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so many ways to process an image

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#1 prefetch

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Posted 03 August 2020 - 03:13 PM

i came across this gallery of images, but the interesting thing is that all of the images are from the same source data, but each of them are obviously processed very differently by different processors.

 

it's a reminder that we all have a very different idea of what looks good, and that while data is data, it can interpreted many different ways!

 

http://www.chilescop...age-gallery/35/

 

 


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#2 Kevin Thurman

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Posted 03 August 2020 - 03:19 PM

It is always interesting to see the different interpretations of what something "ought to" look like. Some take more artistic liberties, others more realism, others more scientific in nature. For me the goal is to put the viewer in space, next to the object. So I would say I tend towards exaggerating the depth while maintaining realism when I am processing.



#3 endlessky

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Posted 03 August 2020 - 03:51 PM

Very nice to see so many different ways of processing the same data.

 

I gave them a quick look and to my personal taste I much prefer the softer, more subtle processing of some, while others are overdone and overprocessed.

 

But all of them amazing, nonetheless.

 

Would love to see more comparisons and, why not, also to have a try at the raw data, to see how bad my processing skills are!


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#4 Rickster

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Posted 03 August 2020 - 03:52 PM

Interesting find. 

I was going to say that the differences are amazing, and then I remembered that some people like red cars and some like brown cars and...

Still, some of those hurt my eyes.


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#5 kisstek

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Posted 03 August 2020 - 05:53 PM

So many different shades of red. No green images. No blue ones. Only one B&W. So despite the differences, still very similar.

 

Could be the "rules" of the contest discourage truly unique interpretations.



#6 WebFoot

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Posted 04 August 2020 - 03:17 PM

Very cool, and a graphic reminder that we're really doing art more than science as soon as we stretch the data.


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#7 Kevin Thurman

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Posted 05 August 2020 - 02:22 AM

Very cool, and a graphic reminder that we're really doing art more than science as soon as we stretch the data.

I sort of disagree, I mean there's certainly a lot that goes into truly "creating" a space image, but what you are revealing in that process *is* actually there. Some interpretations get quite artsy, some even looking like watercolors, but most of what people post is quite true to what's there. We don't create the nebulae but capture them and freeze them into 1's and 0's (unless you're one of those crazy film guys). Are Hubble photos not science? 



#8 WebFoot

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Posted 05 August 2020 - 11:04 AM

I sort of disagree, I mean there's certainly a lot that goes into truly "creating" a space image, but what you are revealing in that process *is* actually there. Some interpretations get quite artsy, some even looking like watercolors, but most of what people post is quite true to what's there. We don't create the nebulae but capture them and freeze them into 1's and 0's (unless you're one of those crazy film guys). Are Hubble photos not science? 

I wondered if I would get push-back!  wink.gif

You're entitled to disagree.  But the fact is that if we were to park a few light years away from these objects, so that we had the same visual field of view as our photos, what we would see would bear little resemblance to most of the diffuse nebulae we see, which generally would show faint (or no color) instead appearing as a ghostly thing in space.  That's why we have to stretch our data so extremely.  Even globular clusters and galaxies would not be so prominent, I suspect, since we get them to look that way with non-linear stretches.

As to Hubble, its "pretty pictures" are no more science than are ours.  But, obviously, Hubble does lots of real science.

 

Yosemite never looked like Ansel Adams's photos; he was a genius in the darkroom.  Celestial objects don't look like our photos, either.

 

That's not to say that no amateurs are doing "science."  Lots of people are doing asteroid hunting.  Some even are finding extra-solar planets.  And there are other, specific, things that some are doing.  But our pretty pictures are not, by any rational definition, science.

 

Mark


Edited by WebFoot, 05 August 2020 - 11:08 AM.


#9 TimN

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Posted 05 August 2020 - 12:19 PM

This subject has certainly been discussed before and I always find it interesting.

