Skywatcher collapsible dobsonian ?

orestis · #1 10-07-2010, 10:58 AM

HI guys

,

Ok i have a 130mm X 900m reflector on an eq mount and after a while am looking to upgrade to a scope that will serve me for quite a while.

I'm currently borrowing a 10'' solid tube dobsonian and while i can see that it makes everything brighter it is a real pain to collimate.I don't have any collimating tools.

Anyways andrews are having a sale on their sywatcher collapsible dobs cheaper than the solid tube gso are they of equal optical quality? I thoght with the fifty dollars that i save i could buy a chesire for collimating.Just wondering whoever owns one of these could give some sort of review on how they perform and if i should buy one.

I'd love to know what you guys think.

Thanks in advance
Orestis

bmitchell82 (Brendan) · #2 10-07-2010, 11:06 AM

Hey mate,

There is no difference at all to the optical quality, its more a case of different tube design. it should work well for you

Liz · #3 10-07-2010, 11:15 AM

Hey Orestis ... I have the Skywatcher coll Dob and very happy with it.
They supposedly hold their collimation very well, which is a bonus as am the worlds worst collimater.

If you are looking to buy one, then do it!!!

orestis · #4 10-07-2010, 11:29 AM

Quote:

Originally Posted by Liz

Hey Orestis ... I have the Skywatcher coll Dob and very happy with it.
They supposedly hold their collimation very well, which is a bonus as am the worlds worst collimater.

If you are looking to buy one, then do it!!!

Hi liz,

just wondering do you have a light shroud for yours as thats what am worried about right now.Also just wondering if you don't mind, how much did you purchase yours for because maybe just maybe it has been lower in the past(price).Also have you installed a fan on yours?How often fdo you colllimate yours?

Sorry for all these q's.Just need to get ther facts right before making the leap.

Thanks Orestis

orestis · #5 10-07-2010, 11:30 AM

Quote:

Originally Posted by bmitchell82

Hey mate,

There is no difference at all to the optical quality, its more a case of different tube design. it should work well for you

Regarding the tube design would the mirror cool down quicker if it had an open tube design?

Orestis

Liz · #6 10-07-2010, 11:36 AM

Quote:

Originally Posted by orestis

Hi liz,

just wondering do you have a light shroud for yours as thats what am worried about right now.Also just wondering if you don't mind, how much did you purchase yours for because maybe just maybe it has been lower in the past(price).Also have you installed a fan on yours?How often fdo you colllimate yours?

Sorry for all these q's.Just need to get ther facts right before making the leap.

Thanks Orestis

yes, have a shroud - these are expensive to buy, so see if someone can make one for you. I know people who dont use a shroud though which is prob Ok in a dark site.
I bought mine about 7 months ago, and was just under $1000 to more door, I think the price has dropped a bit since then.
An older guy in our club has just installed 2 little computor fans at the bottom - very nifty!!! I will send pics if you decide to purchase.
I havent actually done it myself, but a few member of the club go around at the start of the night and quickly look at the scopes coll. and mine only requires a quick tweak.

bmitchell82 (Brendan) · #7 10-07-2010, 11:37 AM

if im correct in thinking upto the 8" varients uses BK-7 glass which will take about 30min - 1hr to cool down, but the 10" uses pyrex, which really doesn't do anything so it doesn't need to "cool down" though the tube and other components need to be at approximate ambient temperature.

To see these effects even in your telescope set it up, put it on a nice bright star, then defocus the star till it nearly covers your field of view. Put your hand infront of the telescope you will see the heat coming off your hand. you can use this method to see tube currents and if your optics are "cooled"

So do i believe in fans? No, they introduce vibrations and in a open newt design will only serve a small bonus.

orestis · #8 10-07-2010, 11:42 AM

Thanks so much guys for a quick response,

You have been very helpfull.

thanks
Orestis

barx1963 (Malcolm) · #9 10-07-2010, 11:47 AM

Orestis.
Mirror cooldown is mainly to avoid tube currents. If you have a chunk of glass sitting at the boittom of a tube sitting in a nice warm room at 15-20 deg then move it outside at night at 0-5 deg, the air around the glass warms up and moves and this shows up in the images especially at high power as stars and especially planets almost seem to "boil". On smaller scopes current really are the only issue, on larger mirrors thermal stability is more of an issue IMHO. I use a fan on my 12" and it definaitely allows faster cooldown. Once I am happy it is cool enough I turn it off eliminating vibrations, once the mirror is at ambient it isn't going to warm up again!
Truss tubes without a shroud abviously suffer less from tube currents, butr a shroud is still very useful if there are any lights from neighbours, streetlights etc nearby.
Not sure about collimation on the SW, I replaced the knobs on my GSO with Bobs Knobs and think they are the Bees Knees!
Haven't really got the hang of the cheshire yet, I just use a simple collimating cap, dust cap with a hole in it and a laser, seems to work fine for me!

