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Equipment Discussions >> Cats & Casses

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Footbag
Postmaster
*****

Reged: 04/13/09

Loc: Scranton, PA
Re: Why do people even buy SCTs??? new [Re: TheObserver]
      #6235022 - 12/05/13 10:00 AM

Quote:

the last time someone showed up with sct to our meet up. first he had 2 horses helping him to pull that carriage . and by the time he setup and started observing we were having pizza. i would never consider buying something that big and heavy. i setup in 30seconds




The CPC's are alt-az. Setup is as simple as it could be. 30s is about right.


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Mark Costello
Post Laureate
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Reged: 03/08/05

Loc: Matthews, NC, USA
Re: Why do people even buy SCTs??? new [Re: TheObserver]
      #6235056 - 12/05/13 10:18 AM

That SCT rig must have been a whopper with all the trimmings. If I were to get one, it'd be in the range of 8-10" and probably closer to 8" (maybe "nine and a quarter"). How long would it take to set one of those on an AVX mount, including all the orientation work? My set up time including all accessories (chair, notebook, charts, etc.) is about six minutes which I find acceptable. For a larger one, a setup time of 15 minutes would be OK since it would be used for longer weekend sessions (Saturday Night Special ).

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David PavlichAdministrator
Transmographied
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Reged: 05/18/05

Loc: Mandeville, LA USA
Re: Why do people even buy SCTs??? new [Re: rmollise]
      #6235114 - 12/05/13 10:45 AM

Quote:

Quote:

the last time someone showed up with sct to our meet up. first he had 2 horses helping him to pull that carriage . and by the time he setup and started observing we were having pizza. i would never consider buying something that big and heavy. i setup in 30seconds




Ah...I see that after only 12 pages of this stuff we have, in true CN fashion, reached the reductio ad absurdum stage!




Good one!

David


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roadi
Pooh-Bah
*****

Reged: 08/18/07

Loc: Great Grey Spot "Denmark"
Re: Why do people even buy SCTs??? new [Re: Eddgie]
      #6235158 - 12/05/13 11:10 AM

"Why do people even buy SCTs???"

Affordable for most, reasonable quality
Nothing wrong with SCT, only some manufactures QC but this might have changed.


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Doug Culbertson
Post Laureate
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Reged: 01/06/05

Re: Why do people even buy SCTs??? new [Re: rmollise]
      #6235159 - 12/05/13 11:11 AM

Quote:

Quote:

the last time someone showed up with sct to our meet up. first he had 2 horses helping him to pull that carriage . and by the time he setup and started observing we were having pizza. i would never consider buying something that big and heavy. i setup in 30seconds




Ah...I see that after only 12 pages of this stuff we have, in true CN fashion, reached the reductio ad absurdum stage!




Sorry, but I went to FSU. Is that Latin for Horse Hockey? If so, I agree.


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TheObserver
sage
*****

Reged: 09/24/13

Loc: Light Polluted, NY
Re: Why do people even buy SCTs??? new [Re: Doug Culbertson]
      #6235223 - 12/05/13 11:44 AM

Quote:

Quote:

Quote:

the last time someone showed up with sct to our meet up. first he had 2 horses helping him to pull that carriage . and by the time he setup and started observing we were having pizza. i would never consider buying something that big and heavy. i setup in 30seconds




Ah...I see that after only 12 pages of this stuff we have, in true CN fashion, reached the reductio ad absurdum stage!




Sorry, but I went to FSU. Is that Latin for Horse Hockey? If so, I agree.




SCT known to start house fire dont believe me check this out http://goo.gl/C33wxK


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: roadi]
      #6235243 - 12/05/13 11:52 AM

Quote:

"Why do people even buy SCTs???"


Nothing wrong with SCT, only some manufactures QC but this might have changed.




about a 38 percent central obstruction cannot be named as "nothing wrong", especially for visual instrument...


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6235276 - 12/05/13 12:02 PM

as you know, central obstruction gives impact on telescope strehl ratio. even if, say, newtonian, both mirrors is excellent, and got a strehl ratio = 1.00. then whole system with CO 25 percent by diameter have strehl only a about 0.9.
if obstruction is 40 percent, then we discuss on about strehl 0.75 - 0.78.
and that is only co introduced fall. if optics at start have strehl, say, 0.92 ( very not bad at all), then in result, we have not diffraction-limited telescope anymore.
there is some proofs:
http://astro-talks.ru/forum/viewtopic.php?f=15&p=18483#p18483
sadly, but in russian. but with graphics, and even more interesting tables.


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rmollise
Postmaster
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Reged: 07/06/07

Re: Why do people even buy SCTs??? new [Re: Doug Culbertson]
      #6235341 - 12/05/13 12:39 PM

Quote:



Sorry, but I went to FSU. Is that Latin for Horse Hockey? If so, I agree.




Yep, HORSE HOCKEY is even MORE descriptive and accurate. I can think of some better synonyms I could have used in place of "stuff," too.


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TheObserver
sage
*****

Reged: 09/24/13

Loc: Light Polluted, NY
Re: Why do people even buy SCTs??? new [Re: rmollise]
      #6235364 - 12/05/13 12:56 PM

Quote:

Quote:



Sorry, but I went to FSU. Is that Latin for Horse Hockey? If so, I agree.




Yep, HORSE HOCKEY is even MORE descriptive and accurate. I can think of some better synonyms I could have used in place of "stuff," too.






