The lens I couldn't shoot without: Sophie Darlington on her wildlife filming career with a Canon CN20x50 lens

Lions are one of your specialist subjects – can you tell us a bit about that?

"Yes. I've filmed lions all over Africa and east Africa, and they fascinate me. But I've still felt that there was a lion film that could be made which would give a fresh angle… not about hunting or killing, but about family. So many of the amazing wildlife shows on right now are sequence-driven, so you'll have maybe six minutes of a sequence, but you are really trying to illustrate one bit of behaviour. Another approach is you can follow one family of lions for a set amount of time and see what happens."

With that approach, how hard is it to get what you need?

"Nature doesn't read a script, but in the Maasai Mara, we got the most heartbreaking story – a very real and very relevant story and one I'm really glad that got told, about poisonings. It had a massive knock on to our pride... we came away with a massive message, which is that there are 20,000 lions left in Africa and maybe 2,000 left in Kenya, which is shocking."

Spending a long time filming just one family of animals seems financially risky, so what's the benefit of this approach?

"I think that ability to dive in and really experience an animal and understand it. Time is what you want in the field when you're making any natural history show, but also having the kit that allows you to tell that story if something happens. If you're there for a year and in that one year, you get 10 minutes of behaviour, you better be damn sure you can cover it."

Do the technical considerations vary a lot, from location to location, shoot to shoot?

"Pretty much every wildlife shoot has exactly the same constraints, which is there will be a moment that you have to cover and it's not enough to have one lens. It's no good just having a mid-shot – it's not going to carry it. You need different shot sizes: the eyes, the paws, the beak, the feathers... but you also need that big wide, so we always use ultra zooms. I am a long-lens DOP."

Is that any long lens in particular?

"The Canon CN20x50 is the only choice. We pretty much all use different cameras, but we all use the same glass because Canon are the only people who make an ultra-zoom for wildlife that does enough."

With that, it appears that you are very considered with your use of depth of field – has this cinematic look always been a part of your aesthetic?

"For me, it's really important when watching wildlife that you know who you're looking at. You can have these epic scenes and you can get lost in all the detail. I started off by shooting super 16 and 35 and it's all about your F-stop or your T-stop. If you use NDs, you're going to get a shallow depth of field. Usually, if you're shooting off speed, you're going to need all the light you can get, which gives you a shallow depth of field. Everything in wildlife points you towards it, and having worked on a few feature films, it just feels right. If I'm looking at the eye of an animal, pin sharp, and everything else is soft, it's beautiful. It's really cinematic."

Your framing is so consistently beautiful – it's perfectly positioned, but when you're at the end of your focal range, as you often are, there's so little margin for movement...

"I get really upset if something visually comes into the frame that shouldn't be there – it happens all the time in wildlife. I was filming Penguins for Disney and there was always one penguin that photo-bombed, and it was so frustrating! You'd have the most beautiful frame and suddenly there'd be... a penguin. Framing is so much a part of it!

"I'm left-eyed, and if I can't use my left eye – because I've been looking through it for four hours and I start getting a twitchy eye (which happens to us all) – I'll go to my right eye... but I cannot film with my right eye instinctively, as I do with my left."

Is that common?

"Maybe people don't talk about it... I worked with a camera assistant once and he had been taking stills, which were great, but they weren't exemplary. We did a test to find out if you're left or if you're right-eyed. He was like, 'Oh, I've been taking pictures with my right eye but this is saying I'm left-eyed.' I promise you, his stills went to being fantastic, from just changing eye. So word to the wise, check your eyes. You never know."

What's your take on the ethical dilemmas faced by the wildlife filmmaking industry?

"Nature does what nature does, and we're not there to intervene – we're there to record it truthfully. I think I like being a long lens cinematographer because, with that degree of separation, you know that you're not influencing the behaviour in any way. I've seen some heartbreaking things. I've seen a cheetah mother being tossed by a Grant's gazelle. She died. Two days later, her three cubs died."

Do you manage to stay emotionally detached, having worked in wildlife for so long?

"I have been known to shed a tear, but most of my tears come from frustration and rage at humans. I can't believe that people will pay the money that they pay to go to watch an animal and disregard it so incredibly. I think phones have been a massive part of that. I think that maybe we're responsible for it slightly as well because we have the luxury of shooting on amazingly beautiful lenses that bring you right into an animal's world. And when people go out there with their phones, they want to get that shot, and the only way they're going to get that shot is by breaking every rule in the book of that park or ignoring the animal's wellbeing."

The behind-the-scenes sections of a show that wildlife series often run now allow the industry to communicate some of those frustrations. You also get a good sense of the challenging dust or weather conditions you work in!

"Wildlife filmmaking doesn't happen in cosmetic environments. It happens in incredibly testing and rough environments. You're by the sea, you're filming on a beach with wind, so there's sand, there's sea, there's salt, there's dust, there's mud, there are bangs, there are bumps. You're picking up your tripod over your head and you're running for a short distance… you want to get the shot, so most probably the kit isn't at the forefront of your mind. We put kit through absolute hell."

I read an interview where you said being tall helps you as a female cinematographer...

"I am tall and, actually, it's a real hindrance when filming because you spend a lot of your time curled up in a one metre by one metre hide – I can guarantee being tall is a definite disadvantage. I think I said it glibly once... in the same way I said that the only advantage men have over us is that they can grow beards in the cold. I'm glib about it, but it's very serious. There needs to be more women doing what I do and there are some incredibly talented women doing what I do, such as Justine Evans, Sue Gibson and Julie Monière. There are more fabulous women coming up as well and I think the more they see people like me doing it, the more normal it will become."

Did you ever encounter sexism, when you were breaking into the industry?

"You know what, it never occurred to me not to be a wildlife DOP. When I started, I don't think it mattered to Hugo. He just wanted to see that I had passion for what I was doing and an eye, and he felt I had both. I've seen women carrying as much stuff, if not more, than the blokes on the shoots. If you're interested and passionate, it shouldn't matter a damn."

So what's your advice for women, and men, who are trying to break into the wildlife filmmaking industry?

"I get emailed pretty much every day by people asking how to get into this business. Can you do what I did? The answer is no, because I did my own personal thing. But it's much more accessible now that you can film, edit, put your videos up, tell your story. You can shoot on really affordable, great kit. The CN20x50 costs what it's worth, but if you've got a Canon EOS 5D Mark IV, you are away in a hack. That's a great camera to film with a 70-200mm lens, or whatever you might have. The secret is the story, because that's what it always comes back to. My advice would be to get out there – you're going to tell the story by being out there and being in it, not by sitting at home watching YouTube videos. That ain't going to do it for you."