Phizzy (Phill) · #10 10-07-2010, 12:04 PM

Hi Orestis,
I have the 8" coll dob and I love it....They do keep collimation very well. I live 4km from Brisbane (lots of light pollution) and have not bothered with a light shroud as the bottom tube is quite long and stray light doesn't seem to be a problem. I have 3 children (10-14) and have no trouble letting them run rampant with it, sure glad I didn't get a 'scope on a tripod!!!?? My dob travels regulary to various sites and is easy to get in and out of my car and mostly I just plonk it down and observe...no collimation (3 children remember). I have added a telrad and a right angle finder.
I love my dob (and my family) buy one and have fun
Phill

Phizzy (Phill) · #11 10-07-2010, 12:11 PM

Hi Orestis,
I have the 8" coll dob and I love it....They do keep collimation very well. I live 4km from Brisbane (lots of light pollution) and have not bothered with a light shroud as the bottom tube is quite long and stray light doesn't seem to be a problem. I have 3 children (10-14) and have no trouble letting them run rampant with it, sure glad I didn't get a 'scope on a tripod!!!?? My dob travels regulary to various sites and is easy to get in and out of my car and mostly I just plonk it down and observe...no collimation (3 children remember). I have added a telrad and a right angle finder.
I love my dob (and my family) buy one and have fun
Phill

orestis · #12 10-07-2010, 01:50 PM

Thanks guys

Orestis

mozzie (Peter) · #13 10-07-2010, 03:12 PM

go for it orestis ive the 8" to take camping and star parties and its a little ripper terad,big naglers,counter weights great little scope

orestis · #14 10-07-2010, 05:23 PM

Thanks guys for the feedback,

Ok if you had the money to buy either the 10'' solid tube gso at andrews for $750 or the collapsible 10'' skywatcher for $650.

Which would you buy and why?

Thanks in advance
Orestis

that_guy (Tony) · #15 10-07-2010, 05:50 PM

Hey Orestis, i own a 10" solid tube GSO that was originally came from Andrews ( i bought it used ), it has excellant optics.... but... i had some troubles with transporting it in my friends car which is smaller than my mums 4 wheel drive, if i had the money, i would go for the collapsible one and save the hundread bucks for a telrad or a cooling fan... However I love my GSO... I will never trade it for anything... (until aperture fever sets in)

Cheers,
Tony

Stu Ward · #16 10-07-2010, 08:07 PM

You have to consider the extras that you get with the solid tube
Right angle finder 10:1 focusser etc

I think the collapsible just comes as standard

bmitchell82 (Brendan) · #17 10-07-2010, 08:20 PM

the answer to your question only you can answer. just look at transportation if needed, weight how heavy it is can you lift it, storage where to store it, future use ect ect.

areyouabus (Pauly) · #18 11-07-2010, 12:47 PM

You also have to consider that collapsible looks way cooler. If i were buying again, i'd go the 10" collapsible at that new price. The money saved will buy that right angled adaptor and a trolley jack to help move the beast.

GraemeT (Graeme) · #19 11-07-2010, 09:42 PM

Although I have very little experience, I thought I would throw in my tuppence worth. My scope is an 8" collapsible skywatcher, which I bought mainly because I can fit it in the boot of my car. I did make a plywood box to protect it. The 300mm that it shortens the tube makes the difference between fitting it in the car on its own or fitting it in with other luggage and people.
Cheers
Graeme

Dean · #20 12-07-2010, 10:26 AM

I have the 10" Skywatcher solid tube dob. Nice scope indeed. Dont plan on transporting mine so collapsible wasnt needed. The 10" does have the Pyrex glass and I haven't really noticed much cooling issues. As such I dont have or seem to need a fan on mine. It definitely does need a Telrad though and I have since purchased and added one to my scope. Even thinking of adding a chain of Red LEDs around the base with a simple switch and small shelf for a battery to run them at night when I need to look at a chart