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Equipment Discussions >> Cats & Casses

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Ed Holland
Pooh-Bah


Reged: 06/16/10

Loc: San Jose, CA and Oxford, UK
Re: Why do people even buy SCTs??? new [Re: maknewtnut]
      #6232498 - 12/04/13 12:14 AM

I appreciate the skepticism about SCTs, it keeps the second hand prices so affordable

That wonky used C8 turns out to be the best scope I have viewed with...


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Roy McCoy
Pooh-Bah
*****

Reged: 10/13/05

Loc: Glendale, AZ
Re: Why do people even buy SCTs??? new [Re: Ed Holland]
      #6232508 - 12/04/13 12:26 AM

Quote:

I appreciate the skepticism about SCTs, it keeps the second hand prices so affordable




You're welcome.


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donnie3
Carpal Tunnel


Reged: 12/15/04

Loc: bartlesville oklahoma
Re: Why do people even buy SCTs??? new [Re: jimbo728]
      #6232528 - 12/04/13 12:39 AM

my take on this subject with the experience I have through the years in the city and at dark sites is this, refractors shine in dark skies, if I lived in the Oklahoma hills (osage county)where its so dark you cant see 2 feet in front of you, the refractor would be the master scope but in town with sky glow, I consider them useless. reflectors and cats for the city. just my simple option. donnie

Edited by donnie3 (12/04/13 12:50 AM)


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6232601 - 12/04/13 01:59 AM

Quote:


I agree that it doesn't pay to favor one kind of instrument. So far, mine run the gamut from apos, apos w/fluorite, Mak-Cass, Newt-Dob, CDKs. SCT would be fun to play with for visual and imaging work.




oh yes!
that CDK was great, isn't?
http://fidgor.narod.ru/Observers/Test/test_84.html

sorry, it's ODK, but anyway....


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: drago]
      #6232870 - 12/04/13 08:52 AM

Quote:

Quote:


I agree that it doesn't pay to favor one kind of instrument. So far, mine run the gamut from apos, apos w/fluorite, Mak-Cass, Newt-Dob, CDKs. SCT would be fun to play with for visual and imaging work.




oh yes!
that CDK was great, isn't?
http://fidgor.narod.ru/Observers/Test/test_84.html

sorry, it's ODK, but anyway....




You don't know much about CDKs, do you? I have a Tak Mewlon 300 CRS (which provides stunning refractor-like views) and a rare Ceravolo 300 f/4.9-f/9 Astrograph. The top manufacturers consider them as CDKs. These instruments have considerably better performance than the scope in that Russian report. BTW, do you read Russian?

http://www.optcorp.com/takahashi-mewlon-300crs-cdk-telescope-tlk3201.html
http://www.ceravolo.com/

Edited by JJK (12/04/13 09:07 AM)


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orion61

*****

Reged: 10/20/07

Loc: Birthplace James T Kirk
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6232885 - 12/04/13 09:00 AM

I thought Trolling threads were prohibited? That is what this one has turned out to be.

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ATM57
super member


Reged: 01/01/10

Loc: Tehachapi, CA
Re: Why do people even buy SCTs??? new [Re: orion61]
      #6233472 - 12/04/13 02:22 PM

Quote:

I thought Trolling threads were prohibited? That is what this one has turned out to be.




Hey Orion61,
Let's see if we can get this thread back on track:

I bet the optics in you C-8 would surprise many as to how well a C-8 can perform. Since Leo was the VP of marketing for Celestron, the optics in your scope are more than likely one of the legendary smooth nulled sets. Inquiring minds want to know

Scopejunkie


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TG
Pooh-Bah


Reged: 11/02/06

Loc: Latitude 47
Re: Why do people even buy SCTs??? new [Re: drago]
      #6233525 - 12/04/13 02:52 PM

Quote:

Quote:


I agree that it doesn't pay to favor one kind of instrument. So far, mine run the gamut from apos, apos w/fluorite, Mak-Cass, Newt-Dob, CDKs. SCT would be fun to play with for visual and imaging work.




oh yes!
that CDK was great, isn't?
http://fidgor.narod.ru/Observers/Test/test_84.html

sorry, it's ODK, but anyway....




Drago, interesting site. I went to the root site http://fidgor.narod.ru and also went through all the test reports (I don't know if they're linked at the top, I just went through test_00.html, test_01.html, ... manually all the way).

Do you know what kind of interferometer they're using? And since I don't read Russian (and online translation is poor), can you tell me who these people are? I find it interesting that most of the scopes they tested showed up poor and almost all had coma and astigmatism that they removed from the final report. Are they displaying only bad ones or all? I can't tell.

