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Dave47tuc
10-06-2005, 07:44 PM
Hi All :D
Observing with an 18” Obsession is a thrill for any observer. On many occasions I have used such a scope. The scope has Argo Navis DSC on it. This makes finding objects in the sky very easy. So more time is spent viewing than finding them.

My friend Julian owns this scope. We observe from a private property on the Mornington Peninsula. Skies are dark to the South and West, with some light pollution to North and East. Limiting magnitude is about 6 at the zenith.

We are lucky that between us we have the drool factor eyepieces to use. Mostly Naglers, just about the whole range. We also use filters with the UHC and O111 being most popular. We also use a 2” UHC that is awesome.

The scope itself is very smooth to move, it has a JMI focuser, which I find very good. I know some don’t like them much. I think my focuser on my 10” a bit better.
The scopes finder is only a Telrad, which is fine with DSC. There is a dew heater on the secondary and the scope is set up permanently in a shed to be rolled out when needed.

I know many have used big scopes so I don’t need to tell you what it is like. For those who have not, I’ll try to paint a picture for you.

My first look with such a scope was very much the wow factor! I see why aperture fever grabbed so many people. I have looked at well over 100 objects with this scope now.
Messier objects are really bright. Structure in a lot of the Nebula, which you cant see in a small scope.

Globular clusters are resolved down the core in most of them. What can I say when it comes to 47Tuc and Omega. These two are better than any photo could show.
Lets take the Great Orion Nebula. In a 31 Nagler and UHC filter I tend to find it hard to find the words to describe it. Its like one of those fans Japanese women use. The structure of the Nebula run way out of the field. I said once it looked very 3D. The Nebula filaments seem to just jump out at you. Just very WOW.

Put in a higher power say 22 Nagler and instead of the 4 Trapezium stars there are 6 easily. They are just beckons in the nebula.

On the night of 9 June I had 6 hours with this scope and it was a great night.
It had just rained in Melbourne so the skies were clear. So one just had to get out and observe. I was lucky having the nest day off.

First Jupiter is so bright in such a scope you think of getting a Moon filter for it. So much detail can be seen. Not just the Normal 2 or 4 belts. Many finer belts can be seen so many bumps and knots festoons white ovals, darks spots it’s amazing.
Forget your little Apo this scope stomps on them.

I have not spent much time on this scope on the other Planets. Pluto has been seen.
I have not looked at any other Planets with this scope yet.





When observing globulars most resolve really well. But I proved this scope could be beat. We tried to find some super faint Globulars. Terzian 5,10 and 11. Sorry to say on this night we could not see any of them. Need to take the scope to darker skies.
Or get a bigger scope.

The Argo Navis has tour modes, so we went on a Planetary Nebula run. We used a 9 mm Nagler with an O111 filter in it. Lets say when they say the Blue Planetary, NGC 3918 is just fantastic. Yes blue it is. What about the Eight-Burst Nebula. NGC 3132.
This is one of the best or even the best Planetary in the sky. Yeh shoot me down but there is so much detail to see and the shape is unreal. There are so many smoke rings in the sky it would take me forever to explain them all.
I have seen many of these in my 10” but the 18” really shows what these objects are.

The Nebulas you can see is just which one do you want to look at.
Go for brighter ones say the Lagoon Nebula M8 and Triffed M20
This scope to me shows more detail than photos do. No not the reds and blue colours.
But detail that photos burn into. The Dark lanes in the Triffed is so alluring its puts you in its spell. Creepy is a good word for it.

Where this scope really shines is on Galaxy’s. M83 is just how a Galaxy should look. Spiral arms, detail that’s hard to explain. Its like it just draws you in. Same with NGC 5128 the dark lane has so much detail in it its incredible.
But what about the faint ones, how many do you want to see. Just pan around the Virgo Cluster, just one after another.

A funny moment was I was looking at Sky Atlas 2000 (I still love my chats)
So I looked at region in Antlia. NGC No’s 3258, 3268,3281,3271,3358 and 3347.
In the scope I panned around and saw over 12 Galaxy’s!!!
Sky Atlas 2000 is not detailed enough for this scope. I left my Uranometria at home. Not any more. I have both new and old editions.