 

Just because our images don't look like we would see them if we were close up, doesn't mean they are any less science. If this was a criteria then infrared images wouldn't be science. Our senses are limited and if an image can show you whats actually there - even though we couldn't see it, then that it is science. For example the Hubble Palette is definitely false color but it can show you gases that would otherwise be hidden by the Ha. So, when I show people my images I don't say my Hubble Palettes are what they would see but that they are false colors to bring out the fainter gases. So, while our images don't normally add to the total science base, they do add scientific knowledge to our friends and neighbors. 

 

Are they art? Of course they are art. Most of us make them as nice looking as we can. However, we stick to whats actually there, whether its something we could see with the naked eye or not. Most of us show these mainly to friends and neighbors and if we honest about what they represent then we increase their scientific knowledge. If we make them beautiful we are using art as a delivery mechanism.

 

So, my view is they are both art and science. 


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#10 WebFoot

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Posted 05 August 2020 - 12:52 PM

This subject has certainly been discussed before and I always find it interesting.

 

Just because our images don't look like we would see them if we were close up, doesn't mean they are any less science. If this was a criteria then infrared images wouldn't be science. Our senses are limited and if an image can show you whats actually there - even though we couldn't see it, then that it is science. For example the Hubble Palette is definitely false color but it can show you gases that would otherwise be hidden by the Ha. So, when I show people my images I don't say my Hubble Palettes are what they would see but that they are false colors to bring out the fainter gases. So, while our images don't normally add to the total science base, they do add scientific knowledge to our friends and neighbors. 

 

Are they art? Of course they are art. Most of us make them as nice looking as we can. However, we stick to whats actually there, whether its something we could see with the naked eye or not. Most of us show these mainly to friends and neighbors and if we honest about what they represent then we increase their scientific knowledge. If we make them beautiful we are using art as a delivery mechanism.

 

So, my view is they are both art and science. 

Our pretty pictures aren't science for the simple reason that we aren't doing science.  We aren't creating, or poking at, hypotheses.  We aren't discovering anything new. And, unlike a science lab in school, we're not learning how to do actual science.  We're just taking images of things that have been imaged millions of times before.  Not science, by any rational definition of science.

Is it interesting?  Sure, a good image is very interesting.  And that can help "science," as a way of encouraging people to like science.

Is it fun?  Sure, assuming you have a high tolerance for frustration, and deep pockets.

Is it science?  Almost never.


Edited by WebFoot, 05 August 2020 - 02:11 PM.

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#11 TimN

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Posted 05 August 2020 - 05:01 PM

I guess it depends on your definition of science. We certainly aren't adding to the body of scientific knowledge or creating new scientific information  so we agree on that.

 

However, we are spreading existing scientific knowledge with our images to friends and neighbors. In that respect they represent science and art. If it was just art we could arbitrarily add or take away parts of an image. Most of us don't do that. 


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#12 WebFoot

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Posted 05 August 2020 - 07:05 PM

I guess it depends on your definition of science. We certainly aren't adding to the body of scientific knowledge or creating new scientific information  so we agree on that.

 

However, we are spreading existing scientific knowledge with our images to friends and neighbors. In that respect they represent science and art. If it was just art we could arbitrarily add or take away parts of an image. Most of us don't do that. 

Sure, but we can't re-define words to fit our purpose, and the correct defintion of science is "the intellectual and practical activity encompassing the systematic study of the structure and behaviour of the physical and natural world through observation and experiment" or something reasonably like that.

We are not doing anything like that.  Some of us learn lots about "the physical and natural world" through our hobby.  Our images can be useful illustrations in astronomy texts, and can contribute to the enjoyment of science by those around us.  In those ways, we can be said to be aiding science.  

But we are not performing "science" by any accepted definition of that word.  And if every one of us who only make pretty pictures, however faithful we feel we are being in interpreting our data, stopped imaging today, the progress of science would not be affected in any way.

 

Please understand, I mean no disrespect to astrophotographers (of which I am a very enthusiastic practitioner).  I love this hobby, and I work very hard (and spend an immense amount of money) to make images as fine as I can.  But I know actual scientists (including my wife and one of my daughters), so I do know the difference between those of us making pretty pictures and those actually doing science.

