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Equipment Discussions >> Eyepieces

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Darren Drake
Carpal Tunnel
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Reged: 10/09/02

Loc: Chicagoland
A 30mm 100 degree 3 inch barrel in the works!
      #5507619 - 11/06/12 10:12 PM

Scott Roberts is reporting on FB that he will soon be field testing one of these. There is a pic and it is enormous. Wow now SI or someone is gonna have to start making more 3 inch focusers for dobs....

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Keith
sage
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Reged: 05/14/05

Loc: Costa Mesa, CA USA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Darren Drake]
      #5507630 - 11/06/12 10:18 PM

He mentioned that a few years ago, but it I was sworn to secrecy on that. It was at the time being discussed as going with a 3" diagonal for larger SCTs that was also possibly going to be supplied by ES.

Now that the cat is out of the bag, I guess it is ok for me to say "I know"

I hinted about it on the "lowest X for cpc1100" thread recently, but would not say more out of respect to Scott. I am no longer in a position to find out such things anymore anyway, this was a few years ago, guess it was a slow moving process.


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Keith
sage
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Reged: 05/14/05

Loc: Costa Mesa, CA USA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Keith]
      #5507655 - 11/06/12 10:38 PM

I went straight to FB to see...

Edited by Boot (11/08/12 01:28 PM)


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Darren Drake
Carpal Tunnel
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Reged: 10/09/02

Loc: Chicagoland
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Keith]
      #5507725 - 11/06/12 11:40 PM

So how much will this go for?? $1500 is my guess....

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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Darren Drake]
      #5507726 - 11/06/12 11:41 PM

Quote:

Scott Roberts is reporting on FB that he will soon be field testing one of these. There is a pic and it is enormous. Wow now SI or someone is gonna have to start making more 3 inch focusers for dobs....




Won't be of much use in a fast Dob until someone makes a 3 inch Coma Corrector... The modern F/3 Dobs are using the 21mm Ethos as the widefield because the 31mm Nagler results in an oversized exit pupil...

Jon


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Darren Drake
Carpal Tunnel
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Reged: 10/09/02

Loc: Chicagoland
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Jon Isaacs]
      #5507737 - 11/06/12 11:52 PM

Right only scopes slower than about f/5 could really benefit from this and perhaps only refractors.

Edited by Darren Drake (11/06/12 11:53 PM)


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SeattleScott
Pooh-Bah


Reged: 10/14/11

Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Jon Isaacs]
      #5507743 - 11/06/12 11:57 PM

The problem with a 3" eyepiece is then you need a bigger secondary, which means lower contrast and light transmission. Maybe for a large aperture scope it would be ok, but there is going to be that compromise. I believe the CO on an 11" SCT is almost 4" already. Do you really want to make it 5" to get a wider field of view? Maybe on an F5 18" dob it would work well. But then you have to balance what looks like a 5-lb eyepiece!

I don't know, I do not see a lot of interest in this outside of observatories that use larger than 2" eyepieces for their huge telescopes. But it is fun to think about!


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Keith
sage
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Reged: 05/14/05

Loc: Costa Mesa, CA USA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Darren Drake]
      #5507749 - 11/07/12 12:02 AM

scott says $12-1500. And it would probably do well in C11/14 and M10/12/14/16 with proper adapter. Only rub is the c11/14 thread is slightly different than the m10/12/14. It looks like they are planning this mainly for their refractors, but when Scott told me about the idea a few years ago, it sounded like a 3" diag to thread to the 3" thread on the back of the larger SCTs and coma free cats was going to be included with the eyepiece.

As I posted comment on FB, I hope this would lead to other 3"ers, such as a 40mm range 82 or more importantly, a 50mm range 68. Would make the c11 a little more interesting, unless the rear baffle limits it. At f10 there is some leeway, but I think it is about 2.5" clear aperture, but I would have to measure. Either way, a 30mm 100deg is probably not using the full 3" anyway, and I have not ran numbers on any of those theoretical others.

Being f10, I personally would like to see wider 40 and 50mm designs in 3 inch, if a diagonal was available. In the old days, there was a thread on 3" eyepiece for the old 3" c14 diagonal, so I know this has been thought of before, not to mention the pentax 65mmXL.


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Jon Isaacs
Postmaster
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: SeattleScott]
      #5507754 - 11/07/12 12:11 AM

Quote:

The problem with a 3" eyepiece is then you need a bigger secondary, which means lower contrast and light transmission. Maybe for a large aperture scope it would be ok, but there is going to be that compromise. I believe the CO on an 11" SCT is almost 4" already. Do you really want to make it 5" to get a wider field of view? Maybe on an F5 18" dob it would work well. But then you have to balance what looks like a 5-lb eyepiece!

