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just picked up a Meade 2080 F/10, what to check?



 
 
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  #1  
Old February 19th 17, 02:29 AM posted to sci.astro.amateur
R2D4
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Posts: 7
Default just picked up a Meade 2080 F/10, what to check?

A neighbor had a Meade 2080 they were about to actually toss out so I
got it just before the trash pick up on Tuesday. He said he was getting
rid of it because he's moving and had no time for sales, I gave him $100
anyway which, if it works ok, would be a steal. This appears to be the
F/10 model. With it came 9x60 finder with illuminated reticle,
equatorial wedge, drive and heavy tripod, a couple of eyepieces, drive
controller and power supply. There's also the diagonals for both scope
and finder and 2 to 1.25" adapters. One thing I did find out is that it
is a HEAVY beast, seems heavier than even the 9.25 I used to have on
GC-5. I sold off all my SCT's years ago and was never really going to
return to astro until I saw this giveaway.

Now the question: how do I check this out optically? I look through
the corrector and the primary seems fine, not sure how to see how the
secondary looks. So any advice here would be welcome as well as how to
test resolution, collimate, etc.

There appears to be one thing missing that I sort of need because I
can't see Polaris most of the time and that is the compass that snaps
into the base-- any idea where I can find one or is there a substitute
that will work?

Thanks for any help,
R2
  #2  
Old February 19th 17, 06:03 AM posted to sci.astro.amateur
Chris L Peterson
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Posts: 10,007
Default just picked up a Meade 2080 F/10, what to check?

On Sat, 18 Feb 2017 20:29:26 -0500, R2D4 wrote:

A neighbor had a Meade 2080 they were about to actually toss out so I
got it just before the trash pick up on Tuesday. He said he was getting
rid of it because he's moving and had no time for sales, I gave him $100
anyway which, if it works ok, would be a steal. This appears to be the
F/10 model. With it came 9x60 finder with illuminated reticle,
equatorial wedge, drive and heavy tripod, a couple of eyepieces, drive
controller and power supply. There's also the diagonals for both scope
and finder and 2 to 1.25" adapters. One thing I did find out is that it
is a HEAVY beast, seems heavier than even the 9.25 I used to have on
GC-5. I sold off all my SCT's years ago and was never really going to
return to astro until I saw this giveaway.

Now the question: how do I check this out optically? I look through
the corrector and the primary seems fine, not sure how to see how the
secondary looks. So any advice here would be welcome as well as how to
test resolution, collimate, etc.

There appears to be one thing missing that I sort of need because I
can't see Polaris most of the time and that is the compass that snaps
into the base-- any idea where I can find one or is there a substitute
that will work?


There is a wide range of quality with the 2080s. They were really
pumped out back in the 1980s when Comet Halley was boosting amateur
astronomy, and Meade's quality control left a lot to be desired. I'd
start by seeing just how well it collimates (there are online
tutorials providing the details, but essentially you look at a star at
high power, in focus and on both sides, and adjust the three screws on
the secondary mirror). If you're interested in a critical analysis,
I'd suggest you pick up Suiter's book, _Star Testing Astronomical
Telescopes_.

A compass is only suitable for a very rough polar alignment. That may
be good enough for basic visual use. Any compass should do. Why can't
you see Polaris? If it's normally in your sky (you're not too far
south), it's bright enough that you should easily see it under almost
any conditions you'd want to observe.
  #3  
Old February 19th 17, 04:08 PM posted to sci.astro.amateur
R2D4
external usenet poster
 
Posts: 7
Default just picked up a Meade 2080 F/10, what to check?

On 02/19/2017 12:03 AM, Chris L Peterson wrote:


There is a wide range of quality with the 2080s. They were really
pumped out back in the 1980s when Comet Halley was boosting amateur
astronomy, and Meade's quality control left a lot to be desired. I'd
start by seeing just how well it collimates (there are online
tutorials providing the details, but essentially you look at a star at
high power, in focus and on both sides, and adjust the three screws on
the secondary mirror). If you're interested in a critical analysis,
I'd suggest you pick up Suiter's book, _Star Testing Astronomical
Telescopes_.


Thanks. I just found a slightly older version of the book online and
skimmed through it briefly. Unfortunately, with my only occasional good
seeing here (maybe ten nights a year), I may have to do the artificial
star test but this could be problematic for the distances required. I
may just have to check Jupiter, Saturn, or the Moon in the meantime once
I check collimation. I kept a set of Bob's Knobs from when I had
Celestron SCT's several years ago, but not sure whether or not they'll
fit this scope.


A compass is only suitable for a very rough polar alignment. That may
be good enough for basic visual use. Any compass should do. Why can't
you see Polaris? If it's normally in your sky (you're not too far
south), it's bright enough that you should easily see it under almost
any conditions you'd want to observe.


