He's using digital single-lens reflex cameras with moving mirrors in an application where you don't need that, but do need a good camera. What do you use today when you need a good camera with no user interface?
it's a bit weird because it often turns out that cameras with user interfaces are cheaper because of economy of scales. that being said, a market for almost barbone sensors on pcb's seems to be building and is lead by raspberry pi's camera modules, where the hq module has a reasonably sized sensor but is still a far cry from mft, aps-c and full frame sizes. the hq camera is almost on parity with most phones. from there it pretty much moves into cameras with ui's but controllable with some kind of vendor sdk or libgphoto. i imagine it's a matter of economy of scale and it's almost impossible to buy a good almost barbone sensor. If it's even possible e.g. the 61mp ff sensor used in the Sony a7rV is available almost barbone for astro photography, it's still very expensive. i imagine there's a pretty big market for all kinds of industrial cameras but from tip toeing into that, it seems very very very expensive.
A Pi HQ camera with a lens of your choice. It's easy to synchronise any number of Pi cameras together, and with the RAM on them each camera can store a long sequence of frames (add an RF-trigger flash using BBC microbits to each one to control motion blur).
That's a component. It needs packaging.[1] That bulky lens needs support that's reasonably rigid and resistant to vibration. Four 2.5mm screws on the PC board of the sensor are not enough. Support needs to be near the center of gravity.
In the original article, the author describes his camera mounting problems.