Tanveer.


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: TG]
      #6233558 - 12/04/13 03:11 PM

Quote:

Quote:

Quote:


I agree that it doesn't pay to favor one kind of instrument. So far, mine run the gamut from apos, apos w/fluorite, Mak-Cass, Newt-Dob, CDKs. SCT would be fun to play with for visual and imaging work.




oh yes!
that CDK was great, isn't?
http://fidgor.narod.ru/Observers/Test/test_84.html

sorry, it's ODK, but anyway....




Drago, interesting site. I went to the root site http://fidgor.narod.ru and also went through all the test reports (I don't know if they're linked at the top, I just went through test_00.html, test_01.html, ... manually all the way).

Do you know what kind of interferometer they're using? And since I don't read Russian (and online translation is poor), can you tell me who these people are? I find it interesting that most of the scopes they tested showed up poor and almost all had coma and astigmatism that they removed from the final report. Are they displaying only bad ones or all? I can't tell.

Tanveer.




The direct link is to a very thin report. The LHS of the web page says essentially you're on your own (caveat emptor). The bottom part suggests the optics might have been wiped by a less than pristine cloth. The method employed was autocollimation. I'll read it again later to get the details.

Edited by JJK (12/04/13 03:13 PM)


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gmartin02
professor emeritus
*****

Reged: 04/11/05

Loc: Santa Clarita, CA
Re: Why do people even buy SCTs??? new [Re: orion61]
      #6233717 - 12/04/13 04:53 PM

Quote:

I thought Trolling threads were prohibited? That is what this one has turned out to be.




With a title like "Why do people even buy SCTs???", what did you expect? The title is begging: "troll me, troll me!"

Fortunately, I have resisted


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Calypte
Pooh-Bah


Reged: 03/20/07

Loc: Anza, California
Re: Why do people even buy SCTs??? new [Re: gmartin02]
      #6233753 - 12/04/13 05:08 PM

Quote:


With a title like "Why do people even buy SCTs???", what did you expect? The title is begging: "troll me, troll me!"

Fortunately, I have resisted



That's what I thought this was from the beginning. Post a hyperbolic remark, then stand back and watch the fur fly.


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DesertRat
Post Laureate
*****

Reged: 06/18/06

Loc: Valley of the Sun
Re: Why do people even buy SCTs??? new [Re: TG]
      #6233808 - 12/04/13 05:35 PM

On the Russian site referred to above if you go to:

http://fidgor.narod.ru/Observers/test.html

using Chrome to get a translation you'll find a list broken into groups of refractors, newts, etc.

You'll note that many of the big mirrors test awful, strehls < 0.3 are shown in some of them. As I mentioned in the recent WinRoddier thread, many times testing a large mirror horizontally is just as much a dignostic of the mirror mount than the optic. Mirror mounts are generally not designed for horizontal use. A sling might be called for to test the primary only.

I'm assuming they have a decent flat, or one that can be corrected for.

The practice of disabling coma and astigmatism in a report is ok as long as they also include the full report. Sometimes they do. I would expect smaller optics generally to test better than larger ones, but maybe not so wildly as they do on that site.

Perhaps many of these optics had previously known issues or complaints. Making any general statements about a given scope type would not be useful if that indeed is the case.

Glenn


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Asbytec
Guy in a furry hat
*****

Reged: 08/08/07

Loc: La Union, PI
Re: Why do people even buy SCTs??? new [Re: orion61]
      #6234237 - 12/04/13 09:17 PM

Quote:

I thought Trolling threads were prohibited? That is what this one has turned out to be.



I'm not sure this began as a troll thread with bad intentions so much as it is a defense of the SCT thread with good intentions. The OP, I think, simply asked a question about the design, being the whipping boy in our community, trying to argue in favor of the SCT - not bash it. His approach was to list everything bad we often hear about the design, and ask ironically, why we even consider buying them - and do buy them in droves, apparently. It may have become a troll thread in that it's beating a dead horse while attracting many replies from folks who are pro and con for the purpose of beating that horse (and the SCT.) It's rekindled the pro and con debate we see all the time with no final word, just firm opinions either way as always. Little will change.


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6234587 - 12/05/13 02:01 AM

Quote:


You don't know much about CDKs, do you? I have a Tak Mewlon 300 CRS (which provides stunning refractor-like views) and a rare Ceravolo 300 f/4.9-f/9 Astrograph. The top manufacturers consider them as CDKs. These instruments have considerably better performance than the scope in that Russian report. BTW, do you read Russian?






