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Main
Date: 19 Jun 2007 07:29:24
From: brucegooglegroups
Subject: view of Jupiter with 4.5;lm13
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I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
Although I could see three moons, Jupiter appeared only white, and I
could not see any details. Is this due to atmospheric conditions, my
viewing site, and/ or limitations of the scope?
I also tried to find m13 and was also disappointed. Even with
magnification, M13 looks similar to m31 in binoculars- unless I was
looking at something else:) I could see no details.
Also, I have been thinking of cleaning the primary mirror which has
not been cleaned since I bought the scope a year ago. There is a lot
of dust on it, and the views at night don't seem as clear. Should I
bother with the cleaning? The scope is collimated. There seems to be a
lot of opinion towards not cleaning the primary mirror unless
necessary.
Suggestions?
Bruce
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Date: 24 Jun 2007 20:58:21
From: Kresimir F.
Subject: Re: view of Jupiter with 4.5;lm13
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"brucegooglegroups" <brucegooglegroups@hotmail.com > wrote in message
news:1182263364.439147.239660@q75g2000hsh.googlegroups.com...
>I viewed Jupiter last night in my Skyquest 4.5 and was .
>
> Although I could see three moons, Jupiter appeared only white, and I
> could not see any details. Is this due to atmospheric conditions, my
> viewing site, and/ or limitations of the scope?
>
> I also tried to find m13 and was also disappointed. Even with
> magnification, M13 looks similar to m31 in binoculars- unless I was
> looking at something else:) I could see no details.
>
> Also, I have been thinking of cleaning the primary mirror which has
> not been cleaned since I bought the scope a year ago. There is a lot
> of dust on it, and the views at night don't seem as clear. Should I
> bother with the cleaning? The scope is collimated. There seems to be a
> lot of opinion towards not cleaning the primary mirror unless
> necessary.
I've been very disappointed on few 1st lights with my 120mm refractor
hovever yesterday I was able to see quite a lot of atmosphere while looking
short after sunset. Jupiter is not SO bright so detailes emerge because your
eyepice is not filled with its brightness so much.
I think magnification of about 60 - 120 x is good for it
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Date: 20 Jun 2007 06:44:48
From: brucegooglegroups
Subject: Re: view of Jupiter with 4.5;lm13
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On Jun 19, 10:09 pm, egdbert <notinthislifet...@sorry.man > wrote:
> On Tue, 19 Jun 2007 07:29:24 -0700, brucegooglegroups
>
> <brucegooglegro...@hotmail.com> wrote:
> >I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
>
> >Although I could see three moons, Jupiter appeared only white, and I
> >could not see any details. Is this due to atmospheric conditions, my
> >viewing site, and/ or limitations of the scope?
>
> Two things that come to mind: Where are you observing from and what
> magnification are you using when viewing jupiter or M13?
>
> AY
Also- the magnification was 25, and I also tried viewing both Jupiter
and M13 with a 10plossl eyepiece, and the 25 with a 2x Barlow.
Bruce
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Date: 27 Jun 2007 21:44:30
From: AstroApp
Subject: Re: view of Jupiter with 4.5;lm13
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On Wed, 20 Jun 2007 06:44:48 -0700, brucegooglegroups
<brucegooglegroups@hotmail.com > wrote:
>On Jun 19, 10:09 pm, egdbert <notinthislifet...@sorry.man> wrote:
>> On Tue, 19 Jun 2007 07:29:24 -0700, brucegooglegroups
>>
>> <brucegooglegro...@hotmail.com> wrote:
>> >I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
>>
>> >Although I could see three moons, Jupiter appeared only white, and I
>> >could not see any details. Is this due to atmospheric conditions, my
>> >viewing site, and/ or limitations of the scope?
>>
>> Two things that come to mind: Where are you observing from and what
>> magnification are you using when viewing jupiter or M13?
>>
>> AY
>
>Also- the magnification was 25, and I also tried viewing both Jupiter
>and M13 with a 10plossl eyepiece, and the 25 with a 2x Barlow.
>
>Bruce
Hi, Bruce!
I'd like to offer my opinions in order to give you some perspective,
as I've been following your travails and disappointments for some
time. My consolations!
Now, I realize that every time I post, there is likely to be quite a
cascade of objections and disagreements; I'm expecting it and won't
argue or debate with anybody. If you put forty planetary observers
together in one room, you are likely to get forty opinions...so I
won't make the mistake of thinking that my advice, experiences, and
opinions are at all representative, reliably useful, and universal.
