10" vs 12" Dob

[drmorbius]

Hi all,

As I get closer to selecting my first telescope, I've come to an interesting fork in the road... do I get the 10" Dob (as I had originally planned) or push myself that little bit extra now for the 12"?

Do I spend $700 or $1000? Is the extra $300 worth 2" more? Will I spend $700 now and want the 12" in another 6 months? Am I better off having that $300 to spend on eyepieces or a Telrad finder? Is the 12" really that much more difficult to cart around? :shrug:

Any guidance would be appreciated...

[davidpretorius]

simple in my mind.

if there is not an issue is transporting a 12" over the 10" then go the 12" without doubt!

2" extra diameter is lots of extra light.

I love ken's 12" dob for views of galaxies and the extra detail on planets.

In terms of transporting, what vehicle can't take a 1.5m long tube but can take a 1.25m tube????

Decent Eyepieces can wait as your eye's / brain need to be trained to see detail. It has taken me 12 months to start to pick up doubles, galaxies thru the finder etc.

Crayford is a must!

[circumpolar]

Bite the bullet and buy the 12" dob!
Aperature is everything!.........Well, maybe good optics are too:P , Good EP's, Mount....etc.

Think Aperature, Aperature, Aperature.

I also had this question befor I bought my 12"er, and I think I made the correct choice. Yes the 12" is a little bit bigger to transport but like most of us you will probably use it in your backyard 99% of the time.

The bigger question is how do you save up to buy the eye pieces you want.
Don't worry, you will buy them.......in time, and yes you do somehow save up the money.:)

[mickoking]

I say go the 300mm (12") Dob. Those extra 2" make a significant difference and the 300mm Dob is not much larger than the 250mm (10") physically. If you have a good finder you don't really need a telrad and you can save at your leasure for extra eyepieces.

[circumpolar]

If you have a sedan and the seats fold down and the head rests come off then there are no probs (removable rests are not necessary but are better). I do find though that the dob mount is hard to fit in. In my car (sedan) it does't fit in the boot and has to fit in the back seat, but it does fit, but most people rarely transit so I don't think it's a bis issue.

Dido on the 2"crayford. A must.

[Starkler]

Is your car a hatchback or wagon with a split folding rear seat? If so get the 12" . If its a sedan then the 10" ota should fit nicely on the rear seat, where the 12" may not.

[dugnsuz]

Hi,
I'm only going to restate previous posts I think but, I bought the 12" as I don't intend to transport it. I live in under dark skies so there's no problem.
The 10" is significantly smaller all round (portable) - scope and mount. So, if you have to leave the house, get the 10. The difference in aperture between 10 and 12 is not as significant visually IMO under suburban skies as others have stated (dark skies is another matter - ie perfect telescopic conditions).
The Crayford focuser is a major plus too and you're in QLD so the fan would be a plus, therefore I would go for the 10" deluxe at $699 from andrews.com if you have to transport.
Also you have the option to mount a 10" a lot more easily than a 12 down the line.
But... if you just intend to drag it out now and again, get the 12!
I don't know if this helps but I hope it does!!?
Bottom line: I've enjoyed both scopes.
Cheers
Doug:thumbsup:

[ballaratdragons]

Hi Randall,

As Davo has pointed out above, "I love ken's 12" dob for views of galaxies and the extra detail on planets". At last Camp Janoskiss took over my 12" (with permission) and gasped and ooh-aah'd at the difference a 12" makes.

And 2" is a LOT more light! There is a method of working out the percentage increase. It's not a simple matter of 2" more. It is somewhere in the vicinity of 30% more (hopefully someone knows the equation and can tell us all).

There is still (reportedly) a noticable difference in medium light pollution and a HUGE difference in Dark skies. As for what Doug has said just above, in heavy light pollution there won't be much of a difference.

But in moderate to Dark skies the 12" brings out the very faint fuzzies!

