Celestron 76 x 700 Newtonian

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GCoyote United States of America
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Celestron 76 x 700 Newtonian

#1

Post by GCoyote »


I've had this one for a couple years but don't use it much. It's only slightly larger than my 70 mm refractor so I don't gain much although it is faster at f 9.2.
It's basically an older version of this one. https://images.app.goo.gl/thJE3P8j7ZEKa7sV8 It does have a heavier tripod than the newer scopes though.

The problem is I don't have much room to insert anything in the optical path. Racking the focuser out a mere 1 cm reaches correct focus at infinity. That only leaves room for a filter. Can't use a Barlow, diagonal, erecting prism, or anything else.

Anything I can do to extend the optical path a bit for more viewing options?

:Think:
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Celestron 76 x 700 Newtonian

#2

Post by Lady Fraktor »


At f/9.2 it would make a nice lunar/ planetary telescope.
Strange that it has such limited focus, is there a corrector lens in the focuser tube or can you tell if someone has changed the focuser?
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
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Re: Celestron 76 x 700 Newtonian

#3

Post by GCoyote »


I just collimated it so there are no extra parts between the primary and secondary mirrors. The focuser looks like the one in the photos so I'm guessing it's original.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Celestron 76 x 700 Newtonian

#4

Post by Lady Fraktor »


I think member Terrynak may have one of these, perhaps contact him and see what he has to say.
Have you made sure the gearing on the axle and tube are not binding up?
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
The only culture I have is from yogurt
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Re: Celestron 76 x 700 Newtonian

#5

Post by GCoyote »


It feels smooth enough considering the plastic parts. Now that it's collimated the image is quite good. It's just that the very short focuser travel distance from all the way in to focus at infinity leaves no room for other optics.

I'll pm Terrynak for more information.

Thanks!
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Celestron 76 x 700 Newtonian

#6

Post by Lady Fraktor »


What is the actual focuser travel from racked in to racked out?
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
The only culture I have is from yogurt
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Re: Celestron 76 x 700 Newtonian

#7

Post by GCoyote »


I just put everything away. I'll get it out tomorrow measure it.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Celestron 76 x 700 Newtonian

#8

Post by GCoyote »


I wonder if I messed up the secondary when I collimated it?

Focus at infinity
focus at infinity.jpg
Fully racked out
Fully Racked out.jpg
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Celestron 76 x 700 Newtonian

#9

Post by Lady Fraktor »


It looks like you have about 60mm of travel so that seems about right. Can the drawtube go further in?
What eyepieces are you using with this?
I see in your first posting above you say you cannot use a diagonal or erecting prism.
These are not usable with a Newtonian telescope, they would increase the lightpath making the telescope unusable.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
The only culture I have is from yogurt
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Re: Celestron 76 x 700 Newtonian

#10

Post by GCoyote »


Yes, the draw tube will fully retract. It just seems strange to me that I have so much excess focuser travel beyond the focus point.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Celestron 76 x 700 Newtonian

#11

Post by Lady Fraktor »


That is normal, as you go from high powers to low powers you will use more of the travel.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
The only culture I have is from yogurt
My day was going well until... people
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Re: Celestron 76 x 700 Newtonian

#12

Post by terrynak »


Gabrielle (Lady Fraktor) is right - can't use other accessories besides standard EPs and a Short Barlow. A long Barlow lens may not work on these Newts.
Scopes: Reflectors, refractors, and 1 catadioptric. Ranging in aperture from 50mm to 150mm.
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Re: Celestron 76 x 700 Newtonian

#13

Post by GCoyote »


Okay, I don't normally use EPs below about 20 mm at home because of the LP. I need to get this out to a dark site and get some experience with it.
Thanks for the help (and the patience!)
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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