 

Mark



#13 TimN

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Posted 05 August 2020 - 08:18 PM

We are talking at cross purposes here. I don't think we actually disagree. We are not doing science. However, I was taught science. The teacher wasn't doing science but he was teaching existing science.  Science comes from the Latin word scientia, meaning knowledge. There is also a scientific process that you defined - I agree with that. We are not doing that.

 

All I'm trying to say that our images are not just art but can convey a lot of scientific information. This can be used to help teach science or just for our own knowledge. If you really think they are just art without anything scientific just try posting the horse head next to the bubble nebula. Or, how about having Mars as a moon of Jupiter. I assume you will get some interesting comments. Great art but not what we do.



#14 WebFoot

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Posted 05 August 2020 - 08:40 PM

Ok

 

:)



#15 schmeah

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Posted 05 August 2020 - 09:40 PM

On the contrary, with the exception of the few that look like cartoons from over-processing, I think it’s remarkable how similar they all look. It reinforces to me the fact that we are simply processing photons that represent a real target with a definite structure and appearance. Of course, if we are up close to it, it will be unrecognizable, but we are all capturing from a similar distance, so this is what it looks like from here. Of course taking a picture is not science. But astronomy is a science. And I have so much more knowledge about astronomy than I did before taking up this hobby. So for me it’s science. And art of course.

 

Derek


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#16 ramdom

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Posted 08 August 2020 - 07:37 AM

As a scientist*, I usually have a fairly strict Popperian definition of science when it comes to mentees and training** but more generally I do see the value in exploratory science and there are many other kinds of science.  I think a lot of us are doing data science, if not astronomical (observational) science.  In terms of data science, it's about processing data in a controlled manner.  One of my standards (controls) is the STF in PixInsight. I (and perhaps others) go about trying to see if manual steps can produce a better image. That's data science. Variation of parametres to see if an image is better or not in some quantitative sense (improving contrast, reducing noise, etc.) is also data science. I have long lists of stuff I've tried and progress made relative to some baseline - again, data science. It depends to a degree on how you approach the capturing and processing of images - if you do it in a scientific or pseudoscientific manner (i.e., have controls/baseline/reference and make changes and determine what works and what does not), then it is data science (informatics). I definitely tend to approach my image capturing and processing (and perhaps even life) this way.  If we compare different noise reduction approaches, that's data science.

 

While there's a subjective aspect to stating which images are best in order to determine which processing methods are better/worse, it is usually possible to distinguish poor images from great ones. It's rare for a really crappy image (I've produced a few of these) to be stated as a "great image" by someone who knows the art. Nonetheless, the visual display of the images is really displaying the underlying data, and the data is where the science part is. See my point below about depiction of nano and angstroem scale molecules. 

 

As far as astronomical observational science, I think narrowband images are definitely examining the signal of nebulous objects: so for instance, I'm able to state that IC1805 (Heart) has a strong Ha signal, a moderate S2 signal, and a weak O3 signal (at least in the context of the data I collected with specific parametres).  OTOH, Sh2-132 (Lion) has strong Ha and O3 signals and a weaker S2 signal. In general capturing an image and examining its shape/texture/depth/features/etc.  is making observations. 

 

It is not about whether you get close up you see visually exactly what you captured.  We make pretty pictures of molecules at the nanoscale and below but I KNOW they don't look the way we depict them on a computer since they are abstracted (i.e., atoms are represented as points, etc.). Yet they are highly informative and can be used to generate and falsify or explain hypotheses and even if you don't go that far (**however, I'd say otherwise to my mentees since that's how our field works), it is still observational or exploratory science.  It is observational data that in theory could be used to do some kind of hypothesis driven science. Every single image/image series we take could be a hiding a potential supernova (or asteroid, or comet, etc.).  It's not just about the visual display, it's about the underlying data that we collect.  At lot of it is unfortunately wasted because no one knows how to use it but that's a scientific problem in and of itself. 

