Canadian cinematographer Robert McLachlan is a Game of Thrones veteran. He’s shot eight episodes of the show, including “The Dance of Dragons,” where Daefonerys faces assassins from dragonback in the Daznak fighting pit, and “The Rains of Castamere,” the episode with the Red Wedding. And most recently, he shot “The Spoils of War,” episode 4 of season 7, where Daenerys takes her dragons into battle in Westeros for the first time. The episode was tremendously complicated, as a behind-the-scenes video reveals — it involved coordinating explosive devices, pyrotechnics, and a vast crowd of extras, in addition to CGI dragons and complicated close-quarters combat.

But McLachlan is used to complicated shoots, and big projects, after decades in the industry, multiple Emmy nominations (including for Game of Thrones), and work on series from Westworld to Ray Donovan to Millennium and The Lone Gunman. In a series of interviews with The Verge, conducted both before and after the episode aired, McLachlan says the climactic battle sequence in “The Spoils of War” took 18 days to shoot, with the crew working six-day weeks to get it all done. Unlike the show’s actors, who are kept in the dark as much as possible about upcoming story events, the crew gets the scripts more than a year in advance, and planning for “The Spoils of War” began as much as 14 months ago for McLachlan, counting location scouting, travel, and working with subsidiary teams. He ran us through the process: the advance planning, the drone shots representing dragon POV shots, the smoke crisis HBO had to shut down, and why he thinks his next episode is even more satisfying.

This conversation has been condensed and edited from multiple interviews.

How did you approach shooting “The Spoils of War”?

Any sequence with a great deal of visual effects has to be really carefully planned. It almost comes down to planning individual frames as you decide how long each shot is going to be, because those shots are insanely expensive, especially if there’s a dragon in the frame. A lot of the creative work for the big action sequences has to be done way in advance. It’s like the way Alfred Hitchcock worked, where he meticulously storyboarded his movies before shooting it, and then he’s been quoted as saying that the filming part was actually the boring bit.

And in some ways, it is. The bigger and more dramatic the sequence is, and the more visual effects are involved, the less it’s satisfying for a cinematographer. I thrive on walking into a blank set in the morning, where what ends up in the film is entirely in the cinematographer’s hands. Whereas with this episode’s grand action sequences, with a lot of visual effects, a lot of that work is done almost by committee in advance. Because those effects shots are so wildly expensive, they’ve got to be nailed down ahead of time so they budget it. And inevitably, they still come in way over budget. And then it’s a question of sitting down with the director and the visual-effects producer, and figuring out how to pare it down so we can afford to do the sequence as effectively as we can.

“The bigger and more dramatic the sequence is, the less it’s satisfying for a cinematographer.”

We get all the scripts for the season more than a year before we start shooting anything, and that’s vastly helpful, because it allows for huge savings in the physical production. The company only has to move 40 trucks and 150 crew members to some remote beach in Northern Ireland once, and then three or four, maybe five director/DP teams will come in and share that crew on that one location, because they’re all out there shooting at the same time. So when we were in northern Spain last year, we shot sequences for multiple episodes, because those scenes would be in the same location. It saved us flying the director back to Spain later, for half a day’s work.

Why don’t they have one director shoot all the Dorne sequences, one director shoot all the North sequences, and so forth? It seems like that would be more consistent and involve less moving around.

Probably a lot of producers would like that! But the Directors Guild of America rules are very strict about a director having authorship of an episode, and the result is that even if you only have one page to film, maybe four hours of work in Dubrovnik or something, according to the letter of the law, they have to fly the director there to direct that sequence. Of course sometimes a director will ask another director who’s already there to do it for them. There’s a fair bit of that sort of switching around.

So you got the script, did location scouting, and sat down with committees to plan the special effects. But you still had a lot of technical challenges to face on this episode. How did you approach them?

We worked with a pretty basic camera package — the Arri Alexa, which is certainly my first choice. All the cinematographers on Game of Thrones are told, “This is the camera package we use.” You have very little choice about it. But I’ve always been very happy with that, because it’s exactly the same gear that I actually own, and I use it myself all the time.

We just tried to shoot as simply and elegantly as we could. For the big action sequence, we used a little hand-held rig called an Osmo, with a small digital camera on it that allowed a horseman to get shots while riding a horse at a full gallop through the cavalry charge. We used custom-built miniature helicopter drones for the overhead dragon shots. HBO has a very strict policy of no drones going anywhere near any human being, so we used those for flying over water, and uninhabited spaces. It came in from Holland with a pilot and a couple of assistants. We brought in a cable-cam, because we needed a lot of repeated passes over the battlefield, with the camera making the exact same movements, so we could digitally composite in all the elements. It’s very heavy to rig, and a pretty tedious process for everybody who’s not involved in making the thing work. We had to schedule around all these elements, and when we had the most extras, and where these huge cranes that supported the cable-cam would go. The cable-cam company, they’re the guys who do most of the biggest movies, all over the world. They basically go from big show to big show, setting up these repeatable rigs with remote-controlled cameras that are safe for anybody underneath.

