Revelation 16" Dobsonian

[russ.will]

Now, these look interesting:

http://www.telescopehouse.com/acatalog/info%2dBC192%2ehtml

Russell

Sent from my iPad using Tapatalk HD using chubby fingers. Sorry.

[knobby]

Mmmmm liking that

[swamp thing]

I thought these were discontinued Russ.

[John]

These have been around for a while - now being branded Revelation obviously. 1/12 wave RMS = 1/4 wave PV. A bit misleading perhaps ?

I thought TH had put a stop to all that with the last Revelation dobs they sold.

Still, a 1/4 wave PV 16" for £1.5K is not bad.

[Mark at Beaufort]

I think that these are a new design and cover a 10", 12" and the 16" truss mentioned in this thread. Telescope House intend displaying these new scopes at the IAS festival on the 17th/18th May at Leamington Spa.

The cost at £1520 for a 16" scope looks very reasonable compared to the Skywatcher at £1750 and the Lightbridge at £2000. I wonder how good its going to be.

Mark

[John]

I don't think it's a new design. This review is from 2008:

http://www.cloudynights.com/item.php?item_id=1817

[Mark at Beaufort]

I don't think it's a new design. This review is from 2008:

http://www.cloudynig...hp?item_id=1817

That is a brilliant find John. From the email that I received from TH it stated 'the new Revelation 16" Dob' - but as you say John it looks identical. Notwithstanding I still fancy having a look at the display model at IAS later in the month.

Mark

[John]

The 10" and 12" look like the same ones they were selling a couple of years back. Made by GSO I think and also available under a number of other brand names around the world. Same optics and mirror cells as the Meade Lightbridges.

There is nothing wrong with these scopes (as long as the mirrors are properly overcoated now) but it's a bit of a cheek to imply that are "new" and rather misleading to state "1/12 wave" without qualification, in my opinion.

[russ.will]

I'm not commenting on the optical quality, one way or the other - Merely that I hadn't seen the truss tube format from GSO before. Of course, I'm not claiming to have an all-seeing-eye in that regard either.

I think there has been a lot said about the 'average' far eastern mirror sets and the likelyhood of your set, approaching the manufacturers claims. All I can say is that my 200p was superb, whilst my 300p has yet to deliver anything like the detailed views of the smaller scope. 12" should deliver a munificent advantage. Despite employing a lot of technilogical methods to ensure the absolute collimation of the 300p, I've still yet to see the crisp views my cheshire collimated 200p delivered, with nowt more than an occasional tweak. SW=Highly variable.

As such, I've often wondered if the fact that GSO are bold enough to claim 1/4 wave PV, means they're confident in the minimum quality of their mirrors? After a year with the 300p, I'm not sure I would claim much about the optical quality, but the mechanicals definitely are, for a word, laughable.

So, I'm finding a lot to like in terms of the mechanicals GSO employ. Their bearings seem to make SW (and Meade for that matter) look low rent. The Alt bearing, in particular, looks like mana for somebody with a 6mm BGO at one end of his collection and a 30mm ES82 hand grenade at the other.

Russell

[John]

Here is the scope on the GSO website:

http://www.gs-telesc...tent.asp?id=113

Telescope Services sell the 10" and 12" solid tube ones and just claim that they are "diffraction limited". 1/4 wave will make that standard.

Personally I'd be much more confident about the consistency Synta / Skywatcher mirror quality than GSO both from reports I've read over the years and my own experience of both brands (2 GSO dobs and 3 Skywatcher dobs / newts) although there will be variation in both brands of course.

It's a bit harsh to claim "SW = Highly Variable" from your single example I feel Russell !.

I don't think GSO or anyone else mention 1/4 wave PV because it's not "sexy" enough. 1/12 wave with no qualification is likely to catch the eye more my rather cynical mind suggests

Hey ho it's all just a hobby anyway

[estwing]

looks a bargin to a beginner...and of course the price of these coming down is welcome,as for mirror quality..i'm not gonna get into that,just remember what happend with Mike73's campus mirror tho to be fair it was all sorted in the end..(hope mikes ok not been on here in ages?)

