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Astrophotography and Sketching >> Sketching

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starquake
sage


Reged: 02/02/08

Loc: Nádasdladány
Re: Sketches with a 40" new [Re: Diabolo]
      #5429283 - 09/19/12 02:00 PM

m42 is ruining your dark adaptation? i wish that would be my biggest fear while observing, not to look at m42 without neutral filter on.

about details: when i've started to observe on a regular base i was always sceptical about the sketches a fellow amateur did. he had a background of about 15 years of astronomical sketching. but after a couple of years I've started to see the details I did not believe earlier. now my limiting magnitude is deeper with about 1.5m. that's enough for a LOT of extra details. and i've glimpsed details i could see only on the better photos. but as i never check out any of the objects before the observation but decide what to see on an ad hoc basis, i know that what i've seen was not a game of my memories, but the proof that the eye is a REALLY sensitive instrument.


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Diabolo
member


Reged: 06/28/11

Re: Sketches with a 40" new [Re: starquake]
      #5430814 - 09/20/12 12:13 PM

Thanks for your posts. I have notice how important is the visual experience. A friend practice visual observation since about 10 months. He spend most of its live at the eyepiece of microscopes. He easy see things that usually required a good practice. In a way, the brain part of the vision seems to be like a muscle that needs training. Also, I remember that good obsever can catch nearly mag7 stars naked eye. Compare to a more classical 5.8 to 6, it's a huge gap, must give a big bonus at the eyepiece ! Wish I could saw so faint a star...

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maroubra_boy
Vendor - Gondwana Telescopes


Reged: 09/08/09

Loc: Sydney, Australia
Re: Sketches with a 40" new [Re: Diabolo]
      #5431891 - 09/20/12 11:18 PM

I have no doubt of the legitimacy of these sketches, Fred and Diabolo. There are little tell-tale signs in the sketches that show that these are done at the eyepiece, and not copied from a photograph:

* One is the "vagueness" of the positioning of the finest of details - at the eyepiece you may only get a relative sense of position of a detail, and the pencil mark is not 100% precise and rather "stunted". This also shows a lot of experience and confidence in technique as so much of these details are done through averted vision. Experience also tells you both "when to quit", and what you can and can't add with certainty.

* Another is the selection of the colours - they are limted to really two, maybe three, not a complete colour palate.

This last point show's that Fred's colour perception is exceptional, particularly at low light levels. Good colour perception is more difficult in as males than women, with at least 1/3 of all males have colour blindness in one form or another, from very mild through to no colour perception at all. Colour blindness in women is not very common by comparison. The range of responses show this variation in colour perception.

Just my opinion.

Alex.


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Diabolo
member


Reged: 06/28/11

Re: Sketches with a 40" new [Re: maroubra_boy]
      #5432049 - 09/21/12 01:41 AM

Thanks Alex. During all the drawing process, after dozens of minutes, FredB sat on a chair and we talk about it's drawing. Once a the house, I saw that on M57 the stars around the nebula were not visible on paper. I ask him if he wanted a pic to simply draw the stars at the correct location. Not the good thing to ask, the answer was "got to go back at the eyepiece with the sketch and put them"

That don't change much things as those stars are really bright but seems that's not the case for him.


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Erik Bakker
Post Laureate
*****

Reged: 08/10/06

Loc: The Netherlands, Europe
Re: Sketches with a 40" new [Re: maroubra_boy]
      #5432092 - 09/21/12 02:59 AM

The variations between observers already happens for me when I switch between my left and right eye. When everything comes together under the stars and scope, seeing, transparency and observer are able to come in sync, amazing things can be seen at the eyepiece.

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starquake
sage


Reged: 02/02/08

Loc: Nádasdladány
Re: Sketches with a 40" new [Re: Erik Bakker]
      #5432102 - 09/21/12 03:25 AM

My eye gets dark adapted really quick compared to a few folks I know. This also means that I lose my ability to see colours real quick.

There's a pretty interesting curve how dark adaptation works and how the rods (responsible for seeing shades but not colours) take over from the cones in the eye:



It was an interesting experience I had this summer, when we observed RS Cyg (a particularly red star) with my friend. We were pretty much dark adapted I think, but when she reported seeing the intense red shade of the star, all I saw was a shade of gray - this is perhaps because of what Alex said about ladies not having colour blindness at all or just rarely. I've then did an experiment and looked into white light for a few seconds to ruin my adaptation. And there came the wonder: the star was magical red for me too. Since then, I often ruin my dark adaptation if I want to see colours.

Ok, what I want to say with this is that maybe the skills of Frédéric come from an oddity that his eyes have a different distribution/sensitivity of cones and rods than what is considered as normal. Even I was struggling to see colours compared to my friend, so I do believe some folks are able to see colours even if they are fully dark adapted, not to mention that in a 40 incher you don't need dark adaptation at all to see details in the Ring nebula.

Perhaps Frédéric has "ladies eyes".

I also recall a little friend of mine, who I met when he was only about 14 or so. He did observations on a very regular basis. He reported details and features in objects, that theoretically he shouldn't be able to see in his 6" telescope. Noone ever believed him, until on one Astro camp he gave proof that what others can barely see with averted vision is a bright object for him, full of fine details.

So I tend to believe that there are simply people with superior sight. But I also know from my own experience, that this can be learned to some extent.


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Ernest_SPB
sage


Reged: 11/13/10

Loc: St.-Petersburg, Russia
Re: Sketches with a 40" new [Re: starquake]
      #5432206 - 09/21/12 07:24 AM

Quote:

I often ruin my dark adaptation if I want to see colours.


Even in full scale dark adaptation I can easily distinguish colour of my red light (used in work with star charts). So I do not think the method will work for me.

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starquake
sage


Reged: 02/02/08

Loc: Nádasdladány
Re: Sketches with a 40" new [Re: Ernest_SPB]
      #5438137 - 09/24/12 01:48 PM

I don't think the brightness of a red flashlight and a red star of any magnitude can be compared. Of course I see the red light of my observing light too, but stars are just too faint I guess.

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ericj
professor emeritus


Reged: 02/17/05

Re: Sketches with a 40" new [Re: Diabolo]
      #5438263 - 09/24/12 03:07 PM

Hi,

Very nice sketches, thanks for posting them. Using the 40" I don't think you will run out objects to sketch anytime soon

Clear Skies,

Eric Jamison


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Diabolo
member


Reged: 06/28/11

Re: Sketches with a 40" new [Re: ericj]
      #5443443 - 09/27/12 12:33 PM

Ericj, yes, a whole life is not enough

thanks Starquake for this very intresting piece of information ! Didn't know the average time necessary to have a good night vision adaptation, I keep it !


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