What Telescope? - Page 2

Robert_T · #21 08-01-2006, 03:47 PM

Quote:

Originally Posted by cjmarsh81

Hi all!

After going through the forums on this site I have changed my mind on the telescope I am going to get. Yes it is a Dob.

I am now looking at the skywatcher 8" or 10". Any recommendations? Does anyone know anything about the skywatcher brand? Which brand do you recommend?

What lenses do I need. I am interested in Planets and now also DSO's

Good luck with the new scope. No doubt either of these would be a good start with a decision on which mostly dependent on your capacity to transport the larger 10in. I wont try and lure you from Dobbing to the dark side of equatorialising... maybe another time

cheers,

cjmarsh81 · #22 08-01-2006, 04:11 PM

Yes, sorry I did mean eyepieces not lenses.

I think the dob comes with a 10mm and a 20mm eyepiece. I will try these for a while and work out what I need after that.

Obviously the 10" will recieve more light than the 8". Everywhere I look people give samples from the 8" and they only show planets, whereas the 10" has nice DSO pictures of nebulae etc. Does this mean an 8" is incapable of DSO and can only see planets?

Nowhere I look gives the dimensions of the Dob's I am looking at. I have seen an 8" scope in a telescope shop here in Newcastle so I know the size of it. Is the 10" much bigger?

Yes, thankyou Micko this all helps.

RAJAH235 · #23 08-01-2006, 05:25 PM

cj, for comparison of telescopes limiting magnitudes >
http://www.go.ednet.ns.ca/~larry/astro/maglimit.html
http://www.celestron.com/tb-trms.htm
All t'scopes will 'see' objects. It's just the amount of detail/resolution etc that is set by the smaller sizes.
That is why the #1 rule = 'Aperture wins'.
Not sure of the physical differences but the 10" @ f5??? should only be 50" long.
eg; My 10" f4.5 is 45" long.
The 8" @ f7??? (please correct here guys), would then be 56" long. (approx).
I think Ken had a link showing the dimensions/weights etc . PM him?
HTH a bit.

L.

janoskiss (Steve H) · #24 08-01-2006, 05:53 PM

Quote:

Originally Posted by cjmarsh81

Obviously the 10" will recieve more light than the 8". Everywhere I look people give samples from the 8" and they only show planets, whereas the 10" has nice DSO pictures of nebulae etc. Does this mean an 8" is incapable of DSO and can only see planets?

Don't know what you mean by "samples" from the scopes, but the 8 & 10" Dobs are comparable in performance on both planets and DSOs. Yes you see a bit more in the 10", though it is a fairly subtle difference. When you are trying to tease detail out of faint objects.

The 10" is considerably larger. Not much taller, but bulkier. Get the biggest scope that you can afford and are comfortable with lugging around. The 8" is huge when you show your non-astro friends, but it looks like a baby scope at a star party.

Check out the photos of 8, 10 & 12" GS Dobs here: (and a 10" Saxon one too)

http://www.iceinspace.com.au/forum/s...ead.php?t=5075

cjmarsh81 · #25 09-01-2006, 10:00 PM

Hi everybody.

Another question. Collimation. With a 10" Dob how often does it need collimating? Should I buy a collimation tool when I buy the scope or is it something I can get later.

myastroshop have an optex laser collimator for $99. Will this work ok with a skywatcher 10" Dob. Think it will but better make sure.

P.S. I appreciate all the help from everybody!!

davidpretorius · #26 09-01-2006, 10:43 PM

cj,

if you travel around with it a lot ie bump it, then i would check the collimation each time.

The smaller secondary mirror near the top needs to be collimated once a year ish.

The primary needs to be checked quite frequently.

Now there are threads and thread and lotsa thoughts on collimation. Laser colimation seemed to been a real "thing" to do, but good old mechanical collimation with a cheshire seems to be making a comeback.

I have a cheshire and believe i will always use it. I want to buy a laser as well. I want two methods. I would recommend a longer sight tube / cheshire for a 10" dob. The sight tube does the secondary, the cheshire does the primary.

