8" Dobsonian to 10" Dobsonian ?

[Dazraz]

Hi

Had my 8" Dobson and been stargazing for about 2 months and already caught the fever for it already and thinking of getting a 10" Dob.

So far i have been looking at jupiter and moon and the great nebula in andomeda. I would like to get a bit closer to jupiter and other planets reason being the step to 10".

At the moment me and my wife can quite easily hold each handle on the side of my 8" and carry it to and from the garden and to the end of my road. With a 10" will this still be possible ?

Also is there a lot of diffrence between the 8" and 10" ?

I havnt seen much else in the sky with my 8" is this because i am not looking in the right places or do i need to learn the sky a bit better or other reason or can i get closer to the planets with better EP's ? At the moment i have a wide angle + a 10mm EP and a 2xbarlow but i get a clearer view using the 10mm ie on jupiter .

Last of all should i hold back on the 10" and get to know the sky a bit better and not rush ahead of mysef.

Many thanks for listening i hope i have made sense as i am a total beginner at this stuff but absolulty love it so far !!

[John]

Hi,

I used to have an 8" Skyliner and it was a great scope. When I was considering a step up the advice I received was that the difference between 8" and 10" was noticable but not substantial wheras 12" was a good step up in performance potential. So I went to 12" and the advice was right !.

I have also owned the 10" Skyliner and it's a great scope in it's own right. It is larger than the 8 but still portable, in one piece if you are reasonably strong and fit. My 12" (a Meade Lightbridge) is also portable but it's definately 2 carries for me - not that it's difficult as the scope tube just drops (is placed carefully !) onto the mount, then, barring 30-60 mins cooling time, you are good to go.

If you can run to / manage a 12" I'd definately recommend that as a step up from an 8".

By the way, the 8" will show you simply loads of stuff including masses of nebulae, clusters and galaxies - perhaps you just need a really good star atlas - it does not sound that you have anyway near exhausted the possibilities of your 8" yet !.

John

[red dwalf]

very easy to let aperature fever run away with you ! you will get better views with a 10" dob as the bigger the aperature the more light gathered and an increase in resolution, i`d give it alittle more time, learn the sky, some nights are better than others for views, there are always going to be offers on telescopes out there then you could go for a 12" or even bigger !

[Ben Ritchie]

Also is there a lot of diffrence between the 8" and 10" ?

There's always a difference as you increase aperture, but a good rule of thumb is that a "one step" increase in aperture is subtle, a "two step increase" is substantial - so, for Dobs, which tend to come in 6", 8", 10", 12", 16" versions, it's the jumps like 6" -> 10" or 8" -> 12" that really stand out, going from 10" -> 12" will show you more but it's a subtle change that affects the limits of what you can see, and not something that stands out and says "wow".

[Beulah]

I concur with John - my next step, when the time and the bank balance is right, will be a 12".

I have a SW Skyliner 8" Dob and I'd say that this scope at a dark site performs magnificently and is pretty portable for a dob.. I have already seen dozens of objects...its.....just....that....it will be nice to have a bigger telescope. If it weren't for the internet inducing aperture fever, I'd stick with what I have got!!

[ollypenrice]

Good, cos I was about to say go for 12 inch or larger! But as has been said there is a lot out there for an 8 inch. Are you light polluted? Have you tried a darker site? As well as atlasses, a Telrad reflex site mekes fnding things easier.

Have fun,

Olly

[acey]

Dazraz, you've only had the scope for 2 months so give it time. If you can, try taking it to the darkest sky you can find, you'll be amazed, both at how easy it is to transport an 8-inch (tube in the boot, base on a seat), and also how much you can see with it.

I agree with the other comments about the 2-step jump. Going from 8-inch to 10-inch lets you see roughly half a magnitude fainter. A very experienced user will see the difference, a beginner won't. Galaxies will all still look like featureless fuzzy blobs and the planets won't show any more noticeable detail.

