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Purchasing a barlow and eyepieces for a fast dob f5 or more)
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Nejedj71
Joined: 10 Aug 2009
Posts: 6
Location: Appleton, Wisconsin, USA
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 Posted: Tue Aug 11, 2009 9:13 pm Post subject: Purchasing a barlow and eyepieces for a fast dob f5 or more) |
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I just bought a Zhumell 10" (1250mm focal length \ 254mm effective aperature = 4.92 visual focal ratio) Dobsonian. I live in Northeast Wisconsin, USA and will be moving the scope primarily between our light infested residence of Appleton and darker sky cottage. My wife and I see our use as being primarily to see the planets and star hop or nebula shop.
I want to make the correct initial purchases when it comes to a barlow and eyepieces so as to stay happy for the long term. I realize price increases with quality. I am willing to spend more up front in spurts, with an understanding that I may want to eventually increase to a larger dobsonian. I do not expect to get into astrophotography or expensive electronics.
Both my wife and I are in our forties and have had eye surgery to get rid of the glasses. She has a problem with astigmatism though. Our initial belief is that we should invest in a barlow and one or two quality eyepieces to compliment the 2" 30mm wide field (x42) that came with the Zhumell. Tthere is also a 1.25 9mm plossl (x138).
After a quite a bit of research, I have come to realize that I have a fast dob at f4.9, which is going to require a barlow to correct coma at higher magnifications. My readings have pushed me away from the televue high priced products and even the super or ultra plossls. Not because of price, but because of Chris Lords 1996 article and some other articles about a fast dobs. I think I will get the right bang for my buck with the following:
- Univeristy Optics 2.8 Klee Barlow
- 12.5mm University H.D Abbe Orthoscopic eyepiece
- 18 mm University H.D Abbe Orthoscopic eyepiece
For under $250, it effectively puts my magnifications at:
x42 2” Zhumell wide field 30 mm
x70 1.25” 18 mm University H.D Abbe Orthoscopic
x100 1.25” 12.5 mm University H.D Abbe Orthoscopic
x139 1.25” Zhumell 9 mm plosll
x152 Klee 2.8 barlow w/ 1.25” 18 mm University H.D Abbe Orthoscopic
x220 Klee 2.8 barlow w/ 1.25” 12.5 mm University H.D Abbe Orthoscopic
x305 Klee 2.8 barlow w/ 1.25” 9 mm Xhumell Plossl (not sure about this)
Grant it I just started and I will be spending plenty of time looking at different eyepieces and setups, but I want to think long term on any investments I make. Any suggestions or corrections to my train of thought (thus far) would be helpful. I ultimately would love to build or purchase a larger dob to compliment our hobby if everything goes well.
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John & Brenda from Appleton, Wisconsin, USA using a Zhumell Z10 Deluxe Dobsonian Reflector Telescope. |
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Nejedj71
Joined: 10 Aug 2009
Posts: 6
Location: Appleton, Wisconsin, USA
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| Posted: Mon Aug 17, 2009 3:42 pm Post subject: |
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I am a beginner. I think there is a hoard of beginners out there like me. I just picked up the Zhumell f5 10" dob that came with a 1.25" 9mm plossl and a 2" 30mm wide field. So, I have a 2" 30mm wide field to start me off.
I have been spending a ton of time looking over the forums. Yes, I have joined up with a local astronomy group and started to meet people. I don't think I will ever be one of those people who have a long list of different eyepieces under my name. I just want a small collection of eyepieces that fit my f5 and work well enough for the things I want to do (by the way I am not sure exactly what I want to do yet).
I do think I will ultimately get one TV “hand grenade” for the spacewalk experience at around the 31mm. However, my wife and I are in our 40s with corrective eye surgery. I want to make sure I choose wisely as far as exit pupils and both of our preferences. We also want to share our hobby with others friends in their 40s and 50s, so I like the idea of putting the money into something like the TV 31mm.
I think the Baader “Z21-adapt” (just gave it a nick name) is great for a beginner with an f5 10” dob. Baader Hyperions seem to be a good match for barlowing in an f5. I like the idea of getting the zoom and the 21mm and making the “Z21-apapt”. I get the 8mm-32mm zoom. More importantly, I get a great 4mm-12mm zoom and don’t have to attempt changing out EPs at higher magnifications with a dob! With the purchase of the two adapter rings I get a 14mm, 17mm and 24mm in the easier 2 inch piece (if I got that right). That is a nice rounded out start with the 2” 30mm wide field that came with the scope.
I might not like it at all and end up selling it. From what I see on astromart and ebay, I don’t think that is a problem.
I just think this is a great way to get your feet wet if you have a fast f5 dob. So… for those of you with a Zhummel Z10, I will keep you updated about the “Z21-adapt”. It will not arrive until 9/11 (not a good sign).
I plan on immediately doing the drift test with a star on the equatorial line (I think I got that right) and letting everyone know what the actual field of views are at the specific settings with a f4.92 = 1250 / 254mm scope.
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John & Brenda from Appleton, Wisconsin, USA using a Zhumell Z10 Deluxe Dobsonian Reflector Telescope. |
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Nejedj71
Joined: 10 Aug 2009
Posts: 6
Location: Appleton, Wisconsin, USA
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| Posted: Tue Aug 18, 2009 8:20 pm Post subject: |
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Pretty sad. I am not impressed with this forum. I was really hoping a site for dobs would be great. You need to find a moderator to at least greet people and explain if they are doing something wrong. I am an excited beginner and was lookng forward to learning from people on this site. I find better info and reaction time at cloudy nights and other astronomy sites. Correct me if I'm wrong....
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John & Brenda from Appleton, Wisconsin, USA using a Zhumell Z10 Deluxe Dobsonian Reflector Telescope. |
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