Let's Start with the Basics

Screwdriverone (Chris) · #1 07-02-2008, 10:54 AM

Hi All,

Chris from Kellyville NSW here.

I am brand new to astronomy and telescopes after buying a 50mm Celestron Refractor for my son of Christmas and finding it frustrating to look at the moon and Mars etc as blobs in the sky, so on Tuesday went and bought myself a Skywatcher 130mm SW135 Newtonian Reflector with RA motor drive on a EQ2 mount. I am also referencing the "Natures Companions - Practical Skywatching" book from Fog City Press which is very good to learn from and has great star charts and starhopping guides. When purchasing the scope from York Optical I also got a Astronomy 2008 guide from Quasar publishing and am deciphering this eagerly and hoping for some clear nights now that the rain seems to be Darwin like in intensity and predictability.

The problems I am having are these:

1) I have setup the scope to the instructions and have aligned the polar axis to be in line with one tripod leg and set the Altitude of the mount to 33 degrees. I have aligned as close as I can to the SCP (through the holes in the rain clouds at 12am) by drawing imaginary lines from Crux's main stem and perpendicular from the line between Rigil Kentaurus and Hadar towards the SCP near Sigma Octanis. When I do this and engage the motor for the RA (or even use the RA slow motion control) the star field does not rotate properly about the eyepiece as expected and when "tracking" a star with the motor, the object wanders away from centre. Is there something fundamental I may have missed? The scope is balanced, the tripod level (or very close to it) and everything else "looks" right with my untrained eye.

2) The Slow motion control cable for the DEC axis is EXTREMELY hard to turn and I have checked the spring and the grub bolt that presses against the DEC control screw and found the spring was rusty? and the control is VERY hard to turn and twangs with every turn of the wheel. Is it too tight? When I undo the bolt slightly, the tension in the spring and therefore the effort reduces but the scope doesnt back up when going away from the other direction. In comparison, the RA axis Slow motion control feels like a well oiled machine with gears and doesnt make the scope bounce around like the DEC one does. Am I just being stupid? or is this normal?

Whew,

that will do for starters, no doubt I will have lots more questions as I learn and I am glad to be aboard this great site and have been spending my free time waiting for clear skies by reading as much as I can from the forums and the how-to guides.

Cheers for now,

Chris

cahullian · #2 07-02-2008, 06:24 PM

Hi Chris welcome to IIS

Both Axis should run smooth. I would be taking the scope back and get it checked out by the dealer or get it replaced.

EQ mounts take a while to get the hang of and aligning the scope to the SCP takes time, practice and patience.

Gazz

sheeny (Al) · #3 07-02-2008, 06:40 PM

G'Day Chris!

Aligning to the SCP can take a bit of learning, and then it actually takes a bit of time to do usually. For precise stuff, like astrophotography you will need to learn to "drift align" i.e. make adjustments to the alignment of the scope based on the drift that you observe in the eyepiece. You're seeing that drift already.

For starters though, try not to worry too much about the drift. For visual observing a bit of drift can be tolerated and for a while you'll need to tolerate it until you get the hang of alignment.

Something about the dec slow motion control doesn't sound good though.

If there's no-one handy who can have a look at it, I'd agree - take it back and get at least some advice or tuition from the shop.

Al.

Screwdriverone (Chris) · #4 08-02-2008, 04:48 PM

Hi Al and Gazz,

Thanks for the advice, I took the mount back and the guys were great, swapped it over straight away, definitely something wrong with it somewhere, the new one is as slick as anything.

I will try and see how I go with the SCP aligning, hopefully, I can get the hang of it soon and start checking things out.

Does anyone know of an online resource for star coordinates (eg. Sigma Octanis' RA and DEC?) as I want to use a known star to set the RA point and then off I go.

Chris

MrB (Simon) · #5 08-02-2008, 05:03 PM

Quote:

Does anyone know of an online resource for star coordinates (eg. Sigma Octanis' RA and DEC?) as I want to use a known star to set the RA point and then off I go.

There's a great free sky chart program called Cartes Du Ceil that will tell you, find the star you want and then right click it for more information.
I would post the co-ords for you but have just re-installed windows on the laptop... sorry.

sheeny (Al) · #6 08-02-2008, 05:03 PM

Chris,

You have Astronomy 2008, right? In the back will be a table of the brightest stars. You will find the RA and Dec of the brightest stars there.

As sigma Octans is so close to the SCP, it's not a good choice to set your RA circle. Choose a star closer to the celestial equator i.e. one with a small dec. In reality a dec smaller than +/- 45 or even 60 degs would be fine.

I use a compass to rough align my scope. For my area, true south is about 168deg mag - it should be pretty similar for you as well I think. I find the compass easier than trying to find sigma octans.

Glad you got the mount sorted!

Al.

sheeny (Al) · #7 08-02-2008, 05:48 PM

At the risk of confusing the issue, Chris, I've started another thread to explain how to align your scope without using sigma octans:

http://www.iceinspace.com.au/forum/s...ad.php?t=28422

Your questions managed to dredge this up from the depths

, thanks!

