For cinematographer George Steel, the key to “The Aeronauts,” director Tom Harper’s $80 million film starring Felicity Jones and Eddie Redmayne as balloonist-scientists who soar to 35,000 feet to break records in 1862, was to take the viewer along for the ride.

When Variety visited the cast and crew on set in London, Steel was crouched into the corner of the 8-by-8 balloon basket. “Tom was adamant that it should feel like the camera was in the basket with them,” says Steel. “[Most] of the shots didn’t deviate from that. There are a few shots on a crane from outside the basket, and then we used a helicopter. If you couldn’t do it for real, Tom wasn’t interested.”

Some of the first shots were of Redmayne and Jones at 2,000 feet above the English countryside, where Steel directed helicopters and drones to capture aerial shots without VFX. Jones’ stunt double, Helen Steinway Bailey, performed the daredevil moves that Jones’ character, Amelia Wren, had to do to keep the balloon on track.

To create the look of the highest-altitude shots, the production moved to a West London soundstage, where the team built a grounded balloon and basket with the lower-third rig on one half of a stage and the summit rig on the other, both with a blue screen and with weather pumped in. They assembled a usable 80-foot helium-powered balloon, which was economical and provided a silent ride.

Christian Huband, co-production designer with David Hindle, got expert assistance in designing the soundstage balloon. “We needed it to be rated to fly, so we enlisted the help of [hot-air balloonist] Per Lindstrand to build it,” says Huband. Evoking the design of the era, they had a scenic artist paint huge, colorful panels, which they photographed and printed, applying them to the balloon’s skin.

To make it look like the aeronauts were up at 35,000 feet, Steel wanted the shot to appear almost space-like, using a crisper focus on the basket to suggest less atmosphere. “We swapped lenses,” he says, to allow for more light. “On Earth, we were 2.40, and then as the balloon goes away from us and they’ve taken off, we actually open up to 1.85.”

For Steel, one of the most exciting parts of working on “The Aeronauts” was the lighting. He tested ways to replicate the harshness of the sun, including severe Xenon lamps, but settled on a 5600K HMI. “The problem is, you can’t dim that,” he says, because it changes the color temperature from a warm yellow to a cold blue.

Using gel filters, the crew created different gradients of diffusion that would go from frosted to clear in front of the light, Steel says. “But the lights were burning through the gel because they’re so hot.” Eventually, the filmmakers enlisted the help of equipment house Panalux in London, which came up with a square-frame box that snapped on the front of the lights. “We filled the room full of smoke, which acted as a filter and diffused the light,” explains Steel. “It was very DIY; I loved that about this film.”