Finnish Sony Alpha photographer Toni Ahvenainen interviewed Dr. Michael Pollmann from ZEISS, who is a product manager for the Batis lens family. In this interesting in-depth interview they talk about the Sony Alpha cameras, ZEISS Batis lenses and aesthetics of lens design. Join in and learn more about what makes Batis lens family a future proof choice for many professional and advanced photographers.
Toni: Hello Michael and thank you for this unique opportunity to do an interview with you. I’m sure there are many ZEISS users out there who are interested to know what does the product manager of the Batis lens family think about Batis lenses and the lens design in general.
Michael: You’re welcome.
Toni: While this interview concentrates on the new Batis lens family for the Sony Alpha cameras, I think we should really start from the ‘New Pro Era’ since this is the slogan ZEISS has been using when marketing these lenses. When I heard it for the first time, I immediately thought that it referred to the way the current camera industry is shedding its skin with mirrorless interchangeable cameras. More and more professional photographers are switching over the mirrorless cameras, especially to Sony Alpha system, and what they require are lenses that deliver professional performance – so this is what Batis is all about. But then I thought the ‘New Pro Era’ could also be interpreted from ZEISS’s own point of view. These are autofocus lenses which present quite a difference to ZEISS’s own tradition, and the Batis 1.8/85 even has optical image stabilization which makes it the first optically stabilized lens in ZEISS’s own catalogue. So there is a kind of a double meaning here, at least in my mind. How do you see it, what is the ‘New Pro Era’?
Michael: Your thoughts about the “New Pro Era” just hit the target. Originally it was directed to the mirrorless system segment. With the smaller sensor cameras this segment got already a lot of interest among amateur photographers. When Sony then launched the first full frame mirrorless system, it was evident, that they targeted the even more demanding photographers. The cameras had the potential for leveraging the benefits of a mirrorless system and providing simultaneously image quality of an SLR system. Having such cameras, we were sure, that matching lenses would be needed – that’s the view on the overall photography market. And that was the original idea of the “New Pro Era”.
But, you’re right, from within ZEISS, lens families having AF functionality implemented, mean also a “new era”. Sony opened the ILCEa system to third party lens manufacturers. So we took the chance to develop not only manual-only, but also AF-lenses. When defining the Batis lenses and their functionality, we stumbled over the different requirements and different expectations of different users. As it’s impossible to meet all requirements and wishes of all potential users, we decided to go for two lens families for the same camera system – not being different with respect to quality or price level, respectively, but lens characteristics: Loxia (manual) and Batis (AF), both covering full format sensors. Together with the Touit family, a family of AF lenses for APS-C sensor cameras, we now offer 3 lens families for mirrorless (Sony) cameras.
Toni: This is interesting to hear because there are currently many different mirrorless camera systems challenging the status quo of the camera markets where the DSLR-cameras have traditionally been perceived as an only option for professional photography. In fact, all of them are offering different kinds of innovative technologies for the photographers of new generation. Why did ZEISS decided to collaborate with the Sony’s Alpha system and what are its strengths from the ZEISS’s point of view?
Michael: Currently the mirrorless system segment is the most innovative one. When we thought about the right camera system to target, several aspects were taken into account:
– We wanted to choose a camera system with a large image sensor format. Even though there are very good camera systems with smaller sensor formats in the market, the potential for high image quality is the highest with larger formats.
– We wanted to develop an AF lens family. Therefore we looked for a system, where the camera manufacturer would be willing to share the needed information.
– Sony showed an immense pace in introducing new models. This showed us the priority and seriousness, which Sony puts in this system. Furthermore, new models clearly showed improved or new features, reassuring that this system is at least one of the most innovative ones.
– Last but not least: we have already a very strong cooperation with Sony in developing lenses. And by the way, this partnership reaches its 20th anniversary this year.
Toni: Now there are currently three lenses in the Batis family and the latest addition is the super wide angle ZEISS Batis 2.8/18. The first two lenses (Batis 2/25 & Batis 1.8/85) have received a great reception and they have said to offer exceptional image quality characterized by the high contrast and extremely high resolution across the whole image field. However, there were some issues regarding the delivery of these lenses and many photographers have had to wait quite a long for their copies. I’ve understood that high performance lenses are more demanding to put together as they require higher manufacturing tolerances. With the current high performance camera bodies with up to 42 megapixels it has become increasingly difficult not only to design, but also to manufacture lenses that are up to the job. Is this one reason behind the delay or are there other factors involved?
