Widescreen From Your Flight Camera

The majority of the popular flight cameras broadcast video formatted with a 4:3 aspect ratio (the only exceptions I can find are a few that utilize a CMOS sensor, such as a 16x9 model sold by Fat Shark and a company called Foxeer, but the image processing in these offerings add about 10-20ms of lag). The majority of FPV monitors and many goggles are configured to display a native 16:9 aspect ratio image.  The end result is you have to choose between viewing the image with pillarbox bars on your display, or stretching the image which causes a distorted picture.  In the latter, case, the stretching feature available on most monitors can be used to your advantage.

To get proper widescreen with this setup, what is needed is a lens that will optically squeeze the image recorded by the flight camera.  When the image is stretched by the monitor, it then appears normal, with the added bonus of being in a proper widescreen aspect ratio.  This is the same technique used to store widescreen images on the film that used to be projected in movie theaters.  In that situation, the image was stretched with another lens on the film projector.  The lenses that squeeze and/or stretch the image are known as an anamorphic lenses.  To squeeze a 16:9 image down to 4:3 requires an anamorphic lens with a 1.33X squeeze factor.  Fortunately, a small 1.33X anamorphic lens is available from a company called Moondog Labs.  Unfortunately the lens is expensive and designed for an iPhone.  

The Moondog Labs 1.33X anamorphic lens

Utilizing the Moondog Labs anamorphic lens requires fabricating a custom mount, and replacing the standard lens on your flight camera with a pinhole lens to avoid vignetting by the anamorphic lens.  For my build, I utilized the MNR1269L pinhole camera from Security Camera 2000, though any pinhole camera should work with a properly fabricated mount. 

 MNR1269L pinhole camera 

Below I've got some test footage showing the effect of the anmorphic lens.  The first video is the standard output from the camera recorded on a DVR I use to record flight footage.  The second video is shot through the anamorphic lens, and the video is stretched by the video player.  The raw video is 4:3 with a squeezed image, and most monitors can perform the stretching.  

As you can see, the image in the second video is quite a bit wider, and fills the entire 16x9 image of a display with no distortion other than the typical distortion from a wide angle lens.  This footage was recorded using a hastily thrown together makeshift mount which set the camera too far back from the anamorphic lens, resulting in the vignetting seen in the video.  When the lens is spaced and aligned properly, no vignetting is seen in the image.

Moondog Labs offers several different lenses.  For my build, I selected the model designed to be compatible with the Schneider Optics iPro lens system.  The bayonet mount utilized by the iPro lens system allowed me to pick up a used iPro lens compatible phone case off of eBay for relatively cheap, and modify it to mount the anamorphic lens to my flight camera without requiring any modification of the anamorphic lens.  For my build, I chose a case designed for a Samsung Galaxy S4, as it appeared to have the correct orientation, layout, and size for my needs.  

iPro compatible bayonet mount on the Moondog Labs anamorphic lens

iPro lens case for the Samsung Galaxy S4 (note: while Moondog Labs advertises their lens as "iPhone only" it is physically compabitble with this case.  The limitation described on the Moondog Labs website is because of the orientation of the socket on this case is rotated 90 degrees from the case designed for the iPhone.  For this project, this wasn't an issue, and was likely an advantage)

The Build

I began my build by trimming the socket off of the iPro lens case, and fitting it with brass standoffs.  The standoffs were placed far enough apart to allow the camera to fit in between.

Modified iPro lens case (note: the brass standoffs were replaced with male threaded standoffs after this photo was taken)

To complete my build, I molded a custom backplate with Polymorph moldable plastic.  First I flattened out the heated plastic, pressed the camera into the flattened plastic, and then embedded the standoffs.  To be sure the standoffs would hold, prior to embedment I partially mounted nuts onto the male threaded portion of the standoffs, leaving a gap for the plastic to fill between the standoff and the nut.  This was done with the standoffs mounted to the iPro lens case for proper alignment.  The base plate was then trimmed to eleminate excess plastic, and to allow attachment of the camera's cable.

Custom molded base plate (note: these photos were taken after the plastic had already cooled and been trimmed to size)

Getting a baseplate with proper alignment took some trial and error.  To adjust the alignment, I reaheated the platic with a heat gun, and tweaked the angle of the camera and the standoffs.  The final result still had a slight misalginment, and some minor vignetting can be seen in the video.  A more precise mount would eliminate this, and could probably be made with a 3D printer.

 Camera placed in assembled mount with lens mounted

The flat back of the custom molded base plate allows me to mount the entire assembly to the pan/tilt mount on my quadcopter with 3M foam tape.

The finished product

First Flight

I had a very successful test run with this rig.  My first two flights are in the videos below.  When viewing  the live feed, the TV I use for my ground station properly stretched the image, and I enjoyed having the wider field of view.  Using formatting tags with youtube, I was able to have youtube stretch the video out for playback of the recordings.  You can read more about formatting tags here:
https://support.google.com/youtube/answer/146402?hl=en 

Using anamorphic video does have a slight drawback.  When the image is stretched by the display, any OSD information that was broadcast with the video will be stretched as well.   Some people may find the stretched OSD to be objectionable.  If you already stretch your 4:3 formatted video to avoid pillarbox bars, your OSD will look the same as it always has, and your video will no longer be distorted.  OSD software can probably be modified to factor in for the anamorphic stretching, but since this is such a niche application, it’s unlikely any OSD makers are likely to implement such a feature.  For the Eagle Tree Vector system, I didn't find the stretched OSD to be an issue. 

Conclusion

Overall I found this to be an interesting project.  I had been interested in getting widescreen from my flight camera for a while.  The cost was a bit high, but the only other options I have found on the market use CMOS rather than CCD sensors, and the processing in the camera adds lag.  Additionally, I hadn't discovered the 16:9 cameras from Fat Shark and Foxeer until I had already purchased the anamorphic lens from Moondog Labs.  At that point, I was committed.  If price is an issue, and you can tolerate the additional lag, the Fat Shark and Foxeer cameras may be a better solution.  Overall, I find the anamorphic lens to be a worthwhile upgrade to my flight camera, though I would make a more precise mounting system if I had access to a 3D printer.  The best solution in that situation would likely be to buy a caseless board camera with a pinhole lens, and mount the board camera directly to a 3D printed mount custom tailored for the anamorphic lens.

Parts list:

Moondog Labs 1.33X anamorphic adapter lens for iPro lens system http://www.moondoglabs.com/store/#!/1-33X-Anamorphic-Adapter-Lens-for-iPro-Lens-System-iPhone-only/p/45749662/category=8525657 

Schneider Optics iPro lens case for Galaxy S4 https://www.schneideroptics.com/Ecommerce/CatalogItemDetail.aspx?CID=1925&IID=9806

Security Camera 2000 MNR1269L pinhole camera http://www.securitycamera2000.com/products/700TVL-Mini-Camera-1%7B47%7D3-Inch-Sony-Super-HAD-CCD-3.7mm-Lens-DC12V.html

Brass Standoffs (easy to find on ebay)

Polymorph moldable plastic http://www.hobbyking.com/hobbyking/store/__83416__ESUN_Polymorph_Hand_Moldable_Plastic_250g_Bottle_.html