Going from 8-inch to 12-inch lets you see almost a whole magnitude fainter. For an experienced user this is a "wow!" because all the deep-sky objects you've got used to seeing suddenly show so much more detail. A beginner who's just ditched an 8-inch to get the 12-inch and still sees lots of featureless fuzzy blobs will be apt to say, "Hmm, maybe I need a 16-inch".

Whatever scope you use, things are never going to look like they do in photographs. I started out with an 8-inch and I reckon that after about a year I'd got to know it properly. I saw all the Messiers with it, all the planets, and lots more besides. I held out upgrading to a 12-inch because of the sheer convenience and portability of the 8-inch. I finally upgraded after about 9 years, and don't regret waiting so long. It's not the equipment that counts, it's what you do with it.

I use my scopes for deep-sky but you only mention planets. This is another reason why I'd say don't upgrade. I don't find planetary views through my 12-inch significantly better than through the 8-inch. Aperture is all-important with deep-sky but with planets it's different, you want resolution and contrast, and that's not just about aperture, it's about lots of things. There are 4-inch scopes that would give better planetary views than your 8-inch (and cost a lot more).

Enjoy your 8-inch, get to know the scope and sky, and don't let aperture-fever spoil your fun.

[TheThing]

Good reply from acey there and I concur with what he says.

I'd suggest that maybe you might want to expand your EP collection and get some filters first. That would certainly help resolve things a bit more for you.

[Dazraz]

Hi,

I used to have an 8" Skyliner and it was a great scope. When I was considering a step up the advice I received was that the difference between 8" and 10" was noticable but not substantial wheras 12" was a good step up in performance potential. So I went to 12" and the advice was right !.

I have also owned the 10" Skyliner and it's a great scope in it's own right. It is larger than the 8 but still portable, in one piece if you are reasonably strong and fit. My 12" (a Meade Lightbridge) is also portable but it's definately 2 carries for me - not that it's difficult as the scope tube just drops (is placed carefully !) onto the mount, then, barring 30-60 mins cooling time, you are good to go.

If you can run to / manage a 12" I'd definately recommend that as a step up from an 8".

By the way, the 8" will show you simply loads of stuff including masses of nebulae, clusters and galaxies - perhaps you just need a really good star atlas - it does not sound that you have anyway near exhausted the possibilities of your 8" yet !.

John

Hi if i move up to a 12" is it still easy to tap the Dobsonian and keep objects in the field of view ?

[iamjulian]

I have been observing a similar amount of time to you Dazraz. I have also seen quite a few beginners selling their big scopes to get something smaller and more manageable. I got and continue to get the impression that starting out with a scope that is too big is a bad idea for a beginner as you will use it less frequently, be it cool down time, or problems transporting it and setting up.

I actually had a budget of £700 but decided to spend half that and upgrade later. After two months I'm not longing for a new scope because I have hardly seen anything with the current one. And my next purchase, as some have mentioned above, will be better eyepieces.

I'd guess it is a bit like people who keep upgrading to the latest DSLR camera, yes it may take more frames per second, and A2 rather than A3 images, but if you spend the money on better lenses, a cheaper camera body with nice glass will take better quality images than a more expenisve one with a kit lens. Just the impression I get, maybe I am wrong

[Dazraz]

I have been observing a similar amount of time to you Dazraz. I have also seen quite a few beginners selling their big scopes to get something smaller and more manageable. I got and continue to get the impression that starting out with a scope that is too big is a bad idea for a beginner as you will use it less frequently, be it cool down time, or problems transporting it and setting up.

I actually had a budget of £700 but decided to spend half that and upgrade later. After two months I'm not longing for a new scope because I have hardly seen anything with the current one. And my next purchase, as some have mentioned above, will be better eyepieces.

