Jump to content

NLCbanner2024.jpg.2478be509670e60c2d6efd04834b8b47.jpg

Skywatcher big dobs

JohnC

Recommended Posts

Crusader

Crusader

Posted
Posted
Ah well think of the collimation efforts...and that should temper the fever a little...:cool:

For 20" of aperture I will definitely try to master the art of collimation even though I hate it.

I sure hope my supplier wasn't under the influence of anything when he mentioned the 20".

Link to comment
Share on other sites
Beulah

Beulah

Posted
Posted

I predict in five years' time, 20 inches will be the new 8 inches for entry level telescopes....

Seriously though, the availability of these larger telescopes to your average astronomer in the street (with a bit of money) is just absolutely astounding to me....now for a bigger garden...:cool:

Link to comment
Share on other sites
epk

epk

Posted
Posted

Although the aperture is always tempting, I think the necessity of stepladders will stop me ever going beyond 16".

As my back is never that good, a night spent with a 22" dob last summer left me in tatters with a twisted back, a cut on my forehead from whacking the Telrad repeatedly in the darkness, and a firm decision that it just wasn't worth doing permanently.

If I bought one I'd be dead within a month!

Link to comment
Share on other sites
Macavity

Macavity

Posted
Posted

Interesting idea via random internet search. Work with an F5 mirror,

but change ANGLE of the secondary - lessening length of the tube.

Seem to come under the generic heading of "Lowrider Dobsonians".

Ultimately one arrives at some kind of... catadiopteric beastie? :cool:

Link to comment
Share on other sites
Albireo380

Albireo380

Posted
Posted

A 20" Dob that might be within my price range - it brings tears to my eyes - even if I need to pack a stepladder to reach the EP. Even the 14" with a drive would be good.

I wonder what the price will be in the UK - probably £ for $.

Tom

Link to comment
Share on other sites
Bigwings

Bigwings

Posted
Posted

Yes but Meade rip off the 16" market because they dont have competition with that format. Just look at the price hike in the last year.

See what happens when Sky W get going.

Link to comment
Share on other sites
Albireo380

Albireo380

Posted
Posted

Hmmm ... If the driven 12" Skywatcher Dob comes in (FLO) at about £1050, perhaps the 14" equivalent would be about £1300. Shudder to think of the 20" price though ... ~£2200 if driven ???

Just guessing here - I really have no idea.

Steve and James (FLO), I would be VERY happy to test one of these out for you any time :) . Then I could maybe buy it as "shop soiled" for half price? Just trying :cool:

Tom

Link to comment
Share on other sites
johninderby

johninderby

Posted
Posted

Going by the price differences of just the mirrors (from different mirror suppliers) I would expect the 14" to be somewhere around £1499.00 and a 20" to be £3499.00 to £3999.00. The 20" mirror is about 2 to 2.5 times the price of the 14" not to mention all the other costs involved. And in this case I'm talking about a cheap 20" mirror, not a premium quality one. I wouldn't hold my breath waiting for a 20".

John

Link to comment
Share on other sites
Macavity

Macavity

Posted
Posted

I see Orion Optics are advertising (see: June Astronomy Now!) a 20" - A "snip" at £5995. A 24" coming later this year. You might be able to scale the prices between manufactures, to some extent? But such remains in the (personal) domain of "merely interested". On a self(ish)-education level, I do wonder about this COMA thing. I see e.g. it is (obviously now) inherent to parabolic systems. I assume it scales with "dimension" ... somehow. I see words like Paracorr etc. "Even a perfectly made 13" f/4.5 parabola has only about 0.1 degree diffraction limited field". Perhaps not a topic for this thread, but a "hmmm" maybe? :cool:

Link to comment
Share on other sites
calibos

calibos

Posted
Posted

As John said, the price increase as you step up in apeture is not linear in Premium scopes and indeed it is not linear for Chinese mass produced scopes either. However because both the mirrors and mechanicals of the Chinese scopes are mass produced, this non linearity in price increases is not as pronounced with the Chinese scopes as it is with the premiums.

