I have an Alkeria Necta N4K2-7C, with which I use to take pictures of stuff like trains.

1 Sony E mount

Today I adapted my line scan camera to Sony E mount. It originally came with a Nikon F mount. There are lots of industrial lenses for Nikon F mount, such as the Zeiss Interlock series, but I use the camera recreationally for taking line scan photos of trains. There are way more high quality manual focus lenses for Sony E mount, or for mounts that can be adapted to Sony E mount but not Nikon F mount (due to the much shorter flange focal distance). For example, Leica M mount lenses can be used on an E mount camera but not an F mount one. Moreover, E mount allows the camera and lens to be way more compact. There are also some legendary and yet relatively affordable lenses like the Voigtländer Apo Lanthar 65mm f/2 which I consider to be superior to almost any manual lens available for Nikon F mount. So that’s why I did it.

The camera has four M4 screw holes.

To make the Sony E mount adapter, first, I bought a Neewer extension tube. The extension tube has two sets of male and female E mounts, so it’s great — even if I screw up one of them, I still have another one to fall back on. There are cheaper extension tubes without electronic contacts but the Neewer one, along with similar products from Meike and others, seems sturdier with four screws on instead of three on the lens mount.

Then, I measured everything carefully with callipers and made a model to attach it to the four screw holes on the Alkeria camera. It’s my first time using Onshape.

I found that, compared to the schematic above, the vertical distance between the four M4 screw holes is only 35 mm rather than 36 mm. Not sure if this was a typo or due to physical changes in later versions of the camera (I bought mine in 2017).

Download STL file

Then I printed it out with my Ankermake M5 3D printer. It took me three tries due to fiddliness with the lens release button and the confusion between 35 mm rather than 36 mm between screw holes. For the final print I used 100% infill and 0.16 mm layer heights. It seems pretty sturdy — even when I exerted some force on an earlier version with only 20% infill to try to pry off the lens, I couldn’t.

There’s only one caveat, which is that due to various mechanical reasons the lens is mounted upside-down. That is to say, when the line is in the horizontal position, the top of the lens, with the distance markers, faces downwards. I could flip it 180 degrees but the lens release button would occlude the L-bracket. However, I would usually use it in vertical position, where the distance marker would be to the side.

Also, due to the potential occlusion with the four M4 screws, it is rotated very slightly — but it is not a big deal as most full frame lenses cover a 36 × 24 mm area whereas the line is only 28 mm long.

2 L-bracket (2018-2020)

To securely attach my line scan camera to my tripods equipped with Arca-Swiss dovetail quick-release clamps, I designed an L-bracket in 2018. The L-bracket allows me to attach the camera both vertically (for scanning stuff like trains) and horizontally (for example, to capture moving cars from above).

Due to difficulties in getting Rhinoceros 3D to work on Linux via Wine, I drew it by hand.

Just kidding, I actually did make it in CAD using Rhinoceros later (more than a year later due to extreme procrastination) but I seem to have lost the file.

Since this part needs to be really strong to support the weight of the camera, whose cantilevered position causes huge amounts of stress, I decided to get it made by CNC at 3D Hubs (now part of Protolabs). It cost me nearly $300.

I also accidentally made it too narrow so it is loose on certain clamps (it is very secure on my Peak Design tripod, though). Later I added some felt pads to it for extra grip.

3 Scope (2023)

It’s really hard to see what the camera is pointing at sometimes, since it only captures a single column of pixels. So I made a janky “scope” to aim the camera.

Download STL file

4 Future ideas

4.1 Rotating line camera

I can make it into a rotating line camera and capture seamless 360 degree panoramas. I’m thinking of gtting a Syrp Genie Mini II or similar.

4.2 Custom compute with display

Currently, the line scan camera plugs into my laptop (a Thinkpad X1 Carbon gen 6 from 2018). The main problem is that the line scan camera functions best in bright conditions, such as a sunny day, since the exposure time of each column must be very short, but the brightness of a laptop screen is quite poor. Even though the Thinkpad has one of the brightest screens at 400 nits, it is sometimes hard to see the screen during the day. Moreover, having to carry a whole laptop in one hand can be quite unergonomic.

Getting a small embedded computer running my capture software with a small camera monitor suitable for outdoor use would be great. There are some that are 1200 nits and above.

For the choice of computer, there are some choices like an MSI MS-C918S.

I would need to make some changes to my capture software to make it work more nicely with touchscreens and run it automatically upon boot.