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Observing >> Deep Sky Observing

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dkbender
sage


Reged: 09/26/13

Loc: Illinois
question for the seasoned visual observers....
      #6163286 - 10/28/13 08:31 PM

I just got my ES ED152CF up and running this past weekend and enjoyed Hercules Cluster, M92, M57, M31 and so forth... The technique I was using was to hood my head and eyes for complete darkness and with the TV 6mm Delos EP, I was getting really good contrast with really black background and after looking with averted vision, I could finally see one dust lane in M31.... but what really got my attention, was when I was looking at M92 for example, there is this background fabric in the black that seems to have a pattern. What is that? Is that billions of really low magnitude stars that my eye and brain are assimilating into patterns in the background??

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kfiscus
Carpal Tunnel
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Reged: 07/09/12

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Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6163392 - 10/28/13 09:29 PM

Billions is overstating it, but it's a least a few hundred thousand. Congrats on the new rig.

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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: kfiscus]
      #6163407 - 10/28/13 09:35 PM

Thanks Ken,

So that patterned "fabric" on the black I'm seeing is 100's of thousands of stars, that I can't individually resolve but they form an overlay on the black and my brain is forming visual patterns.

Just wanted to know for sure what I'm looking at.


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stevecoe
"Astronomical Tourist"
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Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6163526 - 10/28/13 10:36 PM

Dave;

My observing buddy and I have been using the "monk's hood" for decades and have found it really helps the contrast. I use a piece of black cloth and A.J. uses a Navy Blue towel.

When I had a TV 102 it really helps with many open clusters. Lots of faint stars resolve in that fuzzy background. Get good with averted vision as well.

There are many articles about a variety of deep sky objects in the CN archives. Go to "articles" at the top of the page and then to "monthly" and "What's Up". They contain a variety of objects to enjoy.

Clear skies;
Steve Coe


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GlennLeDrew
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Re: question for the seasoned visual observers.... new [Re: stevecoe]
      #6163603 - 10/28/13 11:01 PM

This 'background fabric' could simply be your visual system 'noise' manifesting itself in the darkened sky resulting from the small exit pupil.

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kfiscus
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Re: question for the seasoned visual observers.... new [Re: GlennLeDrew]
      #6163629 - 10/28/13 11:14 PM

The noise idea is intriguing. It would be interesting to know if you could see the same 'fabric' effect away from M-92 or anything else. If it's stars on the edge of resolution, you should see more as you approach the glob and fewer as you move away.

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george golitzin
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Re: question for the seasoned visual observers.... new [Re: GlennLeDrew]
      #6163710 - 10/28/13 11:46 PM

I'm with Glenn on this one. When you're well adapted and all extraneous light is excluded, you come up against your own visual noise, particularly if you're at high power trying to nail down some faint object in a quiet field. This experience is to visual detection what seeing the Airy disk is to resolution. That is, when you see the Airy disk, you're up near the resolution limits of your scope; likewise, when you see that background noise, you're near the limits of visual detection for your scope on that night.

However, if you're in the middle of the milky way, it's a different situation--E.E. Barnard talked about seeing "strata" in milky way fields, and it does seem like that some times. Here I think the variations or patterns in contrast have more to do with attenuation by dust, but I could be wrong.

-george

Edited by george golitzin (10/28/13 11:54 PM)


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galaxyman
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Re: question for the seasoned visual observers.... new [Re: george golitzin]
      #6163756 - 10/29/13 12:16 AM

I also agreed with Glenn.

Anyway, it's good to read some DSO observing using a quality large refractor

Karl
E.O.H.


Chesmont Astronomical Society - www.chesmontastro.org
Galaxy Log - http://www.youtube.com/user/GalaxyLog4565
Galaxy Log Blog - http://galaxylog.blogspot.com/
HASB - http://www.haveastellarbirthday.com
Telekit (Swayze optics) 22" F/4.5 Dob
Homemade (Parks Optics) 12.5" F/4.8 Dob
TMB/APM 8" f/9 Refractor”The Beast”. One great DEEP SKY achro
ES 6" f/6.5 achro. Good one
Celestron Omni XLT 102 refractor.
Celestron 10x60mm Binos


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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: galaxyman]
      #6164137 - 10/29/13 08:40 AM

wow! so it's possibly an artifact of my eye/brain visual system. But we are not sure.