Compare the difference between the 8" and the 10" here:http://www.iceinspace.com.au/forum/showthread.php?t=9807

Then just imagine increasing that quality again by another leap in whatever percentage someone will work out for us.

But if you need to transport it on a regular basis, I suggest going here to take some measurements. All the dimensions are listed, just scroll down to the 12" model: http://www.telescope-service.com/dobsonians/dobsonians/dobsoniansstart.html

[Starkler]

Its a personal thing really. If you can get to a star party and check them out in the flesh you will have a better idea of what you are really willing to move,store and bother to use.

My latest scope gets a lot more use than the 10 incher, and its actually a 5 inch newt :) Its gets more use because its so easy and convenient to move and use :)

[janoskiss]

Yes, Ken! And a few weeks later I ordered one! :lol:

But it's best if you try them both before you buy. The 10" is a lot more handling friendly and the focuser height makes it easier to observe sitting down. With the 12" you are almost standing up to observe (but not quite, which can be a pain in the old spinal cord). It is also a lot more awkward to move the 12" around, if you need to dodge trees/buildings often. It is best to buy both the highly mobile 8" and the galaxy magnet 12". :D

[Miaplacidus]

Just what I was thinking, Steve.

Cheers,

Brian.

[drmorbius]

Thanks everyone... so the answer is: get a 12"... unless you want the 10"...:)

No, but seriously folks... it looks like 12" is the way to go if I can do it. And I did consider getting something smaller to start with... but I think I'm only going to get one go at this (I'm still trying to work out how to break this telescope idea to the missus, I can just imagine her reaction... :lol:)

Sure would be nice to have something to take to Cambroon later in the month...:astron:

[acropolite]

Approximately 44% more light gathering area on a 12 inch compared to a 10, that's a huge amoung, I would go the 12 inch, the weight difference won't be that much and if your car will take it transportation will not be an issue. If transportation space is an issue and you are willing to spend some extra you may you could consider the Meade Lightbridge. For hints and tips on how to get it past SWMBO, consult with Tony (Striker) he's the master of domestic deception... :P

[Starkler]

Oh yes Randall, in this thread are some photos showing the different size dobs for comparison purposes.

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

[janoskiss]

Despite the strong favour in the larger aperture scope (which you will get every time you ask this sort of question), I would recommend you spend a bit of time observing with both before buying if you can, and assess how comfortable it is to use both scopes and how much difference there is in what you can see through them.

Don't get too hung up on the numbers. (Let me explain why with more numbers. :P) The 44% brightness difference is noticeable but rather marginal (many newbies cannot tell the difference). The eye has a dynamic range spanning conservatively a 100000-fold increase in brightness, so a 44% or 1.44-fold increase is not huge by any means.

And consider that the 10" will probably get more use; maybe over 44% more! ;)

[ving]

aperture rulkes unless you cant transport it....
I have a 8" which i can lift in opne piece with out breaking my back. i understand 12" is heavy, but can be over come by using a trolley.

I can fit my 8" in the car easily, but not the family too (its a astra).

[wavelandscott]

The right scope for you is the one that you will use...I think this is the real key...

Yes, in terms of light collection a 12 inch > 10 inch> 8 inch etc...but, if the size of it means that you are only going to get it out to view 1/2 as much what good is the extra light. A smaller scope can provide a life time worth of viewing...the scopes available to amatuer astronomers "blows away" anything that was available just a few years ago...

Go big if you can and if you will use it but as a first scope I'd start smaller and use it regularly (nake sure the hobby will stick)...as others have said, try before you buy if at all possible...

[Miaplacidus]

So what are you saying, David? You put the family on the roof racks?

[ving]

what i am saying kind sir is that it either the scope or the family but noe both...
i am thinking of getting a towbar and trailer tho... for the family ;)

[mickoking]

The tube length of the GSO 250mm is 1210mm and for the GSO 300mm Dob the length is 1460mm. Both are very good and capable visual instruments.

