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16" of aperture for £1,172

John

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John

John

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With the Telescope House 10% off deal over the bank holiday weekend, the Revelation 16" dob works out at £1,172 delivered. 

I'm not in the market for a scope of this aperture I ought to add and I know these budget dobs need some modifications to be useful out of the box and I've had some doubts over GSO dobs in the past, but, for a light bucket for DSO's, that seems a lot of scope for the £'s even to me.

The nearest other 16" dob that I can find is the non-GOTO Skywatcher Flextube 16" which is £500 more.

Or is the Revelation likely to be a poor buy even at that low price ?

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Chris

Chris

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Hi John, I've just had a look at the site and can't see where it says 10% off? I had a look at there 'mega deals' and the deal on the 10" f/5 dob looks very good indeed, especially when you read the spec and whats incuded, I'm just wondering whats the catch?

http://www.telescopehouse.com/acatalog/Revelation-10-inch--F5-M-CRF-Premium-Dobsonian--399-Special.html

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Chris

Chris

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The offer is splashed on their home page with the code to use:

http://www.telescopehouse.com/index.html

The 10" Revelation dob is excluded though. No catch as far as I can see. The Revelations have always been very aggressively priced. They have the same optics and mirror cells as the Meade Lightbridge dobs.

Thanks John I don't quite know how I missed that sign its massive :D Good to here about the dob having the same optics and cell as the lightbridge, wasn't sure if it had the same dodgy collimation springs as the GSO's? but then again even if it was it would be a relatively easy fix still well worth it for the price!

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alan potts

alan potts

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I have bought from Telescope House 3 times and since I have been on their Internet mailing list which was after the first time I have received 10% discount even when they do not have any offer.

I think unless you are spend a fairly large amount all telescopes are in need of tweeks here and there. My LX was over 4000 quid and I still found it necessary to spend more to bring it up to where for that money it should have been in the first place.

However if you are in the market for a large dob and I am, it's tempting and in the words of Oscar Wilde "the only way to deal with temptation is to yield to it".

Being a snob I still fancy a Sumerian scope though.

Alan

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Luke

Luke

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I don't know how the manual 16 flextube compares to my 400P goto version, John, but for me the plus points are I am happy with the optics, goto accuracy and that the base breaks down fairly quickly and is then easy enough to move. The minus point is that I find it really awkward to connect the tube to the base.

The tube needs to go on at just the right angle to connect cleanly to the base. If it doesn't, you then have a very heavy tube not connecting and risk breaking the not terribly strong looking connector (perhaps it is meant to break first to prevent damage elsewhere, like the NEQ6 bolts). If two of you put the tube on, you have the problem of trying to act in tandem to make sure it goes down very level on the base. If you do it on your own, it's a very heavy tube, so either way it is awkward.

I wonder what the Revelation is like for connecting? I can't speak highly enough of the little 66mm Revelation refractor I have for the price paid, it's the only refractor I have not replaced the focuser on.

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alan potts

alan potts

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Alan,

I agree the price is excellent and I am sure everybody would love one if they had the spare cash, but is it a good price.

I have problems with what if the person buying is not good at fettling as you call it or they are in the same boat as me and live in the middle of nowhere and don't have help from friends, they would then have a product that they were far from happy with.

I have the same issue with other scopes like those I have bought, only one was in no need of any tickling up and that was the APM. What I would like to see is the likes of SW and the other marketing scopes that do not need rebuilds or parts replacing due to ify quality even if this indeed causes a price increase, which you are going to shell out in the long run and then some.

Yes I think it is a good price but I bet if I bought one I would spend at least another 300-400 quid on it.

Alan.

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Rustysplit

Rustysplit

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I had a look at, not through admittedly, one of these on TH's stand at a show last year. The focuser is good, the action was good in both alt and az. The tensioning system on the alt bearing seemed to work, with some degree of balance adjustment via side bearing placement too. Does it hold collimation well at all elevations? no idea, but the truss attachments seemd rigid enough. I think any buyer would need to be realistic with their expectations, a sumerian it ain't, but I would expect it to be quite useable. TH are a good bunch of guys, It would not be in their interest to sell an unuseable set up and then have to deal with all the fall out. Far rather own a rev at this price than a Lightbridge @ nigh on £2000 :eek:

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John

John

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The Rev dobs have the same mirrors and mirror cells in them that the Lightbridge's do - GSO made.

