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BillP
Carpal Tunnel
Reged: 11/26/06
Posts: 2209
Loc: Vienna, VA
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No. It's better corrected off-axis without those elements. Quite unexpected. So if all you do is remove the Smyth group in the chrome barrel the edge is quite horrible with the 5mm. Much better when you remove the others as well so you are only left with a 4-element design. Throughput is noticably better as well given 2 doublets just got removed -- not that it was bad to begin with. Again, it's no Nagler (although I lovingly call it my 26H5), but much better correction than simply removing the Smyths IMO.
FYI, I've done this also with the 17mm, and I recall it is not bad either. However, unlike the 5mm, for some reason the elements in the upper housing iof the 17mm are not held in by a retaining ring but instead using the barrel housing to do this. So once you break the light glue seal they use to unscrew the 2" housing (at the joint where the rubber grip is), the elements will fall to the floor if you are not careful with the 17mm. I guess you can figure how I know that huh 
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250mm f/4.7 Orion XT10i Dobsonian
102mm f/8.0 Tak TSA Super-APO
66mm f/5.9 WO ZenithStar SD APO
40mm f/10 Coronado P.S.T.
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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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So, bill....you found that on ONLY the 5mm, taking off the negative lens group provided a far better viewing experience overall?
I know this can be done with ANY of the baader eyepieces without requiring any additional FTR or other accessories.
Simply take a 5mm or 8mm, take off the negative group, and boom you have a 19-22mm eyepiece?
Say i took a 8mm, and took off the negative to make it a 19-22mm. How will this "frankenstein ep" as someone said before, compare to the retail 21mm eyepiece.
will it have less eye relief and a smaller FOV compared to the retail 21mm WITH negative group?
Its interesting that baaders can be modified both ways, using the 2 FTR to make the focal length smaller, or just removing the negative group to get a much longer focal length.
We know that using FTRs to decrease the FL makes for much shorter eye relief and smaller FOV.
What does going the opposite way do?
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
Edited by Brooklyn (08/07/08 06:41 PM)
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BillP
Carpal Tunnel
Reged: 11/26/06
Posts: 2209
Loc: Vienna, VA
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Quote:
So, bill....you found that on ONLY the 5mm, taking off the negative lens group provided a far better viewing experience overall?
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Sorry ...not sure which lens group you are referring to. I found that removing only the Smyth group did NOT produce as good a view as removing both the Smyth group and the next doublet above it. There are 8 total lenses in a Hyperion (except the 24mm). Had to remove 1/2 of them before it became not so bad. To do this it is necessary for one to do some EP surgery and break the mid-seal on the 2in housing to unscrew it, then remove the retaining ring and lens cup from the lower half of the 2" housing, and of course leave the 1.25" barrel off with the Smyth group that it contains also.
-Bill
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250mm f/4.7 Orion XT10i Dobsonian
102mm f/8.0 Tak TSA Super-APO
66mm f/5.9 WO ZenithStar SD APO
40mm f/10 Coronado P.S.T.
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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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alright, i would like to bring your attention to
http://www.alpineastro.com/Hyperion-Eyepieces_com/Images_and_Docs/HyperionandZoomInstructions-Version2.pdf
Go to the table at the bottom and look at 8mm. All the way to the right it says "without first group of lenses."
The 8mm turns into a 21.8mm eyepiece with a field stop of 30mm!! That is a lot more than the normal 10.7mm of field stop that's in the unmodified version.
I called it a negative lens element because that is how it was referred to on one thread that i found (which is listed in this thread up above).
You called it the Smyth group, and the baader website calls it "without first group of lenses."
Are these all the same part/element/group?
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
Edited by Brooklyn (08/08/08 01:30 AM)
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Gaz O'C
Pooh-Bah
Reged: 01/02/05
Posts: 1260
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I have the full set of Hyperions and both fine tuning rings, I can't see that the rings affect the FOV other than in the expected way (ie increasing the mag). The reason I've ended up with the full set is that I don't like fiddling around in the dark with the tuning rings. I also have two 3.5mm Hyperions, one of which always has the 14mm ring in to make a 2.5mm eyepeice, it saves me having to use a barlow to get to x300 and above for lunar work in my 750mm-1000mm scopes.
If you are thinking of getting the full set I'd skip the 21mm as it gives the same FOV as the 17mm. 24mm, 17mm etc is a cheaper way to go IMHO.
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14" f4.5 Dob
10" Meade SCT
180mm f15 Mak/Cass
127mm f12 Mak/Cass
150mm f5 refractor
ED100
EQ6 Skyscan
HEQ5
EQ2
http://stargazerslounge.co.uk/
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Brooklyn
scholastic sledgehammer
Reged: 07/24/08
Posts: 870
Loc: Central New Jersey
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SUCCESS!
The 2 hyperions arrived today, i slept in till 12pm and they were delivered at 9am, so they cooked up in the sun for 3 hours. 
First impression is quite dramatic. The eyepieces are very well made and quite heavy.
One thing i noticed however, it seems that my 5mm was an older production than the 8mm.
The differences were subtle...
The 8mm looked all new and polished and the box that it came in didn't have any dust or scratches on it. You know how you can just SMELL it when optics or other manufactured goods are brand new? they just of that factory lubricant smell, and i love it! Just like new car smell, except new eyepiece smell!
The 5mm came nicely packaged but seemed to have a spec or 2 of some dust on the inside. The box had a couple dents in it, as it is made out of cardboard/hard paper matieral so i guess it was slammed into something or bumped hard but im sure this doesn't affect the inside of the box.
Also, the 5mm did'nt smell as new as the 8mm did.
Neither of the boxes were ever opened. The leather pouches, and all the plastic bags that protect the eyepiece, were all perfectly folded...something i couldn't repeat or recreate when trying to put them back in the box the first time after looking at them.
Which direction are you supposed to rotate to remove the pieces of the eyepiece? I assume it is counterclockwise just as most screwin systems are.
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Meade 8.25"(209.55mm) LX-90 EMC (SCT)
Albert Einstein =>
“Intellectual growth should commence at birth and cease only at death.”
“If you can't explain it simply, you don't understand it well enough.”
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