8" or 10" dob?

[Baz6170]

Hi all

I can buy a Skywatcher Skyliner 200P Dob for £270, or a Skywatcher Skyliner 250PX Dob for £429. Question is, is it worth paying the extra £159 for the wider aperture, or should I go with the 200P and use the £159 on extras?

FYI I'll mainly be using the scope in my back garden, which has relatively dark skies.

Cheers

Baz

[sticks]

Baz - do not under-estimate the cost of extras - see other threads on this http://stargazerslounge.com/beginners-help-advice/176956-true-cost-beginner-salutory-tale.html. Most spend almost as much again on decent EPs, filters, better finder etc etc.

[s7eves]

Just like you I cant decide on a 10"or 8" dob .....and I change my mind every hour ......I keep telling myself "APERTURE RULES" but then I think " will my `average quality` EP`s perform better in an 8" F6 than a 10" F4.8(or there about) , and the problem starts all over again.

I notice that you already have a scope so maybe you should consider if your EP`s are up to scratch to complement the faster 10"...........or you could always buy a nice set of naglers if you win the lottery:hello2:

[Gra]

It is a difficult choice, especially the price difference. Both are solid tube.

I would personally go for the 10" based on the '56% more Light Gathering than 200mm' as is says in its description.

[Moonshane]

Personally, I'd go for the biggest aperture you can carry and afford. For visual astronomy, aperture rules with very few exceptions.

That said, I felt the progression from 8" to 12" to 16" is more impressive when you upgrade. Get the 8" and start saving for a 12"!

[Thirdway]

If you are planning in carting it very far, then the 8" is the limit. The tube fits nicely on the back seat of my car. It is an awkward shape and the 10" is massive. Also think about storage, in the flesh these things are big. The 8" will give you some money to buy: Telrad/Rigel finder, star maps, collimator, moon filter and a selection of better EPs.

I went for the 8" for that reason.

If you have a dark garden and don't need to go anywhere and have storage space the 10" might be better, however, very soon your going to be thinking astro photography and all that good stuff. The 8" is easily good enough for a novice to handle and get used to where things are, in fact the 6" will do a good job. Your going to start considering guiding the scope which is in the other direction from a Dob, so you might keep it for live viewing but think about something different for the photo side.

I was where you were 2 months ago.

[Baz6170]

Hi Thirdway

Astrophotography has already entered my mind, following the success I've had recently in just using an old DSLR without a scope to capture some star trails (basic I know, but does fire the imagination!). With AP in mind I did set out thinking of getting an 8" reflector on a equatorial mount but as soon as I looked into the cost of it, ie drive motors, autoguider etc etc, it made me question my next step in this fascinating hobby. So, I decided to stick with observing for now, and go for a bigger/better scope than my little mak so I can take a proper look at DSO's, and learn a bit more about finding my way around the skies rather than letting a GOTO computer do it all for me.

I'm thinking that the 8" 200P will provide me with better visuals than I can get now with the 4SE, and leave me with some pocket money for extras, even though there's a little voice in my head saying "you'll get more detail with the 250PX!" haha.

Baz

[SeedyF]

10"

Next question - I'm on a roll here

[hemihaggis]

:icon_salut:go for the ten .....

[acey]

Buy the 8" and you'll wish you had more aperture.

Buy the 10" and you'll wish you had less weight. And still wish you had more aperture.

Either scope will show hundreds of DSOs at a dark site. If you were to put them side by side you wouldn't see a huge difference in view. "56% more light gathering" equates to just under half a magnitude.

If you subsequently decide to upgrade then a sensible jump is 50% aperture increase, big enough to see a significant difference (nearly a whole magnitude). From 8" you'd go to 12", from 10" you'd go to 16" (unless you could find someone who makes 15" mirrors). Going from 8 to 10, or 10 to 12, is not really worth it.

I'd suggest you get the 8", use it for a few years, then go up to a 12" if you really think you need to.

[Rob L]

It is a difficult decision and I kept changing my mind before settling on the 10" in the end.

It might be worth your while trying to see one in the flesh. I was worried that the 10" would be too big, but If I'd seen one first I would have actually gone for the 12".

I like the suggestion from Moonshane: "get the 8" and start saving for a 12!"

[Baz6170]

Hi Chris

I notice you've got a 250PX Flextube - do you get many problems with dust/dirt/dew on the primary, and more collimation issues due to the collapsible nature of the scope design?

Cheers

Baz

[RikM]

If you know you will go for a bigger scope in future get the 8" and plan for a 12", if this is to be your biggest scope go for the 10" and save for the extras.

They are both great scopes and not really that much difference between them to the beginners eye. With more experience you will see more with the 10" and it is quite manageable and portable unless you have problems lifting.

[jimmyjamjoejoe]

I'd go with the 8" and get the extras. At the end of the day, the difference between 8-10" isn't like "OH MY GOD I TOTALLY COULDN'T SEE THAT AT ALL IN THE 8!". It's a very subtle difference.

