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Comment by GuB-42 | Hacker News Reader

On the other hand, that should be awesome for astrophotography.

The issue is rotation of the sky about the line of sight axis. Whether the exposures are short or long, over time the sky will rotate more than what an in-camera system can compensate for (the amount of rotation depends on location/time/direction). Over these timescales a rotator that can perform larger movements is needed. This can be provided by an equatorial mount or an internal rotator.

I believe that fancy astrophotography tripods already do that rotation for you, right?

I think that for astrophotography, the shutter times are so long that you have to build it into the tripod, instead of relying on the tiny amount of stabilization that can be done in-camera.

Although maybe it would be helpful to cancel out some motor noise of vibrations from the tripod. But probably the existing image stabilization already does this.

Fancy astrophotography tripods--really, the mount--do that rotation for you. That's why they exist. Even fancier ones exist that permit close-to-arbitrary slewing. Those can be used as a go-to-mount where with the right software, it can image wherever in the sky you're pointed, take the current time, and plate solve for where it's pointed, then finally point at whatever target you actually want to shoot.

For the very long exposure times, you can also hook a second camera up and run closed loop control on a specific star to keep your primary image sensor trained on the correct target to even tighter tolerances. There's companies making cameras that combine both the primary and secondary camera into a single housing so you don't need to fit a second camera + lens to your setup, or insert a prism to pick off part of the image to go to a second camera.

Amateur astrophotography today does tricks you needed access to a dedicated lab to do in previous decades. It's amazing!

Pentax cameras take a different approach with stabilization--rather than stabilize inside lens, which means every lens is shipping its own stabilization solution, they stabilize the sensor itself.

It limits stabilization to two axes, but now any lens is essentially stabilized. And it also lets them do some tricks, since it's so integrated. One is to do sub-pixel sensor shifts for higher res photos, and another is to do astrophotography tracking when GPS data is available.

Much more limited in scope than a full tracking gimbal, but not bad considering it's built into the camera (earlier bodies had a GPS attachment that slotted into the hot shoe connector): https://www.lonelyspeck.com/pentax-k-1-mark-ii-astrophotogra...

Most cameras these days--other than the low end and the very high end--have IBIS (In-Body Image Stabilization) built in, and then stabilization built into the longer lenses (typically > 100mm). In higher-end/more recent cameras that both IBIS and lens stabilization can work together to improve how effectively the system works. I don't know if it's true of universally, but the recent cameras in Nikon's ecosystem which I'm familiar with use a 5-axis IBIS unit. A quick search suggests the K-1ii and some other Pentax cameras also moved to 5-axis IBIS--probably one of the reasons most brands are claiming 5+ stops in-body these days.

OM-1, formerly Olympus, does has some very cool tricks using the tiny micro 4/3s sensor combined with a sick IBIS unit allowing hand-held astrophotography that the larger companies haven't bothered with.

This is also how any IS lenses for film cameras work since moving the film around isn't entirely practical.

Nikon: https://www.nikonusa.com/learn-and-explore/c/products-and-in...

You can see the VR lens element there.

The Canon version: https://www.canon-europe.com/pro/infobank/image-stabilisatio...

> I believe that fancy astrophotography tripods already do that rotation for you, right?

There are various types of mounts, and each type can be either basic or fancy. The specific type of mount that deals with rotation of the sky (around the north/south stars):

* https://en.wikipedia.org/wiki/Equatorial_mount

You can can get non-fancy ones (US$ 240):

* https://optcorp.com/collections/equatorial-mounts/products/o...

Or fancy ones ($20K):

* https://optcorp.com/collections/equatorial-mounts/products/a...

It has no bearing. Tracking is how you keep stars from smearing, not stabilization.

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