I am currently planning a few video projects and was searching for some cheap, preferably second hand, cameras on-line. I stumbled upon the discontinued NX-line of cameras by Samsung and had a browse through the spec sheets of some of them and found the NX300 and NX300M [1], which are more or less identical, except the articulating screen of the NX300M has what is known as a selfie-mode.

For me the most interesting properties are that it can shoot 1080p60 video (while 50fps is more useful for me in Germany), it has interchangeable lenses, manual modes and is a DSLM, so you can essentially adapt every old lens onto it, you can find. Unfortunately there are some downsides: It can only shoot 21 minutes (about 4 GiB) of 1080p50/60 video, the bitrate of that video is not that great, so on higher ISO-values the video gets really blocky and it does not have a microphone input (except a weird proprietary microphone [5], which sits on the hot shoe. However, for about 100 € per camera these are quite obtainable.

So I've started to poke around with a search engine of my choice and found some very interesting posts by people hacking the Samsung NX300 and NX300M and executing their own code [2,4], even for auto-backup over the built-in wifi [6], getting the source from Samsung [7] (which is still possible, however you have to ask for it), hacking the firmware to remove the movie length limit [3], and finding the developer menu [[8]], which also has some settings for removing the video limit.

While all of the resources are still on-line, I will be copying them in a few blog posts, when I find something out. First of all: remove the movie limit. That's easy.

You enter the developer menu by putting a file in the root-directory of the SD-Card with the name nx_dev.adj. The content has to be smart_camera, exactly 12 bytes in length. Make sure, your editor does not add additional bytes at the end, maybe open the file in hexedit or a different hex editor to make absolutely sure. Then you boot up your camera with the SD-Card inside, switch it into AUTO-mode and enter the following: DOWN, OK, UP, OK, RIGHT, hold EV, press and release OK, release EV. Bosh, you should be in the developer menu.

The only really useful thing here is in the system parameters menu, where you can change the overheat power-off temperature, disable power saving features, disable movie length, disable the need of attaching a lens to the camera (especially useful when dealing with defective cameras) and allow you to capture shots even when the autofocus-system cannot lock on.

I undertook other things and looked into the source code, however have not been able to build an image up until now, and have not looked into the hacked firmware for the NX300 camera. I would love to investigate the microphone input, however I did not come across the external microphone up until now (if you have one and want to get rid of it, email me!), I would like to increase the bitrate, however these properties are buried inside a binary blob and I was not able to reverse engineer the drime4 driver or the MMAL-interface to it. The autoexec.sh does not help me, at least not for now.

References

[1] https://www.digitalkamera.de/Kamera/Samsung/NX300M.aspx
[2] https://op-co.de/blog/posts/hacking_the_nx300/
[3] https://www.dpreview.com/forums/post/56754944
[4] https://github.com/ge0rg/samsung-nx-hacks
[5] https://www.dpreview.com/forums/thread/3989299
[6] https://lemmster.de/auto-backup-from-nx300-via-ftp.html
[7] https://opensource.samsung.com