Michael: That’s correct. It’s one thing, to design theoretically a lens, but another thing to transfer this theoretical design performance into a real product. I’ve seen a lot of superb theoretical, optical designs, which looked like hot-sellers – until our manufacturing analyses showed, what we had to expect as real-world lenses.
Nevertheless, there was (and is) another reason for the high delivery times we had in the past: extremely high interest in the lenses. To be honest, we have been overwhelmed by the interest in the lenses. We simply underestimated the need for the lenses. We had to increase our output several times before we were able to meet the demand. But this should now belong to the past. Recently our output had been significantly higher than the stable order income, allowing us to fulfill open orders.
Toni: What’s the situation regarding the Batis 2.8/18? As it is a new addition to the Batis family should we expect shorter delivery times than with the other two Batis lenses?
Michael: For sure we have been clearly better prepared, when the third lens entered the market. Nevertheless we faced a backorder situation in the beginning. That was processed and currently delivery is on time and meeting incoming orders. A specific retailer might have run out of stock and is now waiting for replacement. But such a situation should be only a matter of days.
Toni: While we were discussing about the lens design I would love to ask something general about it as well. One thing that has baffled me in lens design relates to rendition of the different lenses: how are the aesthetics goals achieved for each particular model. I understand that there are certain design objectives that come, for example, from the physics or from the marketing. For example, the Batis lenses cannot exceed a certain physical size or otherwise they don’t align with the expectations of their users who prefer relatively compact mirrorless cameras. But where does the aesthetic objectives come regarding the lens rendering? Are they solely determined, for example, by the chosen optical design and its limits (Planar, Distagon, etc.)? Or is there a taste of ‘what is desirable’ involved which is then translated to optics by gifted engineers? Do you make prototypes of the lenses to explore the selected aesthetic design choices?
Michael: Several aspects have their impact: partially it’s design philosophy, partially it’s evolving out of the design optimization, partially it’s the design types, partially it’s the used technologies/materials, etc.
My first impulse, hearing your question, was: hey, that’s for sure an interesting question. I can give some in depth-information – but now, having thought a bit about the answer, I still think, that it’s an interesting question, just that the answer is nearly impossible to give. It’s a combination of several aspects. We’re trying to cover more and more of these aspects already during the design phase. Still, checking and fine tuning prototypes is one of the major tasks during a lens development.
One should also remember that aesthetics or “look” are quite subjective characteristics, especially when it comes to the question, what’s better: e.g., the sharper image or the more “pleasingly look” for a portrait lens? I’d say, we are targeting a pure look: highest optical image quality, minimized aberrations. It’s the idea of giving the photographer the best possible image, in order to give him the chance to apply his creativity. There are of course fine details in our design strategies that affect the ZEISS aesthetics, but they are highly confidential.
Toni: Now one technological innovation that has really gotten a lot of attention in the Batis family is of course the OLED-display incorporating a digital depth of field scale. Not only is it very clear to read and you see precise numbers down to two decimals, but it also factors the sensor size and pixel pitch which affects the depth of field – something which traditional depth of scale can never take into account. What’s the story behind the OLED-display? Was it developed by request or is it purely an in-house innovation?
Michael: To be honest, it started out of a technical discussion about how we should implement the typical engraved scales. We had been in a discussion, whether it would be possible to implement fully the desired list of functionalities. Taking into account, that we had to use focus-by-wire for the AF-functionality, the question came up: when we are digital anyhow – why can’t we use a digital display? The focus shifted, from: “We’ve to use a specific technology, how can we enable the same classical touch and feel?” to “We’ve to use a specific technology, how can this be used beneficially for the user of the lens?”
