16" Lightbridges are here!

[h0ughy (David)]

they do look nice - - so who will be giving the first light reports?

[rockit]

Oh, it's the same focal length as a 12" f6. Don't know exactly but by saving the extra weight would there be any advantage to a f6 12" compared to f4.5 16". I realise size is king, but it is only +0.5 magnitude increase/ is it not? The reason behind this is I am thinking of well into the future when I get my mirror re figured, I might change it's focal ratio.

[Satchmo]

Originally Posted by anthony2302749

Yep, the inner triangle supports are in the wrong orientation.

No, the triangles are correct for 27 point. The 9 triangles would *normally* be mounted on the apexes of three large triangles which would in turn connect to three collimation bolts in a back plate. By ommitting this 3 triangle layer in the 16" Lightbridge, any micro twisting of the back plate under load at different altitude is transmitted direct to the mirror , nor is mirror sag compensated for if the backplate yields to the changing loads. In a correct 27 point floatation system, a deformation of the rear plate will only cause a slight mis -collimation tilt of a well floated thin mirror, but no deformation of it.

This is a clear example of the compromise that must be expected in such a package at that price. 12" is probably the cut off point at which you can 'get away ' with a lot more , regards mirror material and mounting technology, particularly as mirror flexure goes up by the cube of the aperture, given constant thickness ratio. So just urging some realism in your expectations as always.

[merlin8r]

Originally Posted by Mark Suchting

No, the triangles are correct for 27 point. The 9 triangles would *normally* be mounted on the apexes of three large triangles which would in turn connect to three collimation bolts in a back plate. By ommitting this 3 triangle layer in the 16" Lightbridge, any micro twisting of the back plate under load at different altitude is transmitted direct to the mirror , nor is mirror sag compensated for if the backplate yields to the changing loads. In a correct 27 point floatation system, a deformation of the rear plate will only cause a slight mis -collimation tilt of a well floated thin mirror, but no deformation of it.

This is a clear example of the compromise that must be expected in such a package at that price. 12" is probably the cut off point at which you can 'get away ' with a lot more , regards mirror material and mounting technology, particularly as mirror flexure goes up by the cube of the aperture, given constant thickness ratio. So just urging some realism about these things as always.

And in a perfect world we would all own 20" RCOS scopes. It IS a price point. A 16" scope at an affordable price.

[Satchmo]

Originally Posted by merlin8r

And in a perfect world we would all own 20" RCOS scopes. It IS a price point. A 16" scope at an affordable price.

A true floatation cell is not just the domain of $100,000 professional scopes. Its the domain of the majority of home built and commercial dobsonians.

I would expect the material to do the job properly would be worth a *few dollars* extra Any low cost or fancy home built dob would have a properly designed floatation cell because it is only a few minutes work, and the techniques are well known.

When you buy your low cost mass produced scope, you don't have choices about how things were done, so enjoy, but don't expect some of the things were done to make technical or economic sense .

Anyway I'm sure a cell improvement will appear as an after market `mod' in no time

[rmcpb (Rob)]

If the mirror mount problems become significant then setting up a proper 27 point system should be not out of the question BUT it will need a new cell and longer truss poles as the mirror will sit further up the "tube/bucket".

Still, for less than $3k and getting a 16" scope its not too bad at all.

[skies2clear]

Originally Posted by merlin8r

And in a perfect world we would all own 20" RCOS scopes. It IS a price point. A 16" scope at an affordable price.

True, but Marks point is important. This is a serious compromise and I would expect the "basics" to be at least right even in a cheaper scope. The price dictates other compromises (optical quality and glass type for example), but you don't want your mirror bending all over the place making things worse. I'd like to know how much of a problem this ends up being in practice.

I can't help but think Meade would have been better off going for an 18 point flotation than this setup, and I imagine there will be a lot of talk about this problem with plenty of ways/options of addressing/modifying the scope to overcome it.

Just my 2 cents anyway.

Clear skies

[anthony2302749]

Originally Posted by Mark Suchting

No, the triangles are correct for 27 point. The 9 triangles would *normally* be mounted on the apexes of three large triangles which would in turn connect to three collimation bolts in a back plate. By ommitting this 3 triangle layer in the 16" Lightbridge, any micro twisting of the back plate under load at different altitude is transmitted direct to the mirror , nor is mirror sag compensated for if the backplate yields to the changing loads. In a correct 27 point floatation system, a deformation of the rear plate will only cause a slight mis -collimation tilt of a well floated thin mirror, but no deformation of it.

This is a clear example of the compromise that must be expected in such a package at that price. 12" is probably the cut off point at which you can 'get away ' with a lot more , regards mirror material and mounting technology, particularly as mirror flexure goes up by the cube of the aperture, given constant thickness ratio. So just urging some realism in your expectations as always.

Cool, missed by that much!

[Starkler (Geoff)]

Speaking of things bending, the rocker box material looks pretty damn thin. I think one of the first mods would have to be stiffening ribs.

