Using a Dobsonian

pcool2 (Patrick) · #1 15-09-2009, 07:32 PM

Hey im getting an 8'' Dob and was just wondering how hard it would be to find a planet or even a star? Would it be hard to find a star not visible by naked eye?

mental4astro (Alexander) · #2 15-09-2009, 08:06 PM

G'day Patrick,

Getting an 8"er, way to go dude!!

That is a magnificent instrument!

Will it let you see the planets? Put it this way, you can see all the planets, except for Pluto (now, now!) with just using a pair of 50mm binoculars. Only as pin points in the binos, so imagine the 8"!

You will see transits of the shadows of Jupiters moons across its disc- no worries. The great red spot plus a miriade of other cloud formations. Jupiter is the brightest 'star' in the evening sky right now- easy pickings for the new 8".

Saturn- Cassini division in the rings, no problem either.

Polar caps on Mars.

An emrald green Uranus & a saphire blue Neptune, both near to Jupiter right know, though you will need a map to track them down- PM me if you need a hand.

Oh, and don't forget the Moon! Just don't look at it during full moon- way too bright and no shadows to see the details.

Stars, where do we begin? Galaxies, nebulae, cluster open & globular to boot!

This time of the year presents some of the best Southern skies deep sky objects.

Even in a light polluted city there are treasures to keep you busy for years.

Only thing to get right from the start is a good alignment of the finder scope, easy to do, and a little getting used to the movement of the scope, and you will never look back.

All the best, mate. Enjoy your new purchase.

Clarry (Clayton) · #3 15-09-2009, 08:49 PM

Just packed my 8" dob away after spending an hour or so viewing Jupiter. Started with the 25mm, then the 9mm, then the 25 with 2x barlow and finally 9 with barlow. So yep, you can view planets and it's great.
Also had a gander at Lagoon & Eagle nebs, a few clusters in the milky way and Antares. You won't be disappointed.

Screwdriverone (Chris) · #4 15-09-2009, 10:07 PM

Hey Patrick,

Welcome aboard the Dob train!

Piece of cake, it's a case of point and stare, with the ol' dobsonian.

Do yourself a favour and buy a star wheel if you haven't already got one, the one I got from York Optical has a nifty little card which helps you track down where the planets are (if they aren't that obvious, like Jupiter which is blazing away right now and you cannot miss.)

Looking for stars is easy too, depending on which one you are trying for, star hopping to galaxies and such are quite simple when you get the hang of the finder scope and which constellation is which.

It also pays to have a NICE wide angle or low power eyepiece for scouting the area where you think the thing you are looking for is hiding. I have a 68 degree 30mm 2" eyepiece (which gives me 50x mag in my 1500mm Focal length scope [divide FL by the EP FL, e.g 1500/30=50x]) I got from Andrews Comms which I use as my scouting eyepiece to get me in the neighbourhood, I see what I think is what I am looking for, and then swap out to a 12.5mm [1500/12.5=120x] to zoom in on the object and voila! most of the time, its smack bang in the middle of the view.

Some nice things to try your hand at are;

Jupiter, Uranus, Neptune, 47 Tucanae (Globular cluster near the SMC), the Tarantula Nebula in the LMC, HEAPS of nebulae and globulars around Scorpius (the big question mark thingy overhead around 9pm) and Sagittarius (looks like a triangular teapot) which has lots of nice fuzzies to look at, most of which you will spot as a smudge in the finder, but when you look in the eyepiece will look amazing.

Take your time and you will have a ball!

I hope this helps you pick out some things to start with.

Enjoy!

Cheers

Chris

erick (Eric) · #5 15-09-2009, 11:36 PM

Promise you, if you remember to take the dustcap off, you'll see stars everywhere you point it in the sky!

barx1963 (Malcolm) · #6 16-09-2009, 12:02 AM

Patrick
8" is great size for starting out. I used one for 6 months, knocked over most of the Messiers with it as well as lots of other targets, planets etc.

One thing you may find a bit odd if you aren't used to it is the fact that the view is reversed. As you move the scope the stars etc appear to move the wrong way. If your finder is a stright through one it will do the same thing. If your finder is a right angle finder, things will move the "right" way when looking through it.
As this does take a little while to get used to, its a good idea to practice a bit when you first get your scope. Pick out bright stars you can see naked eye, or bright planets, Jupiter is very obvious at the moment, and try to locate them using your finder then your scope. After a few goes, it will become much easier.
Once you have done that, pick some objects close to a bright star, the Jewell Box near Beta Crucis, M4 near Antares are two obvious ones, and then find the star and try navigating to the object.
One other thing, make sure your finder and the scope are aligned, do this in daylight (remembering DO NOT LOOK AT THE SUN!!! even through the finder) lining up on a reasonably distant object such as a chimney, TV aerial etc. Find the object in the scope with your lowest power eyepiece (longest focal length ususally 25mm for most of these scopes) then adjust the knobs on the finder until it is in the crosshairs. This will save much fustration when you try to find things in the dark.
Good luck with it and remeber to keep asking questions, there is no such thing as a silly question only silly answers!
Oh, and get to a Star Party as soon as you can! There are plenty of opportunities where you are in Qld.

stephenb (Stephen) · #7 16-09-2009, 05:50 AM

Hi Patrick and welcome to the forum and the hobby.

There are 3 items I would recommend for you to buy to help you start out....

1. As Chris suggested, a planisphere of "star wheel". You'll use this for ever. A great tool. - cost: approx $10-20

2. A Telrad, which is a type of "finder scope" but has no magnification. It projects 3 concentric circles onto a diagonal mirror. Sounds strange, I know, but many find it an excellent tool for locating objects. They are sold here in Australia, including BinTel: http://www.bintel.com.au/Telrad.html - cost: approx $70

3. Astronomy 2009 http://www.quasarastronomy.com.au/product.htm
It looks like Ice In Space has sold out, you may have to do a ring around to some telescope retailers, or direct to the publisher at Quasar. - cost: approx $20

Good luck.

Liz · #8 16-09-2009, 10:23 AM

Well done Patrick!!
Grab a copy of the latest Australian Sky and Telescope - good info on whats going on, but also theres a star chart in middle to show you what constellations an d planets are up there.
Also, head along to your local Astronomy Club observing night - lots of experience to show you the ropes.
Download Stellarium (free and great) - put in your lat/long and it will show you the constellations/planets/galaxies/nebula etc - need to alter a few settings to make them stand out.

Craig.a.c (Craig) · #9 16-09-2009, 06:33 PM

Can't go wrong with a Dob. Before I got my 12" dob I was using a 4.5" reflector. First night out with the dob I was blown away. I even pointed it at section of sky that looked empty but saw stars that could not see in the old 4.5". You wont be disapointed.

garyp · #10 19-09-2009, 07:56 PM

Hi Patrick,
Welcome to the hobby and to IIS. I have to second what everyone has already posted. You will love it. I have an 8" Dob and have been using it for about 18 months. I still love the veiws through it. you will see plenty of stuff in good detail.

Cheers

Gary

shane.mcneil · #11 19-09-2009, 09:29 PM

Hi Patrick

Just got my new Dob too. Found Jupiter no worries. Make sure your finder scope is aligned properly and you will have no problems. Download Stellarium if you can and it will show you where to look. As for things you can't see with the eye, I try to reference of things you can. Also, I have a 2" wide angle EP 32mm. It's great for hunting things down. Then I switch to greater magnification.

All the best.

Shane