I just got back into astronomy after a 43 year hibernation period. I don't remember seeing this with my 6" Newt when I was a teenager. I do not see it currently with my 12" Dob but I have seen it with my 4" apo and now with the 6" apo. I figured it had to do with the better contrast but I also figured it was a universe "clouds" of untold numbers of unresolvable starlight in the background. If my head and eyes are un-hooded, I don't see it. The instant I hood my head, I see it.

So, is this another one of those things, that makes you go... Hmmmmmmmmmmmmmmmmm........????

Oh Karl, I'm loving apo's right now because of the image fidelity, even though the aperture isn't very large, I love the quality.

Edited by dkbender (10/29/13 08:45 AM)


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aatt
sage


Reged: 07/26/12

Loc: CT
Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6164417 - 10/29/13 11:56 AM

I have visual "noise" a lot. It makes for some dicey views on low contrast objects. This did not used to happen back in the day, but I am pushing 50 now and need glasses....

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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: aatt]
      #6164484 - 10/29/13 12:30 PM

I just read the description of broadband visual snow and that does not seem to fit what I am perceiving visually.

It's interesting because when I look at the Double Cluster, I don't notice it in the black background. When I switch to the Hercules Cluster or M92, it appears in the black around the cluster but does not interfere with my ability to use my averted vision and see minute details in the clusters.


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WeltevredenKaroo
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Reged: 03/05/12

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Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6164850 - 10/29/13 03:57 PM

Is your body leaning forward into a somewhat cramped curl as you observe objects higher than ~45°? I notice the effects you describe while leaning forward while bending my neck backwards during high-azimuth observing. Body builders train themselves to be aware of under ventilation while doing ab curls. The diaphragm becomes overcompressed without our being aware of it because we're concentrating on doing or seeing something else. Ophthalmologists describe the flickering shimmer you describe as retinal noise from oxygen-deprived synapses. Shallow breaths or unintentionally holding the breath while teasing out that elusive faint fuzzy underoxygenates the blood. The quick fix is hyperventilating the way sharpshooters and archers do—three fairly slow, deep breaths followed by a half-exhale and then pulling in the upper ab muscles and holding the breath. This both supplies and squeezes oxygen flow into the blood. It takes a bit of practice to avoid over oxygenating and its dizziness. When I do this, the false shimmer disappears within seconds and I can see a full magnitude deeper in fully black fields for about 15 seconds. While observing with others, I frequently see objects a magnitude or more fainter than my friends. When I described the hyperventilation technique, they see what I do.

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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: WeltevredenKaroo]
      #6165223 - 10/29/13 07:38 PM

Quote:

Is your body leaning forward into a somewhat cramped curl as you observe objects higher than ~45°? I notice the effects you describe while leaning forward while bending my neck backwards during high-azimuth observing. Body builders train themselves to be aware of under ventilation while doing ab curls. The diaphragm becomes overcompressed without our being aware of it because we're concentrating on doing or seeing something else. Ophthalmologists describe the flickering shimmer you describe as retinal noise from oxygen-deprived synapses. Shallow breaths or unintentionally holding the breath while teasing out that elusive faint fuzzy underoxygenates the blood. The quick fix is hyperventilating the way sharpshooters and archers do—three fairly slow, deep breaths followed by a half-exhale and then pulling in the upper ab muscles and holding the breath. This both supplies and squeezes oxygen flow into the blood. It takes a bit of practice to avoid over oxygenating and its dizziness. When I do this, the false shimmer disappears within seconds and I can see a full magnitude deeper in fully black fields for about 15 seconds. While observing with others, I frequently see objects a magnitude or more fainter than my friends. When I described the hyperventilation technique, they see what I do.




Hi!

I've been to RSA twice. Once in 2002 and again in 2004... loved it there! I was on safari both times. Koffiefontein area the first time and Blomefontein area the 2nd time. Sat out many nights, after the campfire went out, looking at the lovely southern hemisphere sky and marveled at the Southern Cross.

To your post, head/neck position and breathing have nothing to do with it.... but thanks!

Edited by dkbender (10/29/13 08:03 PM)


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Kraus
Pooh-Bah


Reged: 03/10/12

Loc: Georgia.
Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6165999 - 10/30/13 09:30 AM


I too use a black shroud to block stray light. And depending upon how dark adapted my eyes get underneath, I see some other things as well. I just write it off as my eye's pupil is so wide, anything is visible.

Visual system 'noise'!!! Har-dee-har!!!


