FORTUNE — Born into a family of artists, what’s a pragmatic, business-minded kid to do? Become a movie producer, naturally. At least that was Cassian Elwes’s grand plan from the time he was 15 years old. Elwes has shepherded hundreds of independent films during his 30-year career. In the past year alone, Elwes executive produced Dallas Buyer’s Club and All is Lost, both of which have been nominated for Golden Globes. And he produced The Butler and Ain’t Them Bodies Saints. On top of all that, Elwes launched a bridge loan fund called Lifeboat Capital for independent productions in need of cash to hold things over until financing comes through. Fortune recently caught up with Elwes, who discussed how he got his start in the business, why he prefers to avoid big studio productions, and his take on temperamental attitudes in the movie business. The following is an edited transcript of the conversation.
Fortune: How would you describe what you do for a living?
Cassian Elwes: I’m a film producer. And I specialize in financing and distribution. I know how to raise money for independent movies and put the deals together and arrange the distribution for these movies.
What led you to the industry?
When I was about nine years old, my mother, who lived in England, met and fell in love with an American movie producer called Elliott Kastner. He made independent movies when it wasn’t chic to be doing it. By the time I was 15, it was the only thing I thought to do. I made my first movie when I was 23. It was a film called Oxford Blues, with Rob Lowe and Ally Sheedy, it was an early brat pack movie.
What did that involve?
I went out and raised the money with my stepfather. I learned the process from him. And I developed my own taste along the way.
I made 30 movies by the time I was 35. William Morris came along and put me in charge of all their independent movies. And I made 286 films for William Morris.
Aside from budget size, what are the major differences between independent films and big studio productions?
Unlike big studio movies, where you make a movie for $150 million and spend another [several million] trying to release it and crossing your figures and hoping it’ll turn into a billion dollars [in sales], with independent movies, you can look at historical revenues and foreign pre-sales and tax credits and figure out how to make a movie that will turn a profit for investors before you even make the film. You can predict quite closely what the … value of an independent film will be. You can actually start to come up with models that make financial sense.
The studio business is more risky than independent films. Their margins are very thin. They see the movie business as a necessary evil to support their ancillary businesses, like the DVD business, or networks they own, or channels. Hundreds of millions of dollars are being gambled on one movie.
Who are the typical investors in independent movies? Is there a typical investor?
Typical investors are people who are successful at other businesses who like the glamorous aspect of the film business … The movie business attracts lots of different people.
I imagine it’s then a matter of figuring out who is actually serious about it. I bet there’s a lot of B.S. and posturing.
I’ve also developed financial strategies for investors. I set up a fund called Lifeboat. That is a bridge fund … where we loan money to movies that are about to start shooting but the lawyers are working with other banks, and they need cash to keep going.
It’s becoming increasingly necessary … because independent films [are] now being financed with multiple parties. These things were taking a long time to close, even though the deals were all in place. We’re just about to make our first loan. It hasn’t quite closed.
You hear so many stories of temperamental agents and producers, like Ari Emanuel or Scott Rudin. Do you think there’s any benefit to that style?
When there are large amounts of money involved, people tend to overreact, that’s the nature, it may just be a part of their mechanism. But on the other hand, I have always found in the most stressful situations and the most difficult things — and there are many of those — that the best course of action is to remain extremely calm. My whole approach was to be very zen about everything because I assumed everything would blow up at some point.
Blow up, how?
We had a hurricane come through during The Butler. We had to shut the movie down for three weeks. And I just went through a difficult situation where a film ran out of money and investors brought me in to work our way through it. And I just worked on a movie where the financing fell apart five days before shooting and I had to work on refinancing in 48 hours. The financiers and producers came to me. And it just finished shooting the day before yesterday. It’s called Burying The Ex, it’s a romantic comedy with zombies.
Is it any easier to make independent films today?
You are seeing outside financing, non-Hollywood money going to great independent film directors, like Paul Thomas Anderson. There’s alternative financing coming to the top directors now. That’s a positive development. At the same time, distribution has become more difficult and fractured. One of my movies was involved in VOD , which was Margin Call. VOD has become the rallying call for indy films. Distribution in America is hard because the studio spends so much money to get people to theaters. They are spending $50 million as a minimum to put it out there. An independent is averaging $2-3 million [in marketing].
I guess the best — and cheapest — marketing is organic.
Margin Call caught a tailwind because Occupy Wall Street happened three weeks before the film came out.
It’s hard to bank on that, though.
You can’t. Most times, you are making an independent movie for less than $10 million and spending less than $5 million to release it. And you are trying to find an audience that finds out about it from their friends and from television and interviews and people talking about it.
So many variables, it must lead to a fair share of disappointment.
I was really disappointed about a little movie I made, Ain’t Them Bodies Saints. It was one of the best-reviewed movies I ever worked on. And people didn’t come out to see it. I think people will come out to watch it [later on]. It just didn’t catch fire.
How do you bounce back from something like that?
You’ve got to have a relatively thick skin in this business. Not every movie is a huge success out of the gate. As long as you have a financial strategy in place that allows your investors to recoup their money, no matter the success of the movie.
Your brother is actor Cary Elwes, right?
Yes, my brother Cary was a star in The Princess Bride. He was so great in that movie. He’s an actor, a very good actor. He loves acting. He started now to think about directing, and he has a couple projects. And I think he will make a very good director.
Any interest in getting behind the camera and directing?
I did it once, and I will never do it again. So many times, I would get into arguments with directors saying, “You don’t know what it’s like to direct a movie.” And now I can say I do. But I had to focus on the thing that I’m the best at, which is making movies, financing movies, making distribution deals for films.
What was the name of that movie?
Blue Flame. It was made for $150,000. I liked it. It came from a nightmare that I had one night and wrote it down very quickly and directed later.
And never again?
No. I love making films as a producer. My father was a painter, my brother is an artist, my other brother is an actor. My mother is a very successful interior designer. I definitely understand the artistic temperament. They were all artists. I’m a businessman.
I imagine all those artistic personalities make for interesting holiday get-togethers.
[Laughs] Yes, they are very interesting, very dramatic.