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Sky Watcher 18" prototype

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#26 akulapanam

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Posted 02 December 2013 - 12:50 AM

As someone that is looking at the hubble optics 18" f4.5 right now this scope isn't very interesting at $5k and 150 lbs. The Hubble 18" is 72 pounds and $3k and for $5k you can get the full goto and every accessory. Now you add goto and get the weight to 100lbs then this guy gets interesting.

#27 Fireball

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Posted 02 December 2013 - 04:08 AM

As someone that is looking at the hubble optics 18" f4.5 right now this scope isn't very interesting at $5k and 150 lbs. The Hubble 18" is 72 pounds and $3k and for $5k you can get the full goto and every accessory. Now you add goto and get the weight to 100lbs then this guy gets interesting.

That's right, even the Hubble UL20" is lighter and the price for the f4.2 is still less than 5k - worth to think about!

#28 Astrojensen

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Posted 02 December 2013 - 05:55 AM

I wasn't even aware the Hubble Optics scopes were that inexpensive. The 16" UL is CHEAPER than a 16" Meade Lightbridge here in Europe, even with shipping! (but without taking customs into account!) Even with customs and VATT added, the 16" HO UL is only modestly more expensive than the 16" Meade LB, by about 15% - 20%. The Meade LB outweighs the HO UL by more than 100%...

That is ridiculous! I am now SERIOUSLY considering a 16" f/5 HO UL.


Clear skies!
Thomas, Denmark

#29 radicell2

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Posted 06 December 2013 - 10:53 AM

But my question concerns the cylinders between the upper and lower thin solid sections: they are filled with air which expands and contracts with temperature. Does that internal pressure change affect the surface figure of the mirror above the cylinders? The mirror could be perfect at +20C. Does it appear dimpled at -20C?



Don,

I noticed that there were small ā€œVā€™sā€ in the bottom of the cylinders which I assume were needed during the fusing process. These openings should help mitigate the temperature differential a little.


Regards,


Bit odd the thicker baseplate versus the thinner faceplate.If you wont to reduce the mass/heat transfer through the entire blank putting the heavier/thicker glass on the bottom is the wrong way to do things.Also I'd be very concerned over the use of different thickness plates from different melt batches,plus the different melt batches of the tubes from a different manufacturer,plus different melt batches within the numerous tubes.Even a slight Cof.of Expansion difference in the glass melt batches will cause a slight distortion in various areas of the glass as it expands/contracts.Don't expect anything better than 1/2 wave on the surface from this type.

Ric

#30 Zoomit

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Posted 06 December 2013 - 01:52 PM

A few things I noticed:

//cut//

--curved focuser board. I don't know why no one else thought of this. It really improves the rigidity of the focuser mount.

//cut//


Agreed Don. Hopefully the upper truss, focuser board, and focuser can handle the off-axis weight of a binoviewer and a set of eyepieces without bending out of collimation. I suspect that that's a design case that some dob manufacturers may not adequately consider.

I don't care how heavy or light it is if it can't stay collimated.

#31 hbanich

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Posted 06 December 2013 - 04:16 PM

A few things I noticed:

//cut//

--curved focuser board. I don't know why no one else thought of this. It really improves the rigidity of the focuser mount.

//cut//


Agreed Don. Hopefully the upper truss, focuser board, and focuser can handle the off-axis weight of a binoviewer and a set of eyepieces without bending out of collimation. I suspect that that's a design case that some dob manufacturers may not adequately consider.

I don't care how heavy or light it is if it can't stay collimated.


Obsession has used curved focuser boards since 1989, so this isn't new, but it is difficult to do properly. Curving a flat piece of wood needs moisture and pressure, and if you observe in a moist climate the curved board can start to warp.

#32 Starman1

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Posted 06 December 2013 - 04:26 PM

A few things I noticed:

//cut//

--curved focuser board. I don't know why no one else thought of this. It really improves the rigidity of the focuser mount.

//cut//


Agreed Don. Hopefully the upper truss, focuser board, and focuser can handle the off-axis weight of a binoviewer and a set of eyepieces without bending out of collimation. I suspect that that's a design case that some dob manufacturers may not adequately consider.

I don't care how heavy or light it is if it can't stay collimated.


Obsession has used curved focuser boards since 1989, so this isn't new, but it is difficult to do properly. Curving a flat piece of wood needs moisture and pressure, and if you observe in a moist climate the curved board can start to warp.

The SW appeared to be aluminum plate, hollowed out and with a criss-cross web pattern on the back. There may be flex at the upper ring, but that plate isn't going to budge. Or warp.

#33 Zoomit

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Posted 06 December 2013 - 04:38 PM

A few things I noticed:

//cut//

--curved focuser board. I don't know why no one else thought of this. It really improves the rigidity of the focuser mount.

//cut//


Agreed Don. Hopefully the upper truss, focuser board, and focuser can handle the off-axis weight of a binoviewer and a set of eyepieces without bending out of collimation. I suspect that that's a design case that some dob manufacturers may not adequately consider.

