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Light Pollution Topics / Re: Couple Sued For Complaining About Electronic Billboard
« Last post by Owen Khan on February 09, 2018, 10:40:39 AM »
I was out with my RedRider killing stars last night.....
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What jakecru wants puzzles me, given his current equipment. He has a quality 10" Dob. What's a 12" Dob going to do that a 10" just can't, except on the margins? And, given his financial situation (see other thread), are margins really worth it?
I think not. With a $1800 investment, one competing with other life desires, we need to offer him a serious astronomy experience upgrade. As I see it, the options aren't between scopes, but between upgrades to his experience.
Options other than another Dob (YAD):
1. Save the money. Use it as a nest egg for an astronomy account that will, in the future, permit something really super. The greatest advantage of this is that you decrease the time you have to wait before you can afford that something great (all other family needs being equal, of course).
2. Electronic assistance for the 10" Dob (EAA). We all know, or at least should be aware of, the tremendous advantage that things like night vision gear and cameras have over the naked eyeball. A lot of us rebel against the perceived lack of genuineness, but the fact remains that if you want the advantages of greater aperture without, you know, HAVING greater aperture, options exist. And we should at least mention them.
3. Superior tracking for the 10" Dob or replacement. You see more if you can find stuff faster. You see more if you can stare at stuff longer uninterrupted. Can the Zhumell Z10 get a go-to system upgrade or even a full-blown object tracking system?
4. Eyepieces. EAA not for him? Tracking not his bag? That's cool - how about some really sweet eyepieces for the 10" Dob that will also be great on his future scope? Unless he's already rolling in TeleView glass, he will see more and be more comfortable after devoting some of his budget to optics.
5. Refigure and recoat his Z10 mirror and secondary? The Z10 deluxe has pretty decent optics. But jakecru's budget is more than big enough to get him 0.95+ Strell on the primary, 1/10+ waveform on the secondary, and coatings that reflect 96% of impinging light. This means planets are crisper, double stars pop out better, and everything is just that bit brighter.
6. Travel. How about taking that 10" Dob to some of the Nation's darkest, clearest, calmest skies? How about renting time on some of the best publicly-accessible telescopes around, or attending some really eye-opening star parties? jakecru's budget allows for some serious experiences!
Well I'm sorry to puzzle you. My financial situation is fine, I just don't want to spend more than around 1800 since I am saving for a larger premium dob. I already have good eyepieces (see signature). My Z10 already has excellent optics, which is why I'm keeping it. I have had many scopes over the last few years including an 18 inch Teeter with an excellent Swayze mirror, two 8 inch gso dobs, an orion xx12g dob, Starfinder 12.5 dob, cpc 800,explore scientific 102 apo refractor, etx 125, and besides the Teeter I just sold the z10 has the best mirror compared to the others. It star tests very well and I have it it over 450x sharp on planets when seeing is good. It definitely wouldn't be worth it to refigure. I take my scopes out to dark skies often. My wife and I just bought a house and had a baby, which is why I decided to sell my Teeter to fund appliances for our new house. She just returned to work as well. I want a intern scope that is larger than 10" while I save for a new premium dob. I will sell the scope when I get the premium dob a few years from now. I know exactly what I'll get with 12" or 14" aperture wise, I just hope the mirror is decent to good (or excellent if I get lucky again). As I said in an earlier post I'm leaning towards the Skywatcher 14, and I agree the jump isn't that big from 10 to 12 (though it is noticeable for sure). I prefer starhopping over goto, and although goto is nice for tracking during outreach the added weight of the base and added cost is not worth it to me. I am not in to any night vision.. I have Google with hubble for seeing that stuff if I desire. Plus more aperture is more resolution as well as light gathering! I don't feel like my 10 should be taken into consideration since I am only keeping it because it has a gem of a mirror and is only valued at around 250.00 used. It makes a good grab and go scope! Thank you for your suggestions.
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Beginners Forum / Re: What do I buy after an 8 inch dob?
« Last post by incojukam on February 09, 2018, 10:39:50 AM »
If you like to stand, a 12" won't require stooping. But your kids may need a step.
The weight and size difference between 150mm and 130mm is very significant, and is proportionally less than the difference between 10" and 12". Think about bulk, not just weight.
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Eyepieces Questions & Recommendations / Re: Eyepiece center image quality
« Last post by helppomgido on February 09, 2018, 10:39:44 AM »
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Is $250 too high? If not, the TeleVue Delites come to mind (long eye relief and extremely small spot size on axis)
If it is too high, find used TeleVue Radians.
Both have comfortable eye relief at short focal lengths (down to 3mm)
If their prices are too high, look for Plössls or Abbe orthoscopics, both of which have extremely small spot sizes on axis and can be found new at low prices.
However, that latter solution doesn't get around the small eye relief in shorter focal lengths, as you point out.
As was suggested, a longer focal length eyepiece with a superb barlow might do it for you.
A 15mm Plossl, with 10-11mm of eye relief becomes a 5mm eyepiece with >11mm eye relief when a good 3X barlow is added.
And there are some barlows out there that have superb image quality (probably not the $50 and down variety)
It might take some experimentation and re-selling of eyepieces not kept, but the modern generation of 58-62° eyepieces for $55-$100
may have some gems that work well for you, and all of them have more eye relief than Plössls and orthos.
As you know, however, other factors will make a bigger difference in image quality than the eyepieces: telescope optics, seeing, cooling of the optics, collimation of the optics.
"Is $250 too high?"

