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8" SCT v. 11" SCT



 
 
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  #11  
Old September 27th 05, 09:54 PM
Stephen Paul
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"Disappointing" is a highly subjective term. Although I don't necessarily
disagree with the idea that a 3" jump isn't as great as a 10" jump. ;-)

But I would never recommend an 18" Dob. You have to come to that on your
own, as a slow progression up the aperture fever ladder.

There is also by virtue of differences in geographic location, a lot of
subecjtive matter to work through, which is why participating in a local
group of amateur astronomers is the best way to work through all the fuss of
settling on the right scope.

For me, that currently seems to be a C9.25 on a G-11 with ScopeBuggy, and
all the necessary accessories to combat the elements, along with an
electronic finder system. It best suits my style of observing in concert
with my local atmospheric conditions, as well as my budget, and my home base
conditions.

I don't go out of the yard often enough to focus on a scope that best suited
that need. Instead I concentrated on what it would take to get me out in the
backyard on most clear nights, without being thwarted by conditions within
the control of available technology.

Astronomy is not a life pursuit for me, where I venture off into the
wilderness every chance I get, to hunt down the wonders of the universe
under pristine skies. It is something I do in my spare time, from my back
yard.

I've concluded that between tucking the kids in bed, and going to sleep, it
is better to go out for an hour or two and swing the scope around using RA
and Dec counters, than it is to sit in the house on my ass, and miss the
chance to look at all those wonderful star clusters. I don't care how they
get in the eyepiece, the easier that is, the better. Hunting down an object
in a huge scope just doesn't relax me as much as looking through the
eyepiece. I'd rather struggle with a dim object in the eyepiece for 5 or 10
minutes, than struggle with a red light and a chart that I can't read
without my reading glasses.

Keep in mind that no matter what the aperture, there are always objects of
any given class that are "dim". I think it's better to become intimately
familiar with those objects you can see well, in whatever aperture you have
on hand at the time. Including a little 80mm ED refractor on a simple
altazimuth mount. Especially with objects you know so well as to find them
in 10 seconds without so much as a red dot finder.

Subjectively yours,
-Stephen

"Doink" wrote in message
...
Unless you have a very well trained eye, the difference will be
disappointing----you are chasing small increments of "improvement". From
your 8", the next real step upwould be a 18" DOB.

Doink


"Mark D" wrote in message
...
The one thing to remember, is an 8" compound scope (of mostly any type
note), is not technically a 8" scope due to secondary obstruction.

The 11" will show you more detail, nebulosity, fainter stars, and split
closer doubles under virtually any sky conditions, urban, suburban, and
dark sky. Naturally, aperture will truly shine, and have the advantage
under dark, transparent sky conditions.

Also to remember, the larger the aperture, generally, the longer the
cooldown period. There are ways around this. Lymax cooling fans,
setting scope up prior to an observing run, etc.

Dark sky conditions are not needed to do serious Planetary-Solar-Lunar
observation-imaging. What is needed is a steady calm atmosphere, and
equilibration of the scope.

With Solar Imaging-Observing, there probably wouldn't be much gained
between the 8"SCT, and the 11" SCT with white light filter. Mark





  #12  
Old September 27th 05, 10:34 PM
rat ~( );>
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Another Oink from Doink..... oink oink!

Yeah, I owned 8" and 11" SCT's at the same time and the 11" blew the 8"
clear out of the water. Even against my well-optimized 10" Zambuto
Newt, the one extra inch of the 11" still gave it the edge in terms of
light grasp (fainter stars visible at the same x). BTW, I gave the Newt
a tune-up today so I can get back to using it for DSO's. It is
currently my biggest aperture scope. I need to get a new focuser for
it.

rat
~( );

  #13  
Old September 27th 05, 11:17 PM
Doink
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Mark---

Did I say the differences would not be discernable? NO. I said the
difference would be disappointing. You can demonstrate by mathematics what
the differences are---more light gathering, higher resolving power, etc.,
but will he be stunned at the difference when he takes that first look in
the eyepiece? I doubt it. And that is my point.....and size and weight
aside, what about dumping more money into a small increment of gain?

Of course, if he pays ENOUGH, he WILL see a big difference! The AA ego is
huge and I've never seen a bad review!!!!!!!!!!!!

Doink


"Mark D" wrote in message
...
Unless you have a very well trained eye, the difference will be
disappointing----you are chasing small increments of "improvement". From
your 8", the next real step upwould be a 18" DOB.
Doink
======================================

This statement you have made Doink I have to disagree with in part.