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george golitzin
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Re: question for the seasoned visual observers.... new [Re: Kraus]
      #6166436 - 10/30/13 01:37 PM

Quote:


I too use a black shroud to block stray light. And depending upon how dark adapted my eyes get underneath, I see some other things as well. I just write it off as my eye's pupil is so wide, anything is visible.

Visual system 'noise'!!! Har-dee-har!!!




Har-dee-har?

The study of visual systems is a huge area, and noise is certainly an important topic. In one study of the minimum visual stimulus necessary to evoke a human response, the authors found that while the detection of a pulse of 147 photons (a statistical average, obviously) with 60% frequency of seeing resulted in only a 1% false-positive rate (FPR), the detection of a 34-photon pulse with 60% frequency of seeing raised the FPR to 33%. They deduced that the detection of a single photon with 60% frequency of seeing would entail an FPR of 55%.

So when it's really dark under that hood, you're seeing a number of bogus photons.

http://www.opticsinfobase.org/josa/abstract.cfm?id=58340
http://sws1.bu.edu/teich/pdfs/JOSA-72-419-1982.pdf

-geo


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WeltevredenKaroo
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Reged: 03/05/12

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Re: question for the seasoned visual observers.... new [Re: george golitzin]
      #6166771 - 10/30/13 04:27 PM

It helps to do the homework before the har-dee-har. Google 'visual stimulus at low light levels'.

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george golitzin
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Re: question for the seasoned visual observers.... new [Re: WeltevredenKaroo]
      #6167647 - 10/31/13 01:13 AM

I'm going to try the hyperventilating technique, Dana, thanks for the tip.

-geo


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RussL
Music Maker
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Reged: 03/18/08

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Re: question for the seasoned visual observers.... new [Re: george golitzin]
      #6168410 - 10/31/13 12:39 PM

I have heard what you're seeing being called "the lumpy darkness" (someone on here said it a few years ago, I think it was). I see it often when out at night. I didn't notice it until my latter years (I'm 63 right now). Maybe it was there all along to some degree, I dunno. It does indeed make me think maybe I'm seeing something else that isn't ther, possibly. I used to think maybe it was the "fabric" of space, for lack of a better term, although I have no idea if there's anything like that to be detected. The talk of visual noise makes sense. I would assume that each of us varies to some degree in how we see it, or even how much we see it.

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george golitzin
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Re: question for the seasoned visual observers.... new [Re: RussL]
      #6169179 - 10/31/13 08:11 PM

Quote:

I have heard what you're seeing being called "the lumpy darkness" (someone on here said it a few years ago, I think it was). I see it often when out at night. I didn't notice it until my latter years (I'm 63 right now). Maybe it was there all along to some degree, I dunno. It does indeed make me think maybe I'm seeing something else that isn't ther, possibly. I used to think maybe it was the "fabric" of space, for lack of a better term, although I have no idea if there's anything like that to be detected. The talk of visual noise makes sense. I would assume that each of us varies to some degree in how we see it, or even how much we see it.




I think it's reasonable to use the term "lumpy darkness" for this phenomenon, but the term is also used in connection with galaxy clusters, such as the Corona Cluster, where the lighter lumps are real objects--the (small, high-mag) field of view appears mottled because it is so full of unresolved galaxies, some of which occasionally coalesce into view under prolonged concentration and changing seeing conditions. That's an eerie experience.

-geo


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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: george golitzin]
      #6169399 - 10/31/13 11:01 PM

So, riddle me this....

If I close myself in a completely dark closet and stay in there to dark adapt my eyes, it's now pitch black, as dark or darker than looking in the eyepiece with my head hooded and I don't see the same phenomenon. Why is that? If it's visual noise, I should see the same lumpy darkness in the closet, right?

Edited by dkbender (10/31/13 11:02 PM)


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george golitzin
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Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6169509 - 11/01/13 12:47 AM

Well, have you actually performed that experiment? And if so, are you staring hard at the darkness for a prolonged period trying to see something, as at an eyepiece, or are you letting your eyes wander all over? In experiments trying to determine the minimal stimulus to trigger a visual response, the participants are expecting to see something, and are trying to see something, much as you are at the eyepiece. This leads to false positives. That's not the case in a darkened closet. Other weird stuff happens in a darkened closet, if you stay there long enough ...in cases of prolonged sensory deprivation, do not people begin seeing all sorts of stuff that isn't there, the brain trying to fill in for what is missing?

