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djedi
journeyman
Reged: 10/13/09
Posts: 7
Loc: Upstate, NY
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Hi!
Am am new to this forum, although I have been "playing" in astronimy for years.
I have a C5 scope and have had pretty good success with astrophotography through it.
I am considering trying a refractor now.
Has anyone had any experience with the Chinese Achromats being sold on ebay by a company called "DKD"?
Are these worth trying to make a scope out of or should I just purchase a decent used 5" Achromatic OTA?
Sorry, I cannot afford an Apo at this time. 
Thanks
Wolfgang
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Better enjoy the here and now- there are no guarantees afterwards!
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Wes James
Post Laureate
Reged: 04/12/06
Posts: 3942
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Hi, Wolfgang-
Welcome to the group- and BEAUTIFUL picture! I love lunar shots such as this. Can't give you any inputs on eBay refractors, but just wanted to way "welcome"- and comment on your picture. I also sent you a PM...
Again-
Welcome!
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Wes
Atlantic Beach, FL
Some bino’s from Miyauchi 5x32 Binon's up through Garrett 20x110 Signature's,
Some telescopes from a Stellarvue 80mm NHNG up through a couple of 8” reflectors…
And a wonderful 4.25" Delmarva Shiefspiegler!
Some good friends, made here on C/N.
Oh- several cats and a wonderful wife!
Anyone want a cat???? :-O
"When your work speaks for itself- Don't Interrupt" -Gamble Rogers
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sailor70623
Carpal Tunnel
Reged: 01/12/08
Posts: 1516
Loc: Ok.
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Your C5 should out perform any achro. Big difference between an Achro and an ED, and then up to an APO.
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Corornado PST
LB 16" 12" & 10"
Z 10"
LX50 8", 8" CPC
ETX127, 102 & 90mm MAKs
80mm Richfield APO, 102mm & 6" refractors
ETX60
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dougspeterson
Pooh-Bah
Reged: 09/01/04
Posts: 1070
Loc: Murrieta, CA
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A fine achromat of moderate to long focal ratio will outperform your C5, which has a nearly 40% secondary obstruction. I am speaking from experience.
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18" Dob
12" SCT
8" TMB F6 + Chromacor
6" F6 APM/LZOS Fluorite triplet, 32", 32lbs
2ea. 6mm singlets, one blind
"--Granted, that's a worse case scenario. The destruction might in fact be ... limited to our own galaxy."
Edited by dougspeterson (10/17/09 07:16 PM)
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catboat
member
Reged: 12/01/09
Posts: 19
Loc: Maine
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Wolfgang,
Great photo. I'm new to this forum also, and I have the same question as you. Has anyone tried these large objectives "DKD" being sold on ebay?
For me, the price with shipping is still too high to take a risk on unknown quality. And making an OTA from scratch is more project than I have time for -- if the quality of the objective is a gamble. But if anyone in the forum has given these a try, I'd like to know more.
That said, check out the amazing 250mm binoculars made by Luciano using DKD's. There's a thread in this forum where he posted pictures.
Edward
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luciano
super member
Reged: 10/29/06
Posts: 159
Loc: Macau N22`12 E113`32
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DKD Achromats is not suitable for astrophotography.But use low power deep sky observing is suitable.
And had great quality for observing.
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neo
professor emeritus
Reged: 02/12/08
Posts: 723
Loc: Iasi, Romania
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How about those long focus DKDs?
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Russian 15x50 binos
Home made 8" f/5 Newton on eq mount
Home made 70mm f/6 (Rodenstock Rotelar lens) Apo refractor
www.astronomy.ro
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DuncanTCP
newbie
Reged: 08/14/09
Posts: 4
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Someone have written report of DKD's lens which compare with another chinese apo in other forum.
And this pic. was taken by my friend - Wenjia on his DKD's lens report
http://img06.taobaocdn.com/imgextra/i6/125719055/T27N8XXmJXXXXXXXXX_!!125719055.jpg
(over 100kb , I can't post it  )
80ed , 106-600 and 106-900
As Luciano say, used on deep sky is more reasonable
finally, DKD sold the lens on ebady??
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KP3FT
journeyman
Reged: 12/24/09
Posts: 6
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I did a little digging on the internet a while back about these achromats and ran across the following website. It's in German, but I emailed the man who did the testing and he responded in English that the lense they tested had astigmatism to the point where it would be good for low power but not high power. That doesn't mean all DKD lenses are this way, only the one they tested.
http://www.astro-foren.de/showthread.php?p=43090#post43090
his main website is here; it appears they do extensive optics testing:
http://rohr.aiax.de/
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mikey cee
Post Laureate
Reged: 01/18/07
Posts: 4099
Loc: bellevue ne.
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What's an anchromat?? 
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7x35 and 10x50 sears tower binocs, 3" f/10 edmunds reflector, 2.4" f/11.7 manon refractor, 6" f/8 jaegers refractor, "The 8 Ball" 8" f/13.3 brandt refractor, 3" f/15.8 sans&streiffe refractor, 3.1" f/15 selsi refractor(towa 339), 2.4" f/15 sears refractor, selsi 30x30mm spyglass, criterion 5-draw 25x45x75x spyglass(1957), 4.25" f/14.8 tasco 20te.
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