Truss vs standard tube dobsonian

[twinsch]

I'm considering buying a 12+" dob and I'm seeing a lot of truss rod models out there. I understand that their main advantage is portability and a disadvantage is that they cost slightly more. Are there any other differences between truss rod and conventional dobs that I should know about? any advice would be greatly appreciated.

 

[scopenoob]

What's a truss telescope?

 

[bad_drawing]

I have a 10" tube newtonian, and the primary thing that keeps me from lugging it out more than I do is its size and akwardness. It takes two + trips (one for the stand and one for the tube, plus one for the stool and case) As you say I believe that the main advantage of the truss newtonians is portability (which to me is a big advantage.) However, the questions I've always wondered about the truss models: are they more difficult to collimate due to the truss? and what about ambient light and dew on the primary? I imagine they make a cloth skirt or something to block out the ambient light and to act as a dew guard. Soooo basically i'm no help but this thread interests me because I've considered getting one also... either that or a nice portable schmit-cassegrain.

 

[nevers]

I've considered turning my 16" tube dob into a truss for the simple reasons of portability & compactedness (if that's a word!). However, because I live in the desert where it is dusty a lot of the time, I've held off on the thought. Yes, you can get a shroud but people I know who have much larger dobs suggested that I just keep mine as it is because of the ambient light situation. Of course, if you're lucky enough to be able to observe in totally dark locations I can't see where that would be a problem. I have noticed that in windy situations (or let's say breezy instead because who wants to observe when it's downright windy) due to it's weight, my tube design was a little more stable then a truss with a shroud. Also, when I watch truss dob owners setting up their 'scopes, it always freaks me out when they attach the poles - if they slip and drop a pole onto the mirror: ouch! If you get a truss design and think you will do public observing a shroud would be a must - think of all the things that could get dropped on the primary.

 

[jcdenton]

<font color="yellow">Also, when I watch truss dob owners setting up their 'scopes, it always freaks me out when they attach the poles - if they slip and drop a pole onto the mirror: ouch!</font><br /><br />Couldn't you just keep the lid on the primary while attaching the poles and remove it afterward? <div class="Discussion_UserSignature"> </div>

 

[nevers]

I would - but I've seen people who don't. I've seen some mirrors with pretty flimsy covers compared to the size of the poles.

 

[jcdenton]

This may be somewhat off-topic but Meade has now announced a truss dob series of their own. <div class="Discussion_UserSignature"> </div>

 

[nevers]

Hmm - good job! I've been out of the loop lately and had no idea. However, I've always thought that one of the advantages of having a truss tube as we've already discussed it it's portability. It looks like from the picture at the above link they still have a big bulky base and not a nice compact mirror box. It also looks like the primary mirror is located within a section of "tube" that has been cut off and shortened - I don't think it's really a classic truss design. But, they're on the way!

 

[jcdenton]

Yeah, the base of these dobs looks quite large compared to that of the premium dobs, but I suppose making it more compact would need greater craftsmanship and finer materials, which would mean higher costs. Still the thought of getting a 12" transportable scope for such a low price has me interested. I wonder if Meade will go with even higher apertures, and if this kickstarts the market for mass market truss dobs (some competition would be great!). <div class="Discussion_UserSignature"> </div>