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Equipment Discussions >> Cats & Casses

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WesC
Carpal Tunnel
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Reged: 02/06/13

Loc: La Crescenta, CA
Re: Why do people even buy SCTs??? new [Re: Jon Isaacs]
      #6237436 - 12/06/13 01:48 PM

I only bought my SCT to irritate the refractor guys.

Next up, I'm going to buy a refractor to irritate the Dob guys!



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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6237528 - 12/06/13 02:31 PM

Quote:

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...




Then why do you have issues with the Tak Mewlon 300's CO?




dont understand, what you want from me?
i never say, any instrument with 38 or even 32 percent CO can be a great visual instrument.
for me, good visual instrument must have no more than 25% CO, very good - not more than 18%, better - less than 16%.

Edited by drago (12/06/13 02:38 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: WesC]
      #6237555 - 12/06/13 02:51 PM

So Joseph Fraunhofer, Isaac Newton and Bernhard Schmidt were sitting in a bar one evening, arguing over telescope designs.

"Mine's best because there is no central obstruction"

"No, mine is better, because it has no false colour"

"Well mine has the best correction and no false colour"

After a few more beers, I'm afraid to say things got less professional and a fight ensued...

"Take that, you parabolised fool" Thump!
"ohh no you don't, this one's for the crown.." wallop! "..and this for the flint you chromatic ignoramus" thwack!
"You want coma, I'll give you coma" Sockkk!

Of course, they made up and bought another round but next week was exactly the same

Edited by Ed Holland (12/06/13 02:51 PM)


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EFT
Vendor - Deep Space Products
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Reged: 05/07/07

Loc: Phoenix, AZ
Re: Why do people even buy SCTs??? new [Re: Ed Holland]
      #6237577 - 12/06/13 03:05 PM

Quote:

So Joseph Fraunhofer, Isaac Newton and Bernhard Schmidt were sitting in a bar one evening, arguing over telescope designs.

"Mine's best because there is no central obstruction"

"No, mine is better, because it has no false colour"

"Well mine has the best correction and no false colour"

After a few more beers, I'm afraid to say things got less professional and a fight ensued...

"Take that, you parabolised fool" Thump!
"ohh no you don't, this one's for the crown.." wallop! "..and this for the flint you chromatic ignoramus" thwack!
"You want coma, I'll give you coma" Sockkk!

Of course, they made up and bought another round but next week was exactly the same




I think that about sums things up at this point.


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Cliff Hipsher
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Reged: 12/31/08

Loc: North Chesterfield, VA
Re: Why do people even buy SCTs??? new [Re: David Pavlich]
      #6237674 - 12/06/13 04:02 PM Attachment (13 downloads)

I bought an SCT because it was inexpensive. For $350.00 I got a Meade LX5 2080, wedge, tripod, 2" SCT diagonal, 9x60 finder with illuminated reticule, 26mm Plossl, 10mm Plossl, 12mm MA illuminated reticle eyepiece, 8" Thousand Oaks Solar filter, handbox, manuals, 25 foot power cords, and at storage trunk with keys.

I still have the OTA. It now resides on an LXD75.


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WesC
Carpal Tunnel
*****

Reged: 02/06/13

Loc: La Crescenta, CA
Re: Why do people even buy SCTs??? new [Re: EFT]
      #6237679 - 12/06/13 04:09 PM

Hahahaha!!!!

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crow
sage
*****

Reged: 07/09/12

Loc: BC, Canada
Re: Why do people even buy SCTs??? new [Re: WesC]
      #6237695 - 12/06/13 04:18 PM

Now who couldn't love that.....?

The digi display thing, I want one and I have no idea what it is.


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Chaz659
sage


Reged: 12/08/12

Loc: Islip, NY
Re: Why do people even buy SCTs??? new [Re: Cliff Hipsher]
      #6237742 - 12/06/13 04:49 PM

Cliff Hipsher - I see that you're a Chief, but are those dolphins I see in the pic to the right? And a boomer pin?

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Jan Owen
Pooh-Bah
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Reged: 02/12/06

Loc: Sun City West, Arizona
Re: Why do people even buy SCTs??? new [Re: WesC]
      #6237746 - 12/06/13 04:51 PM



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maknewtnut
Member
*****

Reged: 10/08/06

Re: Why do people even buy SCTs??? new [Re: Jan Owen]
      #6238215 - 12/06/13 10:11 PM

Food for thought.....

Can the original question posed, and many of the points brought up thus far also apply to most MCT's?


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barasits
sage


Reged: 06/12/11

Loc: Chicago
Re: Why do people even buy SCTs??? new [Re: Ed Holland]
      #6238324 - 12/06/13 11:36 PM

PC Draco must have been off duty at the time.

Geoff


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: bob midiri]
      #6238341 - 12/06/13 11:51 PM

Quote:

Quote:

Quote:

Why would you want to use an SCT with a 38% central obstruction when you can use a refractor and look through the little hole in the center of the 62% outer obstruction?