 

As far as close up, I think if we get close enough we would see some or perhaps even most objects as we do with an OSC (not with NB of course, since that's abstracted). Sure, we stretch things but think about how the Milky Way looks from an absolute dark site or even some other objects like M31, etc. look in a powerful telescope. We certainly could have the same view we see in a telescope visually. 

 

--Ram (*bioinformatician, complex systems modelling)

 

PS: If capturing, processing, and analysing data in a controlled or semicontrolled (referential) manner isn't (data) science, then more than half of (one of) my field of data science wouldn't be science either. There are a few ideas I've taken from signal processing here and carried it to our research (a lot of which itself is derived from information theory but I had forgotten about it) and  there are other algorithms and ideas from my field I'd like to implement in AP but no time and perhaps it's less urgent than say, drug discovery.  

 

 

I wondered if I would get push-back!  wink.gif

You're entitled to disagree.  But the fact is that if we were to park a few light years away from these objects, so that we had the same visual field of view as our photos, what we would see would bear little resemblance to most of the diffuse nebulae we see, which generally would show faint (or no color) instead appearing as a ghostly thing in space.  That's why we have to stretch our data so extremely.  Even globular clusters and galaxies would not be so prominent, I suspect, since we get them to look that way with non-linear stretches.

As to Hubble, its "pretty pictures" are no more science than are ours.  But, obviously, Hubble does lots of real science.

 

Yosemite never looked like Ansel Adams's photos; he was a genius in the darkroom.  Celestial objects don't look like our photos, either.

 

That's not to say that no amateurs are doing "science."  Lots of people are doing asteroid hunting.  Some even are finding extra-solar planets.  And there are other, specific, things that some are doing.  But our pretty pictures are not, by any rational definition, science.

 

Mark


Edited by ramdom, 08 August 2020 - 01:00 PM.

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#17 WebFoot

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Posted 08 August 2020 - 11:55 AM

I couldn't disagree more, but it doesn't matter.  I don't understand why it seems to be important to people to believe they're doing science.  But it doesn't matter.... 


Edited by WebFoot, 08 August 2020 - 01:05 PM.

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#18 ramdom

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Posted 08 August 2020 - 09:02 PM

It definitely doesn't matter (just a fun discussion I've had many many times), but it's not about belief but rather semantics and agreed upon notions of what constitutes "science". I mean we do have  entire superfields like "social science" and within that, there are some fields that really stretch the definition. I'm not making up these fields or these expansions - they already exist and it's quite clear where AP fits (see it as data collection, not as showing pretty pictures; in order to do the latter reasonably well, the former has to be done in a calibrated  manner). 

 

This discussion is reminiscent of ones I have with colleagues once in a while in my extremely interdisciplinary field which includes math, computing science, physics, chemistry, biology, medicine and engineering. SOME (a few) scientists within some of the more what they consider "hard science" groups (i.e., physics, math) consider what the other people do as being either "soft science" or not science at all.  Some of these people are at the top of their field (Nobel prize winners or academy members and the like) but yet they take what I consider an elitist viewpoint by not seeing why some of these more fuzzy life sciences or medical sciences are a part of "science". 

 

Like I said, to me "real science" has to involve experiments with controls where you examine outcomes relative to what you'd expect by chance or some reference/baseline. It needs to be hypothesis driven and falsifiable. This is a Popperian view which I hold mostly and this is how our funding mostly works but over the years I've come to recognise the value of other kinds of science, like exploratory  (observational) science. I also am heavily involved in data science and there's overlap between how we process images  (different techniques) vs. how we analyse imaging data (NMR/MRI, x-ray diffraction, cryoEM, etc. of macromolecules, tissues, etc.). So I recognise there are elements to  the AP hobby that includes parts of data science and parts of exploratory/observational science (classification, cataloguing, etc.). For the most part, the practitioners are doing science like students do science: they're following existing recipes and repeating what has come before, but this is still science. When you do your observations or data collection in an undergrad data science course, you're still doing science even if it is following the course laid out by the instructor. So it is not truly novel, but it it is still your own "study" each time you image an object.  Just like a fifth grade baking soda volcano project. 

