No tracking down rights-holders, no licensing, and—in theory—no cost. But a quick internet search for public domain footage will reveal a plethora of sites charging for the stuff. What gives?

Public domain, footage that holds no copyright and is free to use by the public, is music to the ears of a documentary filmmaker. But determining what footage is in public domain, and how to get it for free, can be quite a chore.

Footage generally falls into public domain because it was created by an entity not subject to copyright (like most of the US Government), or the copyright has expired. You can check the 2015 US Public Domain and Copyright Term for current laws governing when copyright expires. If you’re new to public domain film, here’s a brief introduction courtesy of Pond5:

However, once you find footage that is in public domain, it can still be hard to get a copy of it for free. (And the same can be said for footage that you plan to us under "Fair Use" but that's another story.) There are usually two reasons you have to pay for something: your public domain footage is sitting in a vault somewhere and you need to pay someone to find it, or transfer it to the format you need, then ship it to you. Or a third party already has a useable copy of the footage and is selling it to you for that convenience.

As we’ve discussed, the search for archives is often the scriptwriting process on a documentary, and can be crucial to your film's success.

If you've stumbled onto footage on your subject that has yet to have been digitized, by all means pay to get your hands on it. But since no one wants to pay for something they don’t have to, especially documentary filmmakers on a shoestring budget, here are some great free sources:

We are making this content available to our customers and contributors without any charge, so they can rediscover part of mankind's history and build upon it in their creative projects. We have designated Content on the Website as being “Public Domain Content” when we believe that it is in the public domain under the laws of the United States, meaning there are no copyright restrictions over that content.

Strings attached: Pond5 started this public domain project in 2015, and all you have to do is create a free account to start downloading.

Prelinger Archives was founded in 1983 by Rick Prelinger in New York City. Over the next twenty years, it grew into a collection of over 60,000 "ephemeral" (advertising, educational, industrial, and amateur) films...Prelinger Archives remains in existence, holding approximately 11,000 digitized and videotape titles (all originally derived from film) and a large collection of home movies, amateur and industrial films acquired since 2002. Its primary collection emphasis has turned toward home movies and amateur films, with approximately 12,000 items held as of Spring 2015. Its goal remains to collect, preserve, and facilitate access to films of historic significance that haven't been collected elsewhere.

Strings attached: If you need written permission to clear your footage, you might need to pay Getty for it. From Prelinger:

“The Internet Archive does not provide written permission to use any material, and the user therefore assumes all risk when repurposing Prelinger footage. By way of contrast, when you license Prelinger clips from Getty Images, Getty Images will indemnify you against claims for copyright infringement relating to copyright in the footage clip.”

Our goal in digitizing these movies and putting them online is to provide easy access to a rich and fascinating core collection of archival films. By providing near-unrestricted access to these films, we hope to encourage widespread use of moving images in new contexts by people who might not have used them before.

Strings attached: Anyone can upload to the Internet Archive, so there is a lot to sort through with all kinds of copyright status. Even when listed as public domain by the uploader, be discerning.

The Motion Picture, Sound, and Video holdings at the National Archives in College Park are vast and diverse, spanning more than 150,000 reels of, 160,000 sound recordings, and 20,000 videotapes. Materials derive from public and private sources as disparate as MCA-Universal Pictures and the U.S. Air Force.

Strings Attached: Not all of National Archives' videos are in the public domain, and many of those that are may not yet be available online, generally incurring extra costs. You can get a sense of what is available for download on the National Archives Youtube page, where videos will have links to the catalog downloads.

The majority of the films and videos in the Library of Congress are not available for duplication due to copyright and/or donor restrictions...The most accessible collections of archival footage in the Library of Congress available for purchase include The American Memory Films. Over 700 historical films can be viewed online and downloaded at the American Memory website.

Strings attached: Not all videos are entirely public domain, so in some cases you may need to contact the LOC, the original rights-holders, or plan to use them under a Fair Use agreement.

NASA still images, audio files, video, and computer files used in the rendition of 3-dimensional models, such as texture maps and polygon data in any format, generally are not copyrighted. You may use this material for educational or informational purposes, including photo collections, textbooks, public exhibits, computer graphical simulations and Internet Web pages.

Strings attached: If the NASA material is to be used for commercial purposes, it can't explicitly or implicitly convey NASA's endorsement of commercial goods or services.

On these pages you find overviews of some of Hubble video clips produced by the ESA/HUbble. The animations can be downloaded in different sizes and qualities. Everything is free for you to use as long as you follow the simple rules in our Copyright info.

Strings attached: ESA/Hubble videos are not public domain, but rather released under the Creative Commons Attribution 3.0 Unported license. They can be used for free but must be clearly and visibly credited. Look into the ESA/Hubble copyright details for yourself, but generally you need to put a credit at the end of your doc.

The National Park Service cares for special places saved by the American people so that all may experience our heritage. This webpage provides links to public domain video of some of those sites, including national parks, monuments, battlefields, historic sites and related areas.

Strings attached: Like NASA, videos must not be used to imply National Park Service endorsement of a product, service, organization or individual.

This should get you started! It's important to point out this article is referring to footage that falls under the public domain according to United States copyright laws. And even if you are in the USA, as with all footage you find on the internet, exercise your best judgement. You should always double check the title to make sure it is in the public domain before you lock picture. Best of luck in your search!

Do you know of another bonafide free source of public domain footage? Let us know in the comments.