[swamp thing]

As such, I've often wondered if the fact that GSO are bold enough to claim 1/4 wave PV, means they're confident in the minimum quality of their mirrors? After a year with the 300p, I'm not sure I would claim much about the optical quality, but the mechanicals definitely are, for a word, laughable.

Russell

What makes you say that about the mechanics Russell?

[Stargazer_00]

that base doesnt deconstruct on this 'rev. Id expect that'd make moving it around a bit more difficult than the skywatcher equivalents which have deconstructable bases.

[cotterless45]

The solid tube 12" for £686 looks value.

I'm looking , but got this allergy to paying vat or much tax at all,

Nick.

[russ.will]

It's a bit harsh to claim "SW = Highly Variable" from your single example I feel Russell !

John, I hope you're right, but my own personal experience of two SW Newts has delivered experiences occupying two polar opposites. It could be that within the QC limits, I got one real goodun and one real duffun, but I've not totally given up hope on the Dob yet.

What makes you say that about the mechanics Russell?

I suppose it's the fact that every SW product that I've owned (EPs aside) has required a rebuild before it's worked even close to adverised. I know out of the box collimation is a non starter, but the 200p was so far out of adjustment, without any screws being loose, it's clear that they aren't checked to even a rudimentary level at the factory.

The HEQ5 was over tight in declination (counterweight collar done up too tight) whilst simultaneously having a large amount of slack due to very poor worm gear setting. RA was just slack full stop. The polar scope was practically adjusted all the way to one side of it's range.

The main drive gear on the base board of the Dob wasn't even approximately concentric with the Azimuth axis. I had to remount it, as the motor almost ground to a halt over 60deg of it's travel. Having done that, there's still so much slack in the drivetrain (on both axis) that you can move an object virtually across the entire field of an 18mm 82deg EP. The Goto is hopeless unless you have set the clutch tension within a 1/8th turn of a locknut and even then, I swear that correct tension changes with temperature. And would it be too much to ask for adjustable feet, on a system that mandates absolute levelling for rudimentary goto accuracy?

All the SW focusers I've had (three), have needed considerable adjustment from new. The 200p would actually fall to it's endstop under the weight of the standard 25mm EP and trinket barlow. To be fair, the WO Zenithstar crayford was worse in terms of lateral play, so it's not just SW.

To be fair, you are getting a lot of scope/mount potential for your money. However, I do wonder how many new entrants to the hobby, just leave because they lack the mechanical nouse/DIY ability to make it all work as advertised. I mean, there's quite a learning curve with your first scope, without having to fight SW's QC too. A four month wait for a new motherboard seemed a bit off too, as OVL don't stock them, inspite of it being the same motherboard on all SW Auto/Goto Dobs.

This could all be coincidence and/or bad luck (and I accept the statistically insufficient population of my sample) but the Bresser has worked like a charm out of the box, banging subjects into the central 50% of the FOV of an 11mm EP since the first day of use. No tight spots, no slack and the polar scope barely needed a tickle for perfect alignment. Quite the opposite of my expectations, considering the Meade reputation for these sort of issues.

Russell

[John]

I think all the dob's I've owned (Skywatcher, Meade and Orion Optics) have needed some improvement here and there to get them working well. The Meade Lightbridge needed the most - stronger collimation springs on the primary cell, a replacement finder and a light shroud were essential really.

I think refractors are generally more "plug and play" out of the box although again the Meade / Bresser ones were where I experienced the most variance with the older Bresser 127L (bought from an SGL member) being very good optically wheras a later Meade AR5 LXD75 (identical to the Bresser) was very optically mediocre even when collimated accurately.

On the other hand, that 16" scopes are available at all for well under £2K is pretty amazing

My only real issues with these 16" Revelations were the rather vague "1/12th wave" claim and that they were new models.

