Tom Keller’s Journey into Cinematography: In-Camera Visual Effects

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Hi guys! Today we are pleased to interview a long-time friend and contributor of Filmmakersworld, Tom Keller.

Tom is a director of photography and a member of the German and Swiss Cinematographer Society. He teaches cinematography at Film University Babelsberg and is based in Berlin. He seamlessly blends technical expertise with artistic flair, pushing the boundaries of storytelling with each project.

Tom shot the feature film “The Exposure” by director Thomas Imbach, which will become one of the first completely In-Camera Visual Effect shot feature films for cinema when it releases later this year.

‘The Exposure’ is now part of the ‘Goes to Cannes‘ selection at the Cannes Film Festival 2024.

Tom’s expertise in blending reality with the virtual realm has redefined cinematic storytelling.

In this interview, we’ll delve into the technique of in-camera visual effects and see how he handled the shooting of the project “Embers,” which he directed himself. You will have the opportunity to learn about his creative visionary approach to cinematography.

Tom Keller
DP Tom Keller working with SFX Supervisor Marcel Stucki on a fire scene. (Photo by Ela Schaich, courtesy of Filmstudio Basel.)

Hi Tom! Congratulations on your recent movies! Before we start this interview, could you tell us how you began your journey?

Thanks for having me. I’ve wanted to become a filmmaker from a very young age. I think I bought my first Sony DV camera when I was in 4th grade, after saving money for a long time. Since I didn’t have any connections in the film industry, studying film was my sole opportunity to pursue cinematography. I gained valuable experience during my time at film school at Zurich University of the Arts (ZHdK), as well as while working as a lighting technician and gaffer on commercial shoots.

In 2012, I graduated with a particularly unique film that I shot simultaneously with the ARRICAM Lite (LT) on 35mm Kodak film and digitally with the ARRI Alexa Classic on a 3D rig. This resulted in two identical films that only differed in the recording medium.

Tom Keller
DP Tom Keller shooting his graduation film “Parachutes” on an ARRICAM Lite and on anARRI Alexa Classic mounted on a huge 3D rig. (Photo by Oliver Christe, courtesy of ZHdK.)

I was captivated by the process of repurposing a mirror rig, originally designed for 3D film production, to explore new creative ways. I see this as the catalyst for my ongoing exploration of new possibilities and the blending of traditional techniques with modern ones.

And then?

Following numerous short films, a documentary, and some projects as a 2nd Unit DP, I was approached by producer and director Alex Martin. He came across an article I wrote about greenscreen usage on my blog and was impressed by my expertise. Shortly thereafter, we began collaborating on a TV series. Our primary objective was to find a cost-effective method for shooting in remote locations while minimizing production time.

Tom Keller
Tom Keller and his crew are shooting scenes with doubles on a hard-to-reach glacier in the Swiss Alps. (Photo courtesy of European Star Cinema.)

Neither Unity nor Unreal Engine could produce photorealistic real-time images at the time. As a result, we primarily utilized plates shot for use in the studio with the actors and filmed on Location with doubles. However, we extensively used 3D environments for the previsualization of nearly every shot, a practice I grew to embrace. This proved invaluable when working on Virtual Production projects later on.

Actor Vincent Leitersdorf in front of a rear projection wall in the studio. (Photo courtesy of European Star Cinema.)

Since then, I shot several feature films and documentaries for both cinema and television. Almost all of my recent projects have involved Virtual Production in some way, and with each project, I’ve strived to push the boundaries of what’s possible a little bit further.

What inspired you to explore integrating real-world elements with virtual environments in your work, as showcased in “Embers”?

I’ve always been fascinated by 3D worlds; the ability to create something from scratch is just great. In filmmaking, we’re constantly trying to build worlds, and since 2022, with the Unreal Engine 5, it’s possible to render these worlds in real time at almost photorealistic levels.

These new possibilities brought director Thomas Imbach to undertake his feature film “The Exposure” as a VP project, allowing me to delve deeply into ICVFX once again. For this project, we selected the ARRIFLEX 416 and shot on Kodak Vision 3.