I don't know, I do not see a lot of interest in this outside of observatories that use larger than 2" eyepieces for their huge telescopes. But it is fun to think about!




I could use the added field of view in my 25 inch F/5, the 31mm Nagler without a Paracorr provides about 0.80 degrees, a 30mm 100degree eyepiece would provide about 0.95 degrees... significant but not significant enough to deal with the hassle of balance and adding a 3 inch focuser.

The usefulness of an eyepiece like this is somewhat dubious in the sense that it is not so useful in scopes that are already optimized for a wide field of view. It would be great in my 12.5 inch F/4.06 if there were a Paracorr available but without one, it would not be workable. The beauty of TeleVue products is the integrated solutions, a Paracorr that works with the 31mm Nagler... The NP series that provide wide flat field so that the 31mm nagler can show it's stuff.

Of course the 106 FSQ would provide some amazing views if the eyepiece were sharp at F/5.

Jon


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Rick Woods
Postmaster
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Reged: 01/27/05

Loc: Inner Solar System
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Darren Drake]
      #5507760 - 11/07/12 12:17 AM

Quote:

Scott Roberts is reporting on FB that he will soon be field testing one of these. There is a pic and it is enormous. Wow now SI or someone is gonna have to start making more 3 inch focusers for dobs....




I'm sorry; what are "FB" and "SI"?


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core
Pooh-Bah
*****

Reged: 02/23/08

Loc: Mostly in Norman, OK
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Rick Woods]
      #5507765 - 11/07/12 12:19 AM

FaceBook

StarlightInstruments (feather touch)

Edited by core (11/07/12 12:20 AM)


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Scanning4Comets
Markus
*****

Reged: 12/26/04

Loc: Ontario, Canada
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: core]
      #5507791 - 11/07/12 12:50 AM

Holy moly! That thing needs a crane just to put it in the focuser.

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Shneor
scholastic sledgehammer
*****

Reged: 03/01/05

Loc: Northern California
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Jon Isaacs]
      #5507867 - 11/07/12 02:42 AM

Quote:

Quote:

Scott Roberts is reporting on FB that he will soon be field testing one of these. There is a pic and it is enormous. Wow now SI or someone is gonna have to start making more 3 inch focusers for dobs....




Won't be of much use in a fast Dob until someone makes a 3 inch Coma Corrector... The modern F/3 Dobs are using the 21mm Ethos as the widefield because the 31mm Nagler results in an oversized exit pupil...

Jon



Not necessarily true. The 9mm ES120 shows pinpoint stars from center to edge in my f/4 without any correction needed. It apparently has a quite different design. Unfortunately, as far as I know, only three CN members have one of these, but several observers have viewed through mine. All were amazed by the sharpness across the entire field.

Clears,
Shneor


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Keith
sage
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Reged: 05/14/05

Loc: Costa Mesa, CA USA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Shneor]
      #5507916 - 11/07/12 04:54 AM

how much for your 9mm ES100? =)

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Mark9473
Postmaster
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Reged: 07/21/05

Loc: 51N 4E
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Keith]
      #5507976 - 11/07/12 07:15 AM

Siebert has been offering large format eyepieces and diagonals for years. I wonder why ES think they will be more successful with it.

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Jon Isaacs
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Reged: 06/16/04

Loc: San Diego and Boulevard, CA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Shneor]
      #5507990 - 11/07/12 07:44 AM

Quote:

Quote:

Quote:

Scott Roberts is reporting on FB that he will soon be field testing one of these. There is a pic and it is enormous. Wow now SI or someone is gonna have to start making more 3 inch focusers for dobs....




Won't be of much use in a fast Dob until someone makes a 3 inch Coma Corrector... The modern F/3 Dobs are using the 21mm Ethos as the widefield because the 31mm Nagler results in an oversized exit pupil...

Jon



Not necessarily true. The 9mm ES120 shows pinpoint stars from center to edge in my f/4 without any correction needed. It apparently has a quite different design. Unfortunately, as far as I know, only three CN members have one of these, but several observers have viewed through mine. All were amazed by the sharpness across the entire field.

Clears,
Shneor




We have been through this one before with other eyepieces... The 30mm Widescan II comes to mind.

Coma is there to be seen at F/4, the coma free region is 1.4mm, the approximate field stop diameter of the 9mm 120 degree eyepiece is 19mm, that's a lot of room for coma. I have a hard time believing moving a bright star like Rigel to the edge of the field would provide a nice round and still clean primary and secondary.

If an eyepiece truly eliminates coma in an F/4 Newtonian, then the reverse coma necessary to do so would be visible in a coma free telescope...

Jon Isaacs


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Sarkikos
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Reged: 12/18/07

Loc: Scotophobe Maryland, USA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Jon Isaacs]
      #5508013 - 11/07/12 08:09 AM

So, a 3" eyepiece might make sense in big SCTs which are not yet available, big slow refractors and marginally in 25" Dobs?