If I was thinking seriously about one (which I'm not) my main concern would be to get one with a primary that matches the claimed spec of around 1/4 PV (1/12 RMS). If you did then all the other niggles could be sorted in due course. If you were unlucky and got a sub-par mirror then the deal goes sour IMHO.

Alan makes a good point though. Some of the issues that need to be sorted with scopes could be done very easily and cheaply by the manufacturer. It's not as if there isn't enough feedback on them out there on forums like this.  

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alan potts

alan potts

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Alan,

That is of course another advantage you have over me, in so much that you can go and have a look at one and based on what you say it don't sound bad at all.

I also agree TH are a good bunch, I had a good deal of contact with them and they told me they were very hard on the quality control for the new items, this scope being one of the subjects I was talking about at the time. I was told a lot of time was spent making sure things would be right with Revelation equipment and other scopes from GSO.

This was about the time when Meade was in all sorts of choppy water and I think they were trying to land new suppliers but wanted it right.

I wish they had a branch in town here.

Alan

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alan potts

alan potts

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John,

I am not much up on mirrors

This 1/4 PV and then you mention 1/12 RMS, I know your scope is 1/8, is this PV or RMS. Can you just put one of your idiot proof lines together so I can understand the difference as 1/4 to me don't sound too wonderful. Is this why they hide behind the words difraction limited all the time.

Alan

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faulksy

faulksy

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John,

I am not much up on mirrors

This 1/4 PV and then you mention 1/12 RMS, I know your scope is 1/8, is this PV or RMS. Can you just put one of your idiot proof lines together so I can understand the difference as 1/4 to me don't sound too wonderful. Is this why they hide behind the words difraction limited all the time.

Alan

mine is 1/10 alan, and i dont no what it means to be honest, but john and moonshane said it was good so that will do me :smiley:

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John

John

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John,

I am not much up on mirrors

This 1/4 PV and then you mention 1/12 RMS, I know your scope is 1/8, is this PV or RMS. Can you just put one of your idiot proof lines together so I can understand the difference as 1/4 to me don't sound too wonderful. Is this why they hide behind the words difraction limited all the time.

Alan

I'm no expert on it either :undecided:

My basic understanding is that something around 1/4 wave PV / 1/14th RMS is fine for deep sky viewing but for more critical performance on the moon, planets, binary stars etc a more accurately figured and polished mirror is desirable. Most of the chinese dobs would meet this or exceed it a little I reckon. A few lemons might not though. There is also strehl ratio where .82 (1.00 is perfect = all the light goes inside the central ring of the airy disk) is considered diffraction limited.

The primary in my OO 12" is 1/9th wave PV and 1/32nd wave RMS, according to the Zygo report I've got with it. The strehl is reported at .987.

With regard to the 16" Revelation, I thought a decent light bucket for DSO's with a reasonable mirror would be good value for a bit over a grand.

Thats about as far as my knowledge goes. Poor collimation and seeing conditions can render a wonderful mirror rather impotent of course. Not that any of our scopes are out of collimation or the seeing conditions less than perfect of course  :rolleyes2:

This is a useful article I think which I can just about get my head round:

http://www.nicholoptical.co.uk/Optical%20Standards.pdf

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AlexB67

AlexB67

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also to add the streyl reading or what ever was is 0.992. same that no idea

That means it is really good you can be rest assured. :grin: The Chinese ones are more in the 0.8x range I believe. The PV rating can as such be a bit useless, as such it says nothing about the average variation of the mirror performance, hence RMS  ( an averaged measure ), and better still Strehl that says something about the mirror as a  whole.

In a very simple rules, higher strehl =  better mirror, 1 / X RMS, the bigger X the better. Of course than you have your nice Hilux coatings as well  for enhanced reflectivity. 

Mike, you have one cracking scope and it makes me drool.

Some good reading on the topic here without getting mathematically involved.

http://www.rfroyce.com/standards.htm

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