 

I just wish we could take all of that data collected and make some use of it, some clever machine learning approach for capturing/processing/etc. for instance or something out of the box. 

 

--Ram


Edited by ramdom, 08 August 2020 - 09:03 PM.


#19 HunterofPhotons

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Posted 09 August 2020 - 12:58 PM


....But we are not performing "science" by any accepted definition of that word.  And if every one of us who only make pretty pictures, however faithful we feel we are being in interpreting our data, stopped imaging today, the progress of science would not be affected in any way.....

 

 

Mark

 

I disagree.

There are plenty of astrophotography amateurs who have made scientific discoveries and advanced science.

Just off the top of my head let us be reminded of Steve Mandel who rediscovered the integrated flux nebulae and added to that catalogue.  Jay McNeil started the investigation of McNeil's Nebula.  Both of these discoveries resulted in scientific papers in proper journals.  

Many amateurs are doing planetary transit observations and that data is worthy of science.

R Jay GaBany has done exemplary work with revealing tidal tails and been a contributing author on many scientific articles.

The list of planetary nebulae discoveries by amateurs is long.  One example is DISCOVERY OF NEW FAINT NORTHERN

GALACTIC PLANETARY NEBULAE in Revista Mexicana de Astronom ́ıa y Astrof ́ısica.  It features several PNs by Nicolas Outters and Felipe Alves, all done with amateur equipment.

Granted the overwhelming majority of people who post here are only interested in "How many objects can I capture in one night?" and pushing color saturation to cartoonish levels and but don't disparage those who have faithfully recorded the night sky and contributed to science however you want to define it.

As is often noted astronomy is one of the last areas of science where amateurs can and do make contributions.

 

dan k.


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#20 WebFoot

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Posted 09 August 2020 - 05:19 PM

I disagree.

There are plenty of astrophotography amateurs who have made scientific discoveries and advanced science.

Just off the top of my head let us be reminded of Steve Mandel who rediscovered the integrated flux nebulae and added to that catalogue.  Jay McNeil started the investigation of McNeil's Nebula.  Both of these discoveries resulted in scientific papers in proper journals.  

Many amateurs are doing planetary transit observations and that data is worthy of science.

R Jay GaBany has done exemplary work with revealing tidal tails and been a contributing author on many scientific articles.

The list of planetary nebulae discoveries by amateurs is long.  One example is DISCOVERY OF NEW FAINT NORTHERN

GALACTIC PLANETARY NEBULAE in Revista Mexicana de Astronom ́ıa y Astrof ́ısica.  It features several PNs by Nicolas Outters and Felipe Alves, all done with amateur equipment.

Granted the overwhelming majority of people who post here are only interested in "How many objects can I capture in one night?" and pushing color saturation to cartoonish levels and but don't disparage those who have faithfully recorded the night sky and contributed to science however you want to define it.

As is often noted astronomy is one of the last areas of science where amateurs can and do make contributions.

 

dan k.

If you actually read my posts, you would see that I made exception for those actually doing science.  I made it very clear that I'm talking about those just doing pretty pictures (as even the little bit you quoted makes clear).

But, yet again, it doesn't matter.  If you, or anyone else, want to believe that taking pretty pictures somehow is science, be my guest.


Edited by WebFoot, 09 August 2020 - 05:22 PM.

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#21 pfile

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Posted 09 August 2020 - 07:55 PM


As far as close up, I think if we get close enough we would see some or perhaps even most objects as we do with an OSC (not with NB of course, since that's abstracted). Sure, we stretch things but think about how the Milky Way looks from an absolute dark site or even some other objects like M31, etc. look in a powerful telescope. We certainly could have the same view we see in a telescope visually. 