You will definitely want an eyepiece or two. At first i'd cover high power (8mm is good) and low power (32mm or so), then fill in any gaps as you get to know the scope more.

You'l want to do some mods too - Blackboard paint for the secondary and shiny screws in the tube, flocking, bearing mods, cooling fan, as well as maybe a finder.

It all mounts up, and you need to remember that extras are transferable to a new scope, and you can always sell an 8" dob for good money if you choose to upgrade later.

[swamp thing]

TBH so many good reasons to go with either that it's no easy decision. The best way to look at it is, with this much support you know whichever you choose your getting a class scope.

FWIW I went 4.5" then 10" then 16" I found these nice sized jumps. But as said 4" to 8" to 12" then 16" is also a good way of going with plenty of worthwhile upgrades to keep you amused.

Good luck with your decision.

Regards Steve

[perrin6]

If you have a fairly dark sky then a largish aperture will let you see a lot of those distant faint fuzzies so I'd be tempted to get a 12inch as Moonshane suggested but an 8 inch is still incredibly useful if you have space and money for both eventually. I built an 8.7 inch and find it gets used on those iffy nights when clouds threaten or I don't have much time and I don't want to put the 13.8 inch out so whatever size you get there is incentive to get another of a different aperture to go with it.

[crashtestdummy]

i was in the same situation 2 weeks ago and i bought the 8".i initially worried it would be too small but its still huge and just fits in my boot.i upgraded the eyepieces and added a polarizing filter and some cleaning goods and plan 2 more eyepieces,a barlow,a few more filters and a case then i will probably be sorted for the year then buy a 12" and i will already have the extras to go with it.i would say go 8",build up experience and extras then upgrade later

[spaceboy]

It is also worth considering that if you're coming from a 4" mak and only have kit plossls to get a coma corrector or better EP's. Maksutovs are pin sharp across the most of the view with even the cheapest of eyepieces. Fast newts show aberrations on all but the very pricey of EP's. If you get sharp star across 95% in the MAK you will get sharp stars across 70% in an F/5 newt and even less in an F/4.8 The wide views in a 10" dob will blow you away but I can almost guarantee it will not be long before your asking what would be the best mid-budget EPs to use in it. At least if you go with the 8" dob you will have a larger budget for eyepieces.

[SeedyF]

Hi Chris

I notice you've got a 250PX Flextube - do you get many problems with dust/dirt/dew on the primary, and more collimation issues due to the collapsible nature of the scope design?

Cheers

Baz

Hi Baz - I check collimation each time I extend it and most times it needs a minor adjustment. I use a laser so it's pretty swift (and I've already tested the laser's collimation )

I haven't had the scope that long and meticulously keep the caps on when it's not in use. I haven't seen any signs of dust yet and haven't had dew/frost on the primary despite observing for long spells on a couple of really moisture laden evenings.

[paul schofield]

I was stuck with the same quandry. I ended up going for the 200p. The points given to me regarding the choice were, The 250px is slightly less forgiving on cheaper e.p's. Collimation not as stable in the 250p. And if I went for the 200p I would have a bit of cash left over for a good 2 inch eyepiece. But then the 250px has a pyrex mirror and cools quicker. I am sure at the end of the day the extra aperture wins out. Good luck with your choice, they are both awesome scopes.

[Baz6170]

Just wanted to say a big thanks to everyone who's responded to my post, all your feedback is gratefully received. I think I'm going to go for the 200P 8" Dob so that I have funds left for an EP and a collimation tool, and then get used to using that scope before thinking about anything larger. Clear skies to all!

[Catweazel]

Hi, just to chip in here, I would go for the 8", they are a nice scope and you will see plenty with it to keep you busy. The bigger dobs star getting a bit weighty, but if it's only going in your garden, then that's not so much of a problem. Obviously the cost of extras depends on which extras you want, and also on your level of self control (I bought a lot of extras ) but you could get away with just replacing the shabby 10mm EP that comes with the scope and also getting a 2 x barlow. AP, as I have been discovering, is another beast entirely, and you might need to get a mortgage for that

[Baz6170]

Hi Catweazel

Thanks for chipping in! Right now I have the Revelation EP set (9, 12, 15, 20 and 32mm), which has been pretty good with the 4SE, and it includes a x2 Barlow which to my beginner eyes, seems to be ok. Of course it might be another thing altogether with the Dob having twice the aperture of the mak! I've considered AP but have realised that the Dob isn't the scope for that, and to get an equivalent 8" reflector on a motorised EQ mount is going to cost wad ; )

Baz

[Catweazel]

Hi Baz, with those EP's you shold be fine for the 200P, and with the barlow you have all the bases covered there

[cotterless45]

Can't go far wrong with the 200p. Once set up it's superb on planets.Enjoy.