So everybody else who offers help here is giving their best shot at
it, and I don't object to differences of opinion.
With respect to the magnification used for Jupiter and M13, you must
memorize the VERY simple equation necessary to determine the power
being used with your telescope; it's just simple arithmetic and you
can do it in your head for all your eyepieces.
MAGNIFICATION = Telescope focal length divided by Eyepiece focal
length (in same units)
In your case, the Starquest 4.5 reflector telescope has a focal length
of 910 mm (~35.8 inches) and the eyepieces of course you know: your
10mm and your 25 mm (and the 2x barlow just doubles their focal
lengths.)
So the magnifications being used are these: with the 10mm eyepiece.
910/10=91x. WIth 25 it is 910/25=36.4. Add the Barlow, in each case
it would be 182x, and 72.8x, respectively.
Now, there are a couple of other factors you should remember.
For observing the highest resolved images of point sources -- stars --
you can use 50 to 60 times the diameter of the aperture in inches with
a PERFECT set of optics and PERFECT sky steadiness. That means you
could theoretically use 225x to 270x with a superb instrument of that
aperture under the most steady "seeing" imaginable.
But, remember that there are some things that separate your scope from
being "theoretically perfect". It has a secondary mirror, which
blocks some of the light and causes a change in the 'diffraction
pattern' and tends to increase the effects of blurry air by at least a
small amount. A very, very expensive high quality apochromatic
refractor -- costing $2000 to $5000 -- with 'diffraction limited
optics' -- could likely give a flawless resolved star image at such
magnifications, with the star WAY up high in the sky, under flawless
weather conditions. But, sadly, not your inexpensive telescope. I
have a very similar model myself, and it's rare that I can use it at
50x per inch of aperture.
So, while some advanced astronomers with deep pockets can recommend
that you go to that amount of magnification, based on how great it
looks in their scopes, it is PROBABLY true that with a $239
mass-produced reflector telescope, you are rarely going to get such
clean views (even with perfect mirror collimation.)
I've done way over 50x-60x per inch of aperture with an $8000
"StarFire" refractor, and occasionally with my Celestron C-11. But in
your case, figure that you will get diminishing returns -- what is
called "empty magnification" that does not yield increased detail --
at such levels of magnification. You may find that your scope works
well under typical skies -- with objects up high -- at, say, 25x to
40x per inch of aperture, which would mean about 112x to 180x.
And, that's for *stars*. With planets, you might have to downgrade
the magnification even a little more.
With my 120 mm (4.7 inch) achromat refractor, I rarely get a good view
of Jupiter with much more magnification than 110-150x. On the night
of Sunday 24 June 2007, however, the steadiness of the air was SO good
that bright Antares, near Jupiter, hardly twinkled at all to the naked
eye, from my driveway in San Jose, CA. at an elevation above sea level
of perhaps 200 meters.
I was so thrilled with the view of Jupiter with my 9 mm eyepiece
(which, in my scope, yields 111x) that I cranked up the power using
instead my 6.3 mm Orion "Highlight" Ploessl, a very good, sharp, high
contrast eyepiece: 158.7x. I then tried other eyepieces and Barlow
combinations but NOTHING much higher in magnification than that was
useful: it was all "empty magnification" and the details faded out.
But, I've looked at Jupiter on at least several dozen other nights
since getting that telescope about 18 mos. ago, and not one other time
has it been really detailed. Not ONE time! It was always blurry,
with only vague details. On this particular evening, however, I saw
so many bands, from pole to pole, with fine details (loops, festoons,
ovals, etc.) that I first thought of trying to make a sketch but
realized it was SO detailed that I simply could not draw all that I
was seeing! Since I don't have a clock drive on my equatorial mount
and had to adjust the right ascension knob every few seconds, it would
have been a pain to make a drawing, which would not have done justice
to what I was seeing.
Now, if I had based my opinion of the optics of that scope (an Orion
120 SkyView Pro f/8 refractor) on the previous views of Jupiter, I
would have thought that the scope was DEFECTIVE.
But my experience in looking at Jupiter, which dates as far back as
1957, has convinced me that if you get a crisp, sharp, clear view once
or twice a YEAR, you're lucky. And by this I mean something that just
makes you gasp; looks better than almost anybody's carefully fine
tuned CCD image; and gives you the feeling of complete satisfaction.
