ICEINSPACE
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28-05-2010, 05:00 PM
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4000 post club member
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Join Date: Sep 2004
Location: Melbourne
Posts: 4,900
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Quote:
Originally Posted by sjastro
Anyone care to place a bet  .
The brightness of the sky background is related to the exit pupil not the aperture. The larger the exit pupil the brighter the background.
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Agreed and this is exactly why I pipe up when people say big scopes are useless in light polluted places, and better off with a small one.
I say rubbish!
Whilst sky background brightness is a constant vs exit pupil, greater aperture allows the collection of more light from wanted targets allowing presentation at a visual size at which they may be visible.
Light pollution makes small scopes particularly useless in comparison to large ones.
Greater aperture = smaller fov per exit pupil and bigger target!
Less noise, more object!
By the way, I think planetary nebs are a fair dso target for the light pollution affected observer as most are best at high magnifications.
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28-05-2010, 05:36 PM
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Registered User
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Join Date: Mar 2005
Location: Shoalhaven Heads, NSW
Posts: 2,620
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Quote:
Originally Posted by sjastro
Anyone care to place a bet  .
Regards
Steven
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Hi Steven,
I am almost prepared to place a bet that you are an engineer of some description? Further, that your discipline is in a field of engineering other than optics ? Actually, I am picking a mechanical or civil engineer. How close did I get ?
Cheers,
John B
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28-05-2010, 06:12 PM
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Registered User
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Join Date: Jun 2007
Posts: 2,926
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Quote:
Originally Posted by ausastronomer
Hi Steven,
I am almost prepared to place a bet that you are an engineer of some description? Further, that your discipline is in a field of engineering other than optics ? Actually, I am picking a mechanical or civil engineer. How close did I get ?
Cheers,
John B
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Hello John,
I'm a scientist (applied mathematician) currently on hiatus (probably explains all the bad weather).
Most of my employment has been based on working closely with engineers.
Regards
Steven
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28-05-2010, 06:50 PM
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Waiting for next electron
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Join Date: Mar 2008
Posts: 2,427
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Quote:
Originally Posted by astroron
YOU KNOW WHAT I MEAN 
I DID NOT MEAN AT THE SAME TIME AS YOU ARE IMAGING 
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Ron I always have two scopes setup, one controlled by computer auto routines snapping pics and a second for visual obs. Problem is where I live a combination of LP and heavy particulates (8km from CBD 100m from the freeway) washout and scatter the light from the universe so much that I can rarely see very much at all, even when the moon is not about. I envy you and your clean dark skies but until I retire this will not be possible for me. I agree that getting all the bits and pieces for long exposure AP can at times be tiresome, but most folks seem to have no such problem with video cameras like the Gstar as they have nowhere near the requirements of long exposure AP. I am not sure why visual astronomers are so adament that people who take pics are not the real deal, especially those who are reduced to narrowband images to see anything worthwhile due to the rotten skies they live under. Without these bits and pieces many of us would just find something else to do as starring at the LP and smog domes that encapsulate most cities offers little for an active and enquiring mind.
Mark
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28-05-2010, 07:14 PM
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Registered User
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Join Date: Feb 2005
Location: Monto
Posts: 16,741
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The Ring Nebula will take as much magnification as you want, I've found.
Video observing is the way to go if your eyesight isn't the best, no squinting through an ep.
You only need a small aperture scope on a goto alt azi mount, a comfy chair and some form of analog display, either a tv or a laptop.
If you feel like taking an image, just click on the capture button.
Tooooo easy.
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28-05-2010, 08:15 PM
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Mostly harmless...
