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Comment by jonknee | Hacker News Reader

> It's a wide-field of view and only a few megapixels, so basically a cell-phone camera.

It's not similar to a cell phone camera at all. Cell phone cameras are usually much higher resolution (current iPhone is 8 megapixels vs the 2 for Juno), but with a much smaller sensor (iPhone cam has a 1.5µm pixel size vs 7.4µm for Juno).

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Also light thresholds need to be taken into consideration. Jupiter is 5x[1] further from the Sun then Earth, so there is much less light to capture in an image.

[1] On average.

Yup, that's what those big pixels are good for.

Um, so the best cell phone camera on the market is within a factor of 2 in linear resolution? I think that qualifies as "basically".

It's the opposite of cellphone camera. It has low megapixels and a large sensor size. This will allow a lot of light onto the sensor and it won't suffer from the noisiness that high megapixels on a smaller sensor suffer from.

The point is that, on the spectrum of all imaging devices you might put on a satellite, both Juno and a cell phone camera are in the same rough neighborhood. They are dwarfed by telephoto lens, or 200 megapixel sensors. Remember especially that the topic we are discussing is the resolution (km/pixel) at a particular distance (see above), and for this the lens are much more important than the particular CCD chosen.

So now it's the lens that you don't like, not the sensor? The imaging camera has a wide angle (11.7mm) because it's going to be so close to the surface that a wide angle is optimal. That's actually a lot wider than cell phones (iPhone 6s is 31mm equivalent). There are also other instruments on board that look through the gas with telescopic reach.

td;dr Juno has a fine sensor and lens

Resolution has very little to do with it. Many images from NASA are stitched, even the ones from New Horizons. The important part is light sensitivity (in the correct wavelengths!) and making sure that it can work in the radiation of Jupiter.

You can go buy a camera with the same sensor if you'd like, but they're expensive:

http://www.qsimaging.com/620-overview.html

I believe it's the same sensor that flew on the Curiosity mission and we all know those photos are fantastic. They are also flight tested, invaluable for missions like this where you only get one shot at it.

As you'll see if you look above, it was you who brought about the size of the sensor when critiquing my comment, which was addressing resolution.

You also seem to feel the need to defend Juno, as if I was attacking it somehow, so I don't think this conversation can be very productive.

Yes, I think the casual "basically a cell-phone camera" comment you made, way above, has been taken to mean "it's a POS".

But, as you have made clear, you were just making a statement about the combination of wide field-of-view (i.e., the optics) and the number of pixels, which both figure in to resolution. (By contrast with the New Horizons LORRI instrument, which had a very narrow FOV, because they did not approach Pluto closely.)

If one takes a breath and re-reads what you wrote, this meaning is evident. On the other hand, it's very easy to mis-interpret what you wrote.

Your thoughtful refereeing here is much appreciated :)

> As you'll see if you look above, it was you who brought about the size of the sensor when critiquing my comment, which was addressing resolution.

Because sensor size is what's important in digital photography, you can always stitch together multiple images to get more resolution. A large sensor like what's flying on Juno is orders of magnitude better than a camera phone sensor regardless of the resolution. In general cell phone cameras (which you decided to compare Juno's to) are high resolution, but with small a sensor (everything in a phone is small!). Juno is the opposite, low resolution and a large sensor. If you want to take pictures of stuff in space you most certainly want a large sensor.

> You also seem to feel the need to defend Juno, as if I was attacking it somehow, so I don't think this conversation can be very productive.

Well you did attack it by saying its camera was the same quality as a camera phone (aka cheap and shitty). It's not similar to a camera phone whatsoever, you were just plain wrong.

That's actually way cheaper than I expected it to be. Though I supposed an actual spaceflight-worthy camera with that sensor would cost far more than the one you linked.

Yup, they made a custom camera (which makes sense!). All the way at the bottom of this page there are photos of it along with a lot of details:

http://spaceflight101.com/juno/instrument-overview/

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