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30 Days of Batis 2/40 CF
A Batis adventure and a personal photography scratch book with a creative touch.
Sharing a new post every day for the next 30 days.




Day #22 – close focus performance

Toni Ahvenainen

Sony A7 & ZEISS Batis 2/40 CF – f/8, 1/60sec, ISO800, raw Photograph by Toni Ahvenainen

Sony A7 & ZEISS Batis 2/40 CF – f/8, 1/60sec, ISO800, raw
Photograph by Toni Ahvenainen

EDIT [9th December 2018]:
ZEISS has informed that they are working on a software update that will allow users to work within a larger focus range with a wide-open aperture. This means that when working at close distances the aperture will close down less than what is described here. The update will be available to download for free from the ZEISS website in early 2019. ZEISS will notify all registered customers via email.

Okay, here is another example of Batis 2/40 CF taken into its minimum focusing distance. The small pine cone which I put on a stump was about 4 cm (1.57 in) long in real life. If anything this picture shows the high optical performance at close distance and I can definitely see a similar micro contrast here as I have seen with many stopped down shots with normal shooting distance – even considering that this picture was taken hand held at ISO800. The small blog post picture doesn't really do justice for it, so you can explore the full size version here.

The ZEISS's press release says that the Batis 2/40 CF has 'a floating lens design for consistently high image quality across the entire focus range'. As I've already explored the image quality at infinity distance (it's superb, see it here), I got very curious to see what would it be at the close focus distance. So, below you can see a front plate of an old 19th century cash register which I thought would make a good subject for the evaluation of the close focus performance. Finding a setup for close focus evaluation was actually harder than I initially thought. Preferably it should be a flat surface with some interesting textures and one should setup the camera in perfect perpendicular angle against the surface. Now, the national cash register might not be the flattest possible subject and I didn't have any extra ancillary to setup the camera (other than tripod), but it does provide some textures and should give us at least some impression of the performance (and I did the setup twice so I could pick the better one). And again, I want to remind you that this test was done with a low end first generation A7-body, the newer bodies, such as A7RII and A7RIII (both of them without anti-aliasing filter), should give you even better results. So, let's see what we got.

When focusing really close under 1 m (3.28 ft) the Batis 2/40 CF closes its aperture a bit. I took these test pictures from about 40 cm distance (1.31 ft) and it means that the aperture is closed about one stop at this distance (see better description here). So because of this behavior, I've marked first the camera setting and then the real aperture in brackets. Every test shot is focused on the embossed 'S' letter at the center, so the focal plane is always at the same level as the 'S' letter (and the treated surface beneath the letters is naturally outside of the focal plane, but comes into it as the aperture closes down). Now, if we look at the big picture we'll see that right from the start there is already a very nice contrast to begin with (this is at f/2 and it looks very solid). But the 100% crops are really the one that look pretty astonishing: the f/2 already looks very good and I can only see a very little improvement going from f/2 to f/2.8. After then the performance is very solid no matter what aperture is used, especially considering the fact that there is no vignetting nor chromatic aberrations. This is a great result!

All in all, what impresses me the most is the fact that Batis 2/40 CF delivers same consistent performance in close distance as it does at infinity distance. It would be easy to perceive the Close Focus ability like some sort of 'a bonus feature' that happens to be there because it is nice 'side-effect' of the chosen optical design – this is how the short minimum focusing distance is often understood, as a secondary feature. But on the contrary, it's evident that ZEISS has invested in Close Focus performance as much as they have perfected the optical performance at infinity distance. This makes the Batis 2/40 CF a very consistent and high performance lens regardless of the chosen aperture or focusing distance – and as such it is a kind of unique design.

It really looks like this is again an example of a great technical feature to which Oberkochen has put a lot of effort, but it isn't emphasized in any way in their marketing materials. This really is typical ZEISS: they put a lot of technical effort to for best possible image quality (like advanced manufacturing technology, rare and costly glass or ambitious optical designs), but these details are very rarely even mentioned in their marketing materials. Normal lens manufacturers and their marketing departments would have produced 3D-rendered videos, new letter abbreviations and such. But the real question is: why don't they drum about these features if they want to sell their lenses?

Well, the explanation is that ZEISS has a very specific philosophical approach to lens design: they think the lenses should be fine crafted tools for photography and as such they should be as transparent as possible to give the photographer as much freedom as possible. In other words, technology should not step between photographer and his subject – so they don't want photographers to worry about corner sharpness or get caught in comparing if technology x is better than technology y. They've got a point here, because none of this really belongs to 'real photography', but the irony here is of course that it is  precisely what many enthusiast do with their charts and tables (a clever self reference here). ZEISS thinks that photographers should trust their premium quality without them explicitly explaining all technical decisions. This is really the core aspect why I like ZEISS, a kind of intellectual stance rather than just going full on sale. But hey, let's admit it: there's also a bit of a exclusivity at play here too because ZEISS wants to differentiate itself from other manufacturers by saying 'our lenses are premium and therefore we don't need constrained technology names or cryptic letter abbreviations like lesser manufacturers' and it comes a bit with a pricing too. So, they don't always advertise their technical features and excellence, but they do design their lenses to be on top of things. The consistent optical performance of the Batis 2/40 CF is just one example of this.