How much of what we see in the battle in “The Spoils of War” is practical effects, and how much is CGI and compositing?

Well, obviously we didn’t actually have 5,000 Dothraki. But to 3-D animate those would be wildly expensive. We did have 50 or 60. And part of the tedious process of doing a scene like that is, you have to do crowd replication. We have cameras that can repeat their moves over and over perfectly, exactly the same way each time. So different segments can be blended together. It’s been something we’ve been doing on Game of Thrones for a long time. I first did it on season 3, when Dany was freeing the slaves. You saw behind her thousands of Dothraki. We did have a lot of dressed extras — I think about 500 — but we had to turn them into thousands.

So you have the camera on a computerized, robotic rig with programmed movements. You take your crowd and move it around the field until it completely fills a vast landscape, then composite the shots. And of course it was the same with the Lannister troops. They spent a huge amount of time doing that with the Battle of the Bastards last year, to fill the field with soldiers. The days of the Russian version of War and Peace, where they physically had thousands of troops on the field, that’s prohibitively expensive now. So we do have real people there, but we duplicate and replicate them. The CG component is just compositing the actual shots we get.

What impressed me most about the sequence was the incredibly thick smoke, and how it changes day to night. Was that enhanced as well?

We produced a lot of smoke. That was something I wanted from the absolute get-go, because I knew the weather was going to be in and out over the days and days we were going to be filming this. We were shooting near a small town in Spain, in a national park. It was late in the year, and we knew the weather would be spotty. And one of the things that can really help you make something more moody is if you can block the sun. I’ve done that quite successfully on a lot of shows over the years, but obviously on a much smaller scale, with smoke machines. Here, we wanted to block the sun out so the shots would have some consistency. And I knew the fire and smoke would be incredibly beautiful.

Fortunately, we had a very good excuse to have it, once the dragon has struck the train. The problem was — our first two days, we were burning all of this material. Special-effects smoke is usually white, and it’s quite innocuous. It’s easy to work in. It’s been proven safe to breathe. But we wanted really nasty black smoke that would look evil and horrible, and the only way to do that is to burn diesel oil. The crew and everybody close to the fires were fitted with masks and goggles. But after two days, everybody’s faces were just black, and we were all coughing and wheezing and hacking. The health and safety officer from HBO said, “That’s it! No more of that!” Everybody was relieved, including me on one level, but on the other level, I was going, “Oh man, there goes my smokescreen.”

I had a template that was inspired by J.M.W. Turner the British painter, who painted those fabulous paintings with the sun poking through haze. And also, I grew up in British Columbia, and I live in California, where there are a lot of forest fires. As a kid, I saw some really spectacular ones on the west coast of British Columbia, and saw the light when the sun was trying to get through that dense smoke. That was the feeling, the look I was always going for. With shots where we didn’t get it, I had to color-correct the film so the light looks like it’s coming through smoke, and then go back to my friends in the effects department and say, “We’ve shot it so it looks like it’s through a lot of smoke, so now you’ve got to help us add a lot of smoke.” I knew that they could do that quite successfully, because they gave me a lot of extra dust in the Daznak fighting pit. Without their help, it would have looked kind of dopey and not right. But luckily, one thing you can rely on in the show is the viz-effects department, for taste and goodwill and ambition. That did help capture that look.

Your establishing shots, with the stone formations in the background, look like 1960s Technicolor Westerns. Were you inspired by Western films?

Very much so, with the wagon trains and a Monument Valley feeling. We added those buttes in the background later, though, because the truth is, the plains in Spain are rather… plain. [Laughs] For want of a better word. So that helped us get a little bit of depth to the shots, just a bit of window dressing in the background.

But from a lighting standpoint… when I was young, I saw Butch Cassidy and the Sundance Kid, and I was impressed, because it was so dark. It just didn’t look like any other Western I’d seen. And then as a young teenager, I really responded to the spaghetti Westerns, which didn’t look like the ones we’d all grown up on.

So in this episode, you’re dealing with fire, smoke, huge crowds, stunts, animals, CGI, a health inspector, and stars who have to keep their faces visibly onscreen and in focus, even when they’re running around in all this mayhem. What was hardest to shoot? What gave you the biggest headaches?