Those kinds of views, where I live, don't come often. And I am in a
region of "laminar air flow" near the Pacific ocean, a few miles from
Lick Observatory's Mt. Hamilton, long renowned for the steadiness of
its air.
Jupiter gets a LITTLE better than my typical driveway views when I
take the scope to a mountain top site I use near Santa Cruz, at 3,400
feet elevation. But, just a LITTLE better. Often, using my excellent
C-11 scope at that spot, Jupiter is little more than a blinding,
featureless blur.
One view of Jupiter at that site, however, was fortuitous: the night
after the collision of the train of Shoemaker-Levy 9 comet fragments
with Jupiter. A friend's 7" StarFire showed the effects in a view
that was seemingly as sharp as the Hubble picture I later downloaded
from the Net. Yet, even with this same scope, Jupiter could look dull
and bland, showing only a couple of vague bands, on other occasions
when the conditions weren't *just right*.
So, you really must not CONCLUDE from random experiences viewing
Jupiter that something is wrong with your telescope.
The person who advised you to try a local star party or astronomy club
group gathering is right on the money. You need to take your scope
out with several others, whose owners have lots of experience with
them, and compare what you see in theirs, while they look through
yours.
Much hand-wringing about collimation is mis-applied.
Here is an example from my last two observing sessions, with my 10"
f/4.7 Orion Dob. These nights, last week, were polar opposites with
respect to seeing. The first one was miserable, even at 3,400 feet
altitude in the mountains. Stars were blurry and fuzzy. I seemed to
be having trouble with some of my eyepieces and noticed aberrations,
including unstable, astigmatic images. I RESISTED THE URGE TO
COLLIMATE!
The next afternoon in daytime, I checked with my chesire eyepiece and
sight tube: collimation was perfect.
The following day, not having TOUCHED the scope adjustments, I took it
back up the mountain. Now, stars were flawless tiny tight pearls of
light: brilliant, stable, steady points. M-11 was such a shocking
experience, in the gem-like precision of its uncountable diadems, that
the view reminded me of the perfection of my friend's 7" StarFire.
No changes or adjustments were done to the scope for either session;
and I have found from long experience that the mirror cell and
secondary do NOT shift at all over time.
The poor results the first night were entirely due to seeing effects.
So, do not CONCLUDE from various random tests of your scope at night
that there is something deficient about the optical figure of the
components!
Finally, with respect to M-13: a four to five inch scope does not
ideally resolve most globular clusters. You are at the cusp of doing
it with your 4.5 incher and can resolve a few bright stars across the
'face' of M-13, and some bright outlying members in really good
seeing; but in many sessions you can't do it and the globular, large
though it may be, can seem blurry and indistinct.
As you increase the aperture diameter you increase the resolution. In
my 10" scope, M-13 is a feast for the eye, and sparkles with rich
detail and myriad fine points. Only in the last four or five years,
in fact, have CCD images begun to replicate the resolution and detail
of the larger globulars AS SEEN BY EYE with a 10 inch or larger scope.
Even so, it takes perhaps a 15 inch or larger one to really enable you
to "get inside" many globulars and see fine details to the core.
A 4.5 inch aperture scope is quite sufficient to *reveal* the
existence of all the Messier globulars; but it won't yield flawless
resolution. You can tell that -- yes -- it's a globular and not just
a fuzzy nebula; but the starry nature will only be suggested in most
cases, rendered as a sort of graininess.
So do not CONCLUDE that your scope is defective merely by making a few
random observations of M-13.
You can also use the maximum possible magnification on a globular
cluster, going all the way up to the rule of thumb values of 50-60x
per inch of aperture in a fine telescope under flawless seeing. Maybe
in an *average* telescope under *typical* mediocre seeing you won't
get much improvement over, say, 30x to 40x per inch of aperture. Try
and see where the detail vs. size starts to yield diminishing results.
If I were impatient with my various scopes -- I have five at present,
ranging from 80 mm to 11 inches aperture -- I would have concluded
that EVERY ONE was defective, poor, and next to useless.
For during the last two and a half years that I have owned them, there
have been nights that were so lousy that each scope gave a totally
unsatisfactory, substandard result.
