Haven't ever heard of this happening to a thick 18" primary. My 16'' has never, ever dewed up.
It happens!! The 17.5" Coulter mirror I mentioned above sits in a classical type mirror box with no shroud around the trusses and it dewed up two nights running around 2-3am in then morning only a month ago in October. I've seen plenty of dewed secondary mirrors but this was the first time I had seen this scope dew up like that, and it wasn't even a particularly cold and dewy night.
18 UC comes with primary and secondary light baffles
Quote:
Originally Posted by tnott
Can't see the point of the shroud to be honest, as most stray light gets in around the top end around the focuser and secondary assembly, and this is above the shroud in this design. Also, light is not blocked from getting into the light path around the primary either. Might be more to do with customer perceptions than blocking stray light. personally, I'd be baffling the focuser and using a bigger baffle behind the secondary instead.
Tim.
Hi Tim,
The scope comes with Kydex light baffles both for the secondary and the
primary, it is just that they were not installed during the daytime when I took the
photographs. You can see the light baffles in the attached photograph taken
by an 18 UC owner at the recent Okie Tex.
In keeping with the fast setup time, both baffles attach in just seconds.
By keeping the primary baffle removed until one starts observing, this may
also assist with the mirror cooling down to ambient much more quickly.
Thanks for that, gary. I went and watched both videos, interesting viewing. It made the counterweight system more understandable and gives a good idea of the size of it. I loved the sound effects - flies, wind and magpies. How Auatralian is that! But at one point the winds gusted up a bit and even with the shroud on it didn't blow about much, which was encouraging. It can get pretty windy at night over here in the west in summer if an easterly kicks in.
Thanks for that, gary. I went and watched both videos, interesting viewing. It made the counterweight system more understandable and gives a good idea of the size of it. I loved the sound effects - flies, wind and magpies. How Auatralian is that! But at one point the winds gusted up a bit and even with the shroud on it didn't blow about much, which was encouraging. It can get pretty windy at night over here in the west in summer if an easterly kicks in.
Hi Blue Skies,
As Dave demonstrated when we were in Texas, the neat thing about the
counterweights is that they open up and you can add or remove sand or
shot to get the balance 'just right'. This is handy if you are adding or removing
something heavy like a 31mm Nagler.
The flies really were something else at Coonabarabran, but we told our
visiting American colleagues they were in honour of that great overlooked
southern constellation, Musca.
The bird calls at sunrise up this location are iconically Australian as well.
As you noted, it was quite gusty whilst filming, but the scope does not sail
around.
The UC looks amazing! So simple and clean cut. I'm glad I didn't get one of the Standard Obsessions.
I must say that he's a bit rougher with his telescope than I am with mine. I cringed a couple of times when he got near the primary and he just chucked the secondary on the ground. It can obviously take the battering but I could never imagine treating mine that way. I love my telescope.
Having said that it looks very impressive. I love the fact that the secondary attachment is so thin. I don't like the large wooden ones. I guess the metal gives it a bit more rigidity. And I like how the Telrad just swings into place.
Gary, how do the encoders attach to the virtual rocker box for your Argo Navis?
The Obsession website has the cost of all their telescopes but wondered if anyone can advise what they charge for the shipping and freight costs to Australia for the Obsession 18 UC and again for the standard (full size) Obsession 18.
Go to the obssesion web site and you can E-mail Dave all your enquiries and he responds back to you in 24hrs with pricing. I was told about $1500 US$ last week to get the UC18 air freighted over including insurance.
Go to the obssesion web site and you can E-mail Dave all your enquiries and he responds back to you in 24hrs with pricing. I was told about $1500 US$ last week to get the UC18 air freighted over including insurance.
Regards Matt.
Don't forget about $500 broker/ port charges on this end plus 10% GST on the total of purchase price + freight.
You might like to request a copy of the latest Obsession DVD. I received a copy today from Dave Kriege and it includes a new segment on the 18Ultra Compact that was video'd at Coonabarabran.
Thanks for the tip, Gary. I received my copy together with various paperwork, posters and price list etc. The one I received didn't have the UC footage on it, but I've seen the YouTube video. No UC mention in the paperwork as well. No problem - there is plenty on the website.