Oh, to answer the question you really asked: yes, it’s an in-house innovation. It was not requested – and I had some discussion to overcome, before it was accepted…
Toni: The other specialty that characterizes the Batis lenses in ZEISS’s own catalogue is the autofocus. Of course the lenses from the Touit family also have this capability, but when introduced earlier they were received with a bit of mixed feelings because of slower focus acquiring speed and a bit noisy motors (though they evolved a lot with the Touit 2.8/50M). Now it’s a whole different story with the Batis lenses which are equipped with a very quick and totally silent focusing technology. Has this been a special challenge for ZEISS which has been known for making only manual focus lenses?
Michael: Yes, it was a special challenge for ZEISS. Other companies (often much larger than our department) worked already 10-20 years on AF technology. That’s a lead, you can’t easily catch up with.
On the other hand, we had the advantage, that we didn’t have to develop completely new technology. Thus we were able to quickly improve our performance. As a result, the Batis lenses don’t have to hide behind any competitor lenses.
Toni: Since the Batis lenses are aimed for advanced and professional photographers they also incorporate weather and dust sealing. Weather and dust sealing is currently a bit controversial topic since many manufacturers are too vague when defining what their products can or cannot take in terms of rain and such. How does ZEISS test Batis lenses for their weather and dust sealing?
Michael: For the water resistance tests we have our own environmental test lab on site, for the dust resistance we use an external test lab. Both tests are done in quite harsh tests. The lenses are directly exposed to water (simulating rain) and dust. After the test, it is checked, whether any water or dust can be seen within the optics, whether the functionality is o.k. and whether any water reached electronic parts, which might lead to malfunction after later corrosion processes. For me personally the dust test was especially interesting. The “dust” used in the test is so extremely fine – I’d not expected, that a lens would pass this test. A grain of sand is huge in comparison to this dust. It’s more like fine powder. The lens sits in the test chamber and the powder swirls around the lens for hours. After the test is shut off, the powder settles and at the end the lens is totally covered in powder. I cannot think of any real life situation, which comes close to this test. Maybe a sand storm, but that’s probably not the typical situation, when you expose a lens to the environment… Nevertheless Batis lenses passed all the tests.
Toni: While the Batis lenses are aimed for professional photographers, they are still not the only lens family in ZEISS’s catalogue to do so as there is also Milvus for the DSLR-cameras. Do you think it’s justified to place the Batis and Milvus on the same level as separate lens families? What I mean is that the Milvus family, with its classic and new designs, has been a ground breaking product family for the ZEISS. It represents the cumulative knowledge of outstanding lens design from many decades and it is, to be frankly, a benchmark for many other manufacturers out there. Is the Batis family designed to be its counterpart in the mirrorless world?
Michael: Yes. Of course there are evident differences: Milvus are purely manual lenses, all mechanical parts made out of metal. Batis are AF lenses with a combination of metal and plastics. But from the image quality point of view, we targeted Milvus and Batis to reach the same performance level. With Batis we wanted to bring the well-known ZEISS full-frame DSLR lens quality to the mirrorless world. We wanted to provide lenses to the Sony a system, which matches the expectations of professional photographers.
Toni: Let’s talk a bit more about the latest addition to the Batis family, the ZEISS Batis 2.8/18, which is a relatively fast super wide angle lens and offers an angular field of 99 degrees. While many users have been waiting for high quality wide angle lenses for the Sony Alpha system, there are now in fact two different options from ZEISS since you introduced the Loxia 2.8/21 just some time ago before the new Batis 2.8/18. Why did you choose 18mm for the new Batis lens?
Michael: We see the Batis and Loxia lens families as two families with different characteristics, addressing different types of photographers. Most obvious differences are the small and compact size of Loxia lenses in contradiction to AF and OIS functionality of Batis lenses. It’s really dependent on the photographer, which lens type suits his needs best. Thus the first family concepts are made independent of each other. With the Batis 2/25 we enlarged the available FE mount lenses into the wide-angle region. But 25mm is only a moderate wide-angle lens, a step into the extreme wide-angle region was targeted. 18mm seemed to be the best focal length to have a clear difference to 25mm with still a reasonable lens size.
And if you put Batis and Loxia in one box, you now have a wide-angle choice of 25mm, 21mm and 18mm. Not too bad.
