As Beatlemania took off around the world, there was a woman standing on the sidelines. Cynthia Powell was John Lennon's first wife, a young woman from The Wirral, England, who fell in love with a musician, before a new kind of fame hit them both. While John's relationship with Yoko Ono is well documented, the love, loss and sacrifice of his first marriage is less well known.

Biographical drama Cyn seeks to change this. Based on her autobiography, rather tellingly called John, the short film subverts the traditional male-dominated narrative to tell Cynthia's story through her own eyes. In 1950s Liverpool, we see the heady early days of her romance, her marriage and the arrival of son Julian, and the subsequent unravelling of Cynthia and John's relationship against the backdrop of the band's stratospheric success.

For cinematographer Tania Freimuth, the project offered the chance to work with director/writer Ben Desmond again – the pair had previously collaborated on the 2017 Second World War film Pitfall – and to give Cynthia her well-deserved voice in rock and roll history.

Faced with a wealth of material and an engaging subject matter, the first task was to choose which parts of the story to tell. "In short form, it was quite tricky to give the film an even feel – without too much of the relationship's drama," says Tania. "It's cherry picking the moments that capture the journey. There were some turbulent times in there and there were some joyous times too."

As the film went into production, the team were faced with the challenges of Covid-19, which meant shooting on location in Liverpool was out of the question. "Suddenly I was presented with a blank canvas, a white studio," says Tania. "That was new for me, as I usually shoot on location."

The white studio setting also forced Tania to rethink the way she would film Cyn. She had originally planned to shoot anamorphic, which was why she had opted for the full-frame Canon EOS C500 Mark II, but as the change to the timeframe made this less practical, she started considering other lens options. "I knew I wanted to shoot full-frame, so I looked at the Sumire Primes, which I've had a bit of experience with," she says. "In conjunction with the full-frame format, they helped me tie in what I wanted to do with the lighting, colour and mood."

Shooting mostly daytime interiors meant devising a sophisticated lighting plan to create shifts in mood from scene to scene. "I wanted the colour temperature to follow the same emotional journey as the story," explains Tania. "We start out nice and warm and peachy, go to a very neutral territory, which then cools off and becomes harder and a bit bluer. I knew these lenses would help me achieve that in conjunction with the lighting plan that I set up with my gaffer."

These three different looks equate to the three stages of Cynthia and John's relationship – the first days of love, a plateauing and the eventual breakdown. Working mainly with three Sumire Prime lenses – a Canon CN-E35mm T1.5 FP X, CN-E50mm T1.3 FP X and CN-E85mm T1.3 FP X, Tania delicately played with their fast apertures to create three distinct cinematic feels to match the couple's shifting emotions.

"In most cases, the Sumire Primes open up to T1.3 or T1.5, and at that point they become very soft," says Tania. "Depth of field gets much shallower, but on the large format it becomes very bloomy, and the quality of the skin is really gentle. That, coupled with the lighting I was planning to use, gives a very romantic, rosy feel. I shot wide open to get that look for the first stage of the film.

"As you close down the aperture, the lens cut gets sharper and more high contrast. You don't have to close it down far – it starts to crisp up just past T2.8. By the time you get to the exteriors [towards the end of the film] we're using T2.8 to T4 to get that hard realism I was trying for."

To reflect the energy of the early stages of the relationship, the first scenes were shot handheld, before transferring the camera to a tripod in the middle, and then introducing some slider moves. "The sands were shifting," says Tania. "By the end there's a lot more movement – they're never standing still."

The Canon EOS C500 Mark II also allowed Tania to shoot in Cinema RAW Light in Canon Log 2. "This meant I could get the widest colour spacing out of the camera, in the bitrate I felt we needed," she says. "The files aren't as hefty as RAW files, so it was better for managing workflow with people working from home. Shooting in Log 2 gave us the most amount of picture information to work with in the grade."

Through Cyn, the team hopes to have given Cynthia her rightful place in the story of the Beatles. "In some way she's a very ordinary person," says Tania. "I think it must have been a huge challenge to go from a quiet, suburban life to dealing with fame. It was a very new thing in that period of history. It probably took her life off in a direction that she never anticipated."