Prior to this, we had tested both the ARRI Alexa 35 and the SONY Venice 2 for the project, but the 16mm grain and the characteristic of Kodak Film greatly helped merge the virtual world with the real one, and celluloid was also the perfect fit for this story.

Tom Keller
Tom Keller in front of an LED wall, testing the ARRIFLEX 416 for the project “The Exposure”. (Photo by Dominic Heim, courtesy of Filmstudio Basel.)

After nearly 8 months of pre-production, we shot the film at Filmstudio Basel at the end of 2023. During filming, I discovered a variety of new creative possibilities, some of which didn’t quite fit that movie. Therefore, I decided to write my own project that maximizes the use and integration of virtual environments.

And “Embers” was born…

Thus, “Embers” was born. We filmed with virtual fire on the screen and real fire in the studio, virtual sets and no set pieces in the studio. Only individual props such as tables, chairs, glass, and single tree trunks were used.

Additionally, it was important to me to keep the crew as small as possible to demonstrate what can be achieved even with the smallest budget.

Still frame of actor Christoph Keller of the movie “Embers”.
Tom Keller
DP Tom Keller on an almost empty set, capturing the OTS shot of Christoph Keller for “Embers”. (Photo by Alex Martin, courtesy of Filmstudio Basel.)

How has the concept of “In-camera VFX” revolutionized your filmmaking process?

I’m already considering while reading a script, whether it might be worthwhile to implement parts of it as Virtual Production and ICVFX. It’s important to understand that VP is not simply a green screen replacement, and Virtual Production does not equate to In-Camera Visual Effects.

While that’s always the goal, in most cases, nothing beyond color grading rarely needs to be done in post-production. In the worst-case scenario, Virtual Production might look worse than a green screen and VFX, yet cost significantly more. Therefore, it’s crucial to be cautious about what is possible.

DP Tom Keller and 1AC Christina Welter taking a shot of Stuntman Roland Siegenthaler (Photo by Tobias Sutter, courtesy of Filmstudio Basel.)

In both “Embers” and “The Exposure,” however, there is no post-production processing of the material, meaning that the DP has the greatest influence on ensuring that the result looks good. ICVFX also gives me much more control over the images.

Otherwise, as DPs, we’re rarely involved in post-production and VFX work. Sometimes, we’re even lucky if we get enough color grading days allocated from the production.

What’s the reason for this?

From a production viewpoint, it’s likely about money. But it could also be that some DPs aren’t the best for VFX work. I’ve always been keen on VFX, using programs like After Effects, Nuke, and Blender before and during my studies.

Maybe I just see things a bit differently and really enjoy visual effects, which some DPs might not. But, honestly, it’s not essential; some of the most famous DPs probably never used VFX software and still made fantastic VFX movies.

Can you walk us through the technical challenges you encountered while implementing in-camera VFX techniques and how you overcame them?

There are numerous technical challenges involved. The advantage is that most problems can be spotted immediately on set. Issues such as bad color rendition of LED, artifacts, genlock problems, viewing angles, tracking latency, moiré, and many more arise.

Each camera sensor reacts differently to the wall. It’s impossible to address them all here, but for those interested, I’ve written two extensive blog posts about them, which you can find on my website

There are countless factors to consider, and for that, you need a skilled VP supervisor who has experience working in that specific studio. In general, it’s crucial to conduct extensive testing beforehand, which is easier said than done, especially in large LED volumes where daily rentals can range from $50,000 to $100,000.

It’s also not always easy for some crew members or directors to understand how the virtual and real worlds interact, especially if they’re older and haven’t played complex computer games themselves.

You need a really good sense of how 3D space works, especially when you’re working without real set pieces and rotating the background for shot/reverse shot while keeping everything else on set still.

Tom Keller checking a replay on a calibrated monitor. (Photo by Ela Schaich, courtesy of Filmstudio Basel.)

Having a colorist on set and calibrated monitors is also essential. Relying solely on your eyes isn’t reliable because the spectral sensitivity of Kodak film and how the CMOS sensor perceives colors differ greatly from how our eyes see them.

Therefore, meticulous testing is necessary when shooting on celluloid, and having a reliable laboratory is crucial. As a side note: Wes Anderson recently included VP scenes shot on 35mm film for his next feature film.