Quite neat to watch the "home video" style. Nothing hidden here, no slick sales pitch. Just a detailed demonstration of the construction, assembly and mechanicals - plus ServoCAT and Argo Navis description/demos.
I'm particularly impressed that Sheryl Johnson can collimate her 20" with the primary mirror cover still in place, but maybe I'm missing something here
Thanks for the tip, Gary. I received my copy together with various paperwork, posters and price list etc. The one I received didn't have the UC footage on it, but I've seen the YouTube video. No UC mention in the paperwork as well. No problem - there is plenty on the website.
Hi Eric,
Great to hear you got the information pack. As mentioned, I did receive one
of the newer DVD's that includes the 18 UC but it was good you were able
to watch it on YouTube.
Quote:
Quite neat to watch the "home video" style. Nothing hidden here, no slick sales pitch. Just a detailed demonstration of the construction, assembly and mechanicals - plus ServoCAT and Argo Navis description/demos.
Dave likes it that way. Just raw. I think he pre-dates a style now made popular
with reality television. He doesn't even tell you he will film you. He just pulls
out a camera and says "start talking" !
By the way, if you have never picked up a copy of the book he co-authored
with Richard Berry, "The Dobsonian Telescope", it makes an excellent read
and a fabulous reference.
Quote:
I'm particularly impressed that Sheryl Johnson can collimate her 20" with the primary mirror cover still in place, but maybe I'm missing something here
So use to it, she can probably collimate with her eyes closed.
18 UC chosen as Hot Product for 2008 by Sky & Telescope
Dave Kriege reports that the 18" Ultra Compact has made the much
coveted U.S. Sky & Telescope 2008 Hot Product list and will appear in the
January issue.
The Tele Vue Ethos 13mm eyepiece is also believed to have made the list.
Having had Argo Navis chosen a few years ago as one of the U.S. Sky & Telescope
Hot Products of the Year, I can tell you how good it feels to be awarded this
honor. This is the astronomical industry equivalent of the Academy Awards.
I was at BinTel the other day and mentioned to Don the Skywatcher look great - but they just aren't an Obsession - having viewed Zane's 24" Obsession with the Argo Navis and Servo cat.
Don mentioned oh yeah (at some length) and had alot of great things to say about about Zane and Magellan, then went on to rave about Argo Navis - saying it should be the product of the year - thought you'd like to hear that Gary (and Zane)!
apologize if this has been mentioned, but will their be an Aussie dealer for these at some point?
Hi Prova,
Customers are just ordering Obsessions direct from the U.S where they will also
customize them with whatever options you request. They even come with
a brass plate with your name on it.
Sea freight is another option that Dave can undoubtedly quote on. This
method of freight is particularly attractive for the classic range of Obsessions
which are somewhat physically larger.
Don mentioned oh yeah (at some length) and had alot of great things to say about about Zane and Magellan, then went on to rave about Argo Navis - saying it should be the product of the year - thought you'd like to hear that Gary (and Zane)!
Thanks g__day,
It is always nice to receive a compliment first hand, but to hear it second-hand
can be even nicer, so we appreciate you passing that on.
Mai and I are very fond of Don and his contributions to amateur astronomy
and his knowledge of telescopes and astronomy is something we deeply admire.
Having seen your gear at Magellan used in competent hands (I did a review on this earlier this year - a tale of two observatories) it worked so ridiculously well, the compliments are simply well earned.
Hmmm. Let's see - it is a very rigid design, with 2mm thick steel-vaned spider. The diffraction spikes would be more obvious than the wire spider on my current scope but the setup has other practical advantages. The poles, themselves connected at the apices for greater structural strength, are connected to where the spider vanes meet at the top and then bolted directly to the sides of the mirror cell at the bottom. It would work well scaled up to a larger size and hold collimation really well like the original version of this design - Greg Babcock's scope from a few years ago ( http://www.synrgistic.com/astro/24inch.htm ).
I think I might build a 22" F3.66 version - feet on the ground for most viewing, almost double the light collection of my 16" Tridob and in as lightweight and compact package as possible.