ED eyepieces - any good
Ashley
There are several brands of eyepieces containing ED glass. They all look the
same and outwardly appear to come from the same manufacturer.
Has anyone used these, and what scopes are they best in. I have both GS 12"
f5 dob and 6" f8 Synta refractor.
I am led to believe they are a cheap copy of the Takahashi LE series.
Anyone got a comment on whether they are better than decent plossls like
Orion Highlight etc.
Thanks, I'd love to know what you think.
Ashley
Tony
it works better than the cheap 7.5mm plossl/2x barlow combination. I have tried
it both with a 6" maksutov and the orion ED80 and in both cases planetary
images are cleaner with much less scattered light and everything just seem
sharper. In the Mak though, the test may not have been valid as seeing was no
way good enough for almost 500x but it did seem easier to find best focus with
the Epic.
Also I have not tried it yet but something tells me, that if I look at the moon
with this EP there is going to be a huge glare problem. We will see when the
moon comes around this month. If I'm wrong I will probably buy a couple more of
these in the shorter focal lengths.
Tony
Jon Isaacs
>
>Ashley
I haven't tried one, I would like too. It seems to me that the advantage of
these eyepieces is their eye relief.
I believe the advantage of these eyepieces over Plossls is that even in the
short focal lengths they still have 20mm of eyerelief. With a short focal
length Plossl or Ortho, I find myself with my eye pressed against the eyepiece.
To me this alone makes the eyepiece worth considering. Unforturately, they
only make a 5mm or an 8 mm, I would like something around 6mm.
jon
Chris1011
I doubth that they have any real ED glass in them. If they did, they would
actually perform rather poorly off-axis. The best way to reduce off-axis
aberrations is to use high index glasses, not low index ED glass.
Roland Christen
CLT
news:20040322110223...@mb-m12.aol.com...
But what if you use a proprietary design with tight zonal control? There's
no telling how many zones you can fit into that last 12mm piece of glass.
(OK --- I'm heading back to my cave now)
;-)
Chuck Taylor
Do you observe the moon?
Try the Lunar Observing Group
http://groups.yahoo.com/group/lunar-observing/
Lunar Picture of the Day http://www.lpod.org/
************************************
Chris1011
>no telling how many zones you can fit into that last 12mm piece of glass.
>(OK --- I'm heading back to my cave now)
It's not about zonal control, it's about controlling the marketing department.
I wonder what the next cool glass will be for scopes and eyepieces? Maybe we
need hyper low dispersion with unusual abnormal absorption centers to really
bring out detail on the planets?
By the way Chuck, are you interested in a really cool optical design program?
Contact me at my e-mail address.
Rolando
Tony
You mean I've been had?? You always ruin everything Roland :-). First Orion
sells me an ED80 APO that not really an APO and now they sell me ED EP's with
no ED. Whats Next?
I think I'll take up collecting rocks or something.
Tony
Chris1011
>You mean I've been had?? You always ruin everything Roland :-). First Orion
>sells me an ED80 APO that not really an APO and now they sell me ED EP's with
>no ED. Whats Next?
>
I think it really is an ED Apo scope. What makes you think it is NOT an Apo?
Roland Christen
Tony
I was more or less kidding there BUT, since I have never had the opportunity to
look thru a real APO I can only go by what I have heard on the various groups.
Some say it is - some say its not - some say kind-of-sort-of. I have had many
small achromat refractors and by comparison to them, in my eyes its an APO. For
me though the question remains since I can start to detect color in it at
stupid high powers (200X+).
Have you ever seen one Roland? If so and you say its an APO I'll take it as the
final word.
Tony
John
>
> I doubth that they have any real ED glass in them. If they did, they would
> actually perform rather poorly off-axis.
Does that include Panoptics?
james
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
From what I understand even a two lens system with one ED glass it is
still posible to show some color. Four curves can only do so much.
Even with one lens being ED, you have only seven variables to adjust
for optimization. Two refractive indices and dispersions,one spacing
and four radii of curvature.
james
jerry warner
Jerry
james
wrote:
>Obviously ED stood for "educationally deprived". Or? Epluribus Demintum ?