It’s fascinating how combining the most advanced technology of Virtual Production with the oldest technology creates the most interesting outcomes.

What advantages and limitations have you experienced while using virtual production techniques in your projects?

I primarily see the advantages on the production side. With my approach, which involves minimal set construction, we can shoot a vast array of scenes incredibly quickly. Take, for example, this sequence from “Embers,” which can be shot in a single day.

Overall, I believe that VP is also intriguing for the independent film industry, even with limited resources. For “Embers,” we utilized VIVE Mars Trackers, which, for the price, offer remarkable precision and are more than sufficient for our needs.

The Unreal Engine is currently free, LED lighting units are becoming more affordable, and large flat screens or, in our case, rear projection can work as well. Of course, there are also disadvantages, most of which are related to the size of the studio.

We can’t follow a person for several minutes. Although we’ve solved this with the treadmill, which controls the movement in the Unreal Engine, I still don’t have the possibility to start a shot with walking feet on the ground and then pan up to the face, as I could do outdoors in nature.

Actors also aren’t as free as they are on location. However, VP still represents a significant advantage over a green screen.

Could you share some insights into the collaborative process between the cinematography team and the visual effects team when working on projects like “Embers”?

In big VP projects, you usually work closely with a Virtual Production Supervisor. They lead the team responsible for creating the virtual world you’ll be filming in. The Visualization Department, which, among other tasks, handles Virtual Blocking and prepares everything so that I can execute my shots in the virtual world with the director.

Then there’s the Virtual Art Department (VAD), which includes the VAD Supervisor along with their VAD Lighting Lead, VAD Environment Lead, VAD Realtime Artist, and so on. Additionally, there are Stage Operations, which include roles like the Unreal Engineer, Camera Tracking Technician, LED Engineer, Virtual Gaffer, On-Set Colorist, Video System Engineer, and more. 

On smaller projects where budgets are tighter, the DP or sometimes the VFX Supervisor may take on the leadership role. In “Embers,” I had the creative lead and shared the technical responsibilities with the VP Supervisor, Marlon Candeloro.

He focused on what appeared on the screen, while I made sure everything was captured correctly by the camera. Since we had previously collaborated, we had a well-established mutual trust, which is crucial not only for such projects but for any collaboration.

As a cinematographer, how do you collaborate with directors and visual effects artists to achieve the desired aesthetic and narrative impact in your films?

It depends a lot on the director. Luckily, I’ve usually had directors who recognized my expertise early on, and I’ve been given a lot of creative freedom.

Generally, I start discussing the script, the theme of the movie, and the narrative perspective with the director. I always try to understand their vision. It’s teamwork, but in the end, the director ultimately has the final say.

Tom Keller
Tom Keller directing the next scene of “Embers”. (Photo by Tobias Sutter, courtesy of Filmstudio Basel.)

Working with VFX artists or VFX supervisors (not to be confused with the VP supervisor) is a bit different. They act as consultants on set and take over the creative work in post-production.

I usually have less influence, especially on CGI shots. Because of this, I naturally prefer ICVFX and the VP workflow where I have a more creative influence.

Before we wrap up, can you tell us about your upcoming projects? What are you currently working on, and what new challenges are you facing?

I’m currently in the preparation phase for a documentary film that will also heavily utilize VP, but I can’t disclose more details at this time. Later in the year, I have another feature film planned, but my main focus and also my new challenges at the moment is on Film University Babelsberg.

I’m preparing a VFX and VP seminar for June and an action seminar for next semester, along with project supervision and administrative tasks, which take up a lot of my time. However, I enjoy sharing my experiences.

I also learn a lot from the students and other lecturers. I think what you’re doing with Filmmakersworld is also fantastic. You promote mutual exchange and provide a platform for young filmmakers to learn. I think that’s great.

Thank you so much Tom for sharing your experience and these valuable insights with the community!

If you wanna learn more about Tom Keller, go check his website

See you at the next exclusive interview we have in the loop and if you missed our latest article, go check it out!

Much love!
FilmmakersWorld Team

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