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Saturn April 4

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#26 kenrenard

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Posted 09 April 2013 - 06:07 AM

David,
This has been a fascinating post. As a beginning sketcher and novice observer your detailed information is wonderful. I look forward to see more of your posts and drawings.


Ken

#27 David Gray

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Posted 09 April 2013 - 06:45 AM

Much appreciated Ken - thanks.

David.

#28 Paul G. Abel

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Posted 09 April 2013 - 07:13 AM

An absolutely splendid rendering David, I really am most envious of your talents. Oh if only I could produce drawings as realistic as this!!!!!

Looking forward to seeing more of your work later in the apparition!

Best wishes,
-Paul

#29 idp

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Posted 09 April 2013 - 03:34 PM

I have been accused of trying to produce planetary works of art; but I say if you get what you see at the eyepiece accurately, then, as they are often objects of beauty, the art takes care of itself!


This is an interesting point you bring up. The Italian astronomical union also emphasized, in its training program, the accurate measurement of intensity and positions over the realistic rendering of the planet. Back then, visual observations were after all the backbone of observing programs and the most important source of information on the planet.

However, it was never implied that artistic representations and accuracy would conflict, and personally I don't see why they should; they certainly didn't historically. The idea was that while few have the hand of an accomplished draughtsman (hey, the spell-checker is taking issue!), almost everyone can be trained to carry out useful and reliable observations.

I hope you will keep using your rare talent, and sharing it with us.

Ivano

#30 Uwe Pilz

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Posted 09 April 2013 - 11:13 PM

Dear David,

these are real great sketches of Saturn. A have such a steadiness of the atmosphere not more than one time a year at my observation site. Thank you for sharing.

#31 David Gray

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Posted 10 April 2013 - 06:27 AM

Much appreciated Uwe and Paul.

I do seem to enjoy much good seeing here: my best seeing 'seasons' seem to be April/May & Sept/Oct; but getting relatively good spells year round contrary to the UK's reputation with this. Perhaps I am favoured with a somewhat unique/anomalous micro-climate.

The lie of the land may have something to do with it as we are considerably, quite abruptly, higher here than to the s'east south & s'west. I have found those good conditions here since arriving to take up home in 1976. It certainly seems more consistently good than when I observed (1961-76)from Trimdon some 8 miles n'east of here - but there were more houses surrounding there: being pretty rural here.

#32 David Gray

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Posted 10 April 2013 - 07:17 AM

I have been accused of trying to produce planetary works of art; but I say if you get what you see at the eyepiece accurately, then, as they are often objects of beauty, the art takes care of itself!


the accurate measurement of intensity and positions over the realistic rendering of the planet.


Yes very much agree; and when they (accusers) say “art” I think they have in mind the more embellished types – what John Rogers (BAA Jupiter) calls “fairy castles”!

Making intensity estimates (done thousands) is a good part of training for a more accurate drawing tonally. Being a baker for 50years (the craft-bakery kind as opposed to the supermarket type!) may well have contributed to my sketching efforts. Intensities (10 = black): I did considerable amounts of oven-work where intensities are a large part: too much darker than ints. 6-7 and you would be sent elsewhere!

John Rogers once told me that my personal equation for central meridian transits was uncannily near to zero – I responded “you have to be able to spot the centre of the cake to get the cherry there”!

Previous post I mentioned my artist mother and her elder sister Florence. I would say both could produce accurate renditions; but I would say to mother that her paintings were more impressionist than my preferred detailed ones by Aunt Florrie. She would reply “Oh I can’t do them like her”!

David

#33 David Gray

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Posted 10 April 2013 - 07:39 AM

With further regard to using a Ramsden to cancel atmospheric dispersion attached is something relating to this that I was working on back in 2009 but never followed up – as with many things!

Actually being a humble Ramsden it was never ideal for the finest detail; so was happy to discover (my prev. attachment) that the prisms in the optical train put enough chromatic inequality back to still apply the Ramsden technique and with much superior eyepieces.

I have come across a CN post (“CPC 11 screwing up Jupiter?”) that dealt with this issue and I see that brianb11213 got it sorted!

http://www.cloudynig...d=nexstargps...

It must be said that as the 415mm D-K works at f/16 (6640mm f.l.) it handles simpler eyepieces very well. But I prefer wider field types such as the Plossls referred to in the earlier post/attachment.