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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Why do people even buy SCTs??? new [Re: rmollise]
      #6235374 - 12/05/13 01:03 PM

Rod I was looking back at other threads and posts from some members, it seems some people just like to go around poking Hornets nests with sticks..
Central obstruction rates bothering final image goes down substantially as the power per inch decreases so it is kind of a moot point.
AW here I go getting suckered in again.. i am just going to put the old ignore blinders on this thread.. not worth the time, has fallen WAY of topic.


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Mark Costello
Post Laureate
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Reged: 03/08/05

Loc: Matthews, NC, USA
Re: Why do people even buy SCTs??? new [Re: Doug Culbertson]
      #6235404 - 12/05/13 01:26 PM

Quote:

Quote:

Quote:

the last time someone showed up with sct to our meet up. first he had 2 horses helping him to pull that carriage . and by the time he setup and started observing we were having pizza. i would never consider buying something that big and heavy. i setup in 30seconds




Ah...I see that after only 12 pages of this stuff we have, in true CN fashion, reached the reductio ad absurdum stage!




Sorry, but I went to FSU. Is that Latin for Horse Hockey? If so, I agree.





Hi Doug, loosely translated, it means "reduce to an absurdity." Actually, it's a technique used to prove a lot of mathematical theorems. The technique involves assuming the opposite of the statement of the theorem, then making logical deductions until you've reached a contradiction to a previously established statemetn (e.g., definition, theorem.). An example is the theorem "The Null Set is a subset of every set." You assume that there is a set of which the Null Set is not a subset and the deductions from there lead you to a position contradicting the definition of the Null Set.

Back to your regularly scheduled programming.


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WesC
Carpal Tunnel
*****

Reged: 02/06/13

Loc: La Crescenta, CA
Re: Why do people even buy SCTs??? new [Re: Mark Costello]
      #6235434 - 12/05/13 01:37 PM

Quote:

Ah...I see that after only 12 pages of this stuff we have, in true CN fashion, reached the reductio ad absurdum stage!




Indeed!!!


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DesertRat
Postmaster
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Reged: 06/18/06

Loc: Valley of the Sun
Re: Why do people even buy SCTs??? new [Re: Mark Costello]
      #6235570 - 12/05/13 02:46 PM

Quote:

Back to your regularly scheduled programming.


Oh no! I was afraid of that.

When the level of half truths, trivalent logic, deceptions and just plain bogosity rise to this level of absurdity I can only hope for a salvo of tos violations. Maybe then someone will stick a fork into this stream of horse hockey.

Glenn


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roadi
Pooh-Bah
*****

Reged: 08/18/07

Loc: Great Grey Spot "Denmark"
Re: Why do people even buy SCTs??? new [Re: drago]
      #6235626 - 12/05/13 03:21 PM

Quote:

Quote:

"Why do people even buy SCTs???"


Nothing wrong with SCT, only some manufactures QC but this might have changed.




about a 38 percent central obstruction cannot be named as "nothing wrong", especially for visual instrument...




The 38% CO is inherent to the design hence assumed considered by the makers!
It is of course a disadvantage compared to an un obstructed system of same aperture which everyone knows, still comparable to an perfect un-obstructed system of 70-75% of its aperture and affordable to a very attractive price in comparison.
I do consider this a very capable/managable hence attractive alternative to the perfect and "to many" non-affordable refractor at 75% of the aperture.
Only issue I have/had with the common SCT's was the often poor execution and lack of QC.
This might have improved as I have experienced good quality with both three refractors and a 12" reflector from far east which I'm very satisfied with.

Edited by roadi (12/05/13 03:32 PM)


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Ed Holland
Carpal Tunnel


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: Why do people even buy SCTs??? new [Re: roadi]
      #6235661 - 12/05/13 03:38 PM


A central obstruction is nowhere near the disadvantage provided by the the local seeing conditions on many nights here.
To think otherwise, would be like owning an expensive HiFi, expecting crystal clear sound from a worn vinyl record, and blaming the cables.


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t.r.
Post Laureate
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Reged: 02/14/08

Loc: Upstate NY
Re: Why do people even buy SCTs??? new [Re: roadi]
      #6235683 - 12/05/13 03:55 PM

I did my best to stay out of this...but I finally caved . Here is the litmus test...

Two scopes side by side.

One a new C14.

The other a new AP 175 EDF refractor.

You can have one for FREE...BUT cannot sell it and must keep it forever as your only scope.

You have NO health or mounting/use issues.


Logic, MTF and Physics would dictate that you must pick the C14...right?

You MUST choose the C14.

How many of you can say that you would?

My


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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Why do people even buy SCTs??? new [Re: t.r.]
      #6235697 - 12/05/13 04:04 PM

ME yup..

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NHRob
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Reged: 08/27/04

Loc: New Hampshire
Re: Why do people even buy SCTs??? new [Re: orion61]
      #6235715 - 12/05/13 04:13 PM

Not I

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Dwight J
scholastic sledgehammer
*****

Reged: 05/14/09

Loc: Lethbridge, Alberta, Canada
Re: Why do people even buy SCTs??? new [Re: t.r.]
      #6235720 - 12/05/13 04:18 PM

Geez, I dunno. With that giant secondary obstruction, thermal equilibrium issue, hours of set-up time, focus shift, dew on corrector plate - I'd take the.....C14 any day of the week. My ego does not require a fancy refractor.

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