Bottom line, I'm no expert on this subject, but I'm pretty convinced I'm dealing with visual noise a lot when I'm out there trying to pull in threshold objects. And I don't know if we're seeing the same thing or not, but I think visual noise, or else the brain's tendency to fill in patterns that aren't there (like Lowell's canals on Mars) is a likely candidate for what you (and I) are seeing.

-geo


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GlennLeDrew
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Re: question for the seasoned visual observers.... new [Re: george golitzin]
      #6169651 - 11/01/13 05:57 AM

Whether in complete darkness or with eyes closed in a well darkened room, I always see a kind of scintillating pattern in the blackness if I look for it. When not thinking about it at all, I notice nothing but the darkness. (If this 'noise' were not so easily ignored--it is suitably subtle, thank goodness--I almost wonder if it sometimes wouldn't interfere with sleep.)

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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: GlennLeDrew]
      #6170001 - 11/01/13 10:58 AM

Hi George,

Yes actually, I have. I get a subtle pointillism effect but it looks and reacts completely differently from what I am seeing in the 2 apo's. Which is why I originally asked the question. The effect at the EP with the 2 apo's is like turning a switch on, when I hood my head & eyes and immediately there is this "texture" in the black. I don't have to stare hard at it, I don't have to coax it out.... it's just right there, instantly. I'm in a comfortable position, I have varied my breathing... it doesn't make any difference. It's so repeatable, I just came to the conclusion that it must be subtle, distant below resolution, background light out there but I wasn't 100% sure, which is why I asked the original question.




Hi Glenn,

I do get the very subtle pointillism effect in the dark but it is easy to distinguish.


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george golitzin
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Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6170582 - 11/01/13 04:13 PM

Hi Dave-

Okay, that's interesting. For my part, I notice something like Glenn's scintillating pattern, or perhaps your pointillism--to me, a kind of mottling in the background that is in flux. (With occasional bogus point sources, unfortunately!) Do you recall the nature of the pattern you see? Is it mottled, or striped, or tendril-like, etc?

Again, when looking within the band of the Milky Way, who knows what is creating the patterns. There is a general wash of light from thousands of unresolved stars, there is lots of intervening dust, etc., and all this creates subtle patterns, to me often striped--Barnard's "strata." But I don't see this when looking out of the Milky Way. Outside the Galactic plane, I tend to see that eye-brain mottling I mentioned. But I need to pay closer attention, perhaps.

Now, Hercules is not far out of the galactic plane, so maybe you were seeing something real. Do you get the same effect in Coma Ber. or Sculptor, for example? And how about within the Milky Way itself? If there is a uniformity to the experience across the sky, I think that is an argument for an eye-brain phenomenon.

-george


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DavidNealMinnick
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Reged: 03/06/06

Re: question for the seasoned visual observers.... new [Re: george golitzin]
      #6170638 - 11/01/13 04:48 PM

Quote:

are you staring hard at the darkness for a prolonged period trying to see something, as at an eyepiece, or are you letting your eyes wander all over? In experiments trying to determine the minimal stimulus to trigger a visual response, the participants are expecting to see something, and are trying to see something, much as you are at the eyepiece. This leads to false positives. ...in cases of prolonged sensory deprivation, do not people begin seeing all sorts of stuff that isn't there, the brain trying to fill in for what is missing?

-geo




During my term in the Army I can remember vividly nights while out on a Field Training Exercise(FTX), staring out of a foxhole at the forest during the wee hours trying to detect Rangers tasked with infiltrating our lines, and seeing things "move" when nothing was moving at all.


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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: george golitzin]
      #6172786 - 11/02/13 11:16 PM

Quote:

Hi Dave-

Okay, that's interesting. For my part, I notice something like Glenn's scintillating pattern, or perhaps your pointillism--to me, a kind of mottling in the background that is in flux. (With occasional bogus point sources, unfortunately!) Do you recall the nature of the pattern you see? Is it mottled, or striped, or tendril-like, etc?

Again, when looking within the band of the Milky Way, who knows what is creating the patterns. There is a general wash of light from thousands of unresolved stars, there is lots of intervening dust, etc., and all this creates subtle patterns, to me often striped--Barnard's "strata." But I don't see this when looking out of the Milky Way. Outside the Galactic plane, I tend to see that eye-brain mottling I mentioned. But I need to pay closer attention, perhaps.