Toni: You said the Batis 2.8/18 is a definitely a step into extreme wide-angle region. Now, there lives a common conception that the Sony E-mount, with its short back focal distance, would be a particularly difficult design target for extreme wide angle lenses. Some have even claimed that because of E-mount it would be impossible to design high performance wide angle lenses for the Sony Alpha system. Did you had any specific difficulties during the development of the 18mm?
Michael: I would describe the situation of designing an extreme wide angle lens for Sony’s E-mount different: due to the shorter distance from sensor to camera mount, the “common” design concepts used in lenses for DSLR cameras are no option. You have to start differently. And, of course, in the beginning you don’t know, whether it works out or not. Fortunately it did with the Batis 2.8/18.
One difficulty in general is, to meet our own standards regarding image and build quality level. That always takes time and also discussions, as it’s often the question, whether it’s worth to still look for an even better design solution. The situation for Batis 2.8/18 was the same. Especially as the first two Batis lenses have set such a high quality level, which we want to keep it with new Batis lens types. Thus the quality level was set as mandatory, even though 18mm is clearly a more extreme focal length, making it harder to meet specifications for the optical designers.
Toni: Based on some reviews the Batis 2.8/18 is said to be ‘one of the finest 18mm lens ever to be produced for full frame cameras’ (I’m quoting the Lloyd Chambers here). This should definitely raise the eyebrows of many landscape, architecture and astro photographers out there regardless of their chosen camera system. While in fact the whole Batis lens family is characterized by very high optical performance across the whole image field this also seem to be visible in lens diagrams. Especially the wide-angle lenses like Batis 2.8/18 and Batis 2/25 contain multitude of double sided aspheric glass elements plus other special glass. When studying these complex designs I couldn’t help noticing that there really is no other lenses in ZEISS catalogue which contain similarly complex optical paths. Are these previously unseen designs a new innovative approach in ZEISS’s own catalogue or do they represent a knowledge that has trickled down, for example, from the Otus family of lenses?
Michael: Using lenses made out of special glass material and lenses with aspherical surfaces gives you more “freedom” in the design. You can correct better the optical aberrations, without ending up with a ridiculously outsized lens. For the Batis lenses, size of the lens was and is an important aspect. The lenses should “fit” to the camera proportions. Therefore we allowed more aspherical surfaces, in order that lens size is still acceptable, fulfilling the targeted image quality. But we had long and tough internal discussions. Aspherical lenses still tend to have higher manufacturing tolerances, with the higher potential for quality losses during manufacturing and assembly. It took me quite some work to convince my colleagues to go for 4 double-sided aspherical lenses (or was it rather persuasion?). And I had some hard nights before prototypes were at hand, fortunately showing the image quality we targeted for.
Toni: Time for the last question and since we have been discussing about the Batis family, it naturally relates to the future. Now, I have to say that the Batis family have been extremely exciting because it has successfully questioned the idea that the professional image quality is only available through a certain kind of tools which has traditionally meant the bulky DSLR-gear. With Batis ZEISS has created a compact, coherent and uncompromised lens family for those Sony Alpha users that do not want to commit to traditional DSLR-sized setups. This of course emphasizes the advantages of the Sony Alpha system, but from the larger perspective it is also connected to the current mirrorless shift in the markets of camera technology. In other words, the concepts are changing. What is your prediction of the state of camera technology in next 10 years? Will there still be mirrors and what kind of new innovations are there waiting for us behind the corner?
Michael: Unfortunately I don’t have a crystal ball showing the future. Therefore I can just give my personal and highly subjective opinion without any guarantee for correctness: I expect the majority of the cameras to be mirrorless. Even though I think, that the differentiation between mirror and mirrorless should or will disappear. It’s more a technical description of the camera concept, less an application or customer benefit. Do I get automatically better images, if I’m using a mirrorless camera? Or do I care, whether it’s an optical or electronical viewfinder (in case they show the same performance)? Mirrorless has gained a lot of attention, especially because of the prospect of smaller system size. It is true for mirrorless cameras, yes, but lenses (unfortunately) have to follow the same physical rules. The size of the average system is for me less a question of mirror/mirrorless but customers focus. In first approximation image quality comes along with a larger size. If image quality is clearly the key, the mirrorless system size gets closer to today’s DSLR systems. If size has priority, the average system size will be smaller.
Toni: Thank you, Michael!