Wua-ha-ha!
see, tak mewlon has 32 percent secondary obstruction!
"refractor-like" views, you say? that must be very poor refractor...
and what exactly "considerably better performance" thats instruments have? what is strehl ratio?
and yes, i read in russian. i growing in soviet union, as so i know russian, and that is good. also as some another things in soviet.


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: TG]
      #6234593 - 12/05/13 02:09 AM

Quote:


Drago, interesting site. I went to the root site http://fidgor.narod.ru and also went through all the test reports (I don't know if they're linked at the top, I just went through test_00.html, test_01.html, ... manually all the way).

Do you know what kind of interferometer they're using? And since I don't read Russian (and online translation is poor), can you tell me who these people are? I find it interesting that most of the scopes they tested showed up poor and almost all had coma and astigmatism that they removed from the final report. Are they displaying only bad ones or all? I can't tell.

Tanveer.




as there is said, there is a root page for tests:
http://fidgor.narod.ru/Observers/test.html
the folks is from moscow VAGO - an amateur organization, who takes amateur astronomers, founded in soviet union times. there are a many smart and experienced folks, some of them also have a professional knowledge in astronomy optics.
i dont remember what type of IF hes used, but there is a more about all that:
http://www.astronomy.ru/forum/index.php/topic,21065.0.html
http://www.astronomy.ru/forum/index.php/topic,82347.0.html


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TheObserver
sage
*****

Reged: 09/24/13

Loc: Light Polluted, NY
Re: Why do people even buy SCTs??? new [Re: drago]
      #6234612 - 12/05/13 02:49 AM

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

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coopman
Post Laureate
*****

Reged: 04/23/06

Loc: South Louisiana
Re: Why do people even buy SCTs??? new [Re: TheObserver]
      #6234788 - 12/05/13 07:51 AM

True dat! Too much patience required.

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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: drago]
      #6234823 - 12/05/13 08:14 AM

Quote:

Quote:


You don't know much about CDKs, do you? I have a Tak Mewlon 300 CRS (which provides stunning refractor-like views) and a rare Ceravolo 300 f/4.9-f/9 Astrograph. The top manufacturers consider them as CDKs. These instruments have considerably better performance than the scope in that Russian report. BTW, do you read Russian?






Wua-ha-ha!
see, tak mewlon has 32 percent secondary obstruction!
"refractor-like" views, you say? that must be very poor refractor...
and what exactly "considerably better performance" thats instruments have? what is strehl ratio?
and yes, i read in russian. i growing in soviet union, as so i know russian, and that is good. also as some another things in soviet.




You obviously have no experience viewing through Tak Mewlon 300 telescopes. Every one I've looked through has produced excellent lunar and planetary views, and it's an acceptable DSO instrument (obviously, it doesn't go as deep as a large Newt-Dob). The CO in The Mewlon 300 is not a significant issue (if it was, I wouldn't have bought such a scope). If you believe it is, produce hard evidence for your case. What is the CO of a SCT?

I haven't measured the scope's Strehl, but I know what views good optics produce. Over the past 17 years, I have had 7 Astrophysics apos (92 mm f/4.9 to 180 mm f/9), 1 AP 10" f/14.6 Mak-Cass (CO ~ 23%), and 2 Zeiss APQs. Each of these scopes perform as expected, given their design, producer's reputation, and aperture (and I've critically compared them to other scopes of simliar aperture, e.g., SCTs). I'm sure you'll have something disparaging to say about each of these instruments, given the experience you have with your own instruments, but the crushing weight of many others' experience with these scopes will argue heavily against you.

If you have any other OT statements, contact me via PM.

Edited by JJK (12/05/13 09:13 AM)


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rmollise
Postmaster
*****

Reged: 07/06/07

Re: Why do people even buy SCTs??? new [Re: TheObserver]
      #6234973 - 12/05/13 09:37 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




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


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seawolfe
sage


Reged: 06/26/13

Loc: N 47.11.23 W 122.20.18
Re: Why do people even buy SCTs??? new [Re: TheObserver]
      #6235003 - 12/05/13 09:48 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




I'm not so sure.... I have an AVX Edge HD and the set up time is about the same as my friend's Orion XX12g truss Dob.

True, his alignment is only 2 stars whereas mine is 2+4 for a nice ASAP for viewing. For spot on polar alignment, it takes more time and effort.

As for horses carrying the heavy load... well, his monster heavy Dob outdoes mine in the weight to carry arena. Good grief, his base unit alone weighs almost more than my whole setup.

But there again, his is a 12 inch as mine is a lightweight 8 inch.


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