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Old 25-11-2009, 03:40 PM
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ManintheMoon (Timothy)
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About to buy 8" Dob!

Hello again! (Mum on behalf of MITM)

Well we are about to place an order for an 8" Dob (Tim has been saving hard! ) and wondered what sort of extra eyepiece we ought to buy as well (if any?) as we've read a bit about Barlow lenses etc but wondering about which brands are good quality. (I'd imagine as with most things price reflects quality)

Here's the specs on the scope if that makes a difference in what type of Barlow we should get:

Skywatcher SW680 Dobsonian
Optical Design: Newtonian paraboloidal
Diameter in mm: 200mm
Focal Length in mm: 1200mm
Focal Ratio: f6
Highest Practical Power: 400X
Faintest Stellar Magnitude: 14
Resolving Power (arc sec): 0.86
Finder-scope: Optical 9x50mm Focuser
Diameter: 50.8mm & 31.7mm
Eyepiece (s): S20 and S10 (31.7mm)
Mount Type: Dobsonian with tension control

Also interested in getting a reasonable set of binoculars for the other son to peer through while waiting for his turn on the big one so some details.... (BTW He wears glasses so I'm leaning to the Gerber)

GERBER Sport Standard: 10 x 50 $105.00 Porro Prism Water/Fogproof.Olive Green Rubberised Body. BAK4 prisms. Long-eye relief

"New "slim-line" Metal & composite black rubberised body. Long Eye-relief. Fully Coated lenses. Complete with cleaning cloth & straps. Gerber have released a new, upgraded version of their popular Sports binoculars. The new housing combines sturdy construction and comfortable handling. Generous eye relief ensures fatigue free viewing even after extended use. Fully coated optics provide a crisp image with plenty of contrast. Supplied with neck strap, carry case and lens cleaning cloth. 2 Years Limited Wty"

ORION WorldView™ Wide-Angle Binoculars 10 X 50 $99.00 Anti-reflection Coating, Strap & Nylon Case

"WorldView binoculars are designed specifically for those who expect both quality and affordability. The prisms and all-glass optics are treated with a complete, anti-reflection coating - something you won't find in most binoculars in this price range. That means crisp, ghost-free images. At these prices, you could buy two models - one for yourself and one as a gift! One-year limited warranty"

Anyhow just hoping for some opinions/advice on these or any other binoculars before we place the order for the Dob so thanks for any help!

Regards...MITM’s Mum
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  #2  
Old 25-11-2009, 05:35 PM
astro744
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The 20 and 10mm eyepieces that come with the 'scope (odd since it is normally 25mm and 10 or 9mm) will give you 1200/20=60x magnification and 120x magnification. A 2x Barlow will make your 20 a 10 and your 10 a 5 (Doubling up a bit but the 5 would give you 240x mag which is a bit high for planets on most nights but possible when the air is very steady, ie. good seeing.

I would recommend a 32mm Tele Vue Plossl that will give you 37.5x and a true filed of view of 1.3 degrees. A very nice low power eyepiece that can be used on any telescope. You can add a Barlow to the 32mm but the eye relief will be too big. You could buy the 15mm Plossl and later the 2x Barlow to give you 7.5mm to give 80x & 160x respectively and that is about all you will need. Tele Vue is a very nice brand and reasonably priced with the Plossl range. The wider field Tele Vue eyepieces do start getting expensive but you are paying for sharp stars to the edge of the field.

Bintel are the Tele Vue agents and they also carry the Meade 4000 series Plossls which are very well priced and quite good eyepieces too.
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Old 25-11-2009, 08:54 PM
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PCH (Paul)
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Hi Mum (on behalf of MITM)

I agree with Astro744, - anything in the Tlevue plossl range is great quality, and the TV barlow I have myself and can vouch for it.

I mainly wanted to mention the binocs. Your post mentions "fully coated lenses" and "fully coated optics". The way binocular optics are described in terms of the way the reflecting surfaces are coated is not usually done casually, and you should be steering yourself towards a pair that is described as "fully multi coated". These are available for a reasonable cost, and will perform the best for you and your son.