>Jerry
>
>
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Extra dumb?
james
Jon Isaacs
>>Jerry
>>
>Extra dumb?
>
>james
>
The question about these eyepieces is not what ED stands for, rather how they
do they perform. Forget the marketing hype, rather what sort of views do they
provide??
The advantage of these eyepieces over Plossls is that even in the short focal
lengths they offer 20mm of eye relief.
Now in my book, if these eyepieces offer views comparable to a good quality
Plossl but with the 20mm of relief then they could be pretty neat.
jon
Smack Dab
>I doubth that they have any real ED glass in them. If they did, they would
>actually perform rather poorly off-axis. The best way to reduce off-axis
>aberrations is to use high index glasses, not low index ED glass.
>
>Roland Christen
Uncle Rolando,
Takahashi advertises several models of their eyepieces to have ED glass
in them. Takahashi usually isn't one to push senseless marketspeech, so
maybe ED can be OK sometimes?
See:
http://www.star-matrix.com/prices/eyepieces_tak.htm
Smack Dab
Chris1011
lengths they offer 20mm of eye relief.>>
Yes, that's easy enough to do by using a long focal length primary eyepiece
coupled to a Barlow. That is how all these long eye relief eyepieces do it. Has
nothing to do with ED. The downside is more elements and lower contrast over
more simple systems.
Roland Christen
Chris1011
>Takahashi advertises several models of their eyepieces to have ED glass
>in them. Takahashi usually isn't one to push senseless marketspeech, so
>maybe ED can be OK sometimes?
>See:
>http://www.star-matrix.com/prices/eyepieces_tak.htm
Yes, indeed. ED, SD. Take a close look at the design and you see where the
supposed ED and SD glass is used. It is used as the flint element in the front
Barlow element. It is impossible to use ED or SD glass in this element. If
anywhere it would have to be in the positive crown element. But nevermind. The
fact that it is used in the negative flint and is cleverly called Extra
dispersion and Special Dispersion should tell you something. These are not the
terms that were originally used for ED and SD. Extra dispersion and Special
Dispersion mean absolutely nothing in the optical world. Only in the marketing
world do they have any possible meaning.
Roland Christen
PS: ED normally refers to Fluoro-phosphate crown glass that has Extra low
Dispersion (thus E.D.). The high end of those glasses are sometimes referred to
as Super low Dispersion (thus S.D.). Neither one can be used as a negative
flint element in a Barlow.
Jon Isaacs
>coupled to a Barlow.
>. That is how all these long eye relief eyepieces do it.
Still, a 3.7 mm eyepiece or a 5.1 mm eyepiece with 20mm of eye relief is pretty
nice, with a 2x barlow one would be using a 7 or 10mm plossl which is already
getting into short eye relief territory.
>Has
>nothing to do with ED. The downside is more elements and lower contrast over
>more simple systems.
I can believe it has nothing to do with the "ED" glass, but these still could
be decent eyepieces, that is really my point.
Those added elements will be there whether one is using a barlow or one of
these 6 element 20mm eye relief eyepieces.
There's a lot of hype floating around, even about good solid equipment.
Ignoring the fat/hype and getting to meat is the sensible approach IMHO.
jon
Jskies187
pretty
nice, with a 2x barlow one would be using a 7 or 10mm plossl which is already
getting into short eye relief territory. >>
Most of the shorty barlows extend ep eye relief somewhat. This actually helps
with short focal length ep's.
john
Jon Isaacs
>with short focal length ep's.
>
>
>john
>
Plossl+Barlow combinations that end up with focal lengths of 3-6mm that I am
familiar with don't provide 20mm of eye relief....
Jon
Chris1011
pretty
nice, with a 2x barlow one would be using a 7 or 10mm plossl which is already
getting into short eye relief territory.>>
I agree, if you need 20 mm of eye relief, you will need to use one of these
multi-element eyepieces with their built-in Barlow, but the downside is reduced
contrast on the most subtle and fleeting planetary detail.
