Cheap 16" Dob alert

[laser_jock99]

http://www.telescopehouse.com/acatalog/Revelation-16---f-4.5-M-CRF-Truss-Dobsonian--Black-.html?utm_source=Telescope+House+Newsletter&utm_campaign=18bd6e9943-Revelation_16_inch_Pricecrash_9_19_2013&utm_medium=email&utm_term=0_2ccd288edb-18bd6e9943-29639249&mc_cid=18bd6e9943&mc_eid=673c0e3f03

Seems like a reasonable offer for such a big scope?

[estwing]

still not convinced...that 3 pole system just doesn't wash with me i'm afraid

[oldfruit]

Does anyone actually have one of these or know someone that has?

[laser_jock99]

still not convinced...that 3 pole system just doesn't wash with me i'm afraid

Can't personally comment on the design- but it was £1550 when I last looked into these. Full discussion here:

http://stargazerslounge.com/topic/185032-revelation-16-dobsonian/

[Moonshane]

it's a lot of scope for the money but why oh why do they insist on those (possibly expensive) machined tiny metal alt bearing systems.

[scarp15]

According to the email received, promoting this, there will be a full review in the October edition of Sky at Night Magazine.

[oldfruit]

it's a lot of scope for the money but why oh why do they insist on those (possibly expensive) machined tiny metal alt bearing systems.

I have those same bearings on my 12 inch revelation dob, whilst myself and others agree that they work well on my scope I am unsure as to how well they would cope on a scope of that size? I am assuming that the bearings are the same size as they look a lot smaller on the 16 when compared to the 12?

[John]

According to the email received, promoting this, there will be a full review in the October edition of Sky at Night Magazine.

There is - I read it this morning. It's not a bad review overall and the scope gets 4 out of 5 stars. It's not in depth though and I sensed that the reviewer(s) had some slight reservations with the optical performance for planetary viewing. Still, thats not what a scope like this is really about I guess.

[oldfruit]

Having read the other threads that have the links provided above, I have to ask myself a few things. There seems to have been a lot of speculation as to the quality of mirrors supplied in Revelation scopes, especially older ones. Is that making people wary?

Some have questioned the 3 truss design, though I would have thought that some thought had gone into the design of this scope beforehand?

Is it really a case of people waiting for someone else to buy one first and post a review to see how good or bad the scope is before they are willing to part with that sort of cash?

Are the above reasons a contributory factor to the price reduction?

I can honestly say that I am guilty of at least 2 of the points made above as I always do some research and read as many reviews as possible when considering a purchase. Naturally I tend to be cautious and go with the majority views on a product.

[oldfruit]

There is - I read it this morning. It's not a bad review overall and the scope gets 4 out of 5 stars. It's not in depth though and I sensed that the reviewer(s) had some slight reservations with the optical performance for planetary viewing. Still, thats not what a scope like this is really about I guess.

Too true, if I bought a scope like this it would be straight to our dark site to see some structure in the dso`s and tick a few more off the list. Whilst it is great looking at the planets, dso`s (and great ones within the reach of this scope) are far more numerous.

[Optical Dob]

The scopes three struts seem solid to me when I moved it. The alt bearing adjusters are plastic not machined metal and they are a bit bigger than they look in the picture. The scope glides fine on the base and the twin speed focuser is in the right position. 

Telescope house have one in their shop, and no I haven't got one 

[estwing]

it moved ok at the sussex astro fest...

[John]

A more in depth review of this scope (or what certainly looks like it) was posted on the Cloudynights forum over 5 years ago so it's not really a "new kid on the block". The price back then seemed to be around £1,600 whereas you can have it now for £1,300 with the reduction:

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

I hope they have upgraded the primary collimation springs now !

[crashtestdummy]

Have looked at the sky at night review and from the pictures I can quite safely say the base excluding the alt bearing arrangement and truss poles is exactly the same as my 16" lightbridge.I would assume the optics are the same too.the top tube spider layout and secondary support are the same as the lightbridge too.

[scarp15]

I made an enquiry about this scope a few weeks ago, mainly to account for how portable it might be and also concerning a shroud.

I believe that the diameter of the base is around 85cm and height is 70cm. The primary section will sit inside this, with 12-15cm pocking out the top, when this section is located on its altitude bearings. It can however sit inside the base, without being attached to the altitude bearings, provided it is packaged well.

Whilst the primary and base are heavy but manageable by one person if handled individually, the secondary tube and poles are very manageable in terms of weight. The GSO mirrors are similar to the Lightbridge. There is no commercially available shroud as yet, so it would involve making one i.e. with a blackout material tube with three loops for securing to the location knobs at the top of the trusses. The retailer - Telescope House, did indicate however that in the fullness of time they may provide their own commercially available shroud for this scope.

[Laurie61]

It does look good value, to put it into perspective Oldham Optical have a 16" mirror with secondary retailing for £1782 (f5) or £2020 for the f4.4 version. Orion Optics are currently selling there 400mm 1/4 wave sets (f4) for £1515. So you could argue you are getting the rest of the scope for free, which is nice   I am waiting for the 18" version     

[emadmoussa]

All this and I'm just thinking how on earth you're going to manage such a telescope...

[Bart]

I believe this is a version of the GSO 16". I enquired about the GSO version in TS as I had bought my 10" GSO from them and still love it. The alt/az movement is just beautiful. They stated they were discontinuing the GSO 16" as they believed the three pole truss design affected collimation. Went for the LB in the end as a result.

Barry

[crashtestdummy]

I had heard the same collimation woes about the gso 16"so maybe they have bought the design?

[pete_l]

There is - I read it [ October edition of Sky at Night Magazine ] this morning. It's not a bad review overall and the scope gets 4 out of 5 stars. It's not in depth though and I sensed that the reviewer(s) had some slight reservations with the optical performance for planetary viewing. Still, thats not what a scope like this is really about I guess.

Hmmm, Normally their reviews are so vague and wishy-washy that I'd never base a buying decision on them.

However in this case I'm willing to make an exception . The article they said that the 3 struts weren't as sturdy as a normal 8-struct construction and caused the collimation to change as you move the telescope up or down. They also said the bearings were small (leading to instability) and the Az. bearing moves too easily. Add to that, that the PTFE pads don't actually touch the base  and finally that the mirror was over-corrected. Yet it STILL got an overall 4 stars. I guess the editors are too scared of Telescope House pulling their product advertising and not sending anything else for review, for the magazine to come out with a verdict that matches the words.

(I wonder what the reviewer actually wrote, before the editors got to work on it?   )

[Moonshane]

in fairness, the struts do look quite sturdy and there are a number of reasons why collimation can shift through the motion, especially at this aperture - secondary vanes may need tensioning a bit more, mirror movement at the primary end either laterally or horizontally, and of course strut 'bending'. personally, looking at the struts,  I suspect that the last one is the least likely of these four.

[John]

GSO primary mirror cells tend to have some "flex" in them and they do have a history of using inadequate primary collimation springs. 

Neither of these things are showstoppers as long as the owner is happy to do a bit of modding, which is always the case with dobs anyway.

My biggest concern with these would be getting a poor quality mirror - 1/4 wave PV or better would be fine at this price but I've seen a worrying number of reports of GSO mirrors that are substantially less than this.

After all, at this price most of what you are paying for is the primary mirror.