Item — HN Reader

This is amazing. Now just FYI, for those curious, some recent "old guard" innovations by pro camera makers for astrophotography include:

1. Leveraging the multi-axis image-stabilizing movement available to an in-camera DSLR sensor with GPS for the purpose of tracking the sky during a long-ish exposure to reduce star trails. Ricoh-Pentax Astrotracer. http://www.ricoh-imaging.co.jp/english/photo-life/astro/

2. Removing the camera's IR filter, allowing it to capture hydrogen-alpha rays (656nm). This captures energy (image, color) not otherwise seen by normal camera sensors. Canon EOS Ra. https://www.usa.canon.com/internet/portal/us/home/products/d...

I know this only because I've been researching a DSLR/mirrorless camera upgrade but also delaying it regularly while I'm reminded how excellent phone cameras have become! Unless you're a pro, a pixel-peeper, an artist, or just someone who simply enjoys the machinery and process.

4 comments

I didn't quite like the article. At the begining it shows a good picture of the Milky Way and it says:

> The image has not been retouched or post-processed in any way.

Then the whole article describes how they've automated a full astroprocessing pipeline inside the phone, that makes heavy postprocessing...

I think what "has not been retouched or post-processed in any way" is supposed to convey is that no work is needed by the user of the camera app to get pictures of this quality. There's lots of in-camera processing of course. That's always been the case for digital cameras: sensors don't produce jpeg files.

The problem is that the definition used to match the capabilities. The capabilities changed. Should the definition? If I say I haven't retouched or post-processed a picture of myself, you used to be able to assume it hasn't been airbrushed or edited to make me look fitter. In fact, that used to be how you'd say it. Linguistically, it's extra weird when you're announcing a new auto-retouching and auto-post-processing feature.

That doesn't mean there wasn't heavy post-processing on the image. It simply means the user didn't have to do it.

Exactly. And heavy post-processing is necessary for even very simple things because a camera's sensors don't match the output picture all that well. See for example https://en.wikipedia.org/wiki/Bayer_filter#Demosaicing. The postprocessing has moved up the semantic stack and now cameras do things like face detection and smoothing, but there's always been some amount of postprocessing in digital photography.

What people are trying to say is that if this is your definition of post processing then there doesn't exist any digital camera system that produces photos without post processing. Indeed such a camera cannot exist.

I know, I work in digital image processing, and I'm an amateur astrophotographer. Demosaicing is not on the same level as star registration, stacking (posibly HDR processing in the middle), plus some more AI driven "magic" in between.

That's what I'm referring to: for the shown image "without post-processing" the phone has performed a lot more actions after demosaicing, that's why i say it was heaviliy processed.

Those lines have been blurring for a good while. Put an Insta filter on your photo? Tut tut, naughty! Your phone's camera app does the same thing for you?* Your phone sure has a good camera!

* Aggressive HDR, sharpening, automatic tint 'fixing', etc. Am I talking about filters or automatic photo processing in flagship phones.

I do get the sentiment in that statement, in that if you take a photo with that phone, you can get the same output without doing much else than pressing the capture button and being still. Very still.

That's the only way for mobiles to get decent results though. They're so physically limited (sensor size, fixed aperture, lens size, &c.) that the original files are horrendous to look at.

What google is doing with their pixel phones is magic, they turned a normal camera into a very very good one. I'm still impressed every time I use night sight. The drawback, as always, is that as soon as you zoom in or see the pictures on a large screen (or printed) it's painfully obvious that they're heavily post processed. It almost look like an abstract painting or an AI generated image (which it almost is).

If you're delaying a DSLR/mirrorless because the camera already in your pocket is good, I would suggest also looking into the highest end point-and-shoots. They're getting crazy useful, they shoot in RAW, they have most of the bells and whistles you'd want outside of physical stuff like changeable lens options. Mine is Good Enough™ for everything hobbyist and I'm super happy with it. And it fits in my pocket.

pixel peeper perhaps, but these images are nice when you look at them on a smartphone screen, print one or view on large screen and the pictures from a mobile phone give a whole different feeling and sense of quality.

(2) is about 15 years old, but can you explain how actually does (1) work?

This is what I understood: I think the software uses the GPS and camera orientation to calculate which way the sky moves relative to the lens. Then uses the camera's image stabilisation to track the sky, i.e. instead of moving the camera, move the sensor.

Yeah, though obviously since this is merely image stabilisation, and not a dedicated de-rotation, there are limits to how far the system can move the sensor and thus to how long the exposure can be.

Fortunately, you can devise rotation error VERY precisely from this optical sensor data. I don't think it's actually a problem.

Eh? The manufacturer datasheet states you can take at most a 300 second exposure with this rotation compensation system, are you arguing this that this limitation isn't a problem?