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Sketches with a 40"

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#1 Diabolo

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Posted 16 September 2012 - 11:32 AM

May be you remember this post :

http://www.cloudynig.../o/all/fpart/1.

It was the first light of a 40 » FD3 telescope I made. I use it for about a year and it has always been a frustration not to be able to make some drawings (to be honest I’m a very bad at that game ;) ) to really show the kind of image this telescope can deliver.

Last august, a group used the 40” and the 32” for a week. Among them was Frédéric Burgeot. I have always loved Frédéric’s work because of its incredible accuracy and rendering. Nights were great, Sqm value were between 21.4 and 21.6 and the seeing was really good. It was easy to use high power, 600x to 1500x. A good opportunity to draw planetary nebula and great other great objects of the summer sky !

Frédéric spend time at the 40” while the rest of the group observe with the 32”. It was a real pleasure to see the slow work in progress. He got incredible eyesight and really know how to draw…. Good for us is also an accomplish observer ;)

Blue Snowball : Posted Image


The ring nebula is Saturday September 15 APOD M57

Cat’s eye, a real beauty (thanks Fred for the original drawing, it’s a gem ;) ) NGC 6543


The beautifull planetary nebula NGC 7008

A great Crescent nebula,
NGC 6888

The pillars of creation,
M16

Bubble nebula, NGC 7635, unfortunately too late, the sun was going up fast…
NGC7635

Nebula in M33,
NGC604

The showpiece Saturn Nebula,
NGC7009

And a galaxy, the beautifull NGC891

Click on Frédéric’s web site to see more of its work, under the word “Rubriques”:
Fred's Website

For some pics taken during those great nights :
Pics

#2 KidOrion

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Posted 16 September 2012 - 04:20 PM

Posted Image

#3 maroubra_boy

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Posted 16 September 2012 - 06:36 PM

What can I say but WOW!

Not only BIG aperture, but probably more important is a great technique!

Many thanks for the links.

#4 rolandlinda3

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Posted 16 September 2012 - 08:01 PM

Great opportunity and nice observations

#5 joelimite

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Posted 16 September 2012 - 08:07 PM

The amount of detail evident in these sketches is literally jaw-dropping. I've looked through a 32-inch a couple times. Now I really want to look through a 40.

#6 Diabolo

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Posted 17 September 2012 - 04:16 AM

"Not only BIG aperture, but probably more important is a great technique!"

Can't agree more ! Is really a gifted observer,

On planets, drawings are also amazing :

http://vimeo.com/user10183762

A friend of him use a software to have a spherical projection, the rendering is.... I let you see !


"The amount of detail evident in these sketches is literally jaw-dropping. I've looked through a 32-inch a couple times. Now I really want to look through a 40.
"

Their is definitely a more detailed image in the 40". During this week we got a very good seeing, each time we start by pointing the 32" on a target, the image was already really impressive, but next, in the 40", it was a second waouuu, more things to see !

#7 azure1961p

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Posted 17 September 2012 - 05:45 AM

His sketches are a little overdone, infact grossly so. He has details in deepsky and planetary even HST doesnt record. Its like the person doesnt know when to quit. Some is good but so much is overworked and over interpreted.

Pete

#8 Michael11

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Posted 17 September 2012 - 06:55 AM

All I can say is that I was sitting stunned after watching those...

#9 frank5817

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Posted 17 September 2012 - 09:08 AM

These are fantastic looking giant scopes. If I had the room, I would consider building a large fast mirror telescope. The sketch by Frédéric is quite impressive as the view must have been.

Frank :)

#10 IVM

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Posted 17 September 2012 - 10:21 AM

The Blue Snowball is 37" across. The diameter of the Airy disk in a 40-inch is 0.14. Under ideal conditions (thermally equilibrated in outer space) there could be 270 lines resolved across the nebula. Under great conditions on Earth - the biggest assumption is that the mirror equilibrates - I'd say maybe 70 lines could be resolved with great care. Now I can't really count lines in this sketch, but the number seems to be somewhere in between.

