Hi guys, just another newby here. I bought a dobsonian the other day. It's a fair bit better than the ebay nasty I bought for $50 or so last year (and a fair bit more expensive). Anyway, the 2 eyepieces it came with were 25mm and 10 I think. I was just looking at Saturn which appears very small in the 25m (I think that's because the FL is 1200 divided by 25 gives 48x). I tried one of the eyepieces (4mm) from the ebay scope which fit the dob and Saturn appeared much bigger. All good. However, I tried the ebay Barlow with both the 25m and 4m and in both cases was unable to focus and the planet appeared as a large circle with a black center. Is this because the Barlow is dodgy, or because the ebay nasty was a refracting scope that the Barlow won't work with a dob? I'd just like to be able to see planets like Saturn and Jupiter as large as possible to discern details.
Also, is this scope any good for looking at DSO like nebulae? The sales guy said so. If so, what eyepieces would work?
Here's a link to the scope
http://www.opticsplanet.net/sky-watc...pe-s11700.html
Thanks for your help.