The CO of the C14 is only 31-32%, the smallest of all Celestron and Meade SCT's. I own one and it puts up some amazing views through the eyepiece. I would take it over the AP 7" just for much better deep sky performance.

Bill



Not sure why anyone would buy one, personally I can't stand the SCT's




Hence, the garage sale.


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: Dwight J]
      #6238365 - 12/07/13 12:17 AM

Quote:

Well Rob, of course it is not for visual. I rarely do visual. It certainly works well with the small chip of a Mallincam. Hyperstar is used with DSLR's so the optics involved flatten the field. SCT's don't require an additional infrared blocking filter to prevent star bloat when using cameras sensitive in that area while most refractors happily pass out of focus infrared bloating star images. Refractors are not immune to curvature of field either given the need to add a field flattener for imaging. AFAIK, only Petzvall refractors have native flat fields. NO telescope design is perfect. The SCT's just happen to be good to very good at most things while a refractor excels in a few areas but fails miserably in others (weight, long moment arm on larger, price per inch, CA, field curvature, tall mounts, laying on ground to view zenith).




The Hyperstar on a C-14 would be interesting, especially with a low-noise CCD camera. If you get a chance to image with that system, I'd like to get your frank impression of it and see some of the images.

Given that the Hyperstar system doesn't accommodate a color filter wheel, (it has an optional single filter drawer), it doesn't seem amenable to remote imaging. For most of us, that likely isn't a severe issue.

Your critiques of refractors are either red herrings or irrelevant to those who make use of the design's advantages. Undesired NIR, CA, and field curvature with an apo refractor aren't factors (these are nil due to filters. the design, and field flatteners, respectively). In addition, the weight and moment arm of a 175 f/8 apo aren't issues for me or my mounts. If the pier height is matched to the telescope, you don't need to observe kneeling. The price per inch can be relatively high, but obviously those who are willing to pay for apo refractors see virtue in them, and they are pretty versatile for a wide range of photo-visual work, including wide-field, medium resolution, and lunar/planetary.


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: drago]
      #6238370 - 12/07/13 12:21 AM

Quote:

Quote:

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...




Then why do you have issues with the Tak Mewlon 300's CO?




dont understand, what you want from me?
i never say, any instrument with 38 or even 32 percent CO can be a great visual instrument.
for me, good visual instrument must have no more than 25% CO, very good - not more than 18%, better - less than 16%.




What are you basing your opinion on? Have you actually ever critically looked through an AP 10" f/14.6 Mak-Cass (CO ~ 23 %) or a Tak Mewlon 300 CDK? Their aperture and optical quality make their COs irrelevant.


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drago
sage


Reged: 01/11/08

Loc: Latvia
Re: Why do people even buy SCTs??? new [Re: JJK]
      #6238494 - 12/07/13 04:37 AM

Quote:


What are you basing your opinion on? Have you actually ever critically looked through an AP 10" f/14.6 Mak-Cass (CO ~ 23 %) or a Tak Mewlon 300 CDK? Their aperture and optical quality make their COs irrelevant.




i based it from my small knowledge in optics, my readings about a topic from amateur astronomers, who at the same time is professional optics ( most known there is Valeriy Deryuzin, i think), as so as another amateur publiced tests result in astroforums, who's compare various instruments and test one instrument with various central obstruction ( create a different masks, and test), and also my own small experience, when i have a newtonian with about 40+ percent CO and small achro at the same time.
and also from theoretical material, like as from link, who i publiced there.
also, theoretically, anyone can test central obstruction involved effects - there is need a good telescope ( apo, say), or off-axis clear aperture mask on newtonian, or SCT. any can look throught its clear aperture without CO, and then induce in that central aperture various circles to emulate a various CO. and compare it all between and without obstruction at all. its not a difficult, but a bit tiresome work, with very demonstratable results. sure, test object must be not very contrast, like moon, but object with small contrasts, where a small contrast loose give a big diff in view. say - jupiter....

also, if aperture make irrevelant CO, than their make irrevelant also instrunment optical quality, be consistent.

Edited by drago (12/07/13 04:42 AM)


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JJK
Carpal Tunnel


Reged: 04/28/08

Re: Why do people even buy SCTs??? new [Re: drago]
      #6238544 - 12/07/13 05:53 AM

Quote:

Quote:


What are you basing your opinion on? Have you actually ever critically looked through an AP 10" f/14.6 Mak-Cass (CO ~ 23 %) or a Tak Mewlon 300 CDK? Their aperture and optical quality make their COs irrelevant.




i based it from my small knowledge in optics, my readings about a topic from amateur astronomers, who at the same time is professional optics ( most known there is Valeriy Deryuzin, i think), as so as another amateur publiced tests result in astroforums, who's compare various instruments and test one instrument with various central obstruction ( create a different masks, and test), and also my own small experience, when i have a newtonian with about 40+ percent CO and small achro at the same time.
and also from theoretical material, like as from link, who i publiced there.
also, theoretically, anyone can test central obstruction involved effects - there is need a good telescope ( apo, say), or off-axis clear aperture mask on newtonian, or SCT. any can look throught its clear aperture without CO, and then induce in that central aperture various circles to emulate a various CO. and compare it all between and without obstruction at all. its not a difficult, but a bit tiresome work, with very demonstratable results. sure, test object must be not very contrast, like moon, but object with small contrasts, where a small contrast loose give a big diff in view. say - jupiter....

also, if aperture make irrevelant CO, than their make irrevelant also instrunment optical quality, be consistent.