I don't care how heavy or light it is if it can't stay collimated.


Obsession has used curved focuser boards since 1989, so this isn't new, but it is difficult to do properly. Curving a flat piece of wood needs moisture and pressure, and if you observe in a moist climate the curved board can start to warp.

The SW appeared to be aluminum plate, hollowed out and with a criss-cross web pattern on the back. There may be flex at the upper ring, but that plate isn't going to budge. Or warp.


Sounds robust (and done right). If the focuser is equally robust, then I'd only be concerned about the upper ring and how rigidly the focuser plate is attached to it. From the pictures, it looks like the focuser board is cantilevered downward from the ring. That's not a promising configuration to keep a binoviewer from deforming the upper ring when the scope it pointed up and the ring is under a torsional load.

#34 Solar Ken

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Posted 06 December 2013 - 05:51 PM

It would be nice to have an alternative to the Obsession.

bob


Why do you say that? Just curious...

#35 AcTrust

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Posted 08 December 2013 - 05:20 PM

I am very happy to see this from Skywatcher. It means the company is doing well and is dynamic. Trying to become better through challenge and change. I am a little worried about buying a first gen model as with any product but I agree and think it's nice to see a scope aimed directly at potential Obsession buyers. Competitive products usually means a better product for a cheaper price.

Either way it's pretty cool to see! Good stuff Skywatcher just don't use those silly focusers with the adapters for 2" EPs lol.

#36 jonstarrysky

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Posted 09 December 2013 - 12:00 PM

Looks a bit like what Orion did a few years back. Difference is Orion seem to have made a school boy error (units mixed up ?) and bizarrely ended up with a 50" dob, like that is the logical step up from 14". Looks like SW are closer to the mark with this one.

#37 Pinbout

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Posted 09 December 2013 - 06:55 PM

Orions 14 was a hubble optics scope
Orions 50monster was a norman fullum scope.

#38 skyward_eyes

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Posted 18 December 2013 - 05:37 PM

I know everyone was going back and forth about the weight, so reweighed the prototype. Now this is without a finder, eyepiece and counter weights.

Telescope weight with optics is 113 pounds fully assembled.

#39 gene 4181

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Posted 18 December 2013 - 05:55 PM

i 'm sorry about going off topic, but it would be nice to see all the other skywatcher scopes available here in the states, eg., maks, mak-newts and eq . mounted newts. ?

#40 Galicapernistein

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Posted 19 December 2013 - 03:16 PM

Mass produced dobs in the 8-16" range are (usually) at least 50% cheaper than the premium brands. That assumes a mirror not made to the stringent standards of higher priced scopes, but good enough for many. The question is whether an 18" scope can achieve the price savings of being mass produced, if there is such a thing as an 18" scope that can be mass produced. I doubt that the new Skywatcher can be sold for 50% less than a premium brand simply because it doesn't seem that the sales numbers would allow that, although I could be wrong. If the price is too high many people may opt to pay the difference to get a higher end scope. Of course, that's assuming the new Skywatcher is going to be sold as a cheaper alternative to the premium brands. It may turn out to be a competitor for the premium ultra compact models. Whatever kind of scope it turns out to be, I'm sure it's going to generate alot of interest.

#41 dvb

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Posted 19 December 2013 - 04:36 PM

Looks a bit like what Orion did a few years back. Difference is Orion seem to have made a school boy error (units mixed up ?) and bizarrely ended up with a 50" dob, like that is the logical step up from 14". Looks like SW are closer to the mark with this one.


That is hilarious! If conceived in centimeters, but developed in inches, a 50cm (20") would result in a 50" ! :lol:

#42 skyward_eyes

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Posted 19 December 2013 - 04:45 PM

I believe the 18" will be in the ball park of $5000 somewhere in there. There are plans to have a GoTo system for the 18" as well but I dont have any other information regarding this. Once we finish the 18" we will move onto the 20" model. We already have a mirror blank for the 20 as well.

#43 Cabrillas

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Posted 20 December 2013 - 06:53 AM

Looks VERY interesting, but a bit big, too. Any hope to see a 16"?

#44 skyward_eyes

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Posted 20 December 2013 - 09:10 AM

I would personally like to see our 16" redone to the lighter weight design. While the collapsible version is good, its just too heavy. If anything happens with the 16" it will probably be after the 18" and 20" models are done.

#45 JosephR

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Posted 20 December 2013 - 02:07 PM

It would be an improvement if the just the base for the "collapsible" scopes could be lighter and more compact, even if the OTA was the same.

#46 skyward_eyes

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Posted 20 December 2013 - 11:54 PM

The bases on the 14" and 16" break down for this reason.

#47 JosephR

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Posted 23 December 2013 - 08:34 AM

A base that breaks down is helpful, but it would be better to have a square base that could fit in a smaller car without having to take it apart each time.






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