Skywatcher truss tube Dobs

[WynneP (Peter)]

Anyone had much experience with these?
How well do they hold collimation during transport? Do they come with covers for the two optical sections so that they can be safely transported (dust excluded etc)? How quickly can they be put into use, in reality?
What is the consensus - solid tube or truss tube.

Would appreciate any opinions.
Thanks, Peter

[AG Hybrid (Adrian)]

I can say they don't hold primary mirror colimation well because the mirror cell is support by ****, flimsy springs.

If you get one. Replace the mirror springs with something beefier like a compression springs from Bunnings. You'll have to grind them in half so they will fit back in the cell. The goal is to get springs strong enough so that you can throw away the locking screws in the mirror cell and just use the tension of those springs to hold the mirror cell in place.

Collimation is then easy. You tighten up the collimation bolts all the way the first time. Then collimate the primary by loosening each collimation bolt. This technique does push your mirror cell forward.
The good part of this that when you go to setup collimation the next time you use the scope only a very minor adjustment is needed.

Pair that with bobs knobs for the secondary and adding a few milk bottle washers to the mirror/secondary stalk and collimation is an under 60 second job for me even after traveling from Sydney to the Blue Mountains for a dark sky session. Only a couple millimeters of adjustment at there primary mirror is generally needed.

My 12" truss dob folds down to under a meter in length. The original base is heavy at over 20 KG. I rebuilt/replaced mine with marine ply. Knocked off about 9 KG. Solid a rock though. Setup is under 10 min - including collimation. Mine only came with 1 dust cap. But a I made another out of plastic that sits practically on top of the primary mirror. - It seems to help.

[gaseous (Patrick)]

They don’t hold collimation all that well, but it should take less than 10 minutes to get one set up and collimated, and regardless of how well they hold collimating, it’s not a bad idea to do it every observing session anyway. I haven’t tried the spring replacement trick, but it sounds good if you’re adept at tinkering. Depending on the size, a plastic shower cap does a good job for a dust cap.