Check out -
www.aoe.com.au
www.bintelshop.com.au and
www.andrewscom.com.au

Best wishes,
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Old 26-11-2009, 08:07 AM
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Batfink (Peter)
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Not sure how many will agree with me out there, but for my 8" SW I bought a GSO 40mm 2" superview EP, it gives great wide views, I'm very happy with it only cost me $49, but I believe the price has gone up to $69 still a good price from Andrews Communication.

Peter.
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Old 26-11-2009, 01:12 PM
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Davekyn (David)
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Your son is lucky to have such a caring mother. I'd be careful thinking that price reflect quality. Although this may be considered generally, there are times when manufacturers take advantage of this and skimp on quality control and rely solely on their name or otherwise their heads are so big they forget about quality control.

I have to agree with Peter, about that particular EP (eye Piece - however my 2inch Super View is a 42mm) although I use it on a 12" Dob. I own a number of 1/25" - 4mm/6mm/9mm/15mm/20mmSV & 25mm GSO plossels from www.andrewscom.com.au not to mention the 2XED Barlow and various planetary filters. I also own some 2" Low Power EPs from GSO which are very useful for a wider field of view...So much so, I am now looking into buying a 2" UHC filter.
I have not used the more expensive brands as I figured taking a chance on the GSO plossels would allow for a much wider collection. The reviews I read on GSO were not wrong...I'm very glad I went for a larger collection. It's easy to know what EP's to select when you've got years of experience, but not so when you don't. If your kid is just starting out, I would recommend not spending too much, so as not to limit you choice of EP's.
Absolutely nothing wrong with the GSO range- spend more if you want, but I highly recommend you buy 2 or 4 gso plossels at their budget prices! (in the case of GSO...cheap does not mean nasty!) If so the 2" 42mm SV Peter mentions is a great EP providing a first timer with a good wide field of view. My only skeptical point on the 2XED Barlow is that IMO your better off with "HIGHER QUALITY" EP to fully utilize it, as I find it much better to simply use one of the higher mag EPs owning so many. I do own a 12.5mm ED EP from AOE and when I Barlow it, it's much better than Barlowing a GSO, however I'm still glad I have a larger collection to learn what Object is best viewed at what field of view. Only now, I know for certain that I will be buying the right EP when spending LOTS of money on such items. Sorry if I'm confusing you...I do it to myself so often

I did the same with Filters (planetary ones I bought for next to nothing) and with the nebula filters (UHC highly recommended down the track) I did the same getting a standard Bintel one for $80.00 instead of $300.00 on another...SPECTACULAR VIEWS!!!

Binos I got from AOE...15X70 , After a few quick lessons my My 13 year old boy can use them easily to scan & star hop with...60mm may be a good size to consider...As for all the Sats you gave/ FMC (fully Multi coated) is fairly standard at most reputable places now...ED Glass (extra dispersion) is the next notch up, but once again not really needed for a kid starting out. www.aoe.com.au

Any of those 3 links given are all good places to buy from (especially if you buy budget to get more equipment)...I wish I had the spare money to buy my kid an 8" Dob, in fact I wish I had one myself! Good size to get about with yet see pretty much everything up there

All I am saying is don't under estimate the quality compared to price. As for the cheaper GSO plossels...in my opinion They are an EXCELLENT starting point for any beginner...practice will bring out more detail than first looking into the EP of a more expensive brand...as one gets better then they can get more excited over branding and so forth.

Just my 2c worth...I'd like to know how you end up going none that less and what your kid thinks when he gets the gear. Good Luck

Last edited by Davekyn; 26-11-2009 at 01:37 PM.
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Old 26-11-2009, 05:38 PM
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ManintheMoon (Timothy)
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Now I'm confused!

Hello all (Mum again)

Thanks so much for all the good advice (even though I don't understand half of it!)

I think we might wait until we get the scope home, play around with it and find a few things then learn some more about what all the eyepieces do. (Feel like such a noob ) Better to spend money on the accessories after you get a bit of confidence with the basics.