Your biggest challenge is trying to keep a consistent look in a scene when you’re shooting over the course of weeks, and the weather’s going from heavy overcast or a drizzle to bright sunshine. We’ve normally got big cranes that bring in big 40-by-40 silks, so the actors aren’t lit by harsh sunlight that’s coming down at the wrong time of day. But here, the scope was too big to use those. In a perfect world, we schedule to make use of the best light through the day. I use an app called Artemis that tells me exactly where the sun will be at a given time of year, in a given location, on a given day, and that helps us decide where to put the camera to keep the shadows consistent. We plan meticulously what shot we’re going to do at what time of day. Scheduling the whole season is an amazing puzzle, especially with a cast this size, where you have to take the sequence out of order, because we had 600 extras working on the scene for a week, and then that went down to 400 the next week, and so on. By the last week of shooting we were down to about 100 people.

There’s a long follow-shot in the middle of the battle where Bronn is stumbling back and forth in a confined space, with burning men and horses all around him. That particularly looks like it took a lot of coordination. Are there particular segments in the battle scene that you’re most proud of?

We were really happy with that one. With a oner, where you run one single shot as long as possible, the longer it runs, the more coordination and choreography you need, and the more perfection in all the elements, because you don’t have shots to cut away to, to fix a little mistake. That shot was a real operating tour de force for my camera operator, who did it with a handheld camera. We got it in three takes, which is really impressive. But it is an amalgam of, I think, three shots that Joe Bauer’s exceptional VFX team married together, and then significantly enhanced with extra smoke, fire, and embers. It couldn't be done practically, for safety considerations. Once the serious mayhem begins, very few shots were not helped by the VFX department.

How much of the fire in the sequence is real and unenhanced?

We had real fires burning all the time, and we shot a lot of fire elements so we could fill shots up with composites, and to give us some better variety than we were physically going to be able to maintain on the really wide shots. On the tighter shots, we’re practical most of the time.

There seems to be such a focus these days on practical effects over CGI. As a cinematographer, is that part of your philosophy, that you’d rather get it all on set and in-camera?

As lot of that is probably coming out of what we heard about the making of Dunkirk. And you know Chris Nolan — and his brother Jonah, when I was working with them on Westworld — don’t like green-screen. They don’t like visual composites, if they can help it. Because they feel subconsciously, the audience is going to be more drawn in and engaged with something if they feel like it was actually photographed, and not superhero-movie cartoon-created. I think there’s something to that. Certainly for a cinematographer, it’s just a feeling that you’d rather be the sole author of everything onscreen, which was traditionally how it’s always been. Increasingly, we’ve worked hand-in-glove with the visual-effects department. I think we all understand — Dave Benioff, in the episode making-of feature, reiterates that the more things we really shoot, the more real it’s going to feel, the less animated and cartoonish it becomes. So that really was 50 guys riding on the backs of their horses, galloping down a hill, while shooting bows and arrows. That’s a lot of training. But if it had just been animated, it wouldn’t have looked as good. It wouldn’t have felt as real, or as visceral.

How did you approach framing the characters in the scene, telling the story through cinematography around the actors?

One of the things I’m most proud of… Very early on, I read the script, and I thought, “Are there really any stakes here?” In the Battle of the Bastards, there’s really something at stake. You’ve got one of the worst characters, who we hate almost more than anybody we’ve ever hated in the series, on one side. We’ve got one of our absolute favorite characters on the other side. The emotional states are very high. When I first read this episode, I thought “Well, here’s Dany flying around on a dragon burning everything up, and Jaime down on the ground, but is that going to work, if we’re not really rooting for somebody?” Then I realized that the characters actually watching this conflagration, this dragon-induced Armageddon, was going to be a game-changing moment. That wasn’t really specified in the outline of the script. As Jaime’s just taking it in, it’s like somebody watching the A-bomb being dropped. He realizes everything is going to change forever.

So we really had to focus on Jaime, and to a lesser extent, Bronn, more than this girl flying around on a dragon, which was technically hard to shoot. So I had this conversation with Matt [Shakman], the director, when we first met, and that’s where we put our focus in the midst of all this mayhem. I felt it wasn’t going to mean anything if we didn’t see it from one specific point of view, which wasn’t really specified in the original outline. And we did that, and I think Nikolaj [Coster-Waldau, who plays Jaime Lannister] delivered one of his best performances in the show so far. I think that’s largely what helped make it work. That, and watching a battle where you’re rooting for both sides. You don’t want to see the dragon get killed, but you don’t want to see Bronn get killed. I think it worked. I’ve gotten emails saying “Best episode ever!” and it’s really gratifying.

You’ve finished shooting season 7 at this point. Have you personally shot anything else that you think will compete with this episode?

They’re starting to prep the final six episodes now, and I’m sure the pressure for them to outdo themselves will be enormous. My guess is that three of those will probably have some big action setpieces, and the other three will be finishing telling the story. That’s just a guess. I’ve got another episode coming up this week, next Sunday, which interestingly, when I read it and saw the rough cuts — a lot of the visual effects weren’t in yet, and there were a lot of unfinished shots and animatics still in them. But watching the rough cut of the two episodes, it was actually the one from next Sunday that I found most satisfying. So we’ll see!