 

as an aside there are many arguments why this is probably not true. one analogy is a wall illuminated by a lamp, or your computer monitor. does it get brighter and brighter as you get closer to it? you can try it right now - it doesn't. as the monitor gets bigger in your field of vision, the portion of the monitor that your eye can see drops in proportion, so the brightness is constant to your eye. by the "i want to represent what we'd see from a spaceship" logic, the monitor should be blindingly bright when viewed from 1mm away and it's just not. similarly if you pull up to some nebula whose width is measured in light years, when you get to it you'll see that there's nothing to see. there's just not enough stuff making photons in your field of view anymore.

 

we are inside the milky way and it is only faintly visible to us. when M31 is right on top of us it's going to look like the milky way does now - only visible under dark skies, and only vaguely - just kind of a ribbon of light with not a lot of structure. the brightness of the milky way from a dark site is nothing like any stretched image of it.

 

the telescope comparison does not make sense as the telescope gathers a whole lot more light than our eyes ever could. if our pupils were somehow as big as the telescope's aperture we'd see M31 as brightly as in the telescope all the time, right now. to think that the telescope "brings an object closer" or represents what it would look like if you were close enough that it subtends the same angle in your vision as it does thru the telescope is to miss the point of what a telescope actually does.

 

rob


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#22 ramdom

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Posted 09 August 2020 - 09:24 PM

I have seen the Milky Way with my naked eye under truly dark skies (middle of oceans and the like) that is 90-99% (in terms of data observed) of what I've seen in the very best  images:  https://capturetheat...lky-way-images/ - these images are stretched with longer exposures and taken under conditions where the naked eye may not see as much, but

I think they're really only capturing what we can mostly get if you keep staring at it for a while in a really really dark place.  I've not seen any picture of the MW more impressive than what I've seen with my naked eye (more detailed perhaps, but more impressive, no). Like I illustrate with the macromolecule example below, both have value.

 

So that's all I'm saying, that as we get closer to these objects, we could see what we currently see of the Milky Way with the best conditions or perhaps with very lower power visual aids.  I don't think the MW looks faint at all. Even in my rural backyard right now if I stare at it for an hour or so I can get about 50-70% of these views.  I'm always struck by how similar what I see with my naked eye and the MW shots are.   It's just a lot to take in at once and it requires sustained sleeping in the backyard for many seasons but you can see structure and colour.  

 

I didn't say anything about a telescope bringing an object closer---that's you misunderstanding what I meant (I meant what we see in a telescope visually is okay/fair).  I have lower power magnification scopes for my cell phone and cheap binocular gifts: these like 3x to 10x. When I take a picture from far away and go near and see it (without the low power telescope) then they do look the same. So I'm saying if we now do 500x telescope and we need a 50x telescope if we get closer, it is okay.  I understand how a telescope works but at the same time, distance does affect what happens to the light that travels to your eye and if you're closer, you don't need these low power 3x to 10x visual aids - I can see with my naked eye what I can see from far away. I've verified this since I can see the city of Toronto from my bedroom window across the Lake Ontario  which is ~50 miles wide. So I can see it with my naked eye on a clear day, I can see it better with the 3x and 10x scopes, and as I get closer to the city I see a very very similar view but much better detailed.

 

Here's an example of a normal cell phone picture without any zooming from the edge of our property: https://photos.app.g...uT2p6BUYDTL5Nk9 (look carefully you can see Toronto in the far distance - this is what I see with my naked eye on a clear day with my glasses). This is what it looks like using the cell phone camera zoom:  https://photos.app.g...mcS7PFLVbwSrNcA - and as you drive (or boat) to Toronto and get closer, this zoomed view is what you see but even better. 

  

But anyways, my point was that using visual aids like telescopes isn't stretching the data to a point of distortion. I don't think it's that different from wearing glasses or wearing solar glasses to view a solar eclipse, etc. In the end, the same photons are going into your eye.  But anyways, this does get to be a slippery slope. Is EAA the same as seeing what we'd see visually? But I'm more flexible about what is acceptable when it comes to purity of "visual only" argument.  I'm saying telescopes used visually are fine but then people could ask why stop there.  But in EAA, we're seeing processed data, whereas in the telescope we're observing the same photons. 

