Rebuilding my StarFinder

I've got an aging Meade StarFinder 16" dob that finally needs some
reconditioning. I know I'll be rebuilding the rocker box, but I'm
trying to decide on whether or not to convert the thing to a truss
design. The solid Sonotube is still in quite good shape. Having a
solid tube has some advantages - my collimation is stable, the primary
mirror is well guarded from everything, including dew, dropped
objects, and dust, plus my setup time is nearly instantaneous. On the
down side is longer cool-down (though I store it in a garage and could
add fans if I so decided), tube currents, weight, reduced protability,
and issues with sliding so much mass around the azimuth bearing.

Specifically, I'm looking for opinions from those here who have owned
both. Which did you prefer? What else will I lose if I move to a
truss? What else will I gain?

I just had my Starfinder 16" converted to a truss by TScopes and it's
awesome! It went from 170lbs to 85lbs (with the heaviest component being
under 50). The collimation was much better than what I had in the sonotube
although I have to set it up everytime from scratch. The 16" starfinder
comes with a 4" secondary that's just way to big and is on fairly flimsy
spider. I replaced that with a 3.1" secondary and a protostar spider. The
thing is rock solid now. A truss done right is much lighter easier to
transport and easier to cool down (important in the northeast). The
sonotube has it's advantages too, but I think they are far outweighed by
these things.

Mike.


"Bob Beauchaine" wrote in message
om...
I've got an aging Meade StarFinder 16" dob that finally needs some
reconditioning. I know I'll be rebuilding the rocker box, but I'm
trying to decide on whether or not to convert the thing to a truss
design. The solid Sonotube is still in quite good shape. Having a
solid tube has some advantages - my collimation is stable, the primary
mirror is well guarded from everything, including dew, dropped
objects, and dust, plus my setup time is nearly instantaneous. On the
down side is longer cool-down (though I store it in a garage and could
add fans if I so decided), tube currents, weight, reduced protability,
and issues with sliding so much mass around the azimuth bearing.

Specifically, I'm looking for opinions from those here who have owned
both. Which did you prefer? What else will I lose if I move to a
truss? What else will I gain?

On Wed, 04 Aug 2004 21:19:12 GMT, "Mike Fitterman"
wrote:

I just had my Starfinder 16" converted to a truss by TScopes and it's
awesome! It went from 170lbs to 85lbs (with the heaviest component being
under 50). The collimation was much better than what I had in the sonotube
although I have to set it up everytime from scratch. The 16" starfinder
comes with a 4" secondary that's just way to big and is on fairly flimsy
spider. I replaced that with a 3.1" secondary and a protostar spider. The
thing is rock solid now. A truss done right is much lighter easier to
transport and easier to cool down (important in the northeast). The
sonotube has it's advantages too, but I think they are far outweighed by
these things.

Mike.

Yeah, I tackled the spider problem a while ago when I inserted strap
steel around the inner diameter of the tube where the spider attaches,
then drilling holes and cinching down the spider. Now I pluck each
arm to a nice middle "C" and the tube doesn't crush. 'Course, the
azimuth bearings had to move forward and the scope got 5 lbs. heavier,
but the collimation is solid.

Do you suffer any vignetting with the smaller secondary?

wrote in message
...
On Wed, 04 Aug 2004 21:19:12 GMT, "Mike Fitterman"
wrote:

I just had my Starfinder 16" converted to a truss by TScopes and it's
awesome! It went from 170lbs to 85lbs (with the heaviest component being
under 50). The collimation was much better than what I had in the
sonotube
although I have to set it up everytime from scratch. The 16" starfinder
comes with a 4" secondary that's just way to big and is on fairly flimsy
spider. I replaced that with a 3.1" secondary and a protostar spider.
The
thing is rock solid now. A truss done right is much lighter easier to
transport and easier to cool down (important in the northeast). The
sonotube has it's advantages too, but I think they are far outweighed by
these things.

Mike.

Yeah, I tackled the spider problem a while ago when I inserted strap
steel around the inner diameter of the tube where the spider attaches,
then drilling holes and cinching down the spider. Now I pluck each
arm to a nice middle "C" and the tube doesn't crush. 'Course, the
azimuth bearings had to move forward and the scope got 5 lbs. heavier,
but the collimation is solid.

Do you suffer any vignetting with the smaller secondary?


No, this is right at the absolute limit to get the entire mirror's light
into the secondary. Collimation is key. I've noticed that if I'm a little
off, things look just a touch dimmer (and it's definitely noticible!). Get
collimation dead on and the scope is amazing.

Mike.