Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Dragonfly: An optical telescope built from an array of off-the-shelf Canon lens

dunlap.utoronto.ca

Post reply on HN
Print view View original

41–50 of 82 posts

Re: Dragonfly: An optical telescope built from an array of off-the-shelf Canon lens

#41

Post by buescher »

dylan604 wrote: post #33
buescher wrote: post #10

Earlier quoted context omitted.

Not that inexpensive - that's a $12000 lens with a nearly 6" aperture. The telescope itself is a fairly specialized instrument. It's more like a redundant array of very fast (for a telescope) lenses. From the paper: "Our primary goal is to test predictions that at very low surface brightness levels galaxies display a wealth of structures that are not seen at higher surface brightness levels." (But yes, the lenses are…

There are plenty of much cheaper telescopes in that 6" aperture range. My 152mm was only $1k. My polar mount was $1500. Even adding in a tracking scope/camera to attach is still a fraction of the price of single lens. Tack on a similar SBIG dedicated astro camera and cheap laptop to run the guiding and imaging would still come in under that price tag. So, is there an advantage of having all of the lenses on the same…

It's more of a "that they could do it at all" sort of feat. They're coming in somewhat cheaper (probably) and at lower project risk by using off the shelf professional camera lenses than by having tubes made for the purpose.

Your 6" scope is slower, probably much slower, than the telephoto lens they used. There really aren't any amateur telescope tubes I know of that you could directly compare to the 143mm aperture f2.8 Canon lens. The right comparison would be to a 6" apo, which would run $8K-$16K and still be slower.

Re: Dragonfly: An optical telescope built from an array of off-the-shelf Canon lens

#43

Post by Aspos »

antognini wrote: post #11

This kind of a setup of a large number of small, cheap detectors works well for observing diffuse objects with low surface brightness. Generally speaking telescopes improve with size because larger telescopes can resolve smaller objects, so you can concentrate the light from your source into a smaller patch and increase the signal-to-noise with respect to the background. But once you have resolved the object (which d…

Can one use millions of smaller detectors if one finds a way to point them in one direction and synchronize them to take pictures at the same exact moment?

I mean, can millions of phone cameras make one giant virtual telescope?

Re: Dragonfly: An optical telescope built from an array of off-the-shelf Canon lens

#45

Post by Aspos »

lvspiff wrote: post #27
shiftpgdn wrote: post #16

Can someone smarter than me explain why astronmers can't stick something like this on the back of an existing geostationary platform (like what is used for the XM radio sattelites) and get amazing data out of them? Surely sticking something like this array 100km into space will yield better results without the overhead of a 20 year mission plan like James Webb or Hubble.

I've always wondered that myself - If the Russians could build and launch sputnik in 1957 and get it around the earth a few times why aren't we seeing a huge number of backyard dad+son duos building rockets to launch their own telescope array. Its amazing that its a 60 year old feat that is still only in the hands of governments and massive corps

But there are actually so so many startups and garage enthusiasts at various stages of readiness to put payloads into orbit

https://www.youtube.com/watch?v=SH3lR2GLgT0

Re: Dragonfly: An optical telescope built from an array of off-the-shelf Canon lens

#46

Post by dylan604 »

buescher wrote: post #41
dylan604 wrote: post #33

Earlier quoted context omitted.

There are plenty of much cheaper telescopes in that 6" aperture range. My 152mm was only $1k. My polar mount was $1500. Even adding in a tracking scope/camera to attach is still a fraction of the price of single lens. Tack on a similar SBIG dedicated astro camera and cheap laptop to run the guiding and imaging would still come in under that price tag. So, is there an advantage of having all of the lenses on the same…

It's more of a "that they could do it at all" sort of feat. They're coming in somewhat cheaper (probably) and at lower project risk by using off the shelf professional camera lenses than by having tubes made for the purpose. Your 6" scope is slower, probably much slower, than the telephoto lens they used. There really aren't any amateur telescope tubes I know of that you could directly compare to the 143mm aperture f…

You of course are correct regarding f-value. My specific scope maths out to an unusual f/4.8 at 731mm focal length. However, I'm not trying to take 1/100th images. I'm doing 30s exposures, so a f/2.8 vs f/4.8 isn't that bad of a trade off.

Even if this isn't doing the same "science", it would be an interesting thing to play with for sciene. Instead of stacking images from the same camera, just stack each image from the array. Or capturing an entire mosaic in one "snap" which is essentially what WASP is doing (mentioned in a post from yesterday).

Re: Dragonfly: An optical telescope built from an array of off-the-shelf Canon lens

#48

Post by llm_trw »

perihelions wrote: post #15
gnatman wrote: post #14

Earlier quoted context omitted.

I was struggling to see the planetary nebula inside that blue circle before I realized that is the planetary nebula. cool!

Somewhere there's a large, bright nebula in the shape of a red arrow no astronomer's ever noticed.

https://en.wikipedia.org/wiki/Redshift-space_distortions

Re: Dragonfly: An optical telescope built from an array of off-the-shelf Canon lens

#49

Post by EnigmaFlare »

Aspos wrote: post #43
antognini wrote: post #11

This kind of a setup of a large number of small, cheap detectors works well for observing diffuse objects with low surface brightness. Generally speaking telescopes improve with size because larger telescopes can resolve smaller objects, so you can concentrate the light from your source into a smaller patch and increase the signal-to-noise with respect to the background. But once you have resolved the object (which d…

Can one use millions of smaller detectors if one finds a way to point them in one direction and synchronize them to take pictures at the same exact moment? I mean, can millions of phone cameras make one giant virtual telescope?

Took me a while to understand what you meant. A phone camera already is millions of smaller detectors .... But I think you mean coordinating millions of people to all take photos of the same direction in the sky and then combining all the photos? I'm sure it can be done with an app and a way to build that crowd of users! But the field of view will still be huge because they're not telescopes/telephoto lenses.

Re: Dragonfly: An optical telescope built from an array of off-the-shelf Canon lens

#50

Post by tocs3 »

Iulioh wrote: post #38
perihelions wrote: post #3

Unfortunately their website is not built from a large, redundant array of off-the-shelf server parts. Here's a mirror, https://web.archive.org/web/20240507234024/https://www.dunla...

>Here's a mirror, Ah! So there's a large mirror involved? (sorry)

No, just the camera lenses and sensors for each lens.

I am wondering if they just "stack" the images or if there is something more involved.

Post reply on HN