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Join Date: Jul 2008
Location: Brisbane, Australia
Posts: 5,735
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Quote:
Originally Posted by marki
Ron I always have two scopes setup, one controlled by computer auto routines snapping pics and a second for visual obs. Problem is where I live a combination of LP and heavy particulates (8km from CBD 100m from the freeway) washout and scatter the light from the universe so much that I can rarely see very much at all, even when the moon is not about. I envy you and your clean dark skies but until I retire this will not be possible for me. I agree that getting all the bits and pieces for long exposure AP can at times be tiresome, but most folks seem to have no such problem with video cameras like the Gstar as they have nowhere near the requirements of long exposure AP. I am not sure why visual astronomers are so adament that people who take pics are not the real deal, especially those who are reduced to narrowband images to see anything worthwhile due to the rotten skies they live under. Without these bits and pieces many of us would just find something else to do as starring at the LP and smog domes that encapsulate most cities offers little for an active and enquiring mind.
Mark
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I agree with so much of what you say here Mark. It was just a revelation for me how much I could do with a pollution filter and DSLR from the backyard.
However, me thinks Ron is also having a bit of a lend of us here - I know damn well he used to do quite a bit of film astroP in days gone by
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28-05-2010, 10:17 PM
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Registered User
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Join Date: Mar 2005
Location: Shoalhaven Heads, NSW
Posts: 2,620
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Quote:
Originally Posted by sjastro
Hello John,
I'm a scientist (applied mathematician) currently on hiatus (probably explains all the bad weather).
Most of my employment has been based on working closely with engineers.
Regards
Steven
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Wasn't far out was I
Cheers,
John B
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29-05-2010, 08:43 AM
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Registered User
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Join Date: Jun 2007
Posts: 2,926
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Quote:
Originally Posted by ausastronomer
Wasn't far out was I
Cheers,
John B
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Unfortunately as a scientist working with engineers meant being portrayed as mad as in the Dr Frankenstein mould.........
Regards
Steven
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29-05-2010, 09:08 AM
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Supernova Searcher
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Join Date: Mar 2005
Location: Cambroon Queensland Australia
Posts: 9,326
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Quote:
Originally Posted by sjastro
Unfortunately as a scientist working with engineers meant being portrayed as mad as in the Dr Frankenstein mould.........
Regards
Steven
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Your Avatar gives some support to the myth
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29-05-2010, 10:45 AM
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No More Infinities
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Join Date: Apr 2008
Location: Townsville
Posts: 9,698
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Quote:
Originally Posted by sjastro
Unfortunately as a scientist working with engineers meant being portrayed as mad as in the Dr Frankenstein mould.........
Regards
Steven
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I'm afraid I have the dibs on that one...I've been called a mad scientist ever since I was a small kid 
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29-05-2010, 03:04 PM
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Searching for Travolta...
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Join Date: Jan 2010
Location: Brisbane, Australia.
Posts: 3,700
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Whooaah! This thread certainly has been busy in the last 24 hours. You guys were doing my head in with the dark side! I see the light by the way, and I'm walking towards it... What I can't see, I'll imagine, or Google (or Look at Rob's pics, I seem to be stalking his web page regularly!). Thankyou for your views from the dark side though.. but I have much to learn, and I want to maintain visual astronomy. You'll do raise a very good point with being able to see so much more in suburbia. But, I just love the rush I get hugging my dob with my eye jammed into an eye piece feeling like I've just put my head into the window of space, nothing around me except for the pure darkness and wonders of space between my eye and eyepiece. And then whilst your being mesmerised at the wonders and endlessness of space, amongst the eerie strange noises coming from the bushes in the wee hours of the morning, a shooting star with immense speed blazes a trail straight across your eyepiece, and it makes you jump back and you realise how much more aware you are of every sound, as Earth seems so far away...
As for the filters, thank you all for your input. Gosh what an entertaining debate that turned out to be.
And poor Ron copped it by defending visual astronomy- and didn't that turn out into another debate. Sorry Ron!