Yep."As was suggested, a longer focal length eyepiece with a superb barlow might do it for you.
A 15mm Plossl, with 10-11mm of eye relief becomes a 5mm eyepiece with >11mm eye relief when a good 3X barlow is added."

I like this idea, but then with a 2x barlow for a 7.5 mm. Just have to make sure the costs of great plossl and barlow don't add up too much.
By the way, isn't the Hyperion using an internal Barlow too?

"It might take some experimentation and re-selling of eyepieces not kept, but the modern generation of 58-62° eyepieces for $55-$100 may have some gems that work well for you, and all of them have more eye relief than Plössls and orthos"

Do you have any specific eyepieces in mind?

"As you know, however, other factors will make a bigger difference in image quality than the eyepieces: telescope optics, seeing, cooling of the optics, collimation of the optics."

I've dealt as many of these as I could, the only other thing I can influence is the eyepiece choice.
Well, at least if you don't count adaptive optics
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General Astronomy & Observing / Re: Top things to obeserve in the sky
« Last post by vidysriret on February 09, 2018, 10:39:11 AM »
Dave's list of double stars is a great one -- I always go to Beta Mon this time of year as a test of seeing. If I can split the three components I know it's going to be a good night! Multiple star systems never get old for me . . . they are among those objects one can observe and think "Wow the universe is a marvelously diverse place!"
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So you still had a coated primary mirror? So you had a single filter blocking that much energy?

It was freshly coated and as bright as could be. I'd seen Jupiter and the moon with it bare, but couldn't wait to get first light at something in the sky - anything - even the sun. But a sun filter makes it safe to view the sun, right? (WRONG) I got the sun into view and focused on it, and was enjoying the incredibly detailed granulation when I started seeing and smelling white smoke wafting out of the eyepiece holder base (it was my black flocking paper). Moments later it audibly popped and a "blinding" flash came through. Fortunately, with the naivety of youth also comes quick reactions. The filter element had a hairline fracture right down the middle, and the metal cell was slightly discolored. That's when I learned that a 6" f/10 is nothing to sneeze at.

This is an interesting anecdote, SteveNH. I have one related to it since includes similarities.

First of all, I did something unsafe in perhaps 1965, when I was a 13-year-old, out of ignorance and insufficient caution, not the only unwise step that I took as a youth. I was fortunate. I suffered no ill effects. On the contrary, as did you, I enjoyed seeing "incredibly detailed granulation."

I had purchased a "solar filter" from Edmund Scientific through mail order. I wondered about the safety, but thought that since it was a productthat had been offered for some time, at least a year or two, it mustbe safe. If not, it would have been pulled from the catalog, or so I thought.

In any case, I used it with my 3-inch Edmund reflector, a rather poor telescope, but the best that I owned at the time. I inserted the solar filter before the eyepiece. Theview was quite fine, as noted above.I looked for only a few seconds.

I do recall that I was aware that the focusing tube might heat up because of the energy being absorbed within the filter and that I was curious to see if it would happen. I do not recall to what extent I checked for signs of heating. I suppose it is possible that the filter heated and rapidly reached an equilibrium state in which energy was being transferred to the environment by radiation, convection, and conduction. I believe that is a plausible explanation in this instance.

Since I was using a 3-inch, the amount of power to be dissipated was one-fourth of what it was when you were using a 6-inch.

I would never, ever repeat what I did then, nor should any other person.
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General Astronomy & Observing / Re: Arizona Sky Village - Anyone Been There?
« Last post by Steven Morrison on February 09, 2018, 10:38:04 AM »
I rented a house there in February 2015. It was great for both astronomy and local hiking. No light pollution. And you can glimpse Omega Centauri and other southern splendors about 12 degrees above the southern horizon.
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And people tend to see these pre-buy tests (OPT, Company 7 etc.) as a positive, value-added service. Well, it is called amateur astronomy.

If I were paying $90 for an inspection, I would certainly expect some kind of written assessment.

For that price, it seems like it would be appropriate to at least produce a measured periodic error curve, and also to program PEC for the customer. This is something that could be done pretty easily in the shop with the proper equipment. You would need to have high resolution encoders and the ability to read and analyze the data, plus software to upload the correction curve to the mount. All of this stuff exists and should be within the budget of someone providing this service commercially.

Note that I don't know what specific service OPT did for $90, or indeed any details of the transaction other than what's been posted here. It's possible that they did something that I haven't thought of. I have been a very satisfied customer of theirs for many years.
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Just like the topic says. I am not sure how these work. And because I am not sure how these work, I don't know if it is possible to get a universal focal reducer for a telescope with a 2" focusser. Can someone help?
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ATM, Optics and DIY Forum / Re: Reducing focal plane by moving primary mirror back?
« Last post by tradunjuwa on February 09, 2018, 10:37:15 AM »
Yes i can see the primary completely at the focal plane with room to spare now
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