First off, I believe the differences would easily be seen by a rank
beginner, particularly, if each of these scopes previously mentioned sat
side by side, and I feel that the differences would not be
"disappointing" as you say. Nor, is the next real step up from an 8"
SCT, an 18" Newtonian.

I feel that in the SCT department, once one starts to go above 8" of
aperture, thats when one can start to appreciate the increase in
aperture. An 8" SCT has always left me wanting more. I've found
personally, that an 8" SCT usually just begins to resolve many globular
clusters, while the larger SCT's will resolve them quite nicely.

While as you say, small increments will be noted, and this will be
somewhat true under light polluted skies with DSO's, the difference in
planetary detail using an 8" SCT vs an 10"-11" SCT will be quite
apparent on Planetary.

Naturally, the downside becomes size, and weight with the larger SCT's.
Mark



  #15  
Old September 27th 05, 11:19 PM
Pierre Vandevenne
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"Doink" wrote in
:

power, etc., but will he be stunned at the difference when he takes
that first look in the eyepiece? I doubt it.


Give it a try.

--
Pierre Vandevenne - DataRescue sa/nv - www.datarescue.com
The IDA Pro Disassembler & Debugger - world leader in hostile code analysis
PhotoRescue - advanced data recovery for digital photographic media
latest review: http://www.pcmag.com/article2/0,1759,1590497,00.asp
  #16  
Old September 27th 05, 11:22 PM
Pierre Vandevenne
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"Doink" wrote in
:

I can resolve many stars with my MK-67 (6") within the heart of M13.
And can also do so with my 8" reflector.


That's what I said

an 8" (my skies are poor, your mileage may vary), it definitely


For example, light pollution makes it impossible for me to get fully dark
adapted - I can read magazines outside at night almost wherever I go in
Belgium.

This being said, all other things being equal, the difference with the C11
is really visible.


--
Pierre Vandevenne - DataRescue sa/nv - www.datarescue.com
The IDA Pro Disassembler & Debugger - world leader in hostile code analysis
PhotoRescue - advanced data recovery for digital photographic media
latest review: http://www.pcmag.com/article2/0,1759,1590497,00.asp
  #17  
Old September 27th 05, 11:22 PM
Doink
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Scary. I find myself growing in agreement with you with each post.

Doink


"Stephen Paul" wrote in message
...
"Disappointing" is a highly subjective term. Although I don't necessarily
disagree with the idea that a 3" jump isn't as great as a 10" jump. ;-)

But I would never recommend an 18" Dob. You have to come to that on your
own, as a slow progression up the aperture fever ladder.

There is also by virtue of differences in geographic location, a lot of
subecjtive matter to work through, which is why participating in a local
group of amateur astronomers is the best way to work through all the fuss
of settling on the right scope.

For me, that currently seems to be a C9.25 on a G-11 with ScopeBuggy, and
all the necessary accessories to combat the elements, along with an
electronic finder system. It best suits my style of observing in concert
with my local atmospheric conditions, as well as my budget, and my home
base conditions.

I don't go out of the yard often enough to focus on a scope that best
suited that need. Instead I concentrated on what it would take to get me
out in the backyard on most clear nights, without being thwarted by
conditions within the control of available technology.

Astronomy is not a life pursuit for me, where I venture off into the
wilderness every chance I get, to hunt down the wonders of the universe
under pristine skies. It is something I do in my spare time, from my back
yard.

I've concluded that between tucking the kids in bed, and going to sleep,
it is better to go out for an hour or two and swing the scope around using
RA and Dec counters, than it is to sit in the house on my ass, and miss
the chance to look at all those wonderful star clusters. I don't care how
they get in the eyepiece, the easier that is, the better. Hunting down an
object in a huge scope just doesn't relax me as much as looking through
the eyepiece. I'd rather struggle with a dim object in the eyepiece for 5
or 10 minutes, than struggle with a red light and a chart that I can't
read without my reading glasses.

Keep in mind that no matter what the aperture, there are always objects of
any given class that are "dim". I think it's better to become intimately
familiar with those objects you can see well, in whatever aperture you
have on hand at the time. Including a little 80mm ED refractor on a simple
altazimuth mount. Especially with objects you know so well as to find them
in 10 seconds without so much as a red dot finder.