 

--

 

Finally this visual requirement is a red herring when it comes to the point about science. We don't "see" nanoscopic objects but we routinely image them and represent them in a computer with pretty pictures. I got into protein structure modelling purely because I consider proteins to be beautiful molecules but as I said  before, what we do with these representations is really a lot like what we do with AP data: graphical viewers of macromolecules have tons of options where you can produce pretty pictures in so many ways and none of these are what they look like visually - they're just balls of atoms - but these visual representations do have their utility in addition to being pretty pictures.  Go here to see what I mean: https://www.rcsb.org/

 

But nonetheless, these visual representations are of what we consider to be the "true" underlying data and both these visual representations and the underlying data have use in science. Mostly the data is what is processed further but the visual stuff lets the human do science using their own neural networks (i.e., their brain). 

 

How's the data we collect on an AP object different from the data collected from an x-ray diffraction experiment of a protein structure? How's the processing of it to produce pretty pictures different? The problem is that the data we collect in AP is wasted in terms of science: we don't have a use for it whereas with protein structures, it is hard to get and there is a use for it (to model it, to discover drugs using it, etc.). If we could find a use for the AP data collected by the average person like we do with proteins, then we could have the equivalent of these citizen science experiments like folding@home, rice@home (our project), or even the foldit video game.

 

The seti@home was one such example but I'm talking about finding a usef for AP data collected using AP cameras of different qualities, etc. Perhaps we could have a game like "spot the supernova" or "spot the asteroid".

 

Finally I understand other people make a distinction, but in my own career and my research group, I don't make a distinction between art, science, and philosophy. I have had this statement on my web page (ram.org) for decades (and I've had this argument likewise for decades).

 

--Ram

 

 

as an aside there are many arguments why this is probably not true. one analogy is a wall illuminated by a lamp, or your computer monitor. does it get brighter and brighter as you get closer to it? you can try it right now - it doesn't. as the monitor gets bigger in your field of vision, the portion of the monitor that your eye can see drops in proportion, so the brightness is constant to your eye. by the "i want to represent what we'd see from a spaceship" logic, the monitor should be blindingly bright when viewed from 1mm away and it's just not. similarly if you pull up to some nebula whose width is measured in light years, when you get to it you'll see that there's nothing to see. there's just not enough stuff making photons in your field of view anymore.

 

we are inside the milky way and it is only faintly visible to us. when M31 is right on top of us it's going to look like the milky way does now - only visible under dark skies, and only vaguely - just kind of a ribbon of light with not a lot of structure. the brightness of the milky way from a dark site is nothing like any stretched image of it.

 

the telescope comparison does not make sense as the telescope gathers a whole lot more light than our eyes ever could. if our pupils were somehow as big as the telescope's aperture we'd see M31 as brightly as in the telescope all the time, right now. to think that the telescope "brings an object closer" or represents what it would look like if you were close enough that it subtends the same angle in your vision as it does thru the telescope is to miss the point of what a telescope actually does.

 

rob



#23 ramdom

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Posted 09 August 2020 - 09:51 PM

To address your analogy/question directly: "one analogy is a wall illuminated by a lamp, or your computer monitor. does it get brighter and brighter as you get closer to it? you can try it right now - it doesn't. as the monitor gets bigger in your field of vision, the portion of the monitor that your eye can see drops in proportion, so the brightness is constant to your eye."

 

It doesn't get brighter, but I can see it better. I can make out details better as I get closer. If am seeing a projection of a faint image from the back of a room or if I move up to the front, there's a difference (similarly with the monitor). THAT was my point.  Now, why we see things better could be due to a lack of interference, etc. but the fact we see it better is indisputable (I'm talking about the faint projection analogy). You may argue it is not that much better but there's probably a middle ground between what we see in a telescope visually and what we see as we get closer with a lower powered telescope. 

