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