Now, Hercules is not far out of the galactic plane, so maybe you were seeing something real. Do you get the same effect in Coma Ber. or Sculptor, for example? And how about within the Milky Way itself? If there is a uniformity to the experience across the sky, I think that is an argument for an eye-brain phenomenon.

-george




Hi George,

I would say the appearance of what I'm seeing is what I would call mottled.... and it is subtle.

I'll keep looking at it and report back when I can add to the description and further the discussion.

Thanks for the replies!


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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6173319 - 11/03/13 09:07 AM

So, I was perusing the previous owner's AP catalog using the ED152CF that I own now and found a photo of M13 that he had taken in June of this year. I looked at it and saw the mottled texture in the black background that I have been trying to figure out what it is.... take a look and you'll see what I've been asking about... What I notice is, that during visual observation at the EP, using the hooded technique, it is even more obvious than what is in the photo below.

http://www.astronomyphotos.com/M13.htm

Edited by dkbender (11/03/13 08:24 PM)


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Anthony236J
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Loc: Ottawa, Ontario
Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6174102 - 11/03/13 05:05 PM

Hi Dave,

Congrats on the new scope!

It looks like that photo is displaying some noise. If what you see in the eyepiece is of a similar pattern and uniformity, I would guess that it is also some type of noise. It seems that if you see this kind of pattern at the threshold of detection in a 4" telescope, then its structure should be even more evident in a 12" telescope under the same conditions.

That would be my guess without knowing exactly what you are seeing.


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Asbytec
Guy in a furry hat
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Re: question for the seasoned visual observers.... new [Re: Anthony236J]
      #6174425 - 11/03/13 08:34 PM

I wasn't wearing my hood at the monitor, so took the liberty to enhance the noise and see what you're talking about. There is a molted background. Is this what you're seeing? That molted pattern?

I think Ken's question above is pertinent, does it appear near brighter sources or in the darkness of space (like being in a closet?) If the camera picks it up (after applying a flat frame?), and if this is the same source of the molted pattern, then it's likely not entirely in the eye brain system. It seems very dim and that you pick it up at all is testament to your dark adaption.

But, like others, with eyes closed I get some light and dark interplay, but if memory serves...been so long since I even paid attention, the patterns are in motion. Sometimes while observing I get a speck that appears, but as we all know those are meteors coming directly as us or a UFO sneaking into the upper atmosphere.

In the end, I can't say I remember seeing such a molted pattern against the black of space. Not to the extent it became bothersome, or at least never gave it (visual noise) a second thought while focusing on the object at hand.

Edited by Asbytec (11/03/13 08:55 PM)


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azure1961p
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Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6174557 - 11/03/13 09:52 PM

With out reading the whole thread it sounds like its your eye-brain trying to make sense of the myriad stars just beyond your visual threshold or teetering on it. Singly for example these stars would probably not be seen at all but as a cumulative glow its probably being sensed on some level by you and patterns and such are the brains way of bringing understanding to it.

Just a thought.

Pete


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dkbender
sage


Reged: 09/26/13

Loc: Illinois
Re: question for the seasoned visual observers.... new [Re: azure1961p]
      #6175539 - 11/04/13 02:00 PM

Anthony, Norme & Pete,

At this point, I've only noticed it around M13 & M92. I had a real good view of M57 but was so captivated by seeing the shades of nebulosity in the ring, that I didn't notice the background texture on that particular view. As previously noted, I had a real good view of the Double Cluster and did not notice it there either.

I'll keep looking and report back any further clarification or new findings.


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Sarkikos
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Re: question for the seasoned visual observers.... new [Re: DavidNealMinnick]
      #6183075 - 11/08/13 02:25 PM

Quote:

During my term in the Army I can remember vividly nights while out on a Field Training Exercise(FTX), staring out of a foxhole at the forest during the wee hours trying to detect Rangers tasked with infiltrating our lines, and seeing things "move" when nothing was moving at all.




IME at night, if I'm looking at a row of trees at the edge of a woods in the distance it's easy to mistake the dark gaps between the trees for people standing together and milling about. Sometimes it even seems that the people are moving around. It can be a little unnerving until you realize that they're only trees.

I've read that sometimes soldiers have fired at trees - especially during low light conditions - mistaking them for the enemy. This happened often during the Civil War.