 

Let's take planets - as we get closer to the planets, or as we get further away, what we can perceive visually changes.  I think of images of Earth from spaceships from far away to near - pale blue dots to bright blue dots - distance affects perception. But I didn't say anything about stuff getting brighter but I am saying we can make out the details better at some optimal distance (both done visually, no cameras). See the Toronto example I provided. Or again, what would Jupiter look like if we were seeing it from orbit, vs. how we see it from a telescope here? Now Jupiter is a bright object but many of the stars we're seeing as very very faint right now from far away would be bright hot suns if we got closer. So we could definitely see those.  Galaxies that look like faint fuzzies would probably look better faint fuzzies. Nebulae might be the hardest to perceive visually the way we do but again what we see in a telescope with nebula filters may be doable with special spaceship windows. As long as the same (filtered) photons are travelling to your eye, it's all fair for "visual".

 

--Ram



#24 pfile

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Posted 10 August 2020 - 11:43 AM

i'm not talking about planets. i'm talking about diffuse objects. i'm also not talking about seeing details. i'm talking about seeing it all! you're really flooding the zone with a lot of irrelevant stuff here.

 

you're just not going to see a nebula if you get closer to it. it's too diffuse. if you can see it it will look exactly like it looks from here. not like a stretched image. you won't see any details. there's practically nothing to see!

 

you can of course see the milky way and that was my point. we are inside it and can just barely see it and only from the darkest places. and again, wrt telescopes, the point was that a telescope gathers more light and so there's no point in comparing what can be seen thru a telescope with what your eye may or may not see "up close" to a diffuse object like a nebula or galaxy.

 

rob


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#25 ramdom

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Posted 10 August 2020 - 08:06 PM

And I was talking about ALL objects and that was what the entire thread was about:  planets, stars, globular clusters, galaxies, and nebulae. So nebulae are a subset of all the possible objects we can see. And even then we have planetary nebulae, bright nebulae, dark nebulae. You're only talking about diffuse nebulae whereas I was referring to ALL objects. I did say this about nebulae earlier: 'Nebulae might be the hardest to perceive visually the way we do but again what we see in a telescope with nebula filters may be doable with special spaceship windows. As long as the same (filtered) photons are travelling to your eye, it's all fair for "visual".'

 

As far as galaxies, the Milky Way shows up beautifully in the night sky at a dark site.  If we can see other galaxies to that level if we get that close (i.e., within the galaxies), that is more than enough.  The Milky Way actually looks BETTER visually than via a telescope given that it is so diffuse and big. So being at the right distance is key to seeing the object in the "best way".  Look at Ptolemy's sketches of the Milky Way from what, 2000+ years ago? Theres's a long history of art involving the MW prior to any telescope - look at the detail in those images. That's more than enough. In fact, the MW structure resembles a very very large and very faint nebulous structure and we can see it "all" (given our particular perspective) and we can see details - so it's possible to do both with the MW. 

 

My comment about telescopes was about what we could see through a telescope visually (with our eyesight, through the eyepiece) rather than a processed image. If we have to use special windows or telescopes to see it as we get closer, that is fine. But it would be better if we got closer (perhaps not that much better with the most diffuse nebulae but there are all other kinds of bright and planetary nebulae that we could see better if we got closer, and even regions within nebulae would be better if we got closer).  I used the planets example to make my point where it is obvious but it really depends on the real brightness of the object from a close by distance not from when we are many many light years away.    

 

Telescopes gather light but they also magnify an object.  This magnification aspect is what won't be necessary as we get closer. As we get closer, light also has do less travelling to get to our eyes and if we still have to use visual aids to see diffuse nebulous objects, that's fine as long as it's the same photons reaching your eye.  If we get too close obviously that ruins everything too - aim your normal telescope at the Milky Way and see nothing but visually you can see structure - so the right distance matters. 

 

I am not referring to anything that is stretched. I'm talking about pure visual inspection but that could involve visual aids like telescopes or filters. It's about the photons involved and the path they take but the same photons are the ones hitting your retina.

 

--Ram


Edited by ramdom, 10 August 2020 - 08:16 PM.



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