-- Matt -observing since fall 2012 16" F/4.5 truss DOB / EON 120mm ED / 10" F/5 strut DOB Paracorr (T1 tunable),telrad, RACI finders, AltAz Tripod mount ES 82° 4.7,6.7,8.8,30mm AT Paradigm 60° 25,18,12mm Pentax XW 70° 20,14mm , Baader zoom observing list/notes.. beginning dslr astrophotos (moon/widefields)
WO Megrez 120 ED on GP Mount
WO ZenithStar 80 ED II on Porta II
10" Meade LightBridge/Paracorr
Orion ED 100 on Polaris Mount
Astro-Tech 8" f6 Dob
Bushnell Ares 5
Meade 226 2.4" f11.7
SpaceScope 2.4" f15
My eyepieces are made from the waste product of exploding stars.
10XTi 102XLT ST80A(2" Focuser); President, Eypieces Anonymous, Denver Chapter (Hello, I'm an eyepiece junky, what's your excuse?)
DAS Dark Site
Quote:Eye relief has nothing to do with focal length, it has to do with eyepiece design.
First and foremost observing love: naked eye.
Last but not least, telescopes.
And I sometimes dabble with cameras.
Quote:This breaks down for more complex eyepieces, which usually include a negative element in the front. Even so, eye relief almost always decreases with eyepiece focal length except in eyepiece lines that are specifically designed to preserve it.
the other night brought out my XLT 102 refractor and had some fun. as its cold i tend to just pop an eyepiece in and use it for the night. I wanted to get some more time behind a 2" 5mm Hyperion. this was perhaps a bit too much magnification for the seeing, but only JUST, but thats not my question..
I noticed I had to take off my glasses and pretty much push my eye against the (already folded down) eyecup. I picked this EP up used when i saw it as I'd heard here they have long eye relief. I just looked it up and this 5MM EP is supposed to be 20mm. all of the other "long eye relief" eyepieces I have bought can be used with glasses. I looked up my Astro Tech Paradigm 12mm 1.25" and that one has 13mm. I just tested it again and I can see the full outer rim with glasses on. Then I tried the hyperion with its 1.25" adapter attached and sure enough the eye relief is better. I am not outside to verify but im sure the FOV is smaller too, but thats not my question either
is there any way I can get that 20mm of eye relief with this 2" EP? I want to get a nice wide field 2" EP at some point and am wondering if Ill run into the same thing. Just looked at their 31mm and the eye relief is a shorter 18mm. The ES 82º has 21mm eye relief. im totally confused why im not getting the eye relief i wanted.
I looked up the specs of it and i dont quite understand all of the adapters and threading options for it. mine didnt come with a manual.
im including a pic with it attached as a 2" to my diagonal just in case theres something im missng that a picture will show.
"The heavens declare the glory of God; the skies proclaim the work of his hands." Psalms 19:1
Orion XT12g 12" f/4.92 GoTo Dob Orion 9x50 RACI - Green Laser Pointer Orion 4.5" f/4 EP: ES82 30mm, ES68 24mm EP: Hyperion 21, 17, 13, 10, 8, 5mm Various filters, including Skyglow, UHC, O-III Celestron Ultima 2x Barlow Celestron 12x80 binoculars & mount
Quote:That's not a 1.25" adapter you removed. That's part of the eyepiece. Leave it on, and your eyepiece will work just fine.
We mostly come out at night... mostly.
GSO Z8 Degree Circle & Digital Level
Celestron 4"(102mm) SLT 660mm f/6.47
2" 30mm GSO WideView
9mm GSO Plossl
ES 82's : 4.7mm, 8.8mm, 11mm, 18mm
BGO's 5mm, 6mm, 9mm
2" 2X ED Astronomics Barlow & GSO 1.25" 2x Shorty
8-24 Baader Zoom III
Baader M&SG, Semi-Apo
Quote:I'm curious about weather that's really a 5mm 2" EP. Do you know what size the field stop is?
Quote:Quote:I'm curious about weather that's really a 5mm 2" EP. Do you know what size the field stop is? Howard:From reading this thread and having owned the 13mm version, it's not really a 2 inch eyepiece, it's a 1.25 inch eyepiece with a 1.25 inch-2 inch barrel. Something I missed but others caught was that the 1.25 inch inner section had been removed. That section contains the Barlow/Smyth lens and is important... Jon
Quote:Thank you Jon, that's what I figured it was, 1.25". As for the OP taking it apart as it seems he did, I find the Hyperions to be too tricky with those tuning rings. I do enough fiddling around in the dark as it is with what I have, I'm glad I avoided them entirely.
Quote:The Hyperions are not 2" EPs. Well in a way I guess that they are, but the nose piece that you screwed off is not just an adaptor for 1.25". It is a lens group. Baader originally marketed these as "Two Eyepieces in One"
Quote:and later added the concept of 3 or more EPs in one with the addition of the so called "Tuning Rings".
Quote:To expand on what Jon has stated above. The Hyperion design is in fact a six element Erfle with a two element achromatic tele negative group (Called a "Smythe" lens, and often compared to a "Barlow" lens - same horse different jockey) added as a nose piece. The 5mm Hyperion is in fact a 22.5mm Erfle with a 4.5x Smythe.
Quote:design is its wide (for its time) field of view ~ 65° or more, and secondarily its long eye relief.Therefore complete with nose piece the 5mm Hyperion is a 5mm 1.25" EP, and without nose piece it is a 22.5mm 2" EP
Rob Astronomy compels the soul to look upwards and leads us from this world to another..... Plato
Orion XT8 Classic, Self built EQ platform
AstroTech 72ED, AstroTech 6 Imaging Newt
Celestron Advanced VX EQ Mount
Celestron NexStar SE 4/5 Mount (for grab and go)
Canon T3i, Canon XT (Hap Griffin Baader Mod)
QHY5L-II Mono/Orion 50MM Mini
Fort Bend Astronomy Club
Quote: ... also, with the 1.25" "adapter" on i can see ...
Dark Arts Observatory - Brockport, NY - Skyshed POD XL5 with iOptron iEQ45 Mount
Scopes: C8, C5, SV110 ED, EON-72 ED, ST 80, ATRC6, Megrez 90
Quote:Quote: ... also, with the 1.25" "adapter" on i can see ... Hi Howard:Just want to re-iterate what others have said, that the 1.25" section is NOT an adapter. It is part of the eyepiece and normally should NOT be removed, even if you use it in a 2" diagonal.Just leave the eyepiece fully assembled and insert it into either a 1.25" or a 2" diagonal. It will work as designed in that configuration. While you *can* remove the 1.25" barrel and lens group and use the eyepiece as a 22mm (which sounds like what you were doing), I would not recommend that. The views suffer and it is not optimized for that configuration. If you need a larger view of the sky, you're much better off buying a longer focal length eyepiece.-Dan
PST 10"f/6 Meade OTA Celestar 8
Quote:Dan, good points. I don't own any Hyperions, I was just trying to figure out why that 13mm did what it appeared to do after it was partially taken apart and used.
Quote: ... is a bit perplexing that everyone is saying i "shouldnt do that". and their material says its designed to do that.
Quote: it is definitely a lower quality view than the 5mm mode.
"Another new world, no beer, no women, no pool parlors, nothing to do here but to throw rocks at tin cans and we have to bring our own tin cans." Earl Holliman (Cookie)- Forbidden Planet