[[1ponders]]

Randall, I think you need to come back out to Cambroon and compare the 12" of Nightshifts, the 16" of Astroron's and the 25" of Argonavis.


Then see which one you want :lol:

Then get the 12" :)

If transportation is an issue consider the option of a Truss Dob

[Gargoyle_Steve]

Paul the trouble with that plan is that Dennis's scope will have that lovely candy apple red tube by then - I think that's gonna cause a biased opinion!

(Can't wait to see it Dennis!!!!!)

[drmorbius]

Good point Steve... maybe I'm worrying too much about mirror size. Maybe I should be trying to find a scope with the right colour scheme. :P

Rats... red's been taken!

[astro_nutt]

Ahhh!..what to choose!!!...If you plan to have it at home, or you can transport it without hassles, (you can buy one of those mini-trailers from Kmart for about $450.00)..then go for the 12 inch. I agree..the light collecting ability speaks for itself and you will be rewarded with brighter images..I own a 10 inch dob and a friend of mine has brought himself a 12 inch Lightbridge..the diffrence is noticeable between the two..use and enjoy!!

[Gargoyle_Steve]

Randall I was originally set on getting the 8" dob, right uo until I was actually on the phone with Lee Andrews ordering .... something happened at the last minute, and as you know I have the 10".

In terms of pure light gathering ability here's the simple facts: if we ignore the obstruction of the secondary mirror a 6" reflector will gather 36 "units of light" (uol) compared to an 8" 64 uol, a 10" 100 uol and a 12" 144 uol. Based on that I did find the 10" to be the best value.

The only thing I Can say is do what you are planning in terms of getting the "Deluxe" version with Crayford focuser, and if you can get the upgrade to the 10:1 fine focus unit at a reasonable price do it. (I have heard it's $20-40 depending on whether you go Bintel or Andrews, but feel free to haggle AND mention you are from the IceInSpace forum too).

As said above it's all a matter of transport vs cost - whichever you buy I can guarantee you will enjoy it, be it white, black, or even candy-apple red!!

(and Dennis's powder-coater IS apparently in the Caloundra area somewhere anyway - we might even get a 2 for 1 price off him ;))

[dhumpie]

The solid tube 10" GS is just the right weight and length to fit across the back seat of most small compact cars. The 12" GS is a good deal heavier and longer (the OTA I mean) so that is why most people go for the 10" GS. I know because I did.

Darren

p/s: from memory the OTA of the 12" weights as must as the 10" OTA and mount put together...doable but more hassle...

[ballaratdragons]

Darren, where do you remember those figures from? You are waaaayyyy off the mark.

GS 10" (250mm) OTA - 15.5kg, Base - 12.2kg Total - 27.7kg

GS 12" (300mm) OTA - 19.5kg, Base - 13.5kg Total - 33kg

Yes the 12" is slightly longer and heavier than the 10", But double????

Randall, and anyone else wanting the FACTS on dimensions, look here for every spec you need on all GS scopes; weight, length, diameter etc: http://www.telescope-service.com/dobsonians/dobsonians/dobsoniansstart.html

I personally don't have a problem carrying, moving or transporting my 12" but you may want a slightly smaller scope for ease.

'Sup to you :thumbsup:

[dhumpie]

Oops...thanks for the correction Ken. Still between the 10" and the 12", I would still go for the 10" if I had to do it all over again. Its one of those comfortable, do it all apertures...

Darren

[vespine]

Obviously it isn't double, but I think the point is that the diff between a 8" and a 10" is not nearly as proportionally large as the diff between a 10" and a 12", I was actually a little surprised when I saw them in person. An extra 2" diameter and 250mm length doesn't look very significant on paper.
I guess the main reason is because the 8 is a f/8, length is 1200mm. The 10" is a f/6 length is a similar 1250mm while the 12" is a f/5 at 1500mm.

At the end of the day, I still went 12" ;)