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DJI Lens Correction for Videos

Discuss the DJI Phantom Vision Camera and FPV System

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DJI Lens Correction for Videos

Postby rmklaw » Sun Dec 08, 2013 10:29 pm

Help. I opened the video clip with Photoshop and applied the DJI lens correction to straighten out the fisheye effect. However, now when I play it back it plays in slow motion. Question: How do you get Photoshop to play the clip at regular speed? Thanks.
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Re: DJI Lens Correction for Videos

Postby jimre » Sun Dec 08, 2013 11:17 pm

You need to render it back into a regular video file. File->Export->Render Video.

Once you've applied the lens correction, Photoshop has to re-build every frame of this modified video in real-time - and your computer is NOWHERE NEAR FAST ENOUGH to do that.
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Re: DJI Lens Correction for Videos

Postby rmklaw » Sun Dec 08, 2013 11:31 pm

Thanks. I am doing it now. Slow process.
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Re: DJI Lens Correction for Videos

Postby BenDronePilot » Mon Dec 09, 2013 12:24 am

I've got a better solution for you. Shoot your videos in 90 degree angle like I do so you get virtually no lens distortion or fisheye that way.
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Re: DJI Lens Correction for Videos

Postby rmklaw » Mon Dec 09, 2013 12:28 am

I will try that. Still new and experimenting.
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Re: DJI Lens Correction for Videos

Postby jimre » Mon Dec 09, 2013 1:21 am

rmklaw wrote:Thanks. I am doing it now. Slow process.

Yep, Photoshop renders video very slowly, and has limited rendering choices. Dedicated video apps like Adobe Premiere, Adobe After Effects, Sony Vegas or others will render video much faster and make better use of your CPUs and GPUs processing power. Photoshop's automatic correction based on lens profiles is nice - but for video it may not be worth putting up with Photoshop's slow rendering.

It may be better to use the built-in lens-distortion correction filters found in dedicated video apps - like the one in After Effects. Not automatic based on a lens profile, but it's easy to manually move a slider until it looks good. And they render a lot faster than Photoshop.
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Re: DJI Lens Correction for Videos

Postby Pull_Up » Mon Dec 09, 2013 7:31 am

A question for those more versed in the ins and outs of lenses than I...

When DJI release the 46mm lens filter adapter kit, is there anything available that could be fitted to that to do a correction? Or is putting it in front of the lens just not going to work? As you can tell, I have no idea about any of this!

Also, does anyone have any video they can share which they took with the 90 degree FOV, just to compare? Thanks...
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Re: DJI Lens Correction for Videos

Postby MikeON » Mon Dec 09, 2013 9:04 am

[quote="Pull_Up"]
When DJI release the 46mm lens filter adapter kit, is there anything available that could be fitted to that to do a correction? Or is putting it in front of the lens just not going to work? As you can tell, I have no idea about any of this!
quote]

I would think it would have to have multiple elements and thus more weight. I have a very old telephoto converter for my camcorder that is like this one except mine is 1.5x instead of 2x:
http://www.amazon.com/Digital-Optics-Pr ... +lens+46mm
I hand-held it in front of the Vision camera and it did reduce the distortion as well as making things look closer. Like the negative review in the Amazon link, mine rounded off the corners like looking through a rifle scope. I'd really like to have a little longer focal length main lens on the Vision, both to reduce distortion and take pictures from a little farther from the subject. Some of the videos I've seen of kids trying to grab a quad out of the air look pretty scary. Shooting from a little higher up would be safer. I understand that longer focal length would have shallower depth of field and the vibration blur would show up more, but would like to have the option.
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Re: DJI Lens Correction for Videos

Postby BenDronePilot » Mon Dec 09, 2013 10:13 am

Pull_Up wrote:A question for those more versed in the ins and outs of lenses than I...

When DJI release the 46mm lens filter adapter kit, is there anything available that could be fitted to that to do a correction? Or is putting it in front of the lens just not going to work? As you can tell, I have no idea about any of this!

Also, does anyone have any video they can share which they took with the 90 degree FOV, just to compare? Thanks...


I have three videos on my Ben7seven7 YouTube channel currently showing the Phantom 2 vision with the 1080p 30 FPS 90 degree angle view. It's not 100% perfect but there is little to no obvious lens distortion, especially as compared to people filming video on wide. Here is a link to one of them.

http://youtube.com/watch?v=tpaYVU5JTio
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Re: DJI Lens Correction for Videos

Postby Pull_Up » Mon Dec 09, 2013 11:35 am

Interesting, thanks Ben. As you say, very little lens distortion. It also seems to handle stabilization software much better without the curved horizon causing the banana bounce you get on stabilized vids with the wider FOV.

Even with that, though, there's something a bit more dramatic about the wide FOV, a bit more "epic" especially when you get up good and high. Still, I guess we're very lucky in that we can change those settings on the fly, so on calmer days in atti mode you can get dramatic wide FOV video with limited wobble.

I'm going to experiment a bit more with the FOV on my next sortie - thanks again!
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