If you want to be real precise, you then do star tests.

Do not try and take the following articles all in one hit as collimation is an ongoing learning curve.

first:
http://www.schlatter.org/Dad/Astronomy/collimate.htm
second:
http://legault.club.fr/collim.html

janoskiss (Steve H) · #27 09-01-2006, 11:54 PM

My 8" holds collimation very well, even after long trips on bumpy roads. I check collimation every time I observe, but usually it's fine or it only needs the slightest nit-picking tweak.

cjmarsh81 · #28 11-01-2006, 10:40 PM

Hello

Can someone please tell me when and where the Newcastle Astronomical Society have their viewing nights. I would like to look through a couple of scopes before I go and buy one.

Thanks

RAJAH235 · #29 12-01-2006, 01:12 AM

cj, here's the link, but it doesn't appear to be up at present......

www.nas.org.au

L.

DRCORTEX (Lance) · #30 12-01-2006, 09:18 AM

Andrews www.andrewscom.com.au have a GSO collimator going for $79

Neo

barees63 · #31 12-01-2006, 09:23 AM

If that is the same as my GSO laser collimator don't expect too much, they are poorly made and don't fit well in the GSO focuser, I had to replace the laser unit in mine since it had a badly elongated "dot" and then to cap it all I discovered that laser collimators are not a really solution in themselves, from what little I've learned you'd be better to spend the money on a cheshire/sight-tube..

davidpretorius · #32 12-01-2006, 09:35 AM

Quote:

Originally Posted by barees63

that laser collimators are not a really solution in themselves, from what little I've learned you'd be better to spend the money on a cheshire/sight-tube..

i agree, go a longer "orion??" sight tube / cheshire

cjmarsh81 · #33 12-01-2006, 09:10 PM

Hello again

Can anyone tell me if there is a decent telescope shop in Newcastle. I have gone to the Telescope/Instrument shop in broadmeadow and although he is very friendly, I am not very impressed for the following three reasons.

1. He keeps trying to talk me out of a Dob (I think he wants to move his EQ mounts)
2. Has never heard of a collimation tool
3. Says that the scope will come collimated from the factory and will never need doing again (I wish this were so).

I will probably end up ordering my scope from myastroshop, but would like to know if there is a shop in Newcastle I can walk into and see one in person first.

cjmarsh81 · #34 13-01-2006, 11:46 AM

Hello Everyone.

I have just ordered my scope

A 10" Skywatcher Dobsonian from the Survey and Instrument shop in Newcastle.

Scope is $750 and I ordered a 6.3mm Plossl for an extra $90.

I should have it next tuesday or wednesday.

iceman (Mike) · #35 13-01-2006, 11:48 AM

How come you ordered it from there after the points you said above?

$90 for a 6.3mm plossl is very expensive. I'm afraid to say I think you paid too much. Is it too late to cancel the order?

But you should be happy with the scope.

iceman (Mike) · #36 13-01-2006, 11:48 AM

Does the scope come with any other eyepieces?

davidpretorius · #37 13-01-2006, 11:51 AM

congrats mate,

i suggest a fresh set of sheets for the new arrival. After you have explained to the better half that the telescope must sleep in the bed, you will need to align your bed north / south. It helps with collimation. If it looks silly in the bedroom, then realign the house!

Get out your sticky tape and coloured pieces of paper ready for collimation

http://www.schlatter.org/Dad/Astronomy/collimate.htm

cjmarsh81 · #38 13-01-2006, 11:51 AM

Iceman,

If the 6.3mm plossl is too expensive I will change it to a barlow.

I got it there because his price is $180 cheaper than anywhere else I have seen it.

It also comes with a 10mm and a 20mm. He said he could change the 20mm to a 25mm for me if I wanted to. Is this a good idea.

iceman (Mike) · #39 13-01-2006, 11:55 AM

What brand of plossl is it?

cjmarsh81 · #40 13-01-2006, 11:57 AM

I thought plossl was the brand. No I don't know what the brand is.

He said he could sell me a barlow for $90. Is that a good price, before I call him back to change it?