Am I upgrading?

[Startracker197]

Ive been into this hobby for about two months now... got myself the cheap Celestron Astromaster to start out with and now I want something a little better. I was planning on purchasing a 6" Dob at a local telescope shop here in town. Right now my telescope is 70mm refractor. My question is am i going to be stepping up fairly well getting the 6" as a still beginner or should I consider waiting and getting something bigger like an 8" or a 10"..... though im not good at waiting lol

[spaceboy]

If you don't mind saving then bigger is better. If you are able to see the size of the scopes at the shop you mention then you will get an idea of how big they can get. A 10" dob will keep you happy for years to come but they are not small.

[Uranium235]

The general rule of thumb is double the apeture to match the refractor. For example, your 70mm would equate to a 140mm newt. So getting a 6" would only make for a little improvement over your current telescope. But an 8" would show a noticeable improvement if jumping up from a 70mm frac.

[blinky1983]

I started with an Astromaster 130, I would go for the 200p or even better get the 250px if you can then you will defo see a big improvement..

The 6" wont make a great upgrade but would be slightly better than what you have now..

[foundaplanet]

The question is how soon will you want to be buying a 10 if you go for a 6 now. An 8 would be a good jump from what you have a 10 would be a big leap.

If you believe you will stick at it hold out for the 10...

[Capricorn]

You are more then doubling your aperture, so more should be visible and ones you can see now should appear in greater detail and brightness.

Waiting for an 8" means more time, then it would be argued is it worth not getting the 8" and waiting for a 10", then the same arguement for a 10" and then a 12". It goes on.

The 6" (150) isn't too expensive.

They say a 4" increment is noticable so 2.75" to 6" isn't bad then you could go 6" to 10" and call it a day. If you get an 8" you will want a 10". However at 10" the step to 12" is significant in weight if not diameter.

[Ags]

The general rule of thumb is double the apeture to match the refractor. For example, your 70mm would equate to a 140mm newt. So getting a 6" would only make for a little improvement over your current telescope. But an 8" would show a noticeable improvement if jumping up from a 70mm frac.

I thought that rule of thumb died out in the 50s... The 6" will gather 4 times as much light than the refractor does, and will have better contrast due to its larger aperture. The CO on an F8 newt is negligible and should not affect contrast.

Because of its greater light gathering you will be able to magnify DSOs a little more with the 6", revealing more detail. You will be able to resolve faint stars much better, so globular clusters like M13 and M3 will be balls of stars instead of the hazy patches the 70mm shows.

You will be able to see more detail on planets as the 6" has twice the angular resolution of the small refractor. Also, the 6" will have no chromatic abberation to spoil the view.

[umadog]

Yeah, I'd not heard that rule of thumb in a while either! I remember it surfacing from time to time in the 90s but I don't remember why it died out. I think I recall hearing that the use of fans and understanding of tube currents hastened its demise.

It's not even clear in what sense the "rule" is supposed to apply. Light gathering? Resolution?

[Ags]

Silicon dioxide coating of mirrors increased the reflectivity from 70% to 90%... Also, in the fifties many of the mirrors were DIY efforts, compared to the commercial mirrors available today.

[bish]

You will certainly notice a difference between a 70mm frac and 150mm newt. There's plenty to see with a 6", even under light polluted skies - take a 6" to a really dark site and there will be a whole lot more to see. Saturn, Jupiter and the Moon are excellent, with good seeing. If it's a stretch to go bigger then the 6" is worth the upgrade.

[umadog]

Thanks, the reflectivity would certainly explain things.

[Luke]

I'm not good at waiting either! So I would probably ignore my suggestion which would be to save up and get the 8 inch dob!

I do think you would see a difference with the 6 inch dob - I can see a lot more in my 6 inch SCT than in my 80mm refractor.

But for me the 8 inch dob is one of the best bang for buck scopes out there if you don't mind saving up.

[perrin6]

Thumbs up for the 8 inch newtonian reflector ! (Especially at the prices you can get them these days - hurrah for China ! ). Whatever you get, even if you get a 12 inch later, the 6/8 inch will still be useful to hang onto for their portability, short cool-down time, accuracy of their figure, as small mirrors are easier to make than large ones of equivalent accuracy. 6/8 inchers are handy to keep for quick observing sessions.

[Startracker197]

Alright... I think im gonna go for the 6 inch because it would be a long wait before the 8" or the 12 but those things can come a bit further down the road when im more experienced. Will be able to getting the 6" in a few weeks.

[spaceboy]

Heads up ST skywatcher 8 Inch Dobsonian Telescope | eBay

[Startracker197]

I dont know that sounds to good to be true is there something wrong with it?

[spaceboy]

As long as you can go and see the item there shouldn't be a problem. Bad feedback or not if someone tries selling me a piece of poop they ain't getting my hard earned.

[rory]

probably nothing wrong with it £200 give or take a tenner is the going rate, thats the buy now on it.

by the time bidding ends it will be around the buy now price anyway.

ohh, and in answer to the question, yep 6 or 8" from a 70mm is a possitive move

good luck with your choice.

[Startracker197]

Coolness.... Ill be getting the 6 inch around christmas actually.... gonna be my present to myself lolz.....

[rory]

well aint santa a good old boy eh .

[Startracker197]

Actually hes been pretty bad... havent you heard he got arrested for SWI... Sledding while intoxicated.....