Newbie needing advice

zultan (Mike) · #1 18-05-2013, 08:07 PM

Hi, I've recently arrived in the southern hemisphere and am faced with a whole bunch of constellations that I are new to me.

To dip a toe in the water I purchased an Astromaster 130eq and quickly found the limitations of the supplied eyepieces. So I purchased a Celestron Ultima 2.3mm Clone.

I've tried pointing at the moon, but can't find the focus with the 2.3mm eyepiece. What am I doing wrong? Any tips gratefully recieved. thanks for reading.

barx1963 (Malcolm) · #2 18-05-2013, 09:14 PM

The 2.3mm EP is really high power for that scope. I think the scope has a focal length of 650mm so that EP will give 282x, which is really high for a 5" scope.
What were the probs with the supplied EPs? Usually there is a 20mm which should be OK and a 10mm which will be harder to use but capable.

Malcolm

zultan (Mike) · #3 18-05-2013, 10:00 PM

To be honest, I'm trying to be cleverer than I actually am. Nearly every review I read of the 130eq pointed to buying extra eyepieces or the Celestron 94303 kit, so when I saw the 2.3mm at a reasonable price I dived in without much thought. I now understand the error of my ways

zultan (Mike) · #4 19-05-2013, 09:07 AM

So as a rule of thumb a smaller mm means more magnification? - what is the practical smallest that the 130EQ can cope with? thanks

barx1963 (Malcolm) · #5 19-05-2013, 12:58 PM

Yes, the lower the focal length of the eyepiece, the more magnification it gives. To work out the power, divide the focal length of your scope by the FL of the eyepiece. So you get 650/2.3 = 282x. For comparison a 20mm ep gives 650/20 = 32.5x.
You may read that a scope maximum practical magnification is 50x per inch of aperture, which in your scope gives 5" x 50 = 250x, but this is largely a theoritical limit. It requires exceptinal seeing conditions, near perfect optics and near perfect collimation to be even remotely possible. In most conditions it is more like 10-15x per inch, so I wouldnt use much more than 50-75x in your scope most of the time. So a 20mm and 10mm ep should be fine. The thing is that the atmosphere interferes with the image, causing it to move and jump (that's why stars twinkle). Higher power magnifies this effect, deteriorting the image.
Again, in your original post you mentioned issues with the supplied eyepieces. Were these actual issues you encountered or were you inferring them from reviews you read? Always treat online reviews with a grain of salt. I have come across some that were not worth a knob of nanny goats pooh! (to use an old friends expression!) It costs someone nothing to put up a review on line and there is no guarantee that the reviewer even knows what they are talking about.
Usually the EPs supplied with thsi class scope will be ploslls. They are generally OK and the low power ones are quite acceptable for beginners use. Premium EPs can be expensive so don't rush into buying them until you know what you are doing.

Malcolm

zultan (Mike) · #6 19-05-2013, 02:40 PM

Thanks for the info. Presently I have not had much joy pointing the telescope at anything smaller than the moon. Getting used to the mount as well as sky navigation. The only limitation I have experienced is that neither of the supplied eyepieces magnify the moon to fill the view. I was hoping / expecting to zoom further in.

Jon (Jonathan) · #7 19-05-2013, 03:38 PM

An f/5 130mm reflector on an equatotial mount was my first ever serious scope, 27 years ago. I still have it and have got some very pleasing images with it even now. The best EP I found with it was 20mm. I had a 6mm to use with planets, lunar craters etc. but to be honest that's not the strength of such a scope. Ayway, you can see all them in the northern hemisphere!

The 130mm with a 20mm or so EP will give you good views of omega centauri, eta carina etc. where you DON'T want high magnification at all. Same with countless colourful open clusters. You'll have a crack at a handful of brighter galaxies if you get to a dark sky site. This is all the stuff you'll never see from the north.

zultan (Mike) · #8 19-05-2013, 06:34 PM

I know I'm running before I can walk. Quite literally it takes me a while to point at the moon..... Near or deep sky have both avaded me. Hence why I'd considered buying http://www.universetoday.com/25777/t...accessory-kit/ (bad workman and tools springs to mind)!

andyc (Andy) · #9 19-05-2013, 09:09 PM

Hi Mike, I have the 130EQ, and I can see why you had trouble. 282x is an awful lot of magnification for the little scope. I never got much joy beyond about 105x (~6mm) or 150x (~4.5mm) - and even at that level, the images are sometimes challenging (often dim). It is most effective as a 'rich field' kind of scope - as mentioned above, look for the bigger, brighter clusters and nebulae. For this, the 130EQ does really well. On a good night, the magellanic clouds are magnificent; and various sights in the Scorpius/Sagittarius area could be added to Jon's suggestion, as well as quite a lot of brighter objects around the sky.