Sorry, I wasn't entirely accurate here. I can often see Polaris, which
of course I'll use to help align, but I also want to use the scope with
stopped down, filtered aperture mask during daytime to do solar
observing, which was the need for the compass. I believe I found a
compass source, however.
  #4  
Old February 19th 17, 04:29 PM posted to sci.astro.amateur
Chris L Peterson
external usenet poster
 
Posts: 10,007
Default just picked up a Meade 2080 F/10, what to check?

On Sun, 19 Feb 2017 10:08:07 -0500, R2D4 wrote:

Thanks. I just found a slightly older version of the book online and
skimmed through it briefly. Unfortunately, with my only occasional good
seeing here (maybe ten nights a year), I may have to do the artificial
star test but this could be problematic for the distances required. I
may just have to check Jupiter, Saturn, or the Moon in the meantime once
I check collimation. I kept a set of Bob's Knobs from when I had
Celestron SCT's several years ago, but not sure whether or not they'll
fit this scope.


I tried thumbscrews at one point, but frankly, they don't work very
well for good collimation. They just don't give fine enough control,
and they don't let you tighten them down as much as you need. I
suggest using good quality stainless steel hex head screws, and a long
handled hex wrench (at least six inches. You get much more control
that way.

Although it's not a requirement, what I found was the greatest assist
for good collimation is a simple video camera or webcam. You can watch
the star on a screen while you're collimating from the aperture end of
the scope.
  #5  
Old February 19th 17, 08:21 PM posted to sci.astro.amateur
Razzmatazz
external usenet poster
 
Posts: 265
Default just picked up a Meade 2080 F/10, what to check?

On Saturday, February 18, 2017 at 7:29:29 PM UTC-6, R2D4 wrote:
A neighbor had a Meade 2080 they were about to actually toss out so I
got it just before the trash pick up on Tuesday. He said he was getting
rid of it because he's moving and had no time for sales, I gave him $100
anyway which, if it works ok, would be a steal. This appears to be the
F/10 model. With it came 9x60 finder with illuminated reticle,
equatorial wedge, drive and heavy tripod, a couple of eyepieces, drive
controller and power supply. There's also the diagonals for both scope
and finder and 2 to 1.25" adapters. One thing I did find out is that it
is a HEAVY beast, seems heavier than even the 9.25 I used to have on
GC-5. I sold off all my SCT's years ago and was never really going to
return to astro until I saw this giveaway.

Now the question: how do I check this out optically? I look through
the corrector and the primary seems fine, not sure how to see how the
secondary looks. So any advice here would be welcome as well as how to
test resolution, collimate, etc.

There appears to be one thing missing that I sort of need because I
can't see Polaris most of the time and that is the compass that snaps
into the base-- any idea where I can find one or is there a substitute
that will work?

Thanks for any help,
R2


Look at the sun's reflection on a powerline insulator. Do this toward evening when ground air has stabilized. You will see a bright star-like dot, and you can then leisurely collimate the scope. Even if not fully collimated, you can judge the optical quality of the scope by looking at the inside-focus and outside focus Fresnel rings. You will see a bright donut with a dark hole (shadow) in the center caused by the secondary mirror shading. This secondary shadow should look the same on either side of focus, but the most important quality criteria are the roundness of the donut ring when inside and outside focus. If it is oval on one side and flips 90 degrees on the other, then the scope will have astigmatism and will not be ideal for high power planetary views.

Google "testing telescope optics" for more thorough information.

Razzy
  #6  
Old February 19th 17, 10:23 PM posted to sci.astro.amateur
R2D4
external usenet poster
 
Posts: 7
Default just picked up a Meade 2080 F/10, what to check?

On 02/19/2017 10:29 AM, Chris L Peterson wrote:
On Sun, 19 Feb 2017 10:08:07 -0500, R2D4 wrote:

Thanks. I just found a slightly older version of the book online and
skimmed through it briefly. Unfortunately, with my only occasional good
seeing here (maybe ten nights a year), I may have to do the artificial
star test but this could be problematic for the distances required. I
may just have to check Jupiter, Saturn, or the Moon in the meantime once
I check collimation. I kept a set of Bob's Knobs from when I had
Celestron SCT's several years ago, but not sure whether or not they'll
fit this scope.


I tried thumbscrews at one point, but frankly, they don't work very
well for good collimation. They just don't give fine enough control,
and they don't let you tighten them down as much as you need. I
suggest using good quality stainless steel hex head screws, and a long
handled hex wrench (at least six inches. You get much more control
that way.


Any chance you or someone else know the correct size screws needed for
this Meade 2080 F/10 with three screws? Also, should the stainless
screws be the same length as the original?


Although it's not a requirement, what I found was the greatest assist
for good collimation is a simple video camera or webcam. You can watch
the star on a screen while you're collimating from the aperture end of
the scope.


Good tip, thanks.


 




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