The Official Astronomy Thread

[Crusader]

I was pretty scared of the idea of grabbing a scope by the mouth and pulling it around before getting my 8 inch dob. I thought you would never be able to control the fine movements required for "manual" tracking at high magnification. But after having operated a dobsonian scope for a few months, nothing can be easier. I have effortlessly managed to track satellites with one hand while adjusting zoom and focus with the other. Hell i even managed to track a 747 the other day (at 48x magnification only ) It looked very weird seeing an upside down passenger airplane. My recommendation would be to buy a dob. And if you have more cash to spend than the R4k needed for a entry level dob., buy a bigger dob.

Ah, a happy convert I see.

Really the only area were I find tracking useful is when there are a group of people lined up to view the same object. Much easier when the object stays in the FoV.

For personal use I prefer my Dobs. No fancy electronics, just me and the universe.

 

[Albereth]

I was posting via my cell so had to keep things brief, and unfortunately also slightly vague. So here's a more verbose reply.

My first suggestion would be to completely forget about photography when starting out. First get a decent knowledge of the skies, gain experience and do visual observing to see if the hobby sticks. Many beginners start out wanting to take Hubble-like images, but quickly give up on that and enjoy visual observing by itself. Even if you do go for astrophotography you will need a background on where the objects are located, how to set up the scope, best time/conditons for imaging etc and then astrophotography has a whole learning curve on it's own.

Imaging is not as easy as it seems to be. Unlike normal photography you'll need to know quite a bit more and have deep pockets to boot.

Unless you have a permanent observatory you'll be faced with this every night:
Set up the scope. Carry weighty mount outside, level the mount, add the OTA.
Provide power for the mount, your camera and most likely a laptop.
Allow scope to reach ambient temperature. (Can be between 30min to a couple hours depending on scope)
Do a very accurate polar alignment (for us in the SH this means going through the process of drift alignment).
Attach camera to scope. Get the correct focus.
Capture flat images. Capture dark images.
Point at target and start capturing images of object for 2 hours or so.
Pack everything away.
Do post-processing by stacking short exposures or tweaking long-exposures.

Equipmet needed:
Very good EQ mount with worm gears and port for auto-guider.
Imaging scope (the main OTA)
Guidescope (to add auto-guider to)
Camera (DSLR will work, but for serious use you need an actively cooled CCD camera)
Laptop
Power supply for scope, laptop etc.

Cost: Entry level type setup would run around: R35000- R40000 (EQ5 Pro Go-To Mount - R18000, 80mm ED Refractor - R10000, Auto-guider - R5000, Finderscope suitable for guidescope - R1500, misc accessories - R3000)

For visual use you can get away with a much lower budget. Depending if you want Go-To or tracking etc. A 8" Dob should set you back around R6000. Everything will have to be done manually but it's lots of aperture at a minuscule price. No extra accessories would be needed to start with. As you grow in the hobby you can add more eyepieces and other accessories as needed.

If you want tracking you can get a SW tracking Dob for around R14000, or wait and see if the Orion Go-To Dobs become available within the next year or two for a similar price.

A typical night out would be something like this:
Carry mount out. Put it on the ground.
Get the OTA and put it on mount.
Wait for the scope to reach ambient (a hour or so)
Put eyepiece in and view.

There really isn't an easy answer to this. For me a Dob was the best choice. The refractor was a cheapish experiment to see how I'd cope with refractors. It's pretty good on star clusters and decent on planets (does have quite a bit of purple fringe (CA) on them ), but for DSO's my Dob wins hands-down.

I find the refractor uncomfortable to use. The Dob is much more comfortable and pointing it is easier and I can the eyepiece stays at a height where I can easily sit and observe.

A Dobsonian is the cheapest entry point for the largest amount of aperture. It does have downsides though. You have to collimate it regularly and when viewing you have manually nudge it to track the object. For most that's no problem, but other people absolutely WANT tracking, which you can get - at a cost.

There are various factors which come into play for what would be right for you.
What do you want to look at?
How old is your child(ren)?
Do you have a problem with light pollution?
How much storage space do you have?
Are you comfortable with nudging the scope around?
Would collimation be a problem?
Are you willing to learn the sky?

