Item — HN Reader

This is quite brilliant.

Here's another approach to tracking, employed by Pentax and maybe others: Use 5-axis sensor movement to track stars (i.e. use the motors which move the sensor for in-body stabilization)

Given GPS coords, software can do this to the limits of sensor movement afforded by the camera body. I don't have a Pentax but modern models can apparently track for at least 4 minutes.[1] (!)

In theory, official or unofficial firmware for other models of camera might be able to do the same.

[1] https://milkywayphotographers.com/article/2021/01/21/pentax-...

1 comments

I think this requires not just a GPS fix but also fairly accurate heading information from an electronic compass and tilt information from the camera's accelerometer, because shifting the sensor in the right direction requires knowing which part of the sky the camera is pointed at. (I haven't bought the astrotracer add-on for my Pentax because it's crazy expensive for what it is, but it should be at least a bit more than just a GPS receiver.)

Surely in camera, it is just a matter of taking a shot, wait an interval, take another shot, then shift/rotate the two images until X number of bright spots line up and then form a new composite, rinse and repeat. If you have a motor in the camera for stabilising you can use that shift/rotate parameter to move the sensor for the next shot.

Modern cameras can physically move the sensor inside the camera. It is called IBIS or In Body Image Stabilization.

Taking one long exposure I imagine would better pick up on faint sources of light compared to multiple short exposures.

> Taking one long exposure I imagine would better pick up on faint sources of light compared to multiple short exposures.

You definitely need an exposure long enough for the light sources to actually show up on the image. But beyond that point, sometimes you can do better by taking lots of separate exposures: https://en.wikipedia.org/wiki/Lucky_imaging Really depends on what the limiting factor is in your imaging system. For cheap consumer cameras, sensor sensitivity is more of an issue than atmospheric fluctuations, so longer exposures are usually better.