#11 JeanB

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Posted 17 September 2012 - 10:34 AM

Wow!!! Those are amazing sketches. You are quite an artist. Love your work and your technique!

Jean

#12 GlennLeDrew

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Posted 17 September 2012 - 06:53 PM

Here we have a powerful demonstration of the lousy resolution of the eye at low light levels. Here we see in a 40" visually what is readily recorded in an image using a mere 3".

As to the red in the M57 drawing, I do suspect a combination of illusion and bias operating here, for the reasons outlined in the thread about this sketch on APOD.

#13 whirlpoolm51

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Posted 17 September 2012 - 10:57 PM

These sketches are amazing and in no way shape or form are they over exaggerated!!!!! i have seen every object he has sketched through my uncles 38'' except for the nebula in m33 which i find absolutley incredible that you can even begin to resolve that much detail in a whole other galaxy!!!!

#14 azure1961p

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Posted 18 September 2012 - 10:30 PM

Here we have a powerful demonstration of the lousy resolution of the eye at low light levels. Here we see in a 40" visually what is readily recorded in an image using a mere 3".

As to the red in the M57 drawing, I do suspect a combination of illusion and bias operating here, for the reasons outlined in the thread about this sketch on APOD.


I'd agree with that about the color, at least in suspecting the possibilities.

Pete

#15 Diabolo

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Posted 19 September 2012 - 01:13 AM

Frédéric Burgeot draw, I post its answer on the forum. I made the dobs he used to make the drawings on the page.

----------------
Hi,

I see that there are suspicious people...

I only regret that they have not been there to see in the eyepiece. I hope they looked in a 40'' telescope (or more) with great seeing conditions at least once.

Thank you whirlpoolm51 for talking about your similar experience in a 38'' scope.

About the reddish color of the external parts of M57, all the 6 persons that were there have seen it. But we endless can discuss the honesty and expertise of the 6 observers.

The general blue color was obvious to me.


I found some images to compare with my drawing of the cat's eye.

Posted Image


I think the sketch is quite similar the upper right image, for the shape and the texture. Of course, if we count precisely the filaments represented in the sketch, we can find that it's over interpreted and that the observer doesn't know when to quit !

Everyone will make it's own opinion watching this pictures.

Compared to the other pictures, the lower right picture shows different aspect, some portions appear more obsiously while others tend to disappear. The outlines of the two large rings are another form. The «red arms» are larger.

This shows that the result depends on the CCD sensor, its sensitivity to certain wavelenghts. The image processing occurs to.

What I mean is that Hubble pictures are not the unique way to validate observations. You should take complementary pictures for that.

«Here we have a powerful demonstration of the lousy resolution of the eye at low light levels. Here we see in a 40" visually what is readily recorded in an image using a mere 3"».

On the cat's eye, I'm not sure that a mere 3'' telescope should show the tiny details viewed in the 40'':-)). just look at the sketch.

We are not comparing digital imagery with visual observation, it's obvious that the first goes farther for detecting faint light. Is this a reason to abandon the pleasure of visual observing ?

Don't confuse resolution and low brightness perception.

I encourage everyone to take advantage of opportunities to look in a big telescope. Visions are very different.

Fred.
---------------

My point of view, those night the seeing was really good. It was possible to use about 700x to 800x on Jupiter without any problem and keep a very good image. On my observing site, I often use 1000x on PN and one of the night was even better, so for a very good observer, the possibility to catch small details were very good.

For the reddish color pereception : I have personnaly always see red colors in M42, since the night I saw it on a 16". I see green/blue as easily on it despite many people can see this color. With the aperture I can see this reddish color on other object. IC 418 of course, obvious for many observers, also on the external last "layer" of NGC 7009 and M57. I ask childrens about NGC 6543 without give the a clue about that possibilities and some of them speak about pink/red color on the perimeter of the np.