There are lots of eyepieces that do it with the built-in Barlow. Naglers,
Radians, LV Lanthanums, etc.
Roland Christen
Tony
coupled to a Barlow. That is how all these long eye relief eyepieces do it. Has
nothing to do with ED. The downside is more elements and lower contrast over
more simple systems. <<
Not doubting you at all. I dont know if the Orion version of these is even
remotely similar to theTak's the OP mentioned but I can say that the 3.7 mm I
got is vastly superior to a $35 Plossl + $29 barlow combination both in terms
of contrast and sharpness. Beyond that for sure there is nothing great about
them and if the same comparison were done with a more expensive EP/barlow
combination these would probably fall short.
Roland. I took this thing apart (I couldn't resist). The barlow part of it
appears to be two small but different diameter lenses glued together. The
strange thing is the outer 25% of each lens face appears "frosted" or "ground".
It seems when using this EP that any bright light at the edge of the FOV gets
scattered buy this frosted section. Likewise looking into the EP from the
scope end and aiming it at a bright light fixture the frosted section becomes a
brightly illuminated ring. Whats up with that? Any comments?
Jon. You keep mentioning eye relief. Again I dont know if these are the same as
the ones the OP mentions but the eye relief is very nice. I thought that with
the resulting small exit pupil when using 3.7 mm that it would be hard to keep
my eye centered without blacking out and such. Not so - very comfortable to use
and not so critical. In fact I like the eye relief aspect of these better than
the Orion Ultrascopics. One downside is this thing is huge.
Tony
Chris1011
>scattered buy this frosted section.
Don't know. I have not seen one of these myself. Should produce some
interesting ghost flare when using it on extended objects like the Moon.
Roland Christen
Jon Isaacs
>I agree, if you need 20 mm of eye relief, you will need to use one of these
>multi-element eyepieces with their built-in Barlow, but the downside is
>reduced
>contrast on the most subtle and fleeting planetary detail.
I have found longer eye relief to make viewing more "comfortable". While it
seems especially true with binoculars, I find it also true with scopes. Helps
keep the eye lashes from oiling up the eye lens.
>There are lots of eyepieces that do it with the built-in Barlow. Naglers,
>Radians, LV Lanthanums, etc.
So do you that Naglers, Radians etc also have reduced contrast? Many folks
seem to be happy with the Radians as planetary eyepieces.
It seems to me that these ED-2 eyepieces are similar to the Radians in spec,
sort of a "poor mans" Radian..
Jon
Tony
interesting ghost flare when using it on extended objects like the Moon.
I'm afraid your probably right as usual. I have not had a chance to try it on
the moon yet but I did point it a street light and the glare was obnoxious. The
entire FOV was lit up and hazy almost as bright as the street light. Its seems
fine on planets but something funny does happen when the planet is at the edge
of the view which is what made me suspicious of this.
Tony
Reef1969
mine from scope stuff, 66 degree FOV, $40 each. Luckily I bought them for low
power viewing. They scatter a lot of light on Jupiter. Looks like bats flying
around in the FOV.
Clear Skies
Richard
Reef1969
So do you that Naglers, Radians etc also have reduced contrast? Many folks
seem to be happy with the Radians as planetary eyepieces.
It seems to me that these ED-2 eyepieces are similar to the Radians in spec,
sort of a "poor mans" Radian..
I am no fan of Radians really, but these are not Radians. I ghosting will
drive you nutts. Luckily mine are for low power viewing.
Clear Skies
Richard
Chris1011
Compared to what? Other eyepieces of similar design or eyepieces of less
elements?
> Many folks
>seem to be happy with the Radians as planetary eyepieces.
Many folks seem happy with almost anything, even toy telescopes. It all depends
on your level of expectation. The last ounce of contrast may require that you
give up something.
Rolando
Jon Isaacs
The 66 degree FOV eyepieces are a different series than the Orion ED-2 series.
jon
Jon Isaacs
>
>Compared to what? Other eyepieces of similar design or eyepieces of less
>elements?