A chinese 16" is indeed double the price of a scope only one step in apeture down at 12" but remember one is starting from a very low price for a Chinese 12". One also has to take into account that any company will charge what the market will bare. With GSO having the 16" market to themselves with the (GSO)Meade Lightbridge 16 and the GSO/AT/Zhummel/Bintel 16" they could beat premium 16" pricing by a large degree and still make a heafty margin on the 16". It wouldn't suprise me if their margins on the 16" were dramatically more than their margins on the smaller sizes in which they have to compete with the Synta brands.

So as someone said above, it wouldn't be suprising to see the prices of the GSO 16" ers come down when the Synta brands start coming out with the 14" and 'possible' 20".

One of the reasons for the dramatic price increase after 16" is because thats were the mass produced mirrors of the Chinese top out. After 16" one has no choice but to go premium. If Synta have perfected the mass automated production of half decent 20" mirrors, although they are still bound to be twice the price of A GSO 16", the pricing will still be a far cry from the $8500 Premiums. I'd be thinking about GBP3500. Then again the tables will have turned and now Synta would have a market segment to themselves and could thus charge what they like. They could charge GBP5000 and still have a massively attractive product price wise when compared to a premium.

I'd have written this rumour off as pie in the sky due to only having one source so far only for the fact that this source was very specific. Not only did he say he ws told about a 20" at a skywatcher distributor show in China but he was told the focal length would be 2200mm which is F4.3. The other fact is that it is only a matter of time before the chinese perfected the automated grinding techniques to start churning out half decent mirrors larger than 16". Who's to say, that time isn't now?

Link to comment
Share on other sites
Crusader

Crusader

Posted
Posted

I'd have written this rumour off as pie in the sky due to only having one source so far only for the fact that this source was very specific. Not only did he say he ws told about a 20" at a skywatcher distributor show in China but he was told the focal length would be 2200mm which is F4.3. The other fact is that it is only a matter of time before the chinese perfected the automated grinding techniques to start churning out half decent mirrors larger than 16". Who's to say, that time isn't now?

Just to clarify. The supplier did state that he was at the Skywatcher factory. I'm assuming it was during the distributor show, he did not specifically say that it was during the event.

He did specifically mention a 14" and 20" with a focal length of around 1800mm for the 14" and 2200mm for the 20" 'if his memory serves'.

Doing some research shows some details for the 14" surfacing. In actual fact it has a focal length of 1700mm. So he seems to be right on that count.

With regards to the 20" some else (Dave on Cloudy Nights) have made inquiries to his local distributor who don't seem to have any knowledge of a 20" - specifically that it was not mentioned at the distributors conference.

What to make of it at this stage is unclear. Everything is based on hearsay so it might be best to just wait and see what Skywatcher does. I sure hope that the 20" is a reality, but it is very strange that other Skywatcher distributors don't know about it.

Link to comment
Share on other sites
johninderby

johninderby

Posted
Posted

The 20" might be an R&D project to see if they can make the 20" mirrors to an acceptable standard. Perhaps they are developing the capability to produce bigger mirrors and it might be a while before they are ready to go into production. This might explain why no retailer or distributor knows anything about them.

John

Link to comment
Share on other sites
Crusader

Crusader

Posted
Posted
I agree with John. Thats probably the most likely scenario. I smell conspiracy though. Those Skywatcher guys don't want us to have it......:cool::icon_salut:

Don't we all wish that it IS a conspiracy!

Link to comment
Share on other sites
ollypenrice

ollypenrice

Posted
Posted

A couple of things; collimating a big Dob is DEAD easy if you have a laser like the one made by Astro Engineering. It goes in the focusser. You have a centre dot on both mirrors and once the primary is set I have never known it move. (That's in three years of use with guests.) You then stand at the top looking down onto the primary and tweak the secondary's screws till the laser hits the primary in the middle. Lastly you toddle round to the bottom end and, looking at the return target on the laser collimator (which you can see from where you are) you centre the return beam using the primary's adjusters and Bob's yer uncle. Honestly it takes about 90 seconds. The result is fairly accurate and can be perfected with a star test and a friend at the other other end. We never bother, though, because the laser gets you to a very decent standard.

We can't have guests climbing ladders in the dark in this day and age so I welded up a little platform to stand on or put a stool on for sitting. It has two wheels at one end, feet at the other and a wheelbarrow style handle for trundling it around. The handrail goes nearly all the way round so you won't fall off. Mine's a two-person model but a little solo would be more nimble. A fabricator would make one in two hours if you don't have a friend with a welder.

Olly

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.