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Old 04-04-2021, 11:12 PM
Steve514 (Steve)
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10 Dobsonian Shroud

Hello everyone, new to astronomy and on the Gold Coast.
Ive just purchased a skywatcher shroud for my SW 10 Dobsonian. Im hoping it will help contrast wise from my light polluted backyard.
My problem is the four bars sewn into the shroud to keep it out of the light path seem to be in the wrong place. There are four and they are all equally spaced.
When you wrap it out around the 3 struts two of the match up with the truss bars which means they are not holding the material away enough from the open sections of the tube.
Am I putting it on wrong (Ive tried several positions) or do I need to sew new pockets and move a couple of the bars?
Does anyone have experience with these?
Thanks!
Steve
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Old 05-04-2021, 08:30 AM
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Allan_L (Allan)
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Its been a while since I used one, but there should be two holes for the knobs to sit in. This should determine the correct positioning of the shroud?

But yes, I do recall a number of occasions when the shroud got in the way. and needed to be pulled tighter.

But I don't remember 4 plastic ribs, only 2, and they went around the shroud, not running the length. But that was a few years ago now. Maybe they changed the design.

Edit:
Like the image below.
Allows you to collapse the dob without removing the shroud.

Your one must be a new design.
Probably an improvement
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Last edited by Allan_L; 05-04-2021 at 11:55 AM. Reason: more info
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Old 05-04-2021, 10:31 AM
Startrek (Martin)
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Steve
I have a 3 year old Skywatcher 12 Goto dob and my shroud only has 3 pvc struts sewn in at 120 degrees apart ie: they are positioned centrally between each of the 3 main truss Rods
When I bought the shroud 18 months ago , I found when the dob is fully extended that they dont quite fit between the edges of the OTA tube , I had to pull them out and trim them shorter by 3 to 4mm

I cant see how 4 struts would work ??
Check with your supplier !!
Unless they changed the design of the dob in the past couple of years ?

Martin
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Old 05-04-2021, 01:28 PM
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gaseous (Patrick)
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That's bizarre. The shroud I have for my 8" dob only has 2 internal rods, and when positioned correctly with the 3 rods on the OTA (which aren't at 120), creates a pentagonal effect which works fine. Larger shrouds like Martin's may have an additional rod for a hexagonal effect, but 4 seems very strange. Allan must have the newer shroud version with the thinner plastic straps running around the OTA to allow collapsing without removing the shroud - it's the same system for the shroud on my 20" dob (which can't be collapsed). It sounds like you may have a dud shroud.
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Old 05-04-2021, 07:18 PM
Steve514 (Steve)
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Quote:
Originally Posted by Startrek View Post
Steve
I have a 3 year old Skywatcher 12” Goto dob and my shroud only has 3 pvc struts sewn in at 120 degrees apart ie: they are positioned centrally between each of the 3 main truss Rods
When I bought the shroud 18 months ago , I found when the dob is fully extended that they don’t quite fit between the edges of the OTA tube , I had to pull them out and trim them shorter by 3 to 4mm

I can’t see how 4 struts would work ??
Check with your supplier !!
Unless they changed the design of the dob in the past couple of years ?

Martin
Hi Martin, thank you for your reply,
No my 10" is the same design as yours. Three main struts to extend it. The four pvc rods are all equally set apart which looks neat I suppose but doesn't line up well when you wrap it around. If they worked out to be two equally spaced on each side of the "long space" it work well but they don't. Half of them end up right next to the main strut or very close to it which is useless. They may as not be there.