On a more mundane point, how would one fit a light shroud around a 3-pole truss-type design ?. I guess stiffeners will be needed within the shroud to keep it out of the light path.

[russ.will]

On a more mundane point, how would one fit a light shroud around a 3-pole truss-type design ?. I guess stiffeners will be needed within the shroud to keep it out of the light path.

That's easy - You stand on the shoulders of giants, just like I did:

http://stargazerslounge.com/topic/171204-diy-12-flextube-truss-shroud-mk-ii/

I think I blew £50 odd, looking for an intelligent solution that would be the saviour of the world in general (and therefore worth the expense) before that was pointed out to me. I blame the forum search facility, which is worse than a Google search at returning a partial positive hit on this forum. That's my excuse and I'm sticking to it!

I take your point regarding SW scopes, but I think I'm not alone (Sarah - Swag? is another) in having had enough of SW in general.

My next scope is probably going to be a short tube frac for wide field DSO, but there isn't a cat in hells chance it will be the stock solution of an SW ED80. The most parroted quality of the ED80 is that it has an FLP-53 crown element, but who knows what flint, or indeed the figure of either, nor the sample variability? Now, it may be a good combo, reliable for it's results, but the next most common thread is based upon it's owners spending £200-300 on a replacement focuser that won't hold an EOS 450d at Zenith. Regardless of the optics, the focuser is junk. My WO 80 EDII left as quickly as it came for the same reason, so again, SW are not alone, but they seem to straddle a wider sphere, with repeatedly similar issues.

At the end of the day, I'm also aware of another very important factor. I'm lucky enough to be able to buy something more expensive if I want to. Many others aren't and for them, the price is doing battle with what they can afford. Indeed, we're in an amazing situation compared to even ten years ago in terms of choice at all price and quality levels - The boundaries have never been more blurred, with more opportunity for those on a budget to attain amazing results, when armed with a bit of resilient ingenuity. You can't knock that, in any way shape or form, but my personal stance is that I can afford not to take the risk. I won't be buying SW again.

Now there's a petard to get hoisted by and you CAN quote me!

Russell

Sent from my iPad using Tapatalk HD using chubby fingers. Sorry.

[John]

No problem Russell - hope you find something really nice

I think the "other" element in the Skywatcher ED's is a Schott glass but I don't know which type. A number of brands use the same optics that Synta do though so be sure to avoid those if you want to steer clear of anything Skywatcher related.

Personally I've thought the optics on the Synta ED's that I've owned (I think I've had 5 in all) excellent for their cost. The build of their tubes / focusers etc is nothing special though I'd agree with that.

This is all very off topic from the GSO / Revelation 16" F/4.5 dob though so we can save it for another thread

[swamp thing]

Sorry John that was probably my fault for asking the question.

Thanks for your explanation Russell

I look forward to seeing one of these Revelations in the flesh at some point. Hopefully TH will have one in their showroom.

[russ.will]

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Sorry John that was probably my fault for asking the question.

Thanks for your explanation Russell

I look forward to seeing one of these Revelations in the flesh at some point. Hopefully TH will have one in their showroom.

I am as prone to the next bloke when it comes to wandering off topic. On that basis, I'm not about to complain, especially given that my subtext was that this is a SW alternative. As the OP, please feel free to wander, subject to Mod approval, of course!

Russell

[russ.will]

No problem Russell - hope you find something really nice

Your avatar appears to be standing next to it..

Russell

[Moonshane]

this does look to be a great buy at the price stated. personally, I am not a fan of the three truss scope although I have never used one and they may be fine. logically, it seems less structurally robust than the 8 pole, four point fixing.

[estwing]

can't for the life of me understand why there not four poles on these things..oh well

[russ.will]

Given that the poles are captive and they, plus the associated fixings, are heavy, three poles is the minimum number for a rigid structure that minimizes weight.

Russell

[swamp thing]

Personally I don't see the point in captive poles on a scope of this size. You want the scope to disassemble into manageable parts not be left with an enormous OTA that is hard to lift onto the rocker.

I just don't get it.