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Archive republication: This article was originally published on 17 December 2020. It has been translated into English and lightly updated for clarity while preserving the original reporting and context.
This article originally appeared in DIGITAL PRODUCTION 06 : 2020.
It may have been a while since the Wachowski Brothers made film history with The Matrix, but the bullet time effect is still elaborate and spectacular. Martin Hoppe assembled his first rig with 25 cameras 7 years ago and travelled with different variants, mainly at trade fairs. Through productions that address Instagram, YouTube and the like, photography and film have moved closer and closer together. They have acquired the flavour of events, shoot&post in the professional corner, so to speak. Many producers, photographers and filmmakers have gone along with this drift to a greater or lesser extent. And some have even switched completely to social media events. This is how Martin Hoppe, the operator of Zeitfeld, ended up in the event sector. The DSLR camera fields he designed and programmed himself were originally intended to create the bullet-time effect for high-end TV and cinema productions. Bullet time has been familiar to many since “The Matrix” at the latest: several cameras trigger simultaneously, the film clips from the individual frames then lack time, Trinity and Neo hang frozen in the air in a fighting pose. Movement without time – something that can’t really exist.
Martin was a programmer for business applications, his brother Christian is an internationally active photographer who photographs brands such as New Yorker, Basler and Marc Cain under the artist name Seregel. At some point, Christian had the first digital edition of Vogue on his iPad, which featured animated photos: a male model, upper body exposed, with shark teeth around his neck. When you tapped the teeth, they rattled and wiggled with a sound.
Christian realised that a new era was being ushered in here: moving photos. He started looking around for cool ideas and found the bullet-time effect. He then called Martin to see if he could build him something like this. He did some research and started building a camera array with Powershots. Canon Powershots are not actually capable of being triggered by an external signal, but this problem could be elegantly circumvented. As the operating system of the Powershots is hacked (CHDK = Canon Hacker Developer Kit), the cams can be equipped with functions that would otherwise be complicated or expensive to realise. For example, a Powershot can trigger automatically when something moves in front of the camera – integrated motion detection on a €250 camera. With CHDK, it was also possible to misuse the battery’s temperature sensor as a remote trigger input. As the cameras were connected to continuous power anyway, this was freely available.
In the beginning, it happened from time to time that all 50 memory cards had to be removed, individually recorded and reinserted due to an error in the programming. Soon, however, it was possible to distribute the underlying software to the cameras via USB hubs, some of which were stacked several times. After this breakthrough, things moved quickly: the cameras could be read out and, above all, controlled by software. White balance, resolution, exposure time, aperture and download – everything could be controlled centrally. The first camera field was successfully tested during a production for Marc Cain. Zeitfeld was born.
50 Camera Rig
In the meantime, Zeitfeld has advanced the technology to such an extent that the sequences come out of the computer ready stabilised immediately after the shutter release, using RAW, with grading and, if desired, also with input and output sequences from high-speed cameras, i.e. slow motion. After the request from an agency could not be realised because the JPG quality of the power shots was not sufficient, the construction of a second-generation camera array was started. The Powershots were partly built into a battery-powered, rollable, steam-punk-style rig for guerrilla actions and mini-events. The new camera arrays now consist of DSLRs, which are also connected via a much faster Gigabit Ethernet.
DSLRs are not built to react in a truly time-critical manner. Whether a camera reacts 0, 2, 10 or perhaps 40 milliseconds after receiving a trigger signal is not technically described anywhere; worse still, the cameras are not consistent. Zeitfeld’s systems therefore work with mirror pre-release in order to minimise the variations that definitely occur.
Due to their architecture, the camera fields are infinitely scalable without affecting the speed: whether 10 or 300 cameras, 20 or 6000 MB, the download time remains the same, it corresponds to that of one camera. Within seconds, the images are on the computer and a finished preview is running on a monitor. This makes working on set relaxed and efficient.
The system is open to all camera brands, including smartphones, as long as the devices support PTP, the standard for transferring images. Sensors connected to GPIO ports, such as light barriers or sound detectors, enable precise triggering or triggering with a delay of 35 ms, for example. For example, a ball can be placed in a light barrier and triggered 35ms after it has been shot. The system can also emit signals to trigger an action, such as an explosion. And because the software is available in source code, even unusual requirements can be realised. For example, the possibility of a double exposure was created for one job: first exposed at 1/200th, then again at 10 seconds, for example. This made bullet-time images possible, to which a light painter added dazzling light sculptures that seemed to hang in space like real objects. It is now also possible to trigger the cameras with a time delay in order to achieve a slight slow-motion effect or to simulate a normal tracking shot at crazy speed. The technology has become so fast that production formats aimed at direct streaming to social media channels are now also possible – even from the studio. A major sporting goods manufacturer, for example, organised a prize among store owners for the best bullet-time concept. The winners were invited to Berlin for a photo shoot and, of course, treated to some delicious food. Customer loyalty. The finished sequences were sent from the studio to the social channels, a kind of pop-up shoot with bullet time.