Seems like i lost the race. I ordered my 15" SDM truss dob back in early November thinking I could have it before the LB became available. I know that my SDM at a bit over double the price of the LB will be worth waiting for

[rmcpb (Rob)]

Originally Posted by Starkler

I know that my SDM at a bit over double the price of the LB will be worth waiting for

Especially if the mirror is not distorted by the cell Strange that they compromised with their design there. If the mirror was average BUT held its figure then it probably would have been acceptable at the price but when it was distorted by poor design that would have added $20 to the price then that is not really acceptable. A poor choice................

[GrahamL]

well friday and a dark weekend ..takeing her out for a meet and greet anywhere ?...people will make there own judgements soon enough
I guess

[AstroJunk (Jonathan)]

The cell flotation design may not be "old hat" but it has certainly been designed. It would have been a no-brainer for them to use the std design, but instead they have produced a version which seems to maximise airflow for coolling.

Maybe it's poor, mabe it's great. I think we should try the thing before we rubish it!

Dunno why people are lining up wanting it to fail! I want it to be a massive sucess personally. The other lightbridges i've used have been fantastic fun and this should be too.

[gbeal]

Originally Posted by AstroJunk

Dunno why people are lining up wanting it to fail! I want it to be a massive sucess personally. The other lightbridges i've used have been fantastic fun and this should be too.

Well put, I too am amazed by the negative sentiment. It is great to see such affordable and useful scopes out there. Given the most used scope was a homebrew 6" when I started, this availability is a revelation.
I am very happy with my 10" homebrew as most know, but the look of the 12" LB late last year in Bintel Sydney nearly had me swayed.
Sure you might have to tinker slightly to get the best from them, but this is part of the fun, and isn't confined to the LB line. I can think of a very popular GEM or two that are well known for this as well.
Gary

[rmcpb (Rob)]

I don't think we are lining up to see it fail!! We are simply discussing some of the design aspects we have noted. Hopefully they will not make any difference BUT there has to be a reason for everyone else to set up a floating system for their mirrors. As you say, it will be interesting times to see if this system is as efficient at keeping the mirror figure.

What else are we to do until someone gives a first light, ignore the new toy????

[Satchmo]

Originally Posted by AstroJunk

Dunno why people are lining up wanting it to fail! I want it to be a massive sucess personally. The other lightbridges i've used have been fantastic fun and this should be too.

I simply pointed out the non-flotation `flotation cell' as I 've never seen one before . There is the potential for mirror distortion. We all know a little more about cell design as a result of this thread. Unless we are to not take the scope seriously because it is so cheap, it needs to be scrutinised like any other piece of gear that hits the market.

I would hazard a guess that whatever image quality , or magnification range it was designed to satisfy, it probably does it with knobs on or would not have hit the market. Anything that stimulates the larger end of the telescope market is a good thing.

[merlin8r]

Unfortunately, a $20 cost at the factory does not equate to a $20 price rise at the end market. If we add all the little things up that people would like in their scope (blackened edges at the lips, shrouds, better cells, right angle finder scope etc), pretty soon your $3000 telescope is costing $4000.

Clear skies,
Shane

[toetoe (Peter)]

I look forward to comments like the ones in this post. Weather they are positive or negative they are a wealth of information for people who are new to this hobby and are picking up on things that will increase there knowledge in this field. I must say that the L/Bridge Telescopes are a mighty fine looking piece of gear to me and i would have one in a flash if i was able to. 16" at a affordable price and the portability of the L/Bridge makes it a very attractive investment to some people.

[maksutover]

wow! thats enormous! I just wondering how hard it will be to star hop with that?!? ALso when disassembled does it easily fit into the boot or what ?
I cant imagine how spectacular jupiter will be through that!

[merlin8r]

Originally Posted by maksutover

wow! thats enormous! I just wondering how hard it will be to star hop with that?!? ALso when disassembled does it easily fit into the boot or what ?
I cant imagine how spectacular jupiter will be through that!

For those that need to know:
The scope's shipping box dimensions are (in cm):

101.5 X 62.7 X 62.1

This does not include the base. I dont think people would want to disassemble/reassemble that lol

Clear skies,
Shane

[shredder]

Well I would have to say people seem to be a bit picky on this one... A new scope comes out and all most people seem to do is try and pick the faults???

Anyway I didnt buy one (the 16"), I opted for the smaller 12" LB and its problems are very minor indeed. All this fuss I have seen on posts about the locking bolts, and not bringing the eyepiece to focus, well they must have fixed them cause they dont cause a problem for me.... What does get me about the scope, and I have never seen it mentioned, is the need for an allen key to adjust the finder (try that at night), my $50 Celestron Unit Finder had adjustment knobs.... so should this one.... And just for the record, while I cant speak for the 16" the 12" is a very nice scope indeed!

Anyway I would say the 12 is probably on the limit for a sedan style car for easy transport. Even though it colapses, it is still a big scope, and the 16 is even bigger.