Mobius



Since the mobius action camera is available as a successor of the famous Keycam #16, I don't use my Gopro Hero 2 on planes and mulitcopters anymore.
The imagequality i would say is a little bit better compared to the hero 2. But if you take price (<60€), weight (approx. 50g), size (70mm*35mm*20mm) and the customizability into account, the Gopro Hero 2 has definitly lost in my opinion.
You can buy the Mobius cheap directly from china as Wide Angle and Standart Angle Version. The only difference is the lens.

The instructions and a tool to upgrade the firmware as well as adjusting the settings can be downloaded here: http://www.mytempfiles.info/mobius/



So I ordered the wide angle mobius together with some cablestuff and a mountingclipthing (1st image on the left).


The case can be opened by unscrewing two small screws on the bottom front. Next you need to tilt the upper halft just a bit and then lift the whole case straight up to get the two plastic clips at the back out without breaking them (they often get stuck between the case and the lipo).
If you happen to have the wide angled version you can simply change the field of view to narrow in the setup tool, so that the image gets cropped down for the 1080p video or you can just buy another lens.
Every lens wich has the MTV mount (12mm thread with .5mm pitch) you fit just fine.
The lens can be unscrewed (ccw) by loosening the small setscrew. Turning the lens also adjusts the focal distance (screwing the lens in (cw) moves the focal point further away).
To adjust the focus of a new lens, it is advisable to connect the Mobius to a computer via USB (the lipo needs to be connected). After the camera is recognized as storage device just press the shutter button to change to webcam mode. Then choose the highest resolution in a webcam viewing software of your choice. Now screw the lens slowly into the module until the image is sharp. If you're not going to film only flowers try to set the focus to a point far away. If finished dont forget to tighten the setscrew.


If you take a look at the backside of a genuine mobius lens you will notice a red and green cast. This comes from the build in ir-cut filter. Most cameras like fpv boardcameras do have this filter on the sensor itself.


To use a different lens than the genuine ones you need to add a ir-cut filter to get normal colors.
Without ir-filter the non visible infrared red light with a wavelenght of 700nm to 1000nm also falls on the sensor and gets recorded by the red channel. Therefore the image gets a red tint and leafs for example appear white, because they reflect the ir light from the sun.
Because I dont want this pinkish look but also want the ability to use some other lenses i baught a IR-Cut filter from insanware. Its primary meant for laser applications and is also a bit too big for a single lens, but it should work for this purpose.
With a glasscutter the round glass can be cut into some squares wich fit at the back of a MTV lens. Because of the small size of the filter is was not easy to get a clean cut, but as long as there are no scratches in the middle where the light falls through it should be no problem.


I glued the piece of glass with some drops of epoxy glue to a 3.6mm lens.


Here the result: Left: an image with a lens without IR filter, on the right with IR filter.



Again some pictures for comparison:
1st Image: 3.6mm lens with IR-Cut mod (same lens as seen above)
2.Bild: 2.8mm Lens without IR filter (from Surveilzone.com. Cannot find the link anymore, label on the lens: "2,8mm 1/2.5" IR 5MP")
3.Bild: 2.?mm Mobius Lens B (Standard Mobius lens B, focal length is somewhere between 2.8mm and 2.1mm)
4.Bild: 2.1mm Lens without IR filter (surveilzone.com/mtv-mount-2.1mm-wide-angle-lens-cl1162, lot of blur at the corners)
5.Bild: 2.1mm Lens with IR filter
For higher resolution images see the directory with the source JPEG files.


With the 2.1mm lens from Surveilzone and a glued on IR filter the fov is really good, but only sharp in the center.
For FPV-Racing this is not that much disturbing: Youtube: FPV Miniquad - 2.1mm Lens Test