But, I've owned maybe thirty scopes over the past 40+ years, and know
from experience that this happens... and am patient. So, as expected,
I always encounter one of those GREAT nights when the optics perform
better than I even imagined that they COULD do. Such a night was last
week, when my 10" Dob just blew me away with its spectacular, sharp,
high contrast images.
The range between "lousy" and "great" is closer in a 4 inch than in a
very large aperture scope (which is more sensitive to the variations
in seeing than a small scope.) Practically every time I use my 3" to
4.7" scopes, I can find SOMETHING to look at that is pretty
satisfying. If planets and stars are not so sharp and clear, try
larger scale objects (like large diameter nebulae.) You may not,
though, always be able to see them from in-town.
The presence of streetlights won't hinder your planetary observing;
some people think that in fact ambient light AROUND the telescope
venue (as long as it isn't shining right into the tube) will help your
eyes use its sharp resolution receptors rather than the fuzzier
dim-light receptors. That is exactly my experience in my San Jose
driveway, where three gigantic sodium vapor lights blow my dark
adaptation away. But, I can see the Moon or planets very nicely.
Yet, as I did last Sunday, if I move the scope over to see M-4, it's
just practically invisible. (In a dark sky, without those
streetlights, in the same scope it's quite a spectacle, since my eyes
get fully dark-adapted.)
Finally, as to colored filters, my experience is contrary to many
other people's advice.
I don't find them particularly useful with SMALL aperture scopes.
In fact, last Sunday I did a great deal of experimentation on Jupiter
with my filters, using the 4.7" refractor. In each case the planet
showed far more detail with NO filter.
In a large scope the planet is so bright that "irradiation" occurs in
your eye, and filters will help diminish its effects.
And in very bad seeing conditions, a blue or green filter will
SOMEWHAT improve the contrast of dark-against-light details such as
dark equatorial bands.
But in excellent seeing with a small (i. e., 3 inch to 5 inch)
aperture scope, I don't use colored filters for Jupiter.
I have done so for Mars with some slight improvement.
I have also done tests with the 7" StarFire on Jupiter and Saturn and
found that, almost always, more detail was visible with no filter.
So: try a filter at a star party, and see what you think. Years ago
they were pretty cheap but I see that the cost is coming up. I rarely
use my colored planetary filters, and don't really think they were
worth the money (but I use my nebular filters constantly.)
The one value of my colored filters, with planets, has been in doing
CCD images in monochrome mode. Even with my C-11, if I can manage to
stare at Jupiter's glare -- which wrecks your dark adaptation for deep
sky objects for the next hour! -- I haven't found colored filters
particularly essential for visual observation.
Jupiter's Great Red Spot used to be so much brighter that the filters
would help bring it up into higher distinction and improve the
contrast; in recent years I don't find that to be the case any more.
Now. The great debate begins...
Steve - "AstroApp"
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Date: 27 Jun 2007 21:55:45
From: AstroApp
Subject: Re: view of Jupiter with 4.5;lm13
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Bruce,
I forgot to add a very important point:
I *agree precisely* with Dennis that you should not CONCLUDE now that
you need to clean your optics.
I have seldom cleaned telescope mirrors more often than every five
years or so; in some cases I've waited ten years!
You are not losing resolution merely because there are some tiny
particles of dust on your mirrors.
You will do far more harm than good by cleaning a one-year-old scope,
assuming that you have stored it carefully between uses with the tube
cap on, something stuck into the eyepiece holder, and maybe a plastic
baggie around the base of the tube near the primary mirror.
My Orion f/4.7 Dob is over 2 years old and there is noticeable dust
all over the primary and secondary (the site I use is VERY dusty, and
sometimes trucks barrel along the dirt road near me and throw up a
huge cloud of stuff; I cough and wipe my eyes!) Yet, as I said, my
view of M-11 and other objects just last week BLEW ME AWAY because the
images were so sharp, clear, and high contrast. With all that dust on
my optics!
I will probaby wait two more years before I clean the 10" scope's
glass.
Then, it is a delicate, tedious process, to be followed by hours of
work getting everything perfectly lined up again. Yucch!
So, just keep the thing covered when you are not using it and don't
worry.
I believe all your disappointments are LIKELY to be the result of bad
seeing. Everything you've said about all your frustrations is
something I too experience from time to time -- yet, I make no changes
to my scopes and -- voila! -- the next time, I get a better night and
confirm that there is nothing physically wrong with them.