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#34 kenrenard

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Posted 10 April 2013 - 09:13 AM

David,
Pardon my ignorant understanding of eyepieces, but being a skilled planetary observer as yourself. Can you make a recommendation for a good eyepiece say in the 10-12mm range with decent eye relief. I often see many post speaking of very expensive eyepieces which no doubt may be good but am wondering how much a novice observer with a 8 inch 1200FL F5.9 reflector will see such as myself. I enjoy viewing planets from my home and just started sketching deep sky objects and would like to try the Moon and planets at some point. I would like to get your thoughts on what you think is important and what is just sales hype.

Also do you have a website or a place where some of your articles are? I would certainly enjoy to read more. You have a very interesting telescope as well.

Thanks

Ken

#35 David Gray

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Posted 10 April 2013 - 11:11 AM

Thanks Ken: I’m not well abreast of what is on offer these days but the Meade 5000 Plossls mentioned/shown in my recent attachment I have found to be perfectly suitable for my purposes. With your scope at f/5.9 this type should be well suited for planetary work with one proviso: seek out a good quality Barlow a variable one if possible then you do not have to use what I call peephole high power types. For example a tiny 4mm would give x300 – if your scope/conditions can handle it! So if you seek powers twixt 150-300 your proposed 10-12mm with a x2 Barlow would give 240-200. I have used a friend’s 8” Celestron at these powers and had very good views of planets. Also the 415mm D-K with a 6” off-axis stop at up to x365 (c.f/44!). When my 10" f/8 Newtonian was in use I used x250 (8mm Orthoscopic) very successfully.

I can’t tell you the pleasure and comfort it is to be using larger eyepieces at high powers without risking compromising (and with more eye-straining) fine detail and delicate contrast detection with those awkward 4mm and even 6mm ones. From what you observe now (DSO) I guess you will already have some of the larger long-focus types: if they are of good design and quality then all you may need is a good quality Barlow of appropriate amplification?!

I do not have a website or such, but have considered it - we'll see! My 415mm Dall-Kirkham was made to my specification back in the mid-70s by James Muirden (optics) and Peter Drew, now at the Astronomy Centre Todmorden UK, did the mechanical components. The mirrors were last re-coated in 1989 by (in person) non other than, the now late, David Sinden (formerly of Grubb Parsons) who also worked with such as the 98” Isaac Newton and larger (AAT etc). Testimony to his work that in recent years I can still see stars accurately determined fainter than mag. 16 (tho’ 15 with the binoviewer attached).

David.

#36 kenrenard

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Posted 10 April 2013 - 11:48 AM

Thank You David,
I really appreciate it. I have a 24mm Panoptic eyepiece which I am very fond of. It is very clear edge to edge. I bough a TMB 5mm eyepiece and do like it but found it to work only a few nights a year with seeing here in the Northeast US. I will look into a good barlow as you have suggested.

I certainly have enjoyed reading your posts as well as learning more about your telescope. It must be an impressive scope to look through. Thanks for taking time out of your day to answer my questions. I really appreciate your response.

I look forward to seeing your other drawings and posts.

Clear Skies

Ken

#37 chrisrnuttall

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Posted 12 April 2013 - 03:49 AM

David
What a beautiful drawing of Saturn, the colours are many and varied, but also subtle and realistic (no candy colours here). I'm not sure how anyone can say that such a rendition could be astronomy-art, rather, it is simply a faithful reproduction of a beautiful planet, and this is the goal of everyone who contributes to this forum. It's the reason we draw the objects we see through our telescopes; they are beautiful, awe-inspiring things, which we try to reproduce on paper or screen as perfectly as we can, and in doing this we can capture the changing details on these objects which collectively form a useful scientific record which grows over time.
I too love the personal connection I feel with the object I am drawing and whilst imagers are able to record finer details with less uncertainty, I think that it is a colder and less enjoyable pursuit, obviously others disagree, and that is what makes it all so interesting.

David, it is fascinating to read your posts here, your drawings have amazed me for several years but I had no idea that you held so much knowledge about the process/art/science of visual observing, I am glad you seem keen to share it. Like Pete I am intrigued by the idea of cancelling atmospheric colour smearing with the introduction or contrary chromatic aboration in the optical train. I wonder if the prism in my binoviewer will be doing this to some degree?