For starters, compared to your favorite eyepieces.
>
>Many folks seem happy with almost anything, even toy telescopes. It all
>depends
>on your level of expectation. The last ounce of contrast may require that you
>give up something.
I would guess that my level of expectation is low when compared to yours. I
would probably be happy with Orion ED-2 eyepieces or with Radians....
jon
Jskies187
familiar with don't provide 20mm of eye relief.... >>
That's true. But I think 20mm of eye relief has become sort of a sacred cow
lately. Exactly, precisely 20mm is nifty, but just not that critical.
Klee's and Ultima clones that I have used, frequently extend the eye relief on
low power ep's out into the realm of inconvenience. But they can make simple 3
and 4 element short focal length ep's more comfortable to use.
john
Jon Isaacs
>lately. Exactly, precisely 20mm is nifty, but just not that critical.
20mm is not an exact number, rather a ballpark figure. I do like having
sufficient eye relief so that my eye is not pressed against the eyepiece. But
20mm without an adjustable eye cup might be too much...
jon
Tony
FOV) I was having with the 3.7mm ED-2 . I simply blackened the exposed frosted
areas of the barlow element. I did both the inner and outer faces but probably
would be sufficient just to do the outer. Doing the outer could be done without
removing the element by using a brand new sharpie marker (or one without a worn
point) and simply tracing around the retainer ring opening - carefully though -
its rather small.
Orion or whoever made these could have prevented this problem by either using a
retainer with a smaller opening that would fully cover the ground face or
simply do what I did. A simple but important detail that was overlooked. I
wonder if all of them in the series have this problem. Seems like I'm the only
one that has one of these as no one else has chimed in about them. I'll
probably go ahead and order the 5mm so I'll know soon.
Tony
Chris1011
would probably be happy with Orion ED-2 eyepieces or with Radians....
>>
In that case, look no further and buy yourself a set of these.
Rolando
Stephen Paul
> Many folks seem happy with almost anything
Happiness comes easy. Dissapointment takes experience. <g>
-Stephen Paul
Russell Martin
> >But what if you use a proprietary design with tight zonal control? There's
> >no telling how many zones you can fit into that last 12mm piece of glass.
> >(OK --- I'm heading back to my cave now)
>
> It's not about zonal control, it's about controlling the marketing department.
> I wonder what the next cool glass will be for scopes and eyepieces? Maybe we
> need hyper low dispersion with unusual abnormal absorption centers to really
> bring out detail on the planets?
>
> By the way Chuck, are you interested in a really cool optical design program?
> Contact me at my e-mail address.
>
> Rolando
I understand materials are being developed with negative refractive
indices (at least for microwaves, but not optical wavelengths, yet).
Marketing could probably do something with that. :-)
Regards,
Russell
Chris1011
>indices (at least for microwaves, but not optical wavelengths, yet).
>Marketing could probably do something with that. :-)
>
I'm actively pursuing eyepiece designs with >120% light transmission. I figure
if we rob some of the light going to waste in the infrared and ultra-violet and
stuff it into the visible spectrum, we could easily raise the efficiency of the
overall ocular transmission to well over 100%. maybe even 200% is possible. Who
knows. The glass is under development, but I don't know how many parsecs it
will take to bring it into production. What shall we call this new design? How
about: Ultra-Infra-Super Dispersion Tellurium High top Oculars with extended
magnitude control??
Rolandomaxissimo
Brian Tung
> The glass is under development, but I don't know how many parsecs it
> will take to bring it into production.
I like the idea of light-parsecs--the amount of time it takes light to
go one parsec. About 3.26 years. How long is the wait for an AP 155?
About 1.5 light-parsecs. (Or whatever it happens to be at the moment.)
> What shall we call this new design? How about: Ultra-Infra-Super
> Dispersion Tellurium High top Oculars with extended magnitude control??
How about Bandwidth Suppression eyepieces? In fact, given that it's
such an outstanding specimen, perhaps it should be *Total* Bandwidth
Suppression eyepieces.