Personally I'll take aperture over tracking and Go-To, but you might be different. An 8" Dob would be a great starter scope to test the waters.

If you are very serious (R20 000 worth of serious!) and want tracking. Something like the Celestron 8SE would be good. It's an excellent visual scope, has Go-To and tracking and later you can use the OTA on a EQ mount for photography.

So I dropped the question over dinner the other night about whether the family would be interested in getting a telescope. The girl child asked if we could watch NCIS, the boy child is at boarding school, and the SO contributed by saying that a friend of hers has a telescope and that you need a good window to point it out of.

So I helped find the remote.

Back to your questions.

I want to look at the Horse Head Nebula
The children are both 14
I live in Joburg so light pollution is an issue - I also have a 4x4
Storage space isn't an issue at the moment - I have a whole wendy house/shed to my self although it is full of power tools.
I don't mind nudging things but a GoTo would be seriously cool if I try and resell the idea.
Collimation wouldn't be a problem, the SO is quite handy in that respect
And learning the sky isn't the end of the world - I actually studied astronomy just as something to do. We do visit the planetarium every so often and have tried to do the star gazing thing at Maropeng - it rained.

 

[SYN]

Is there much use in a wide angle low magnification eyepiece? I have a few Rand burning a hole in my pocket and can decide if I should buy a UHC filter or this eyepiece first. It is a 33mm 72 deg FOV williams optics SWAN eyepiece. - What is the lowest useful magnification I can go to on a 8 inch reflector? I want to buy the biggest (highest size in mm) eyepiece i can

 

[Crusader]

So I dropped the question over dinner the other night about whether the family would be interested in getting a telescope. The girl child asked if we could watch NCIS, the boy child is at boarding school, and the SO contributed by saying that a friend of hers has a telescope and that you need a good window to point it out of.

So I helped find the remote.

Back to your questions.

I want to look at the Horse Head Nebula
The children are both 14
I live in Joburg so light pollution is an issue - I also have a 4x4
Storage space isn't an issue at the moment - I have a whole wendy house/shed to my self although it is full of power tools.
I don't mind nudging things but a GoTo would be seriously cool if I try and resell the idea.
Collimation wouldn't be a problem, the SO is quite handy in that respect
And learning the sky isn't the end of the world - I actually studied astronomy just as something to do. We do visit the planetarium every so often and have tried to do the star gazing thing at Maropeng - it rained.

Use a telescope through a window? Blasphemy! You never do that unless it's one of those toy scopes you want to use to spy on the neighbours. The glass will distort the images and the thermal imbalances will play havoc.

The Horsehead is a very challenging object to view visually. You need absolutely dark skies and complete dark adaptation, but a 8" should be enough to observe it. Some observers are able to spot it in much smaller apertures. This is one object that's still on my "to observe" list.

From the rest of your answers it seems a Dob would be a good fit. The kids are old enough to be at "eyepiece height" and they will be able to understand how to use and move the scope themselves.

GoTo scopes have a cool factor to them, but that soon disappears and it comes with requirements and hassles of it's own. First the need for power... either from a battery or from AC power outlet. Now you have wires around which people could trip over, and perhaps even topple the scope with. As the scope moves around it takes it's time to get from one target to the next. About 10 times longer than what you could manually do and you need to be constantly on the lookout to prevent the scope from strangling itself with the power cord. Fun times! Seriously though, they are fun to have but do come with a set of logistics of their own. Another major worry is that if something goes wrong, it would mean an expensive replacement. More complexity means more potential of problems. Most of the GoTo scopes can't be used manually if the need arises (such as you run out of power in the middle of nowhere) so that's something else to keep in mind.

If you forget about photography and you want to buy one this year, you should go for the Orion SkyQuest XT8 Intelliscope @ R7750. It has Push-to technology which will show you were to push the scope to find a certain object. Great for light pollution when you don't have enough visible stars to use for starhopping. It only needs a 9V battery for the handset, the rest is manual. You can also use it to starhop, without using the handset at all.