Subjectively yours,
-Stephen

"Doink" wrote in message
...
Unless you have a very well trained eye, the difference will be
disappointing----you are chasing small increments of "improvement". From
your 8", the next real step upwould be a 18" DOB.

Doink


"Mark D" wrote in message
...
The one thing to remember, is an 8" compound scope (of mostly any type
note), is not technically a 8" scope due to secondary obstruction.

The 11" will show you more detail, nebulosity, fainter stars, and split
closer doubles under virtually any sky conditions, urban, suburban, and
dark sky. Naturally, aperture will truly shine, and have the advantage
under dark, transparent sky conditions.

Also to remember, the larger the aperture, generally, the longer the
cooldown period. There are ways around this. Lymax cooling fans,
setting scope up prior to an observing run, etc.

Dark sky conditions are not needed to do serious Planetary-Solar-Lunar
observation-imaging. What is needed is a steady calm atmosphere, and
equilibration of the scope.

With Solar Imaging-Observing, there probably wouldn't be much gained
between the 8"SCT, and the 11" SCT with white light filter. Mark







  #18  
Old September 28th 05, 02:39 AM
Llanzlan Klazmon
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Default

"decaf" wrote in news:1127796199.636743.25410
@g43g2000cwa.googlegroups.com:


Unless you have a very well trained eye, the difference will be
disappointing----you are chasing small increments of "improvement". From
your 8", the next real step upwould be a 18" DOB.



Upgrading from 8" to 11" aperture, assuming same quality and type of
instrument means a nearly two fold increase in light gathering and 27%
increase in resolving power, respectively. That is _quite_ significant
even to the
casual observer. Planets will be more colorful and show more detail,
the
Moon will be painfully brillliant, and DSO's will have substantially
greater
visibility.


Actually, I don't think it makes any difference at all to the brightness of
the moon. This is true in a telescope of any size. Surface brightness
cannot be increased by a passive optical system as it would be a violation
of thermodynamics.

Klazmon.



And-- you can run the magnification up to 150x higher than
with the
8"er if conditions warrant it; I'd say that's more than a "small
increment
of improvement". A longer cool-down time will be required though.

Dan Chaffee


  #19  
Old September 28th 05, 03:36 AM
external usenet poster
 
Posts: n/a
Default

Of course, if he pays ENOUGH, he WILL see a big difference! The AA ego is
huge and I've never seen a bad review!!!!!!!!!!!!


Doink
------

Some thoughts:

I have seen more than a few negative reviews. If you want a review
which severely critizies a scope, a "BAD REVIEW", here's one for you:

http://www.cloudynights.com/item.php?item_id=1105

I like David Knisely's reviews on Cloudy Nights, he has been around a a
long time and knows what's what, he writes a descriptive review that
pretty much lets one know what a skilled observer can do with a given
scope, what its strengths and weakness are, just a good well done
review.

---------------

Personally I see very few "large egos" here or on other astro forums.
What I see here are people with varying amount of experience sharing
that experience with the hope of helping someone else. That is how I
view my role here, helping others and getting help for myself.

-----

I will say that my experience with people who are looking through
scopes where one collects about twice as much light is that they are
indeed impressed. Myself, I am very impressed with the difference
between my 70mm Pronto and my 100mm "Burion" (=Burgess OTA + Orion
100mmF6 Achro.) The Pronto is a much higher quality scope but these
days I rarely use it simply because the added aperture of the Burion
shows more, both DSO and planetary.

Jon Isaacs

  #20  
Old September 28th 05, 04:17 AM
Michael Wood
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On Mon, 26 Sep 2005 21:48:07 +0000 (UTC),
wrote:

I have an 8" Celestron SCT w/ Starbright XLT coatings, and am considering upgrading to an
11" Celestron SCT w/ Starbright XLT coatings. While I have looked through another amateur
astronomer's 11" SCT and was very impressed, that experience was at a dark sky location,
and I'm accustomed to urban skies. So I'm hesitant; how different will the 11" really be?
What more can I expect to see that I cannot see with my 8"? Any experienced responses would
be appreciated.


I have 8" Meade and 11" Celestron SCTs. The 11" runs rings around
the 8" as far as resolving DSOs. There is a noticable difference. I
use the 8" mostly for photography but it's a very good scope on its
own merits. My NS11 is relatively heavy but is quite manageable and
compact for an 11 inch scope. I used to have a 10" Dob with a very
nice Parks mirror and the Celestron has proven to be even better. I
don't think you can go wrong, especially under light polluted skies,
with more aperature.


 




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