Try an experiment:
Take the scope outside every night; leave it for an hour after dark to
cool down; and then look at the same stars OVERHEAD. Each night
they'll move a few degrees but not enough to matter. You will notice
that your results will vary significantly, night to night.
Jupiter, however, is not that high at present. Seeing conditions
closer to the horizon will be exaggerated. So your results on Jupiter
will vary HUGELY, night to night.
After six or seven days of viewing the same things consistently, with
the scope cooled down to ambient temperature, you'll start to get a
base line of performance and understand the difference between good
and bad (or at least better and worse.)
Steve - AstoApp
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Date: 20 Jun 2007 06:43:14
From: brucegooglegroups
Subject: Re: view of Jupiter with 4.5;lm13
|
On Jun 19, 10:09 pm, egdbert <notinthislifet...@sorry.man > wrote:
> On Tue, 19 Jun 2007 07:29:24 -0700, brucegooglegroups
>
> <brucegooglegro...@hotmail.com> wrote:
> >I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
>
> >Although I could see three moons, Jupiter appeared only white, and I
> >could not see any details. Is this due to atmospheric conditions, my
> >viewing site, and/ or limitations of the scope?
>
> Two things that come to mind: Where are you observing from and what
> magnification are you using when viewing jupiter or M13?
>
> AY
Hi Ay,
I am viewing Jupiter and M13 from New England.
Clear skies.
Bruce
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Date: 19 Jun 2007 22:09:01
From: egdbert
Subject: Re: view of Jupiter with 4.5;lm13
|
On Tue, 19 Jun 2007 07:29:24 -0700, brucegooglegroups
<brucegooglegroups@hotmail.com > wrote:
>I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
>
>Although I could see three moons, Jupiter appeared only white, and I
>could not see any details. Is this due to atmospheric conditions, my
>viewing site, and/ or limitations of the scope?
Two things that come to mind: Where are you observing from and what
magnification are you using when viewing jupiter or M13?
AY
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Date: 19 Jun 2007 18:14:48
From: brucegooglegroups
Subject: Re: view of Jupiter with 4.5;lm13
|
On Jun 19, 7:17 pm, "jimandlaura26" <jimandlaur...@comcast.net > wrote:
> Bruce,
>
> >
> 3. M13 - Can in-fact look blob-like (no stars resolved) in light-polluted
> skies and/or using a small aperture scope and/or when positioned low in the
> sky. Since you have a fixed aperture scope, the most immediate solution for
> you get to a darker site, wait for more favorable sky seeing/transparency,
> and when it approaches the zenith. One or more of these factors can make a
> huge difference.
>
> The bottom line is... that the quality of what you can see is a function of
> a chain of factors from your brain, to the eyepiece, to the filters, to the
> scope aperture/optical quality, collimation & mechanics, to the mount, to
> sky conditions, to the type of object. You have to work all of these
> simultaneously... and the bad news is that any degradation in the chain will
> degrade the view.
>
> Jim M.
> Northern Virginis
Jim,
Thanks so much for your reply. I feel better about the situation after
reading it. I have been spending the past year learning the sky- I am
new to this- and I want the maximum enjoyment without the hassle.
Despite reading, and looking at charts- getting to the deep sky can be
challenging.
I own a skyscout, which makes navigating much easier, Orion Vista
Binocs and the Orion 4.5 Dob. - but I was leaning towards eventually
buying a Nexstar 8 .
The best times I have in skygazing are usually with the binocs, the
Skyscout or just looking at the sky and recognizing new stars and
constellations.
However, I want the same experience with the telescope. So far, aside
from the moon viewing, it's been disappointing. I want the same hassle
free enjoyment with a telescope as with the skyscout and the binocs.
I will consider the filters. However, the mechanics in my scope are
the big drawback. I did collimate the scope. The mirror spot is dead
center. But the views seem not as clear as when I first got the scope.
There are one or two bits of debris on the the primary and I have
toyed with the idea of cleaning it.
Also- I will admit that there was a bit of light in the neighborhood.
I could only see Jupiter from one place, and a number of lights were
on.
Clear Skies.
