What is the cure for Aperture Fever

[Macavity]

Buy TWO - The paired 22" bino scope seems quite popular!

[albedo0.39]

Love it - As someone told me when I went to buy a classic sports car, once you have crossed the line of irrational, you might as well be very irrational !

[calibos]

My advice Steve is......

DON'T BUY IT!!

There are several reasons.

The 22UC seems to be afficted with the same problems as the 18UC. Look them up.

Its an Ultra compact, not an Ultra Light. Its not much lighter than a Standard 22". With the exposed Mirror and delicate hinges and linkages, it really needs to be transported in its flight case for safety. The flightcase for this takes up almost as much space as a Standard Obsession of equivelent size.

On the objects I looked at with the same EP in a premium 20" compared to how they looked in my Old Orion XT12i 12". Eh the difference wasn't dramatic. There was no WOW from me. I couldn't believe how my 12" almost held its own. It nearly put me off on my plans for the LB16. It was only the deal of the century, the truss made it fit easier than a 12" solid tube in my car, and the posibility of a servocat drive option for the LB (Which I eventually took up), that made me proceed with the LB16 purchase. It certainly wasn't the extra 4" of apeture in the end.

I think you are going to need a 25" to get a decent WOW factor over your 16"

Also think about the expectation baseline. View as much as you can in the 16" before you upgrade. Then you will see the improvements when you jump in apeture which will blow you away. If you jump in apeture without seeing much with the LB16, then the new apeture will be the baseline for that object.....Erm, I'm finding this hard to explain. Take my first view of M13 say. At the time I was just learing to lower my expectations from my pre-telescope days. I already knew not to expect astrophoto's but still couldn't help feel a little underwhelmed. So M13. Hmmm thats nice I guess, Lots of pinprick stars bunched together. I was about to move quickly on when a fellow observer asked for a look. "OMFG!! WOW. Thats fantastic. I've never seen so many stars in M13. Its resolved to the core, its like diamond dust." He was blown away by the view because he had only seen it in his 4" achro and a mates SN6

I reckon you should invest in the premium EP's that you can enjoy now, will last a lifetime but will also work great in the superfast large apeture scope I think you should wait a few years for.

The ball is really starting to get rolling on that front, with a lot of premium mirror makers planning super fast mirrors. Televue have a new paracorr in development that'll work down to F2.5. Just imagine the widefield views with a very well corrected 21mm ethos combined with the new paracorr in such a fast F2.5 scope with a 30" mirror that you can view at zenith with at most a step stool!!

[calibos]

Forgot to mention. Collimation on a Fast or uber fast scope is no harder than on a slower scope. Its just more important that you get it right. If you already have the tools, the aptitude and the desire to got your collimation right on your LB16, well then a super fast scope changes nothing.

[Breakintheclouds]

Don't forget that with these monsters there's one other collimation issue: when you're stood up at the top staring down a Cheshire eyepiece, the person twiddling screws on the primary will be so far away you'll probably need a telephone to give them instructions!

[calibos]

Don't forget that with these monsters there's one other collimation issue: when you're stood up at the top staring down a Cheshire eyepiece, the person twiddling screws on the primary will be so far away you'll probably need a telephone to give them instructions!

Which is why its worth investing in a Glatter Laser and Blug. Blug for the Barlow method which gives cheshire accuracy and you can collimate from the back and the Glatter because even if you drop it from the top of the ladder, it won't have lost collimation.

[Peter Drew]

No cure, but it can be treated! I made a 30" F4.1 as a result of the fever, the coma issue (which can't be cured by design if you need a paraboloid) did not cause much of a problem as most of the DSO's that it was worth going to 30" for were pretty small and kept within the useable field. It was fun showing people M31 because you just couldn't see it as expected, it was so large and bright it was like looking through the eyepiece in daylight, a better complete view in the 80mm finder. The big issue is useability, even at F4.1 a massive ladder was needed to reach the eyepiece and by the time those who dared the experience often found that the object had drifted out of the field, kept me fit up and down the ladder checking it! The scope is currently mothballed awaiting a rebuild to suit an equatorial mount for a stab at astrophotography with it. 42", only in America, I've been on a 42.5" project for sometime but don't hold your breath for a first light report.

[albedo0.39]

Keith / Peter - many thanks for your inputs to the equation - I confess, that I think that the 25" would be a better bet from a "wow" factor but that F4.2 sure makes up for the lack of convenience.

Keith -your specific issue of the "expectation baseline" is a good concept and one I am well aware of from my insane addiction to high end analogue hi-fi (the law of diminishing returns is often used to explain this). Indeed, I think I already went through the "wow" when I went from a 6 year old memory of a 4.5" tasco reflector with SR and H lenses to the LB-16. It's amazing.

Whilst at Kelling this year and in a group of fellow enthusiasts where my scope was the smallest, we were all going very deep and looking for smudges like NGC1 and 2 and I got the idea that to slay some of these dragons, I needed more mirror.

In no way am I remotely bored with my 16", but the portabilty is not ideal.

Peter - that's a terrific story and I'm going to have to push back a little on the figuring the mirror to be coma-free (??) so could you point me to a resource or experience that allows me to understand what prevents this in a Parabaloid ? (Perhaps I need to speak to OMI)

Anyhow, I have plenty of time to take opinion and listen to people who have walked that path (and that is the true value of SGL in my opinion)

Rgds

Steve

[ollypenrice]

Do buy a big Dob, certainly! We have a 20 inch here and it isn't big enough, but they never are. However, you don't need to buy an Obsession. That's where the consumer society bit kicks in. There are people nearer home who will build you a great scope for half that price and leave you with enough change to buy a couple of TeleVue EPs and a five inch Tak! Check out David Lukehurst. He makes good telesocpes.

