add that the cheap primes are volume produced on automated production systems, and the very expensive ones are very low-volume items with many manual processes, plus the hefty margins associated with luxo prdducts, and you have it!
    So, to come back to Pascal’s point, how do the Zeiss twins compare both to the state-of-the-art lenses and to the cheap-and-cheerful ones? Simply put, they perform at the low-to-mid end of the state-of-the-art segment. As you can see from the MTF, they can’t challenge a Leica 50 Summicron AA, or a Zeiss 55 Otus, but whether that difference is at all visible in any but extreme conditions and for arcane performance criteria is a real-question.

    There is another ponit worth mentioning. These Zeiss lenses are not speed demons. One might have expected at least a Zeiss 35 f:2.0 and a 55 f:1.4 at those price levels. That they are not may be a sign of changing times. In film days, the photographer was “stuck” with whatever film he had loaded in his camera, so, if he needed to shoot in lower-light conditions than expected, a fast lens was essential. Then early digital sensors came, but they were noisy as soon as one wanted to push ISO above 400 (that is the case with, for example a Leica M9), so fast glass was again the only go-to solution. Now, with all modern sensors being much less noisy, the way to go is simply to push ISO by a stop or two. That lets one use less fast glass, which has benefits. Fast glass is very hard to correct perfectly, thus it is costly, large and heavy. Less fast glass can be better corrected yet less expensive, with lighter thrown in for good measure. Proof of this is in the performance of the 24mm Leica Elmar f:3.8 and its twin the 21mm Super Elmar f:3.4, which easily outperform their heavier, more expensive 24mm and 21 mm Summilux f:1.4 stablemates for anything but fast shooting. Similarly, Leica have just introduced the X-Vario, which sports a zoom rated at f:3,5-6,4 a slowness at the long end which left many reviewers and would-be clients gasping when set against a sales price of 2000€.
    Even the Zeiss Otus and Leica Summicron AA are less fast than glass both those companies produced long ago. Part of the problem being that very-high-resolution sensors like the Nikon D800’s or the Sony A7’s, especially in their AA-filter-less form, show many more “issues” with a less-than-absoutely-perfect lens than ever before, if only because of the higher magnification factor that greater resolution viewed at 100% brings.
    So expect less fast glass in the future, there are now more important factors to judge lenses by, and on which I confidently expect the new Zeiss twins to shine.

    • Thanks Philippe. The mirrorless configuration also makes it easier to design great lenses with a “simpler” design. As you explain, it can take many lenses to correct many aberrations in a complex design. And the two new Zeiss / Sony lenses have relatively few lenses, which should promise lovely micro contrast.

  6. Excellent article and excellent discussions. Just want to add my own two cents on the RX1s 35mm 2.0 Zeiss lens – this is easily the best lens i have ever used. I know we cannot compare fixed to interchangeable lenses but still it shows what a fantastic lens you can produce at a decent cost when you go mirrorless. If I remember correctly DXOmark rated it as one of the sharpest lenses ever produced. It will be very interesting to see if the new Zeiss FE 35mm 2.8 will be able to deliver the same quality – if so I will be upgrading from my RX1 to the A7. Any views on this? Would it be an unfair expectation from me?

    • Thanks a lot Ted. There’s no reason why the Zeiss 35mm f/2.8 can’t be as excellent as the fixed lens on the RX1. The RX1’s 35mm has the advantage of not having to incorporate a lens mount so it can be positionned and designed specifically with the sensor in mind. That being said, I do not think the advantage is huge over a mirrorless mount such as Sony’s, which is very close to the sensor. I’ve ordered one for myself in spite of owning a Lecia Summicron-R 35/2 whih is excellent on a D800e (review elsewhere on this site) and should be equally excellent on the A7R.

      Let’s hope some real world tests on finalized products soon ends all the speculation and anxiety 😉 😉

  7. Honestly, I do not think this is a fair review, which dosent mean it is not fair to you. But basically, you are comparing the lenses to Leica lenses mostly, and Leica is well known for their extremely high prices for ‘luxury’ photography. Of course when you are comparing with Leica, everything will look cheap! How about comparing with the normal stable of dslr lenses like nikon, Canon, and the multitude of great lenses recently offered by sigma (eg 35mm 1.4) or tamron?

    I’m sorry, but with a simple 50 1.8 lens going for 100-200 bucks for nikon and canon, it’s just hard to accept a 55 1.8 going for near 1000 bucks. Sure, it’s compact and has better built /characteristics, but it’s 5 to 10 times the price!

    Thank you.

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