Brian Tung <br...@isi.edu>
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt
Chris1011
>such an outstanding specimen, perhaps it should be *Total* Bandwidth
>Suppression eyepieces.
Supression implies that something is lost. Not good marketing. We need a
whizz-bang name!!
Rolandomaxissimo
Vahe Sahakian
> knows. The glass is under development, but I don't know how many parsecs it
> will take to bring it into production. What shall we call this new design?
Such a glass exists, the darn thing glows in the dark, it is
radioactive glass, now if you could only convert some of that
radiation onto the visible spectrum you sould be able to achieve 300%
efficiency, and if that is not good enough consider further benefits
with such a glass, it will stay pretty warm and keep the dew away.
Thanks,
Vahe
Smack Dab
> What shall we call this new design? How
>about: Ultra-Infra-Super Dispersion Tellurium High top Oculars with extended
>magnitude control??
(1) Just call them Rollo's
(2) Offer them in the following focal lengths:
0.1mm, 0.2mm, 0.5mm, 1mm, 2mm, 5mm, 10mm, 20mm, 50mm
(3) Through use of new Super-Fluorite, they are modular, so if you need
a 3mm eyepiece, you screw the 1mm and 2mm units together. Anything
from 0.1mm to 70mm is possible by simple screwing of the user!
(4) For twice the price you can get the Magna-Rollo, which has gold line
around base where field stop is inside. Users feel scientific knowing
where field stop is.
SD
Chris1011
>(1) Just call them Rollo's
>
>(2) Offer them in the following focal lengths:
>0.1mm, 0.2mm, 0.5mm, 1mm, 2mm, 5mm, 10mm, 20mm, 50mm
>
>(3) Through use of new Super-Fluorite, they are modular, so if you need
>a 3mm eyepiece, you screw the 1mm and 2mm units together. Anything
>from 0.1mm to 70mm is possible by simple screwing of the user!
>
>(4) For twice the price you can get the Magna-Rollo, which has gold line
>around base where field stop is inside. Users feel scientific knowing
>where field stop is.
>
>SD
I love it. Gotta get cranking now.
UncaRollo
Alan French
>
> I love it. Gotta get cranking now.
>
> UncaRollo
The real marketing coup would be disposable eyepieces. Use it once, then
toss it, or send it back for recycling. Guaranteed laboratory clean every
time for the highest possible contrast. Available in handy twelve packs, or
by the gross for the serious planetary observer.
Clear skies, Alan
William Hamblen
wrote:
>I understand materials are being developed with negative refractive
>indices (at least for microwaves, but not optical wavelengths, yet).
>Marketing could probably do something with that. :-)
A mirror works just as if it had an index of refraction of -1.
jerry warner
contrast" ...by reducing aberrations ? Youc an go right to their sites and
read in almost that exact language, and in TeleVue's case, that is the language.
Thats where I got it.
Jerry
Chris1011 wrote:
> >>The advantage of these eyepieces over Plossls is that even in the short focal
> lengths they offer 20mm of eye relief.>>
>
> Yes, that's easy enough to do by using a long focal length primary eyepiece
> coupled to a Barlow. That is how all these long eye relief eyepieces do it. Has
> nothing to do with ED. The downside is more elements and lower contrast over
> more simple systems.
>
> Roland Christen
Chris1011
>contrast" ...by reducing aberrations ?
It depends on their definition of ED. I can call any glass ED and nobody will
be the wiser what is actually used in the eyepiece. Real ED is not conducive to
improving contrast by reducing aberrations. The refractive index of ED is too
low for good field correction.
The way to reduce aberrations in eyepieces is to go the opposite way - increase
the index of refraction of the crown and flint elements to reduce their
curvature and get a flatter field with less astigmatism.
Of course if one defines ED as being "Extra Dispersion" then that term can be
used to describe any high index / high dispersion flint material, which, by the
way, is exactly the opposite of ED glass used in Apo refractor objectives where
ED is defined as Extra LOW Dispersion.
Roland Christen