If your eyesight is excellent, I recommend you check out views through very well-made, relatively large aperture telescopes with COs (e.g., the AP 254 mm f/14.6 Mak-Cass and Tak Mewlon 300 f/~10) when the seeing is very good. I think you'll find that with telescopes of this quality and aperture, the effect of the CO on contrast is essentially irrelevant (which is what I should have said). I've spent a lot of time reading textbooks on optical theory, but the time spent behind the EPs of well-made telescopes of different designs & apertures was equally enlightening.

Why don't you ask Valery Deryuzhin, who collaborated on the AP Mak-Cass project with Roland Christen, about that scope's performance? I've found it to provide large refractor-like views (high contrast views of Saturn, Jupiter, Ganymede; tiny pinprick stars; delicate network nebulosity in M42; central star in M57; etc.), that no 11" SCT I've critically looked through up to a decade ago ever did (not even close).


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Vondragonnoggin
Post Laureate
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Reged: 02/21/10

Loc: Southern CA, USA
Re: Why do people even buy SCTs??? new [Re: maknewtnut]
      #6238585 - 12/07/13 07:22 AM

Quote:

Food for thought.....

Can the original question posed, and many of the points brought up thus far also apply to most MCT's?




The relative numbers of sales for each respective scope differ too much to support a fan base that will accumulate enough respondents to warrant a 15 page thread debating the odd design they love.

The numbers of sales on MCT's vs SCT's is meniscuscule by comparison...



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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: JJK]
      #6238674 - 12/07/13 09:31 AM

Quote:

Quote:


Given that the Hyperstar system doesn't accommodate a color filter wheel, (it has an optional single filter drawer), it doesn't seem amenable to remote imaging. For most of us, that likely isn't a severe issue.






With the size of the C14, you do have the option of the QSI583ws with its compact size and internal filter wheel. S&T did a test with just this setup. And because of the short focal length of the HS equipped C14, the 8300 chip would be terrific.

David


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Wmacky
Carpal Tunnel
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Reged: 11/24/07

Loc: Florida
Re: Why do people even buy SCTs??? new [Re: David Pavlich]
      #6238708 - 12/07/13 10:03 AM

Soooooo-

Edggie Creates the thread out of his frustration about the constant SCT bashing that goes on. (In case you didn't know why?)

And then several take the opportunity to do just that?

What a group!



I really don't see what the mystery is? I, as many on the site, have built a small observatory with a centrally located EQ mount for both imaging , and visual duty. I can easily swap out refractors for imaging, and SCTs for visual.

What the hell would I do with a DOB? Balance it on top of my GEM? Put it on the roof? I don't care how good the views are, a Dob is worthless in my observatory. Refractors work nicely, and I do use them to image, but they are too small for many many DSOs. If your are a retired Doctor, or lawyer with a giant AP refractor, then good for you, but I would think most people will never own a giant premium refractor. Beside they would not fit into the average size home observatory.

I just don't see the mystery?

For me - A SCT offers decent aperture for DSO's, but can still be quickly mounted on a GEM - Can be used for imaging DSOs at long focal lengths for close ups. - Is a preferred planetary imaging platform. - Can be easily swaped out on the GEM with a refractor for widefeild imaging, and views- Finally they don't cost much.

?????????????

Edited by Wmacky (12/07/13 10:48 AM)


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eklf
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Reged: 05/12/07

Loc: Carrboro, NC
Re: Why do people even buy SCTs??? new [Re: Wmacky]
      #6238760 - 12/07/13 10:39 AM

Why did I even get a SCT?

I have three refractors: ST80, 102mm F10, 127mm f6.5; and a 200mm f6 dob. I also have a lower back issue (an unfortnate hernieted disc that makes it painfull to lean forward even slightly), and reside in a third floor apartment.

I got a C6 SCT, and made a diy dob-like base for it on an existing tripod. This has been become the most used scope because I can sit comfortably, straight backed, with my feet under the scope and view in heavenly comfort. To me this aspect of sct is worth the price of admission for me. The 127mm refractor did some similar, but not to the extent as the swing in eyepiece height when changing the altitude was much more than the sct.

One of Mike Costello's post has given me an idea to see if I can combine the 127mm refractor and C6.


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