I recently responded to an online ad for someone selling a Zhumell Z12 dob with multiple eyepieces for $350.
Being a newbie in this hobby, and suffering badly with my little outdated 114mm newtonian, I quickly contacted the seller and told her I'd be right over to take a look at the scope. Upon arrival, she informed me that it had a 12" mirror and had only been outside twice in the 2 years she owned it. It looked like it came right out of the box. Needless to say I was more than excited to pick up such a fine scope at such a great price.
I inspected the eyepieces, took a quick glance down the tube (I can only imagine the twinkle in my eyes when I saw that big shiny primary), checked out the alt/azi bearings and all were in perfect condition. Even 3 of the 5 eyepieces were still in original packaging. I eagerly handed over my money and loaded up the scope, anxious to get it under the stars for some viewing.
Arriving at home just before dusk, I set it up in the backyard and was amazed at the wild views I was getting. I spent hours in the dark just cruising the sky, hopping from Jupiter to Saturn, Vega to Arcturus, wide angle 30mm ep to tight 8mm, tried a couple Messiers but hadn't quite got down my star navigation yet but nevertheless, I was hooked. This completely blew away my little 114mm. Money well spent.
Then I started a couple little mods. Nothing big, just added a Telrad, moved the 8x50 finderscope over 3/4 inch to accommodate the Telrad, and added a shower cap dust cover to the bottom of the tube. Then I decided to make a lightshade for the end of the tube which, of course, required some measurements. Circumference = diameter x 3.14....but my tube diameter only measured just a hair over 12". What gives, I thought. Looking down the tube, I saw there was at least 3/4 inch gap on each side of the primary...how could this be a 12" mirror as advertised? Then it dawned on me and my heart sank just a little bit, by like 2 inches, my Z12 had become a Z10. In my haste to improve my aperture, I failed to take measurements before purchasing. Taking the kind lady at her word of it being a 12" mirror, my excited newbie status had bit me in the hind quarters.
Don't get me wrong, I LOVE THIS SCOPE, and I still got one heck of a deal on a practically new scope, but I would've much rather had the error in aperture go the OTHER way.
So now I find myself suffering from aperture envy yet again. Wondering how much the amazing views I am getting with a 10 inch would improve with a 14 or even 16 inch dob. At some point I'd like to get into AP but that is years down the road for me since it is such a major investment for proper gear. So being just a visual astro guy for now, I'd like to get into the biggest aperture I can manage. A 12 inch seems just a modest jump so I've been eyeballing the 14's and 16's. I've seen the Orion XX16 and the thing is a monster but being that it collapses into manageable pieces, I believe it would fit my needs and cure my aperture envy for visual observing.
I suppose if there's a question in all this it would be is there a large amount of difference in viewing power between a 10 inch and a 12 or 14 inch, or even a 16 inch? Enough of a difference to justify the expense of a new king sized dob?
Other than those questions, I just wanted to go off on a rant a little bit about my experience being new to the hobby and lessons learned about the 2nd hand market...buyer beware and always know your measurements and bring along your tape measure.
Edited by Muddman97, 18 July 2017 - 06:48 AM.