Re: Kenrenard, I have found that Televue plossls, University Optics orthoscopics, and Baader Genuine orthoscopics give fine views of the planets. There is much to read on the web about eyepieces for planets, but in general go for simplicity of design and highest available quality. Don't spend hundreds on wide-field eyepieces for planets, they are a waste of money.
I also use a binoviewer with a glass-path corrector which amplifies the power of the eyepieces, meaning I can use longer focal length eyepieces at high power, it is very easy on the eye to do that.

#38 David Gray

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Posted 12 April 2013 - 07:35 AM

I too love the personal connection I feel with the object I am drawing and whilst imagers are able to record finer details with less uncertainty, I think that it is a colder and less enjoyable pursuit, obviously others disagree, and that is what makes it all so interesting.


Many thanks Chris:

I had thought that in later life with perhaps failing sight that I would have by now resorted to imaging, As I am soon 69 yrs I had thought that by now my eyes would have deteriorated somewhat. Apart from becoming slightly longer-sighted some ten years back, which seems to have stalled in recent years, I find no loss whatsoever. I often joke I can read the time on a church clock etc. a mile away with more ease than the watch on my wrist!

Imagers are producing wonderfully detailed work now and far more scientifically useful than I ever could and hopefully never pretended to! However in recent times when getting those rarer exquisite views I have come realise that I could never go to imaging. I am not a religious person but when experiencing such sightings there is something there that neither myself nor the imager (even Hubble!) manages to capture and defies recording – but as you say “personal connection”. The legend I understand is that trying to capture this contributed to Van Gogh’s madness…??! So it is that I would never go over to imaging: if not contradictory - stunningly detailed as they are; for me they become the poet’s “Cold-star bane that deadens human hearts” - Blake? Milton? Educate me someone!

When the acuity fades I may well go more into the speculative astro-art al la Bonestell, Hardy et al. Of course applying, as they, scientific discovery/principles for accuracy!!

I agree with what you say to Ken about eyepieces. My choice of the 20mm Meade 5000 Plossls with their 65 deg. field proved ideal for planets as there is barely noticeable distortion right across the field – even at the edge! The relatively wider flat field is good in another regard: my D-K has had no working drive for many years (you adapt) something I had hoped to rectify when I retired: but so many diversions! Also fairly inexpensive as oculars go – a big consideration when you have to buy in pairs for binoviewers!

Again my thanks for your compliments – your work has my high regard also.

David.

#39 kenrenard

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Posted 12 April 2013 - 07:52 AM

Chris,
Thank You for your assistance with eyepieces. I often see so many new folks just buying equipment for the sake of having the latest gadget. When I see sketches like yours and David's I see a keen observer. I trust your and David's opinion on eyepieces by looking at your skilled drawings. I just started sketching and I only have a few years observing under my belt. I have learned so much in the sketching forums and I am glad I started sketching and reading the posts here. I will look into a binoviewer down the road. Unfortunately sitting at a computer all day my eyes are not the best. So eye relief will help. I will look into the eyepieces you suggested. I think a 10 -12 mm may be my sweet spot with seeing where I live.

Thank You again. Your drawings are very beautiful.

Ken

#40 chrisrnuttall

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Posted 12 April 2013 - 02:33 PM

David / Ken, I work mostly at a computer these days and I have developed a dioptre of astigmatism in both eyes over the last five years; my eye sight was always razor sharp until then and it lead me to believe I had defective eyepieces, binoculars, even an entire telescope, not to mention the TV! Eventually the unthinkable entered my head and I got an eye test. I now have glasses for screen work. Luckily for us astronomers it seems that a bit of astigmatism doesn't matter with smaller exit pupil images through telescopes, and apparently myopia can be corrected with the telescope too.
I can see the attraction of imaging; I captured dozens of driven digital camera photos of Comet Panstarrs the other week and I quite enjoyed it, but I think my first love will always be to spy with my own eyes at those secret things in the sky, and then to draw them.

Once the clouds go away I really must turn my 12" to Saturn for the first time, I have always done fairly well with its belts, but detail on the disk has never come easily 'til now, (the dragon storm in my Avatar excepted!)the biggest scope I have used on Saturn so far was my 8", which whilst being an excellent scope was just not big enough!

I hope to be able to see the kind of detail in the sketch at the top of the page, that will be very exciting!

#41 chrisrnuttall

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Posted 12 April 2013 - 02:38 PM

Oh, btw David, my wife is an English lit teacher, up to A-level, with a degree in English lit.... and she can't help with your poet, sorry!

