Rosenberg hexagonal SCTs

[miketheobscure]

Stumbled on to this link for new hexagonal shaped SCTs coming out of China. Apparently the guy moved from the US to China to build them, hence the very un-Chinese name of Rosenberg Scopes.

The link to scopes on his web page didn't work when I tried it -- emailed him to let him know & he replied in a few minutes so he's responsive! -- but the three pics here are interesting.

http://www.astromart.com/classifieds/details.asp?classified_id=595114#ph otos

Wonder how the shiny flat tube sides go with reflected light? Seems badly under-mounted too (but that's by the by).

- Mike

[erick]

What would be the benefits of a hexagonal tube, apart from the fact it shouldn't roll off the table! :D

I would have thought there were more negatives than positives?

[Wavytone]

The tube assembly is shockingly bad on several scores.

(a) the last photo shows the corrector plate is held by three clips and the front of the tube is open, there is nothing to stop stray light entering between the corrector and the tube, reaching the primary and then the focal plane. The clip visible in the photo is intruding into the light path through the corrector, so expect to see spikes. Secondly it looks a pretty fragile mounting, either likely to misalign during transport or possibly break the corrector if it suffers a high point loading due to a minor bump in transit.

(b) the inside of the tube appears to be highly reflective metal. No thanks.

(c) leaving the hexagonal tube open might help the cool down but its going to collect dust and insects, and the optics are going to get dewy and dirty meaning the coatings won't last long. The sealed tube construction of Meades, Celestrons and Maksutovs is a huge advantage in terms of coating life.

(d) metal tube = expansion problems. Focus will not be stable, thermally.

(e) it is a very very ugly assembly. I wouldn't pay for that.

(f) the corrector looks uncoated.

If he's so mean he can't afford to build a decent cylindrical tube it leaves me wondering what else he has skimped on and how much of it is really true. For example I came across a commercially made scope some years ago which claimed to be a "schmidt cassegrain" but the "corrector" was just plate glass without the schmidt profile to it. Quite a few people shelled out good money for those scopes and were conned.

It's also possible its just a temporary prototype or lashup for testing, and a more appropriate commercial assembly follows later. If thats the case he's doing himself a disservice by showing such rubbish prematurely, far better to show the finished product.

His first name suggests he's really a russki, culturally. Beware.

[Miaplacidus]

Hi Wavy. I think you are too generous giving such a detailed answer.
I would have just said it looks like cr@p.

[Omaroo]

I'm not a big fan of things being different for the sake of being...well...different. If the hexagonal shape was so beneficial over circular in any one major area then maybe there'd be an argument.

I really don't like the cheap adaptation of a newtonian crayford focuser, with its inherent curvature, simply bolted to the flat rear surface.

[netwolf]

Umm I saw this before and back then only one photo was shown this one
http://www.astromart.com/images/classifieds/595000-595999/595114-1.jpg
Can some one please explain how that OTA is balanced on that EQ mount, against what looks like a Sofa???? Who would in there right might lean there Telescope up against a sofa and leave it in such a position. Disturbing that it is stored in this way and my mind cant fathom why it is standing and not fallen over.

[miketheobscure]

Apparently the hexagonal version was indeed a prototype - the guy's emailed me back with some photos of another version which looks more conventional. Looks like a RC, which I would have thought would be harder to make. Quality's somewhat better but not setting me on fire either. Oh well, an interesting diversion from looking at expensive refractors. :)

- Mike

[Ian Robinson]

Checked out their site , they claim "up to 1/60 wavelength accuracy".

mmm....

[miketheobscure]

That's mighty accurate. ;)

OK, seems it could be one for the best not bothered with files. - Mike

[Ian Robinson]

That's what I thought too , now if they said 1/10th wave , I might think they are serious , though 1/6th wave is probably as good as you can get most places.

That page is no longer viewable .... BTW ....

[g__day]

A line from lost is space springs to mind... Warning Will Robinson!

[Ian Robinson]

Check out the Astromart ad :
The classified you requested could not be found.

:lol:

Sounds all a bit dodgey to me.

[TrevorW]

Rosenberg Telescopes the truss you can trust, "trust me my boy"


Dodgy Brothers Inc, Somewhere in China, trusted eBay retailer pay now maybe see scope later!!!

[g__day]

Even on the new model - look at the joins - it looks schoolboy quality.

[Ian Robinson]

Actually , we've absolutely no idea where they are actually are , may not even be anywhere near SE Asia.

[Garyh]

The strange thing is they don`t have any images of there mirrors with test results etc or of there mirror cells and there scope page doesn`t exist with a 404 error. not the best way to launch a new business.

[JethroB76]

His astromart ad says he is in China