Truss vs Solid DOB

[gdheib0430]

Wondering if a truss 200mm dob would be better than a 200mm solid tube as far as LP and dew are concerned. I am in NC, USA and we usually are around 70% humidity in the winter and 98% in the spring and summers so dew is probably a battle here...Wondering if the truss system will give me any other benifits over the solid tube. I am seeing the truss is slightly lighter but I am a strong lad so weight isn't an issue considering they are both 8" anyway.

Probably the only difference is the main mirror...the truss is a skywatcher 200 dob and the solid tube is Orion. They are both pretty much the same price so just wondering what everyone's thoughts are on the matter.

[kniclander]

I would think that as far as LP is concerned, the solid tube would be better and possibly for dew too). IMHO the only real benefit of a truss is it requires slightly less space for storage and transport.

[John]

I don't think there are any advantages to the truss design until you reach an aperture of 12" or more.

[sunshine185]

Was told by the shop that a truss weighs more than a solid tube, but I a not totally sure. had a few nights where the dew was horrendous, outside of the 8inch dob was soaked, but the mirrors seemed fine, was imposible to use the 2 inch 42mm ep though.

[johninderby]

The truss does weigh a little bit more than the solid tube (a couple of pounds). The truss mechanism is heavier than the length of tube it replaces.

John

[John]

The Skywatcher Flextubes do weigh a little more than the solid tube versions. If you keep your eyepieces a little warmer than the outside temp then it should reduce dewing / fogging issues with them.

Edit: Beat me to it John

[Chris H]

Skywatcher and Orion (USA) are both owned by the parent company Synta so the mirrors would be exactly the same.

[RikM]

Haven't had a problem with dew with the solid tube Dob, though I do have a 15" long dew shield fitted on the front.

[gdheib0430]

So basically I am looking at storage capacity with the different DOBs...the truss will be a bit smaller for storage but everything else has it's own way of minimizing dew on the mirrors...good stuff guys thanks for all the input will be talking to the significant other to decide which one to get

[osbourne one-nil]

I've got a 10" truss that weighs less than 10kg and have never, ever had a problem with dew on it. Perhaps it's because there's nothing in the way of the primary reaching equilibrium? I'm not sure, but never caused me any problems, and I observe underwater in Cumbria.

[WayBig]

If you buy or make a shroud for the truss section (i've heard that weed suppressing fabric from garden centres works well) then the light pollution and dewing performance should be very similar

[ollypenrice]

In the big ones the problem with solid tubes is cooldown. The big Sonatube cardboard Meades and others were terrors for this. In smaller sizes I doubt this applies.

Olly