Mike


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choran
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Re: question for the seasoned visual observers.... new [Re: RussL]
      #6191074 - 11/12/13 04:26 PM

"Lumpy darkness" is exactly it! Great description. I see what looks like a black quilt, mainly black, but with a seeming pattern of light areas. I have assumed, with no real evidence, that it is a background of very distant/faint stars, but I'm not at all sure. I see it through all of my scopes, and even with binoculars occasionally. Is it possibly just an artifact of magnifying a couple of hundred miles of atmosphere, with its dust, smog, etc? Doesn't seem likely, but I just don't know. I am more conscious of it at higher powers, but as I say, I can even see it in binoculars at times. Wish I knew for sure.

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Starman1
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Re: question for the seasoned visual observers.... new [Re: choran]
      #6191365 - 11/12/13 06:55 PM

A few comments:
1) Look at the background in Sagittarius in the Milky Way. The sky appears 'grainy', which is incipient resolution of extremely faint multitudes of stars. You might also see this in Cygnus with the naked eye.
2) Look at the ground or surroundings (but not the sky) once you have dark adapted. You may see, as I do, your visual reality break up into a series of dots--the 'pointillism' of visual reality when insufficient light is entering the eye. Is it noise in the retina? Perhaps.
3) Look at a star cluster of moderately bright stars (say, NGC7789 in Cassiopeia). Do you see the stars all surrounded by very slight fuzziness that makes the stars look as if they all sit on stalks pointing at you? If so, this can be evidence of dew beginning to form on the optics (eyepiece, or lens or mirrors). In fact, this can cause the 'mottled sky' effect you mention.
4) Visual noise appears in differing ways. When I look at a galaxy cluster I can 'see' galaxies where there are none, and sometimes not see ones where they really are. When you observe at the limit, visual noise often appears 'real'.
5) Have you sought stars at the very limit of your scope by using some magnitude charts for specific areas? Stars at the very limit are only visible to averted vision a small percentage of the time. If a star winks in, it appears as a very small pinpoint.
If a galaxy or nebula fragment just winks in, it appears as a slightly brighter portion of the background sky. This makes identification difficult. I usually have a chart of the area of the faintest targets so I can look exactly where it is. This increases the odds that something that winks in and out of visibility is real and not just noise in the eye+brain combination.
6) Stars "move" when you stare at them if the patterns are arranged to fool the eyes. A recent thread here on CN had a chart with a series of ovals on it, arranged in vertical and angled rows. The ovals crawled back and forth and seemed to undulate. When you stood back several feet from the monitor, they stopped moving. I often see objects at the limit, especially stars, crawling in position. This is an example of where the eye and brain are being fooled.

if you study many of the references on the web concerning vision, you will see how easily fooled the eye is. Stare some time at a uniformly black piece of construction paper in a poorly-lit (or very dimly-lit) room. The black paper appears mottled and sometimes shows gray patterns on it. This is the poor visual system nature gave us to deal with really low light conditions.
Despite that, we do have better night vision than you might expect for a daytime animal. It probably had significant survival value in the youth of our species.

But it obviously isn't perfect.


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MrJones
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Re: question for the seasoned visual observers.... new [Re: Starman1]
      #6191740 - 11/12/13 10:13 PM

When I first learned about visual noise it was called hallucinations. As per above there's been a lot of research in the area. Also look up Eigengrau.

CEV wiki

Eigengrau wiki


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Re: question for the seasoned visual observers.... new [Re: choran]
      #6192201 - 11/13/13 08:52 AM

Quote:

"Lumpy darkness" is exactly it! Great description. I see what looks like a black quilt, mainly black, but with a seeming pattern of light areas. I have assumed, with no real evidence, that it is a background of very distant/faint stars, but I'm not at all sure. I see it through all of my scopes, and even with binoculars occasionally. Is it possibly just an artifact of magnifying a couple of hundred miles of atmosphere, with its dust, smog, etc? Doesn't seem likely, but I just don't know. I am more conscious of it at higher powers, but as I say, I can even see it in binoculars at times. Wish I knew for sure.




This is exactly what caused me to post the original question. Black quilt with texture is another good description.

Don, thanks for your thoughts! I'll continue to pay attention and see if I can determine more clues. What is interesting is how when I hood my head and eyes, the quilt, fabric texture literally snaps into place and it is stable... which makes me believe it is real and not an artifact of my visual system.


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Re: question for the seasoned visual observers.... new [Re: dkbender]
      #6196721 - 11/15/13 03:26 PM

The term for this condition is called visual snow. You can google it for more info.

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