Bruce
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Date: 19 Jun 2007 15:23:26
From: brucegooglegroups
Subject: Re: view of Jupiter with 4.5;lm13
|
On Jun 19, 12:06 pm, galwacco <claudio.ferna...@gmail.com > wrote:
> On Jun 19, 11:29 am, brucegooglegroups <brucegooglegro...@hotmail.com>
> wrote:
>
>
>
> > I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
>
> > Although I could see three moons, Jupiter appeared only white, and I
> > could not see any details. Is this due to atmospheric conditions, my
> > viewing site, and/ or limitations of the scope?
>
> > I also tried to find m13 and was also disappointed. Even with
> > magnification, M13 looks similar to m31 in binoculars- unless I was
> > looking at something else:) I could see no details.
>
> > Also, I have been thinking of cleaning the primary mirror which has
> > not been cleaned since I bought the scope a year ago. There is a lot
> > of dust on it, and the views at night don't seem as clear. Should I
> > bother with the cleaning? The scope is collimated. There seems to be a
> > lot of opinion towards not cleaning the primary mirror unless
> > necessary.
>
> > Suggestions?
> > Bruce
>
> Did you consider buying some filters to add some colors into the
> planets? They do not perform much of a miracle but if you are looking
> for colors it might make you happier.
>
> Another thing to consider is that the human eye cannot catch so many
> colors from too distant objects, they are there though your eyes can't
> see. I am color blind for green and brown, but my wife can see really
> well and she says that Jupiter is fairly white with my 4" reflector
> though she can spot some colors out of it.
Hi ,
I may upgrade my telescope, so I may not buy the filter.
About colors, on occasion, I do see red and blue in stars. In a recent
article in Sky News, it seemed that I would be able to see colors of
Jupiter. Perhaps I am expecting too much.
A good article on skynewsmagazine http://skynewsmagazine.com/pages/jupiterguide.html
is a good guide to viewing Jupiter. I reread the article, so I may
need to buy filters.
Clear Skies.
Bruce
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Date: 20 Jun 2007 13:06:52
From: Llanzlan Klazmon the 15th
Subject: Re: view of Jupiter with 4.5;lm13
|
brucegooglegroups <brucegooglegroups@hotmail.com > wrote in
news:1182291806.787717.255450@g4g2000hsf.googlegroups.com:
> On Jun 19, 12:06 pm, galwacco <claudio.ferna...@gmail.com> wrote:
>> On Jun 19, 11:29 am, brucegooglegroups <brucegooglegro...@hotmail.com>
>> wrote:
>>
>>
>>
>> > I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
>>
>> > Although I could see three moons, Jupiter appeared only white, and I
>> > could not see any details. Is this due to atmospheric conditions, my
>> > viewing site, and/ or limitations of the scope?
>>
>> > I also tried to find m13 and was also disappointed. Even with
>> > magnification, M13 looks similar to m31 in binoculars- unless I was
>> > looking at something else:) I could see no details.
>>
>> > Also, I have been thinking of cleaning the primary mirror which has
>> > not been cleaned since I bought the scope a year ago. There is a lot
>> > of dust on it, and the views at night don't seem as clear. Should I
>> > bother with the cleaning? The scope is collimated. There seems to be
>> > a lot of opinion towards not cleaning the primary mirror unless
>> > necessary.
>>
>> > Suggestions?
>> > Bruce
>>
>> Did you consider buying some filters to add some colors into the
>> planets? They do not perform much of a miracle but if you are looking
>> for colors it might make you happier.
>>
>> Another thing to consider is that the human eye cannot catch so many
>> colors from too distant objects, they are there though your eyes can't
>> see. I am color blind for green and brown, but my wife can see really
>> well and she says that Jupiter is fairly white with my 4" reflector
>> though she can spot some colors out of it.
>
> Hi ,
> I may upgrade my telescope, so I may not buy the filter.
>
> About colors, on occasion, I do see red and blue in stars. In a recent
> article in Sky News, it seemed that I would be able to see colors of
> Jupiter. Perhaps I am expecting too much.
>
> A good article on skynewsmagazine
> http://skynewsmagazine.com/pages/jupiterguide.html is a good guide to
> viewing Jupiter. I reread the article, so I may need to buy filters.
> Clear Skies.
> Bruce
>
Jupiter is great for us down under as it is a winter opposition for us. i.e
Jupiter gets to a very good altitude above the horizon where the seeing
conditions are much better. Can you make out the bands, even if you can't
detect colours which are very subtle anyway?
Klazmon.