Our Dob was amateur built with Beacon Hill optics and the Veil, as has been said, looks like a photograph. So does M42. You can see the bright patches at the ends of the elongated arms of M101. In a nutshell it's good and it didn't cost 10,000 bucks.

As for being sexy, no. But the views are damned sexy...

Olly

[Doc]

Moral to the story Steve, stay away from kelling

Best of luck on what ever you do and does this mean I need a bigger tent

[johninderby]

You could always commission another 48" dob like this one known as “Barbarella”.

http://www.opticalmechanics.com/evolution_dobs/Evo-48_intro/index.html

John

[MG1]

If I had his garage then sure.... I'd have a scope like that too!

I don't suppose it happened to bee two SGL'ers that won the euro millions? I'd love to see a 48"er at Kielder or Kelling next year!

[albedo0.39]

You could always commission another 48" dob like this one known as “Barbarella”.

Now that is a top machine. Do you think that will fit into the back of a Mini Cooper (like my current scope ?)

[Breakintheclouds]

I don't suppose it happened to bee two SGL'ers that won the euro millions? I'd love to see a 48"er at Kielder or Kelling next year!

If two people from here were sharing £90 million, I'm pretty sure they wouldn't stop at 48". You could probably get a 100" rig and an observatory for that!

[Astro_Baby]

I dont know what EPs you have - you said you dont have a great collection. I'd suggest (along with afew others on the thread) that a super fast focal ratio scope wont show great views without great EPs to go with it. I have recently had a rather dramatic demo of what happens to EPs under the stress of a fast focal scope - F5 is fine - much below it and ooooeeerrr things dont look so pretty.

When you get right down to it its the EP that gives the view - the scope is only a light collector and as I have found with my humble 8" the quality of the EPs is a bigger factor with its views than aperture.

In short an 8" with a quality EP will give better views than a 12" with a duff EP. Like someone else on the thread I have had someone peer through mine and go all gooey because their baseline was a sligghtly smaller 6" scope but critically with bog standard eyepieces supplied with the scope. Seeing M13 through my 8" with a better quality EP amazed them.

Theres another reason not to buy it as well - UK skies are TERRIBLE. Would a 20" plus scope really ever get much use ? I had a look through a 24" Obsession as a public outreach event last year and though its views were rather good they werent that much better than the views through a WO APO (cant remember whatt size it was but a lot less than 24" ).

Have you been out much with your scope of late ? I ask because whenever I dont get out with mine I start to think in terms of buying more hardware. When I get to be out with the scope I tend to forget about upgrades.

I'd let head rule heart on this one and just mull it over for a long time - decide to make no decsion for say 2 months - than you'll know if its a fad or a serious need.

If you decide you simply have to spend ten grand I'd buy some better quality EPs because the EPs you will have with you always while ANY scope ends up being merely a spring board for the next one.

[Beulah]

Mel, great post. It would be interesting to find out the ideal maximum aperture for our skies.

[George]

Oh lordy... hadn't even thought of that. Next thing, you'll be suggesting I get a radio controlled airplane (bound to end in tears)

An RC airplane with an imaging train.....great idea to fly above the clouds and image.

[Macavity]

There was a US-based site (naturally?) pondering the "maximum size" idea. But, if I was "loaded" (and strong!), I might indeed be more intrigued by the binocular (Dob) idea. There seems something "logical" and fascinating, about the claimed (economical) gain to be had therein...

Have even ponderend stringing together TWO MAK127's at times...

[Peter Drew]

Hello Macavty. I built a couple of Mak binoscopes but found the rather small FOV and the image shift issue when focusing somewhat defeated the object. I ended up making a 12" f3.5 reflecting Dob binoscope which probably reaches the point of diminishing returns based on cost. Anything much larger might be just as well be a single unit with a binoviewer.

[dobserver]

Still love the LB though and perhaps all I need is some good EP's to get the very best out of what I have.

but still....

I think that you hit the nail on the head with this statement. Once you have invested in some great EPs to use with the LB you will know more if the urge to move up is still burning. But then you will already have your EPs to use with a bigger scope if you can't resist! And if you come along to Bude you can play with the 20" - promise I'll let you have a little go....

Steph

[chuenmanc]

I've also dreamed of owning one of those. Could never afford one, but in browsing around, I found David Lukehurst (previously mentioned in this thread). It looks like he can build you a very similar scope. Looks lighter, and cheaper too, once you factor in VAT, import duty and shipping.

As for the Obsession, will you be able to lift the 41kg lower assembly into your car boot? I know I couldn't! I think in the US, lots of people have trailers or flat bed trucks and use ramps.

Have you read this thread on the UC?

[IanC11]

You do know that Orion do a 20" Dob for around six grand, they also say they have a 24" in the pipeline.

Dobsonion OD500

[albedo0.39]

chuenmanc - thanks for the heads up on the cloudynights thread. Indeed, I'm a touch shocked that some of the most basic aspects of a $10k scope have been somehow overlooked

I'm going to contact David Lukehurst regarding a potential scope, (and it keeps someone in the UK busy) but we'll see how things pan out.

Thanks again

Steve

[mdstuart]

How about give 10% of the value of the scope to Tearfund

And then you will be able to spend the other 90% on the scope and feel the purchase did some good as well.

Mark

[ncjunk]

Love it - As someone told me when I went to buy a classic sports car, once you have crossed the line of irrational, you might as well be very irrational !

Ahhhh music to my ears...I ended up with 20 grand loans following this kind of advice on Guitars, amps and computers (over a number of years). Paid it all off now though...and still the irrational side of the brain screams "you´ve done it once you can do it again, the first was just a practice run! buy the 6,000 pound "scope":iamwithstupid:

Neil C