And then the Planetary Nebs.. Thankyou all for your input. I'm excited that I have a list of what appears to be achievable thru my scope. If only the bad weather would buzz off. I bought a Vixen LVW, and there it has sat for the last week and all I can do is look at it and hold it. My Pentax XW has only seen one good run and I got that a month ago. *Sigh* (we need a "sigh" emoticon!) I think a lot of us here have been buying too much lately, judging by the busy for sale forum here! Stop buying everyone, so the weather can clear!
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29-05-2010, 03:24 PM
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Registered User
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Join Date: Feb 2005
Location: Monto
Posts: 16,741
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Visual vs Imaging  ..... 
To each their own I reckon.
We all started by looking through an eye piece.
So it was YOU that bought the rain this weekend.  Bad girl.
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29-05-2010, 04:01 PM
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No More Infinities
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Join Date: Apr 2008
Location: Townsville
Posts: 9,698
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You can still observe visually using a GStar...just that you don't look through an eyepiece, but on a monitor
However, you have the luxury of running off some happy snaps if and when you like, without having to fiddle about putting a camera into your focuser  It's already there
But it is nice to look through an eyepiece
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29-05-2010, 04:12 PM
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Supernova Searcher
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Join Date: Mar 2005
Location: Cambroon Queensland Australia
Posts: 9,326
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Quote:
Originally Posted by renormalised
You can still observe visually using a GStar...just that you don't look through an eyepiece, but on a monitor
However, you have the luxury of running off some happy snaps if and when you like, without having to fiddle about putting a camera into your focuser  It's already there
But it is nice to look through an eyepiece 
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Sit inside watch the Tely, go outside put a camera onto your Tely scope 
and watch the Tely   
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29-05-2010, 04:55 PM
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Registered User
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Join Date: Jun 2007
Posts: 2,926
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Quote:
Originally Posted by jjjnettie
Visual vs Imaging  ..... 
To each their own I reckon.
We all started by looking through an eye piece.
So it was YOU that bought the rain this weekend.  Bad girl.
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Sorry for the bias but imaging wins hand down.
Here is an image of the planetary Bran A/B which is beyond visual
detection as its surface brightness is fainter than the sky glow from the darkest sites.
http://users.westconnect.com.au/~sjastro/bran147c.html
Regards
Steven
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29-05-2010, 05:24 PM
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No More Infinities
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Join Date: Apr 2008
Location: Townsville
Posts: 9,698
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29-05-2010, 05:52 PM
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Supernova Searcher
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Join Date: Mar 2005
Location: Cambroon Queensland Australia
Posts: 9,326
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Quote:
Originally Posted by sjastro
Sorry for the bias but imaging wins hand down.
Here is an image of the planetary Bran A/B which is beyond visual
detection as its surface brightness is fainter than the sky glow from the darkest sites.
http://users.westconnect.com.au/~sjastro/bran147c.html
Regards
Steven
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Two orange splogges in between a lot of white dots 
All as it's made you is a image processor, you never saw it either
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29-05-2010, 06:06 PM
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Searching for Travolta...
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Join Date: Jan 2010
Location: Brisbane, Australia.
Posts: 3,700
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Quote:
Originally Posted by astroron
Two orange splogges in between a lot of white dots 
All as it's made you is a image processor, you never saw it either 
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   Good one Ron.  Uhmmm... Sorry Steven, but that was a good comeback.
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29-05-2010, 06:15 PM
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Registered User
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Join Date: Feb 2005
Location: Monto
Posts: 16,741
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Quote:
Originally Posted by sjastro
Sorry for the bias but imaging wins hand down.
Regards
Steven
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 Oh, you don't have to convince me Steven.
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29-05-2010, 06:20 PM
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Registered User
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Join Date: Jun 2007
Posts: 2,926
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Quote:
Originally Posted by astroron
Two orange splogges in between a lot of white dots 
All as it's made you is a image processor, you never saw it either 
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And there lies the greater satisfaction of imaging and processing over observing, in being able to confirm the existence of an object that visually isn't there.
Regards
Steven
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