My first truss dobsonian

[osbourne one-nil]

Hello,

How come I didn't find this place sooner? Anyway, I've just ordered my first truss dobsonian; a 10" model with Orion Optics 1/6th mirrors made by Sumerian Optics in the Netherlands, and I wondered if anyone had experience with lightweight truss dobs? I realise they'll have their drawbacks and might require a quick check on collimation during an observing session, but wondered if there's anything I haven't thought about?

I live in a small village in Cumbria which is lucky enough to be located in one of those black sky areas on the light pollution maps. The trouble is, my garden is surrounded by trees and there are about 8 or 9 streetlights visible from it. So to make the most of the dark skies, I wanted something lightweight. Initially, I was going to go with an 80 or 90mm apo on a Portamount, but being used to 8" to 12" dobs, I thought a small refractor just wouldn't cut it. Luckily, someone on Cloudynights pointed me in the direction of Sumerian Optics, and my 10" model weighs in at about 9kg in a package about 15" x 12" x 5". I should be able to haul that the 1/2 mile I need to to get away from any lights.

Any good tips?

[MikeP]

It will be worth getting a shroud. It blocks out unwanted light but more importantly it will help prevent dew forming on your mirrors.

Mike

PS Welcome to SGL

[osbourne one-nil]

Thanks Mike,

I'm hoping where I'll be observing will be free from any artificial light, but the point about dew is a good one; I wondered how prone this might be to dew. The secondary comes with a heater. Perhaps I'll need to add one for the primary?

Also, in the field at night, is the best way to collimate simply to do a star test, or would a laser collimator be better and quicker?

[MikeP]

Mines a Skywatcher flextube so the primary is enclosed. It does dew up eventually but long after the secondary does. You should be fine with just a shroud.

I used to use a secondary heater but found that with a shroud and also a dew shield (rolled up camping mat held in place with a bungee cord), it wasn't necessary.

It takes me less than 5 minutes to collimate with a laser and is dead easy - I normally do it while I'm waiting for it to get fully dark - don't waste observing time that way and I find it easier to see the return dot on the collimator (Baader).

Mike

[osbourne one-nil]

Thanks again Mike. I think while the scope is being made, I'll order myself a nice new Hyperion 31mm eyepiece and a laser collimator. The shroud will have to wait until I get the scope I think, but I imagine some blackout blind material and a bit of velcro should suffice?

[MikeP]

The wife of another SGL member made the one I use. It is made from thin black fleecy stuff that I think gardeners use (not the coarse landscaping material). It is held in place with velcro and a pull cord at the top and bottom. My Flextube only has three poles, so there are a couple of stiffeners sewn in to stop it flopping into the light path.

Mike

[Kai]

It was the material you use under gravel to stop plants growing (1 roll did 4 shrouds iirc) and was under a tenner , along with some plastic dowling inserts ,velcro along the length and a toggle.

I think the total cost of materials was around £15.

I think there was a thread i did at the time on here.

[MikeP]

Thanks Steve. Still in use and still works a treat.

Mike