Al.

MrB (Simon) · #8 08-02-2008, 06:02 PM

Dunno if it's still of use to you, but re-installed CDC, Sigma Octans co-ords are: RA: 21h15m42.15s DE:-88°55'22.2"

Screwdriverone (Chris) · #9 08-02-2008, 09:19 PM

OK, Now my brain is officially starting to hurt.

I have tried out the CDC and its quite good, however, I just found the Celestron TheSky CD from my son's 50mm refractor and this is GREAT!. You can "play" the scene from any view in a planisphere and watch the stars and planets rotate. Click on the object and the RA and DEC comes up. You can even see it from a Solar System view. COOOL!

Man, now cloudy nights are going to be spent playing with this new toy......

Thanks guys.

Chris

MrB (Simon) · #10 09-02-2008, 01:19 PM

CDC does all those things too (oh, except the solar-system view)
In CDC the RA and DEC and Alt-Azi for the mouse pointer are in the bottom left of the window, or, right click the item of interest and select "Identification : Nearest Object"
For the rotation, click the stopwatch icon, an 'animate' window will popup.
You can also track items like the moon and comets etc, eg: right click the moon, select "Track Moon", the 'Animate' window will popup.
Handy for finding Occultations(sp?) and getting timing info for future eclipses etc.

But , whichever you prefer... OK

Screwdriverone (Chris) · #11 09-02-2008, 02:01 PM

Hi MrB,

I have had another play with CDC and you are right, it's quite good.

I have to say though the Celestron one is very nice and easy to operate (probably my newbie factor kicking in) due to the fact it comes with such a toy telescope.... ha ha.

Now, if we could just get a view of the sky out from under these Thunderstorms!

Lucky we are in a drought here hey?

Screwdriverone (Chris) · #12 10-02-2008, 04:40 AM

Hi All,

Just wanted to spout off a bit as I had a great night right from Dusk to 2am spinning around the sky looking at stuff, namely M42 in Orion and that BIG planety looking thing that is in Leo, oh yeah SATURN.

I used Al's (Sheeny's) 168 degree method of "point and click" and off I went, setting the RA circle off Sirius and then learning / guessing / testing my way around.

Before the kids went to bed I showed them M42 to the cries of WOW, cool, what else can I see etc...... and then after Saturn popped up I realised I could just look the sucker up in the back of the Astronomy 2008 mag, spin the scope around and BAM, planet with Rings in the finder and the eyepiece! Mars is just a reddish round ball compared to Saturn.

All three of my boys (13, 11 and 7) got a look at Saturn and I was even hoping to glimpse Jupiter, but the clouds made a return about 3:00am, so I will have to wait for that one..!

I even managed to sort out the plastic camera mount adapter and took bucketloads of grainy, out of focus and just plain sad photos of Saturn, this one is probably the best one I have.... hopefully these will get better as I go...the only way is UP!
I will have to see if I can find my Kodak Digital as the Pentax is a bit screwy to try and get the exposure right, this photo was taken on a 10 sec delay timer (to stop the wobbles) and just a standard photo setting.
http://i268.photobucket.com/albums/j.../IMGP1196a.jpg

I cant be too sure but I think there is a DOT on the left side, is this a moon? or a DOT?

I may have to buy myself a 4mm Plossl as I only have a 10mm and 20mm that came with the scope. Perhaps a Barlow may be a good investment too.

I think I still have a bit of work to do with the Drift Alignment method as I kept having to correct the scope after about 3-4 mins with the RA motor on by using the DEC control to bring the planet back to view central.

I also had a bit of a problem later on with dew on the eyepiece and all over my books,

but not too bad.
The 130mm aperture and optics were quite good and with the finder and scope set up properly, pointing was a breeze. Now I will just have to learn how to fold myself in half to see some of the eyepiece positions on the GEM Netwonian...

Thanks again for the advice and the posts, it really helps to have it all click into place and work pretty much the first night I had clear skies and scanning around with my Planisphere and A2008 mag made it fun and challenging.

Finally, all I can say is how cool is it to see another planet or Nebula from your own backyard!

Damn it, I think I am hooked...

Cheers for now

Chris

tbentley · #13 10-02-2008, 01:27 PM

Well done Chris. You've had much more success starting out than I ever did, mind you I hadn't found IIS then. Watch out or you may end up being sent to rehab for this addiction.
Just a word of advice on the eyepieces from a guy who made the mistake. If you are going to buy a barlow either now or the future keep in mind the effect that this will have on your eyepiece collection. Make sure that you don't buy EP's that will be the equivalent of one of your existing ones with a barlow. I have a couple that are equivalent (or that close to it) because I forgot to consider the future purchase of a barlow.
Glad I got in quick before someone else gave the same advice. It's rare that I know enough to help even the newest amateur.
Good luck.
Travis

sheeny (Al) · #14 10-02-2008, 01:34 PM

Glad you had a great night, Chris!

I don't think your dot is a moon. I think at Saturns moons are in the plane of the rings, and that one seems a long way off. It could be a star though, but it also seems to be a very sharp since pixel so most likely a hot pixel.