So, if I have to make a drawing of M42 or one of those planetary nebula with this reddish color, I draw it because it's my own perception. Unfortunately I don't know how to draw but Frédéric Burgeot know and I was really happy to see what I see on paper. If I want to make a representation without human perception, I take a pic but unfortunately even for that the software work on the pic got a human perception influence. It's obvious for example on Jupiter, saturation color, contrast, wavelets and other things are based on human perception. Give an AVI files to two different amateur astronomer and they will give two different Jupiters.


#16 GlennLeDrew

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Posted 19 September 2012 - 02:20 AM

On very high surface brightness objects where color is seen without difficulty, the eye's performance is much better resolution wise, for the higher-density color-detecting cones are operating to form the image. And so the eye doesn't lag so very far behind the camera. The brightest planetaries, and the inner region of M42 are notable examples of this brightness regime.

But for low surface brightness objects where color is impossible to detect, the eye's resolving power is very much worse and the camera greatly surpasses it. This would apply to such a nebula as M16, and even more so those objects which barely announce their presence through the air glow.

Not all planetaries are alike. They differ over a large range in surface brightness, relative emission line strength, apparent size, and of course structural detail. While there are a handful in which red is certainly at the detection threshold, I'm pretty sure the H-alpha in M57 is fairly well below this. The same goes for M27 (and most assuredly the Helix, NGC7293.)

#17 Diabolo

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Posted 19 September 2012 - 03:53 AM

In the 40", with an OIII M16 pilar are easy targets in direct vision, to be honest, the problem is, it's easy to be lazy and use only direct vision on many objects. If you observe M42 and look at the sky naked eye just after, you see the "shape" of the nebula on the sky, you simply loose some of your night vision and the difference between the observing eye and the other is huge. If you take a white paper and put it an inch away from they eyepiece, the nebula is also faintly visible.

I have own 16/22/32 and 40", the things I learn is, it's hard to guess what's visible or not and the potential of the instrument till we got an eye at the eyepiece. I observe the veil nebula at about 270 to 350x to see details that I tought where absolutely invisible.

I never see color in M27 personnaly, "only" parts of the external shell, I also don't see any tint in Helix, but on M57 when seeing/transparency is good, at low power it's obvious on the outer edge, easier than on the central part of the nebula, but if I increase the power the colors slowly disapear. We definitely got different perception, observe with a group of amateurs immediately show how the image we record with the eye are different.

On M42, during a great night with the 32", I ask a couple of visitor how was the image, the answer was "many colors visible". Their is a "rainbow like" area next to the brightest part of the nebula, the outter parts look reddish. This was their first sight in a telescope. I can't supect them to any interpretation because they were not astronomers and didn't know the object they where looking at and what expect on them.

#18 ManuelJ

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Posted 19 September 2012 - 06:17 AM

I can also see the external red color in M57 at low power with my 20".

#19 mdowns

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Posted 19 September 2012 - 06:59 AM

Diabolo,
Thanks for sharing these amazing drawings. It seems that some are skeptical but all to often I've experienced that side,side one observer sees details that the other cannot. I use to easily see the reds in M42 on transparent evenings in my 16",my very experienced observering friend did not. He could always see Antares companion while I could not. The point being,everyone's eyes and experience are different.I was most interested in your comment that you were able to watch the work in progress (paraphrasing). To me,this removes reason for doubt,should one have doubt.I see these as splenid representations from a skilled observer and artist with great equipment.I really appreaciate your posting of these and hope to see more!

#20 banatop

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Posted 19 September 2012 - 09:53 AM

Superb sketches Frédéric. Thanks for posting Diabolo. You and your circle of friends are some of only a few people on earth who know what can be seen through the eyepiece of a 40" Reflector. For everyone else it's just theory. The sketches on the website are some of the best I've ever seen. Keep on posting. Amicalement, John

#21 starquake

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Posted 19 September 2012 - 01:00 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.

#22 Diabolo

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Posted 20 September 2012 - 11:13 AM

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...

#23 maroubra_boy

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Posted 20 September 2012 - 10:18 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.

#24 Diabolo

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Posted 21 September 2012 - 12:41 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.

#25 Erik Bakker

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Posted 21 September 2012 - 01:59 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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