#42 David Gray

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Posted 12 April 2013 - 04:01 PM

Oh, btw David, my wife is an English lit teacher, up to A-level, with a degree in English lit.... and she can't help with your poet, sorry!


Yes thanks Chris and zilch from Google. I know I saw the quote years back in S&T: the poet's reference to astronomy as "the cold star bane............" and seemed to remember Blake as the offender but Google has cast doubt!

When are these clouds going to shift - I'm getting observing withdrawal again and it makes me tetchy!

David.

#43 Asbytec

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Posted 12 April 2013 - 07:52 PM

Yes very much agree; and when they (accusers) say “art” I think they have in mind the more embellished types – what John Rogers (BAA Jupiter) calls “fairy castles”!

David


David, I hope you know that is not the context of "art" I was referring to. You do seem to take "accurate" measurements of the planet and make them beautiful to look at. I guess you could put numbers all over it, or list them as bright or vey bright. That would be more technical and less artsy. I prefer you keep up the good work. :)

I like Ivano's take on it.

#44 David Gray

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Posted 13 April 2013 - 06:38 AM

Norme,
Artist/artistry/art/draughtsman: perhaps I have come across as making too much of a deal on this. I will say at once that I have gratefully taken all the complimentary remarks on here as genuinely felt – even in my most paranoid moments!! I can usually spot the insult wrapped in a compliment type! No problem with “art” comments: my mother and aunt Florrie would be proud! Should hear what some back at the bakery called me!

When I commence a session I always try to routinely do intensity estimates of every feature I am sure of: could be 30 or more. Including some that are not strictly required on the BAA Saturn programme. I regard this as an essential prerequisite to doing drawings; after completing this I believe it gives more feel for getting the tones right on the drawing. It also leaves open the possibility of doing a retrospective drawing in special circumstances/requirements. So with every drawing, in the main, there is an accompanying prior one with “numbers all over it”: see attached!

David.

Attached Files



#45 idp

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Posted 13 April 2013 - 07:14 AM

X-p I Counted 37 estimates on that sketch, and seeing was just average! Speaks volumes on how diameter helps on Saturn (and maybe on the advantages of a binoviewer, too?).

That's more or less the best I could do on Saturn with an 8" newton, but in excellent seeing, with rings wide open and when I didn't travel much. Then I started graduate school :tonofbricks:

Just a "technical" question: I assume like usual dark background sky = 10 and RingBinn = 1 (when rings are open enough), then I find it troublesome not to have an intermediate reference. Do you find the same? How do you manage?

Steady skies,

Ivano

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#46 David Gray

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Posted 13 April 2013 - 08:11 AM

Just a "technical" question: I assume like usual dark background sky = 10 and RingBinn = 1 (when rings are open enough), then I find it troublesome not to have an intermediate reference. Do you find the same? How do you manage?


Yes sky=10; but BAA has B outer (adjoin. Cassini) taken as 1 but I feel this is too variable throughout an apparition to trust: earlier I even got it as dull as 2.5; and brightens markedly around opposition (Seeliger). An intermediate would be nice: best I could think of is limb-shading - but dicey I reckon. I suppose it comes down to a lot of practice, and as I said earlier here I guess my baker's ovensmanship (50 yrs.) has given me more than a little edge with intensity judgement!

Can't believe it; turned nice outside - may be gone a while. Even longer if it clears (against forecast) tonight!!

David.

#47 ericj

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Posted 13 April 2013 - 11:43 AM

Hi David,

Thanks for all of your sketching suggestions. Very interesting.

With regard to eyepieces for the planets here are a couple of articles I have written on comparisons of different eyepieces I have used over the years:

http://ejamison.net/..._reviews.html#2

It includes:

Zeiss Abbe Orthoscopics, Pentax SMC Orthoscopics, TeleVue Plossls, and University Optics Orthoscopics compared

Clave Plossls compared with TeleVue Plossls, Brandon Orthoscopics, and Aus Jena Orthoscopics

Clave Plossls compared with TeleVue 9mm Nagler

Clave Plossls compared with Zeiss Abbe Orthoscopics and Pentax SMC Orthoscopics

University Optics Orthoscopics compared with TeleVue Radians

Also TMB Super Monocentric Eyepieces:

http://ejamison.net/...t_reviews3.html

Best,

Eric Jamison






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