I could go on and on which I have done, but I hope you have enjoyed the read.
The 18” Obsession is a pure delight to use. If you have never looked through big glass, do try to some day its amazing.

Clear Skies. At night. Let it rain by day. :D

[1ponders]
10-06-2005, 07:57 PM
Thanks for that great report Dave:( Ya lucky bugger.:thumbsup:

jackenau
10-06-2005, 08:40 PM
:painting: Great report Dave, makes one a little envious. :astron: Whilst I have not had the experience in viewing through a scope of such size, I can only relate the experience to viewing through a 35mm Pan (which is now my favourite) ep, or a 16mm Nagler :thumbsup: as opposed to standard ep's :eyepop:

The views are so much crisper and the wider fov :2thumbs:

Ken M

Daring Dave
10-06-2005, 09:14 PM
Great report Dave...Ive got aperture envy !! :astron:

Sice reading your report ive been researching ATM again.....

gaa_ian
10-06-2005, 09:35 PM
Excellent report Dave .... Yep, when I set up my Observatory (a few yrs off yet, unless the club gets an extra large grant !) I want & will get one !

ballaratdragons
10-06-2005, 09:47 PM
Excellent write up Dave. And very well narrated by you.

Makes me want to run out and buy one!!!

Is Julian and his 18" Obsession the ones that are coming up to the Star Camp in Oct. Hope so.

asimov
10-06-2005, 09:48 PM
Geez! I've never even looked threw a nagler or a pan, let alone an 18" reflector!

Good stuff Dave.

toetoe
10-06-2005, 10:38 PM
Thank you so much for a great insight into something i can only dream about Dave.

Orion
11-06-2005, 08:50 AM
Hello Dave you certainly did write a good report on the 18' Obsession.

I also have an 18" Obsession clone that I've have built. I have the ArgoNavis and the ServoCat (goto) as well. It is great to have the convenience of pressing a button and watch the telescope slew from one object to next.
I have to agree with every thing that you have said in your report although I haven't had the opportunity to observe with some of the eyepieces that you have but I can only imagine. I was also thinking about getting a filter for viewing Jupiter because it tends to get a bit on the bright side.

Starkler
11-06-2005, 11:43 AM
I have had the pleasure of observing with Dave and Julian on a few occasions and yes the 18 incher is certainly an impressive scope giving some :eyepop:-ing views :D

A few that stand out in memory are m42 with amazing detail, the trapezium with the E and F stars showing as mdium bright and standing out like the proverbial, instead of quite faint stars as seen in my 10 incher.

What this scope excels in is viewing planetary nebulae. In my 10 incher, I mostly see a blueish disk and if Im lucky see some rudimentary structure. In the 18 , the structure and detail jumps out at ya ! Truley amazing views :)

Oh and incidently, its also a lovely looking scope :) I would love sometime to own its baby brother, the 15 incher, thats my dream scope :love:

Dave47tuc
11-06-2005, 01:23 PM
Many thanks for your replies guy's :thumbsup:

Ken we shall see re the 18" at the 2005 Camp. :D

Geoff, the 15" is high on my list as my next scope :jump2:

fringe_dweller
11-06-2005, 02:41 PM
Dave! now thats what i call a report!! :2thumbs: you had me transported to the eyepiece and beyond - that should be in a magazine :painting: wow!
Kearn

beren
11-06-2005, 09:38 PM
:thumbsup: Great read Dave , it would be a real thrill to get a chance to look through a scope like that and equally to have yourself at the helm :2thumbs:

astroron
11-06-2005, 11:44 PM
:astron: If you come to the Queensland Astrfest in August you will probably see scopes from 30 inch down to 60 mm refractors ,my 40cm (16inch) and I will be there to make up the numbers of medium to large scopes in attendance regards astroron :astron: :stargaze:

astromark
19-06-2005, 09:33 PM
Good informative and interesting read Dave. The Wanganui Soc., has obtained the 20 inch reflector made by Joseph Ward. Trouble is, it was never finished.he died in the 1930's. Its focal length makes it about 18 feet long. we are going to need a longer lader. Time for some latral thinking a... Its going to be a good scope and from a very dark sight, she will be great. I will keep you informed of progress. Mark.

Orion
19-06-2005, 09:46 PM
Mark if the mirror is not polished or aluminized you can always make it a shorter focal length.