 

[Crusader]

Is there much use in a wide angle low magnification eyepiece? I have a few Rand burning a hole in my pocket and can decide if I should buy a UHC filter or this eyepiece first. It is a 33mm 72 deg FOV williams optics SWAN eyepiece. - What is the lowest useful magnification I can go to on a 8 inch reflector? I want to buy the biggest (highest size in mm) eyepiece i can

In general you wouldn't want anything that gives an exit pupil of more than 7mm (most people's pupil only enlarges to 7mm when at prime, older you get the smaller it gets and the more light will be lost). 203/7 gives a magnification of around 29x, which translates into a theoretical maximum of a 41mm eyepiece.

And the use for low magnification eyepieces are mostly for use as a finder eyepiece and occasionally to view large extended objects.

 

[Crusader]

If you've got a solar filter or know how to safely do eyepiece projection with a refractor then there is a very nice sunspot visible at the moment.

I managed to get a very nice view using an old spotting scope for eyepiece projection. Even at 20x there was some nice structure visible.

Guess I need to get a solar filter now...

 

[caspa]

Crusader, so help please..

Would i be able to see anything at all with these..Celestron SkyMaster Giant 15x70 Binoculars.

I would like to maybe show my kids the moon close up and possibly see a very small Venus or Saturn? would i be wasting my money as a beginner?

Any info would be appreciated.

Caspa

 

[Crusader]

Those 15x70 binoculars would be very large and heavy, so unless you are going to mount them on a stable tripod I'd rather get a 10x50. For most people that's the max weight they can handle handheld.

The moon will be great in binoculars. Venues should show as a tiny disk and Saturn and Jupiter will also be tiny round disks with their moons visible as bright dots around them. Sadly not much detail will show on the planets themselves.

 

[caspa]

Thanks for that, i was thinking of mounting them on a tripod. For a spend of R1200 and there many uses i though it might be a good investment

 

[Crusader]

Managed to capture a reasonable image of the Sun showing a couple of sunspots (AR 1093, 1097 and 1098), Focus isn't all too great since this is pressing a digital cam to the eyepiece.

Sun with sunspots

 

[Crusader]

Between 14:00 and 15:00 today the moon will occult (move in front of) Venus. This should be easily visible using binoculars, so be sure to check it out!

 

[Kalvaer]

HAHA... Last night I was sitting outside when I looked up at the moon and Venus' position, I ran inside and told Claire that I think we had just missed an occultation. She laughed and told me that I was almost right, but that its actually today. To much cloud cover here though for us right now to see though. At least we "MIGHT" get our first summer rain

 

[LazyLion]

HAHA... Last night I was sitting outside when I looked up at the moon and Venus' position, I ran inside and told Claire that I think we had just missed an occultation. She laughed and told me that I was almost right, but that its actually today. To much cloud cover here though for us right now to see though. At least we "MIGHT" get our first summer rain

Looks great right now!

 

[Crusader]

It was stunning to see. I was able to capture a couple of images, but the quality isn't very great. The T-adapter I used to attach the camera resulted in loads of dust to fall on the sensor after attaching the camera. Time was too short to do anything to remedy the situation. I was also basically clueless as to how to use the camera (and it shows!).

In any case, the composite image can be seen here: Venus Occultation from South Africa

 

[Crusader]

And here's a little Youtube video I threw together. At least you get the general idea.

[video=youtube;XVKDaBUDKbQ]http://www.youtube.com/watch?v=XVKDaBUDKbQ[/video]

 

[wrathex]

And here's a little Youtube video I threw together. At least you get the general idea.

Nice one Crusader, the music, I was expecting Jaws to come swimming across the moon

 

[Crusader]

Nice one Crusader, the music, I was expecting Jaws to come swimming across the moon

Thanks. Movie making isn't my forte, and that was the only music I could quickly add to the Youtube vid using their Audio swap feature. And space just has to have some epic sounding music!

 

[Crusader]

Woot, I'm famous! Just noticed that the image made it to the front page of www.spaceweather.com!

 

[Kalvaer]

NICELY DONE!!!!!! That's really awesome.. I took some photo's much later at about 8:00pm after the clouds cleared, though nothing as good as the broad daylight shots

 

[Crusader]

NICELY DONE!!!!!! That's really awesome.. I took some photo's much later at about 8:00pm after the clouds cleared, though nothing as good as the broad daylight shots

Thanks. I'm chuffed to bits. Best of all I didn't even know how to use the camera properly. Turned out pretty well though.