I have a Nikon D5100 that I use as a backup on video shoots. During some interviews and presentations, the 20-minute limit means that I have to stop the camera after 20 minutes or at least be on top of it to restart it running, which means that if it's the only camera recording, there will be a gap. 

Canon users have long used Magic Lantern firmware for Canon cameras to give them video choices that Canon hasn't officially wanted them to have. Canon, of course, doesn't sanction this, so using it may* void your warranty or worse, brick your camera. Though the latter is rare.

It offers things like allowing manual gain control on audio and for a video clip to be longer than 12 minutes. The 12-minute limit was mostly due to the 4GB limit per recording, which is still about 12 minutes of full-res (but compressed) video. There's also another reason why DSLRs have shorter video recording times: taxes. In the EU, any device that can record longer than 30 minutes is considered a video camera and subject to about 5% additional tax. Why does that affect U.S. buyers? Likely because the manufacturers don't want to make multiple firmware versions for different countries. Or perhaps buying cameras from out of the country to use there.

There are those who will say that it's also because of the heat buildup on the sensor, but I don't buy that. I've read enough reports of people monitoring sensor temperatures that can tell you the sensor will reach a certain (safe) temp and stay there. The conspiracy theorist in me thinks the manufacturers of many of these also don't want to cut into the sales of their more expensive, more full-featured video cameras. 

Canon users have Magic Lantern, but Nikon users have had no such choice for third-party firmware. Until now. Simeon Pilgrim has written a firmware patch tool that will enable certain options for consumer Nikons. The following are the features you can change:

Nikon D3100:

• Changes the video clip time limit from 10 minutes to 17:28

• Allows use of a non-Nikon-branded battery

Nikon D3200:

• Remove Time Based Video Restrictions – Currently in beta testing

Nikon D5100:

• Remove Time Based Video Restrictions
• NEF Compression Off
• NEF Compression Lossless
• NEF Oversampling, to allow testing by Astro folks – BETA
• Jpeg Compression – Quality (vs. Space)
• Allows use of a non-Nikon-branded battery

Nikon D7000:

• Remove Time Based Video Restrictions

So far, those are the only cameras supported and tested. The Nikon D3200 is still in beta testing. No word on when/if updates are coming up for cameras like the D7100 or D5200 yet. Via email, Simeon did mention that plans are in the works for something for the D800. 

It's an easy update. You go to NikonUSA.com and find and download the most current version of your camera's firmware. When it's downloaded, go to Simeon's page to find the patch tool HERE. The directions are easy. You use the online patch tool to open that firmware file, change the features you want, then you need to save the patched version under the same name as the downloaded firmware. You can save it to the root directory of an SD card. Then eject the card, plug it into your camera, and follow your camera's directions on upgrading. For the D5100, it required inserting the card, turning on the camera, going into the menu and navigating to the firmware. When it sees the XXXX###.bin file, it offers you the chance to update your firmware and admonishes you to do this only on a full battery or with the camera plugged into an AC source. It took less than five minutes for the whole thing.

I've tested it, and so far it's run to almost 30 minutes before the single, not-fully charged battery died. The file size would be a factor much over that with the settings I had, since FAT32 only allows for a file size of 4GB (THERE's a spec that's antequated and needs to be fixed!). But on recent projects, 30 minutes is fine. The only way past the 4GB limit is using the HDMI feed from the camera into a dedicated recorder, like the Sound Devices PIX 240 Production Video Recorder. But that's a different type of production than some of us usually work on.

Keep in mind that this IS third-party, unsupported firmware changes, and there is the slightest possibility that you could brick your camera. Any time you modify something outside of the manufacturer's explicit intentions, you become responsible for anything that happens. Overheating, fire, mechanical damage, pestilence, sloth, greed, longer videos, better functionality; you name it! 

This is an exciting development for Nikon users. With this patch, we have more control over certain functions we've been wanting. Knocking out the time limit makes it better for recording longer interviews, presentations, even kid's performances. If you have a feature you're interested in, contact Simeon via his blog. He's very responsive and helpful.

*Canon answers that a firmware change won't void the warranty for any defect or problem as long as that firmware was not the cause of the malfunction.