We are fortunate to have fairly dark skies here and as there's no sign of rain lately, should be clear too so I think I'm just as excited as the boys!

Anyhow will check all the links re the binoculars too so thanks for taking the time to explain the ins and outs.

Hopefully by this time next week we'll be star-gazing with the rest of you!

(And no doubt we'll have 20 more Q's...)

Regards...'Mum'
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Old 26-11-2009, 10:24 PM
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Batfink (Peter)
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Opps I meant 42mm sorry.
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Old 27-11-2009, 02:03 AM
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Davekyn (David)
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I do that all the time Peter Your right though, I'm always using that EP.
Sounds like a good Idea mum! I found asking the guys Questions at all the above shops very helpfull as they in turn ask me what objects I best liked looking at as well as what type of scope I am using. They then made recomendation and were very helpful.
Ask as many questions as you can. I knew nothing before joining here, and must say the guys here really know thier stuff and are more than willing to help newbies like us make the right decisions.
I think you've made a terific choice on telescope. Do as you say though...learn about the different "eye pieces" & how each afects "magnification" & Field Of View. Learn about what objects are best suited to the different EPs. Google or search "Telescopes/Astronomy - Choosing the right eye piece" I've just got back from observing, but if I find time, I'll send you some good links (Basic) on the topic
zzzzzzzzzzzzzzzzz...good luck & enjoy.
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Old 27-11-2009, 08:32 AM
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Davekyn (David)
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OK, I’ve enjoyed learning a little more myself on selecting the right eye piece. Here are some Basic Utube links that might help you better understand the basic concepts. The other Link may be a little to in-depth however, just take on board what you can understand for now, and keep the rest for later.

Without really understanding the Basics, you really can’t make an informed decision.
My take on it is to know what you telescope is good for looking at. The Focal Ratio (F/R) of your scope is F6…The higher the number that slower it is & the lower the number the faster it is. Not important to understand why just yet. The recommended Focal Ratio for viewing planets is around F9 and more suited to Refractors which your scope is not. Don’t get me wrong…you will still be excited seeing Jupiter and it’s moons, but to do so at your scopes optimal level you will have to be more selective with your eye piece & careful not to choose an EP that gives a to high Magnification as it’s more suited to Medium to Low powers. Just give the Links I have provided a going over and you will slowly understand the basic concept.
You should have a range of EPs that cover High/Medium & Low Powers…Some advice on choosing this range is given at those links. It’s for this reason again, I decided to get more budget EP’s rather than expensive ones to start with. The quality of the mirror in your telescope will also play a factor as well as collimation…collimation is critical when viewing at high mag…Given all this, you may very well be better to wait and see how you go with what you got, before spending $100.00 + on a single ep, or just buy a range of Budget - but effective plossels to learn with.

Best I can explain it…here are those links so that you may get a better grip on the topic:
http://www.actonastro.com/eyepieces.htm

http://www.wonderhowto.com/how-to/vi...escope-192365/

http://www.youtube.com/watch?v=wH2FbKy8zWE
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Old 27-11-2009, 03:21 PM
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ManintheMoon (Timothy)
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Ordered it!

Well its been a few months in the planning (originally asked the Q here about what scope would be best for a beginner) but we ordered the SW 8" Dob today!

Should take a week all going well (long way up to CQ from Sydney) but the binos will be here first so we can get started with them...just in time for full moon. BTW never having looked at it with anything powerful, are there any safety concerns with peering at full moon with 10x50's and later on when we get the scope?

Now I have to do a crash course in EP, FOV, F/R and I think my NY resolution will be to learn enough to read all your helpful replies and actually understand them!

Thanks Davekyn for the links too - more to study up on over the weekend.

Regards...Frieda
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Old 27-11-2009, 03:36 PM
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mental4astro (Alexander)
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No problem in viewing the full moon with binos. Will make your eyes react the same as going from bright day light into a darkened room. What will help is resting them on something to help hold them steady, like a post, or get a little adaptor to fit the binos to a photo tripod.
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