Al.

edwardsdj (Doug) · #15 10-02-2008, 01:53 PM

Hi Chris,

Great to hear you're having success

I find magnifications of 130x to 200x to be good with Saturn. It is rare that conditions allow me to exceed 200x. A 4mm eyepiece (250x) would be about at the limit I'd try to push this scope to with good seeing.

Have fun,
Doug

Screwdriverone (Chris) · #16 12-02-2008, 12:08 AM

Hi Guys,

A quick question on this, namely, Doug's and Travis' comments on the eyepieces, I currently have a 10mm and 20mm Plossl that came with the scope. I assume that if I went and got a 2x Barlow, then the 20mm with the 2X barlow will be of same magnification as the 10mm, but with the greater eye relief of the 20mm?

Similarly, the 10mm will become an effective 5mm eyepiece but retain the FOV of the 10mm.

So, having said this, is this one of the easiest solutions for me to get around 200x considering the focal length of my scope is 1000mm and the 10mm plus the 2X Barlow would therefore make it a 5mm which works out to be 1000/5 = 200 X power?

edwardsdj (Doug) · #17 12-02-2008, 04:27 AM

Hi Chris,

Some eyepieces barlow well. Some don't. Not many of mine do so I don't use barlows much. The field of view tends to get too restrictive for my taste compared to using an eyepiece of the appropriate focal length. I'm sure this is just due to the combination of eyepieces and barlow that I have. Others love them. You do retain the eye relief of the eyepiece though it can be much more difficult to get your eye in the right spot if the eyepiece doesn't barlow well.

I've got a good Celestron Ultima 2x barlow but in practice only use it for barlowed laser collimation of my dob and to improve image scale on planets with my webcam.

If you get a barlow, get a good one like the Televue, Celestron Ultima, Orion...

If I were in your position and wanted a bit more magnification on planets, I'd get a decent Plossl eyepiece providing about 150x or a bit less. Really wide fields of view are of little use for planetary observing so I'd just go a Plossl. I'd say that 200x would be ambitious on most nights with this scope and as I said 250x is about the limit I'd push it to under good conditions.

The workhorse eyepiece I use on most nights for planetary observing in my C8 (2000mm focal length) is a reasonable 15mm Plossl providing 133x magnification. If I'm really in the mood to spend some time with the planet (and the conditions are reasonable) I'll push it to 200x with a 10mm.

A quality eyepiece can make all the difference when trying to pick out planetary detail in a Newtonian. If you combine a budget eyepiece with a budget barlow the results will probably not be as impressive as getting a decent eyepiece for planetary work.

Barlows are great for boosting the magnification on those rare nights of exceptional seeing though

Have fun,
Doug

Screwdriverone (Chris) · #18 15-02-2008, 11:53 AM

Thanks Doug,

This really helps. I am thinking of a 2X or 3X barlow, so my scope will get to around 300X if I use the 10mm eyepiece and with its 1000mm focal length. I am a bit surprised they included only a 10mm and 20mm eyepieces. They are supposed to be Plossl ones but I cant see any markings on them apart from Super - 20mm etc. If the 20mm is effectively a 10mm with a 2X barlow, so thats why I am thinking a 3X would give me better value than the 2X even if the 3X on the 10mm eyepiece may be pushing the setup a bit far.

Any ideas on how much to spend? I have seen barlows of the brands listed by you for around $50 and up, what's the rule of thumb? The idea is that I can get a bigger view of the planets and nebulas I want to see, without too much money. A 4mm quality eyepiece a better idea?

Probably the same question again, sorry.

Chris

Screwdriverone (Chris) · #19 23-02-2008, 03:27 PM

Moot point now, check out my signature for my updated bits and pieces.

The wife has banned me from the local Telescope shop until I can deliver on some special Solar System images. (and pay off my purchases too!)

Chris

Kokatha man · #20 23-02-2008, 05:00 PM

Hi Chris - with a 130mm scope you aren't likely to ever use more than 250x and that even rarely, in nights of extremely good seeing (like once in a blue moon.)

The general rule says 2.4x the aperture in mm - meaning theoretically with a 130mm scope you could get up to about 300x, but realistically 200x-250x would be the limit, and then only rarely.

Don't want to be a downer but that's the truth, if you bought a 3x barlow it'd only ever be used with the 20mm ep - a 2.5x barlow with your current eps would give you magnifications of 50x 100x 125x 250x which would leave a gap that something like a 12mm ep could fill somewhat, with approximately 83x and 200x - much more likely to be used.

A barlow does increase eye relief, lessening the need to "surgically remove" your eyeball from the ep when used, if your ep's don't have good relief.

Bintel stock 2.5x GSO barlows that are quite reasonable for normal circumstances, I have one that I use quite regularly even though I've also got a TeleVue 2x as well.

Check out other threads in IIS to get other opinions also: btw couldn't see any dot/star in your image of Saturn, but Titan is very easily seen under low power. Hope this helps, Darryl.