The eyepieces shipped with my scope were not so great. One was plastic, too, and the image quality, even in comparison to the Bintel basic $40 Plossls, was terrible! Not sure a whole box of Celestron goodies is quite necessary - maybe two or three eyepieces giving a range of magnifications. Lowest might be a 32mm (6.5mm "exit pupil", about as big as your eye can handle), highest I'd suggest would be 4-5mm or so, mainly for planets, and a good middle 'general' eyepiece might be a 15-20mm. But a lot of that is personal preference (and how much you value the extras), and the Celestron box might do you for a future scope too, if you're that way inclined!

Clear skies!

barx1963 (Malcolm) · #10 19-05-2013, 10:04 PM

Mike
I wouldn't touch one of those kits. There is not anything actually wrong with them, but mostly you will not use many of the items. You will get plossls of 32, 15, 9 6 and 4 focal lenth. Odds are you will only find the first 2 remotely useful and maybe the 9. As for the filters, yeah coloured filters can be used to improve the views by incraesing contrast on planets, but it sounds like the main issue is finding objects with an EQ mount.
Unfornately EQ mounts require a fair bit of practice to handle well. Best idea is to see if there are any clubs or regular observing nights near you where a more experienced user may be able to assist with using the mount.

Malcolm

andyc (Andy) · #11 19-05-2013, 11:31 PM

Something else Malcolm's comment just reminded me of - I replaced the (rubbish) 1-power finder with a simple 6x30mm finder - literally drilled new holes and bolted it on. It made finding and centreing objects vastly easier, especially if you have light pollution (IMHO). The finder will show you some of the brightest objects, and many more of the stars in the region of something you're looking for. Moon and planets are a snap! So if you're struggling with pointing the scope, that may be another idea to consider?

zultan (Mike) · #12 20-05-2013, 09:40 AM

Thanks everyone for the guidance, it is appreciated. I guess am drawn towards the Celestron kit because it a. comes in a funky box and b. At this stage, I really don't know what I don't know. I need an opportunity to play with different things and learn (the hard way) what does and doesn't work for me.

zultan (Mike) · #13 20-05-2013, 09:45 AM

Quote:

Originally Posted by andyc

simple 6x30mm finder - literally drilled new holes and bolted it on.

Can you recommend a find scope? thanks

zultan (Mike) · #14 20-05-2013, 09:49 AM

Quote:

Originally Posted by barx1963

Unfornately EQ mounts require a fair bit of practice to handle well. Best idea is to see if there are any clubs or regular observing nights near you where a more experienced user may be able to assist with using the mount.

Thanks for this tip, I have joined the Canberra Astro Society. Amusingly the best advice I've had is to buy a scope with GoTo mount.

barx1963 (Malcolm) · #15 20-05-2013, 10:14 AM

Quote:

Originally Posted by zultan

Thanks everyone for the guidance, it is appreciated. I guess am drawn towards the Celestron kit because it a. comes in a funky box and b. At this stage, I really don't know what I don't know. I need an opportunity to play with different things and learn (the hard way) what does and doesn't work for me.

The problem with learning the hard way is that it can be expensive. These kits cost around $300-400 which is a LOT of money for a set of plossls!
You will find that once you get into it, you will largely only use 1 eyepiece 90% of the time. I have 5 eps in my kit ranging from 41mm to 10mm and I use the 17mm easily 90%. When I had my previous set on my 12" I basically used the 24mm Panoptic 90%, the 13mm Nag 5% and the rest 5%.
The point I am making is use the gear you have and learn the various strengths/weaknesses, what you like about it and what you like observing before spending that sort of cash. I cannot think of a single regular observer who uses one of these kits.

Cheers

Malcolm

zultan (Mike) · #16 20-05-2013, 10:39 AM

I wasn't considering that much cash, these kits can be picked up for $165 delivered from sellers in the US on eBay. It is amazing the price difference between the US, UK and Aus for this particular item.

barx1963 (Malcolm) · #17 20-05-2013, 12:26 PM

I you can get for $165 thats not so bad. I am used to warning against the Aussie prices! Celestron is very restrictive with regard to dealers territories, so make absolutely certain they will ship to Oz.

Malcolm

zultan (Mike) · #18 20-05-2013, 01:25 PM

I'll let you know how I get on.

andyc (Andy) · #19 21-05-2013, 01:15 AM

Quote:

Originally Posted by zultan

Can you recommend a find scope? thanks

I got the 30mm one from Bintel for $50, doesn't need to be fancy for your needs. You may need a mounting plate, can't quite recall. I still use the same finder on the 16" scope these days (though I am tempted to upgrade)!

Jon (Jonathan) · #20 22-05-2013, 11:26 AM

If you really want a kit why not a home-grown one? http://www.bintel.com.au/Eyepieces-a...oductview.aspx

But if it were me, and I had $165 to spend on eyepieces with your setup, I'd get http://www.bintel.com.au/Eyepieces-a...oductview.aspx. As Malcolm says, this is the one you will use 90% of the time. invest in a nice one!

If you want to see what the planets can look like then add $40 and get http://www.bintel.com.au/Eyepieces-a...oductview.aspx

My 2c