Last edited by Steve514; 05-04-2021 at 07:30 PM.
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Old 05-04-2021, 07:22 PM
Steve514 (Steve)
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Quote:
Originally Posted by gaseous View Post
That's bizarre. The shroud I have for my 8" dob only has 2 internal rods, and when positioned correctly with the 3 rods on the OTA (which aren't at 120), creates a pentagonal effect which works fine. Larger shrouds like Martin's may have an additional rod for a hexagonal effect, but 4 seems very strange. Allan must have the newer shroud version with the thinner plastic straps running around the OTA to allow collapsing without removing the shroud - it's the same system for the shroud on my 20" dob (which can't be collapsed). It sounds like you may have a dud shroud.
Thanks for your reply Patrick,
Yes what you describe sounds like exactly what I need but alas, even with four rods they don't line up equally.
I'm wondering if it is meant for a collapsible dob that has only one strut. Do they make such an instrument?
I just can't get it to equally hold the fabric out of the light path on my 10" SW dob.
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Old 05-04-2021, 07:27 PM
Steve514 (Steve)
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Quote:
Originally Posted by Allan_L View Post
Its been a while since I used one, but there should be two holes for the knobs to sit in. This should determine the correct positioning of the shroud?

But yes, I do recall a number of occasions when the shroud got in the way. and needed to be pulled tighter.

But I don't remember 4 plastic ribs, only 2, and they went around the shroud, not running the length. But that was a few years ago now. Maybe they changed the design.

Edit:
Like the image below.
Allows you to collapse the dob without removing the shroud.

Your one must be a new design.
Probably an improvement
Hello Allan, thank you for replying,
They are not ribs, they are rods, or perhaps they are vertical ribs! :-)
The one you have in the photo looks like a great design, folding up the way it does.
Also, my shroud doesn't have holes which is frustrating. I can imagine (1) wearing a hole in the material over time as the knob is held through it, and (2) Fumbling to move the scope smoothly when the handle is not defined properly because of the material stretched over it.
When I place the elastic edge UNDER the knob the material becomes too loose and collapses into the light path. Very frustrating.
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Old 05-04-2021, 09:35 PM
Startrek (Martin)
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Quote:
Originally Posted by Steve514 View Post
Hello Allan, thank you for replying,
They are not ribs, they are rods, or perhaps they are vertical ribs! :-)
The one you have in the photo looks like a great design, folding up the way it does.
Also, my shroud doesn't have holes which is frustrating. I can imagine (1) wearing a hole in the material over time as the knob is held through it, and (2) Fumbling to move the scope smoothly when the handle is not defined properly because of the material stretched over it.
When I place the elastic edge UNDER the knob the material becomes too loose and collapses into the light path. Very frustrating.
My 3 PVC struts are actually half inch or 16mm electrical conduit with the ends cut back in half about 20mm
I pulled my struts out of the shroud and cut the rebate section about 3mm shorter to allow them to fit between the OTA tube top and bottom
To be honest this method to hold the fabric away from the OTA tube is a poor design as mine sometimes pops off the tube and fall inside
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Old 05-04-2021, 11:46 PM
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Just remembered, my shroud was not a Skywatcher product, but Astrozap if i remember correctly
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Old 06-04-2021, 08:29 AM
Steve514 (Steve)
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Quote:
Originally Posted by Allan_L View Post
Just remembered, my shroud was not a Skywatcher product, but Astrozap if i remember correctly
That looks like a good design. Bulkier, mine is some kind of stretchy, spandex material, but yours looks wider and better able to get out of the light path.
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Old 05-05-2021, 06:59 AM
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mura_gadi (Steve)
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Stray light

Hello,

Can't help you with the shroud as I made one up on my 8" sw. I used doubled over black cloth with some stiff carboard ribs glued in, velco edges, cut two triangles out for the nobs and stitch elastic across the top. Under $15 of material from lincraft or similar.

However if your chasing light scatter reductions you might want to include a light shroud/dew shield on the end of your newt.

Old school would tell you that a light shield equal to the diameter of the mirror forward of the focuser(top edge not center). That has gone over time, I use one in my urban backyard viewing and it helps a lot with reducing stray light from the neighbours and street lights etc.

Simple stiff black plastic sheet, or a black foam gym mat in my case works well.


Steve

Last edited by mura_gadi; 05-05-2021 at 07:12 AM.
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