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Date: 19 Jun 2007 19:17:20
From: jimandlaura26
Subject: Re: view of Jupiter with 4.5;lm13
|
Bruce,
Don't despair...
1. Jupiter - Even with larger and.or more expensive scopes... Jupiter will
be a difficult target because it is very low in the sky for most of us
(presuming you are in the northern hemisphere). That means detail (with or
without a filter) will be challenging, but not impossible if you observe for
long periods where moments of atmospheric stability provide good sharp
views.
2. Filters - Spend some time (and $) here thinking this through, as the
common inexpensive colored filters don't usually live up to their advertised
feature enhancements (they can actually distort the subtle features you're
trying to tease out or block too much light for your modest aperture scope).
For an example of an alternative look at Alpine Astro Baader Filters. There
are others manufacturers and distributors as well... look in any astronomy
magazine. Spending a little more cash here is worth it.
3. M13 - Can in-fact look blob-like (no stars resolved) in light-polluted
skies and/or using a small aperture scope and/or when positioned low in the
sky. Since you have a fixed aperture scope, the most immediate solution for
you get to a darker site, wait for more favorable sky seeing/transparency,
and when it approaches the zenith. One or more of these factors can make a
huge difference.
The bottom line is... that the quality of what you can see is a function of
a chain of factors from your brain, to the eyepiece, to the filters, to the
scope aperture/optical quality, collimation & mechanics, to the mount, to
sky conditions, to the type of object. You have to work all of these
simultaneously... and the bad news is that any degradation in the chain will
degrade the view.
Jim M.
Northern Virginis
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Date: 19 Jun 2007 09:06:11
From: galwacco
Subject: Re: view of Jupiter with 4.5;lm13
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On Jun 19, 11:29 am, brucegooglegroups <brucegooglegro...@hotmail.com >
wrote:
> I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
>
> Although I could see three moons, Jupiter appeared only white, and I
> could not see any details. Is this due to atmospheric conditions, my
> viewing site, and/ or limitations of the scope?
>
> I also tried to find m13 and was also disappointed. Even with
> magnification, M13 looks similar to m31 in binoculars- unless I was
> looking at something else:) I could see no details.
>
> Also, I have been thinking of cleaning the primary mirror which has
> not been cleaned since I bought the scope a year ago. There is a lot
> of dust on it, and the views at night don't seem as clear. Should I
> bother with the cleaning? The scope is collimated. There seems to be a
> lot of opinion towards not cleaning the primary mirror unless
> necessary.
>
> Suggestions?
> Bruce
Did you consider buying some filters to add some colors into the
planets? They do not perform much of a miracle but if you are looking
for colors it might make you happier.
Another thing to consider is that the human eye cannot catch so many
colors from too distant objects, they are there though your eyes can't
see. I am color blind for green and brown, but my wife can see really
well and she says that Jupiter is fairly white with my 4" reflector
though she can spot some colors out of it.
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Date: 19 Jun 2007 10:59:04
From: Dennis Woos
Subject: Re: view of Jupiter with 4.5;lm13
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"brucegooglegroups" <brucegooglegroups@hotmail.com > wrote in message
news:1182263364.439147.239660@q75g2000hsh.googlegroups.com...
>I viewed Jupiter last night in my Skyquest 4.5 and was disappointed.
>
> Although I could see three moons, Jupiter appeared only white, and I
> could not see any details. Is this due to atmospheric conditions, my
> viewing site, and/ or limitations of the scope?
I would try a colored filter to bring out more detail. Google "Jupiter
colored filters" for a bunch of info.
>
> I also tried to find m13 and was also disappointed. Even with
> magnification, M13 looks similar to m31 in binoculars- unless I was
> looking at something else:) I could see no details.
M13 should look much better than this.
>
> Also, I have been thinking of cleaning the primary mirror which has
> not been cleaned since I bought the scope a year ago. There is a lot
> of dust on it, and the views at night don't seem as clear. Should I
> bother with the cleaning? The scope is collimated. There seems to be a
> lot of opinion towards not cleaning the primary mirror unless
> necessary.
Don't clean the mirror - this is not your problem.
>
> Suggestions?
> Bruce
>
Find your local astro club, wherre you will find folks who can evaluate your
scope and help you to get the most out of it. It may be that the optics are
not very good, or it may be that the collimation is not as good as you
think, or it may by something else. They can help you, and you will have
some fun observing with others.
Dennis
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