I'd guess it is a bit like people who keep upgrading to the latest DSLR camera, yes it may take more frames per second, and A2 rather than A3 images, but if you spend the money on better lenses, a cheaper camera body with nice glass will take better quality images than a more expenisve one with a kit lens. Just the impression I get, maybe I am wrong

Hi yes i agree with you - the thing is as well because im not up to date with the sky im not looking in the right places and not seeing much only jupiter and the moon at moment -

I am going out with my binoculars more at present and really just learning the constellation lines etc etc

I suppose also i have been taken in by the wonderful glossy pictures you look at on the net , but this in no way has put me off stargazing as what i have seen so far has definatly been great and a great learning event for my kids who love it !

Also i have been told that a very good way to learn is to join a local club which i have done only this week and weather permitting will be attending on the 18th of this month (cant wait)

Regards Daren

[acey]

Hi if i move up to a 12" is it still easy to tap the Dobsonian and keep objects in the field of view ?

Yes - but it's no longer so easy to move the scope from one side of your garden to the other. And it'll take longer to cool. And you'll need to collimate it every time you use it.

Sounds like you're doing all the right things already, so keep at it and enjoy.

Julian has said it in terms of scopes and cameras, I'd also suggest trampolines and garden swimming pools as examples. Don't get the biggest thing you can afford, get the biggest that you need and that is convenient. You've got it already.

[TheThing]

Not having a dob, I stand to be corrected, but I'm sure that you don't need to collimate them everytime you use them. There is a lot of discussion about collimating and, whilst is is an essential tool or the reflector owner, it is not always needed as often as people say!

With care when moving and storing, you should be able to go months (even years) without needing to collimate. I have only ever collimated a reflector once after transporting it in a car. Other than that, the 3 reflectors I have/had haven't needed touching in 5+ years.

[The Warthog]

I seldom have to collimate my Newtonian, even though I move it about frequently. Apparently truss-tube scopes do need to be collimated every time they are set up, but I think if you leave them set up they should stay in collimation.

If you want a bigger scope for better views, it's a good idea to increase your objective by at least half. This gives a magnitude deeper light grasp, and 50% more resolution. That being said, an 8" scope is still a pretty good beast to observe with.

[acey]

I only ever needed to collimate my 8-inch once in a while, despite a bumpy drive every time I used it. But as the mirror gets bigger and heavier - and just as importantly, as focal ratio gets faster - a scope can't hold collimation as well. Sure you can get away with not collimating, but you'll be using a scope that's not perfectly collimated, and for faster f-ratios, small errors make a bigger difference.

I took this into account when I upgraded to a 12-inch - I only made the move once I was sufficiently confident about collimating the 8-inch. Mine's a flextube which is a further reason why it needs doing every time. Again, I know that people say it holds its collimation adequately after collapsing and reassembling, and I'd say this is true (at least for deep-sky work), but if you only want a scope that's adequate then you might as well have one that's smaller, because you'll quite possibly get the same performance for less money and less hassle.

As for aperture, I always try to spend money on petrol before glass. If I can drive somewhere that gives me another magnitude of darkness then I've effectively increased my aperture by 50 per cent.

[TheThing]

Thanks acey. As I say, I'm not a dob owner, so have been corrected. The point about dark skies is another good one. M31? A no-no from Surrey. Naked eye at the uncle-in-law's in Somerset though!

[Beulah]

Mr Acey sir, you are a man of wisdom! Thanks for your insight to temper the fevered brow of Aperturitis - I have enjoyed reading your thoughts on this subject!

[acey]

Much appreciated.

We learn from our mistakes - and I've made plenty to learn from.

[ZOG]

Hi Dazraz, you say a couple of times that you are only seeing the moon and Jupiter. Ok time for your first galaxy. Get into the field and away from the local LP. Look up and find the constellation Cassiopae which makes a big W in the sky. Use the right hand V of the W as a pointer to a bright star below it and line your scope up on that star. Pan slowly right until you come to a second bright star. Pan slowly right again about the same distance and an oval smudge will float into view.

It doesn't look startling at first, but hey, it's your first galaxy. Enjoy