The fact that the results can be instantly streamed as interactive images on smartphones also caught the attention of the event industry at some point. For the opening of the BIKINI House, a mall next to the Gedächtniskirche in Berlin, 50 cameras were used for ten days to download visitors’ personal bullet-time shots onto their mobile phones. The clips could be scrubbed on the mobile phone screen and immediately posted to friends, who were then also lured to the event.
Advertising was not necessary for Zeitfeld: the audience was so enthusiastic about the experience and the spread was so great that almost every assignment resulted in a follow-up order. And that led to the aforementioned drift towards the event industry. The camera fields became smaller, because an 8-metre ring with 50 cameras is usually too expensive for event agencies looking for a Photobooth 2.0. And the smaller camera fields were buzzing: Microsoft, Adidas, Reebok, Nike, Bangkok, Beijing, Miami.
LuxMatrix
At the same time, Zeitfeld is dealing with the topic of “stopping time” in general. For example, a controller has been developed that creates a completely new type of effect: LuxMatrix. Similar to bullet time, time is frozen to a certain extent, but it is not the viewer who moves around the subject, but the light. The LuxMatrix controller emits a timing signal to which a high-speed camera is synchronised at up to 12,000 fps. A different flash is then triggered for each frame. This results in frames that all show almost the same subject, but with different exposures. In post-production, this can then be processed into a sequence that shows the subject from a perspective with alternating lighting situations. By blending the frames, an effect is created that makes surfaces appear hyperreal and waxy and evokes associations with Madame Tussauds. It’s as if the museum attendant is taking his lamp for a spin around the wax figures. Of course, it can also be used to photograph still objects. The prototype of the controller has already been used to photograph 120 of the world’s most expensive vehicles on the occasion of Grand Basel, a spin-off of Art Basel. The premise for the commission: interactive images. Zeitfeld purchased 27 studio flashes for the project.
High-speed cablecam
As he had already purchased a high-speed camera with up to 30,000 FPS for the bullet time anyway, Martin then had the idea of travelling this camera along a cable system. Initial tests at 30 km/h have already produced interesting results. He is now in contact with a manufacturer with whom he wants to realise speeds of up to 75 km/h. This high speed again creates an effect similar to bullet time. The Cablecam should be able to trigger certain actions, such as bursting a water balloon, via radio using waypoint markings on the cable recognised by sensors at precise points on the journey. This could lead to a new type of spectacular footage. Martin Hoppe is always coming up with something new. He has plenty of time at the moment, because then came corona. Events were cancelled, orders cancelled, requests not followed up. Of course, the rudder cannot be turned around that quickly in the direction of production. The end of this long, exciting journey?
Hopefully not. In order to continue, Zeitfeld would like to integrate itself into a running company, complete with software, technology, ideas, man, mouse and material. A newsletter therefore asked for help in finding a new umbrella under which Zeitfeld could continue to operate. This call for help also reached our editorial team.
The entire bullet-time / photogrammetry technology consisting of cameras, carrier systems, monitors, light and computers with networking and a high-speed camera are now available. The in-house software in source code for camera control and stabilisation, the software on the microprocessors and triggering systems, etc. And on top of that, the LuxMatrix technology and all the expertise with the manpower. All the material produced to date is also included for the acquisition.
Incidentally, Martin Hoppe already harboured the desire to move more in the direction of production before corona: “As nice as it is when visitors look forward to events when they see themselves hanging in the air in strange positions … A staged shoot in which, for example, a swimmer emerges from the water and is literally frozen in a column of water simply does more justice to the aesthetic possibilities of the technology”.
In terms of content, Martin Hoppe is open to many things. “I can imagine both an employment and a permanent, exclusive integration or cooperation with an agency, a photo studio, a VFX company, etc., preferably in Berlin. I would find a company that has recognised the possibilities of the upcoming Unreal Engine 5 for film exciting. That recognises that photogrammetry will become an even more important element in film. Because working on the topics of the future has always been my thing.”
Time field on tour
Especially with this topic, photos can’t really give an impression. That’s why Martin has set up the showreel website http://www.zeit-feld.de/dp for this article. You can also find an interview I did with him online on my post-production tutorial page.
Martin is also thinking about a small tour. If we have enough enquiries by November, he wants to set up his large setup for a few days in a location in Mannheim so that you can enjoy a Bullet-Time or LuxMatrix without a huge budget or travelling to Berlin. The exact dates and prices will be announced on the website.