Eh... I think I'll pass.

Mike


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Keith
sage
*****

Reged: 05/14/05

Loc: Costa Mesa, CA USA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Jon Isaacs]
      #5508020 - 11/07/12 08:17 AM

people's tolerance or ability to detect coma varies greatly. Once the astigmatism found in the more basic designs is gone, most people are happy, and really picky folks start to notice the coma. I also found MANY people like to use the word coma to describe any edge of field abberation, and some even use the word to describe "feild curvature in newtonians". Even fairly knowledgeable guys I have known, maybe they just wanted to make the explanation simple.

In my experience, the elimination of the rest of the abberations, coupled with the barlowing effect of the nagler type eyepieces, makes most people happy, especially when upgrading from eyepieces like said widescan or its cheap chinese clones, to a nagler or more modern chinese nagler clone. At that point, adding the paracorr eeks that extra bit of perfection out of the field. I am kind of bummed that televue only does type II now, because that sucker is expensive. I can understand eliminating the original smaller lens (t-thread) versions and forcing the universal system and it's available tunable top, and T adapters and spacers, but they should have at least kept the universal type 1 in the lineup.

I have owned the original photo-visual version, and then the second to last version of the visual only paracorr. Of course it was vignetting with the 31 that prompted me to get the visual model. At f5, the 31nagler still did very well, and when I was offered a trade I couldn't refuse at a star party for the visual, I let it go figuring I could still use the original for the 22nagler, which totally blew chunks without a paracorr. At f4, the paracorr was a much bigger necessity than it was at f5.

When I sold my 8"f4, I included the photo-visual as a package, because imaging was the main interest of the buyer.

If I get back into dob's, I hope I am lucky enough to get a paracorr at a good price. I am one of the guys who can see the difference, and would not have traded that visual model had I not had the original photo/visual as a backup. It is a non issue for me now being newt free, but I spent a good portion of a decade as a newt guy.


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Keith
sage
*****

Reged: 05/14/05

Loc: Costa Mesa, CA USA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Sarkikos]
      #5508025 - 11/07/12 08:26 AM

Quote:

So, a 3" eyepiece might make sense in big SCTs which are not yet available, big slow refractors and marginally in 25" Dobs?

Eh... I think I'll pass.

Mike




wondering what you mean by big scts that are not yet available. Were you just referring to the diagonals not being available? IIRC ES might have been planning a 3"barrel refractor type diagonal (which makes sense since Scott was ref their APO). Even if that is the only diagonal they offer, and they do not offer 3" visual backs for SCTs, OPTEC already does for their 314 and 316 3" .75 reducers, for folks who want the benefit of those reducers (imaging) without having to shell out the big bucks for the TCFS-3 focuser. 3" slide in optics are already on the market in the imaging scene, so getting a visual back for the SCT is not a problem, should ES intend their diagonal only for refractors.

Either way that EP looks to be 10lbs easily, It is one thing to have to slide a CW to rebalance for a 31 nagler, but this would require adding another weight for sure in some cases.


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Keith
sage
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Reged: 05/14/05

Loc: Costa Mesa, CA USA
Re: A 30mm 100 degree 3 inch barrel in the works! new [Re: Keith]
      #5508036 - 11/07/12 08:38 AM

Oh, JMI had a 3" focuser too, so getting them on a dob would have multiple options, but coma would be an issue. My experience with ethos and ES100's in f5 and slower is that they are in the "good enough" range like the 31 nagler. Of course Jon has VERY good points about issues like this being an even bigger field where more intense coma would be, and requiring a bigger secondary. Not to mention trying to balance a dob with an EP that heavy.

I think this EP will be a winner with the BIG cassegrain guys, RC's and CDK's and Classical Cass, and of course the aforementioned big SCTs, where a field that large is actually NEEDED. If I had one of these I would have a 4"-3" sleeve made and take the sucker to the 60" on mt wilson or palomar, but it would have to be very good seeing, IIRC they are f16 and that would be over 800x! This is where it would be sweet if ES considered 40 and 50mm range 3" eyepieces with 82 and 68 degrees. Maybe even less critical designs since they would only be used on f7 or slower scopes. More realistically, the local club has a 21.5" Cass in f8 mode (has f16 secondary as well but never used), last I knew it had a 4" WO focuser on it, so all that would be needed was a 4"-3" sleeve to adapt the diagonal (which ES hopefully includes with the EP or has available at least). I know the 31mm nagler and my widescan III look great on that scope, this sucker would probably be pretty awesome at 146x with a TFOV approx .68 degrees w/3.75mm exit pupil. *BLEEP* now we need a 3" UHC filter!

Just speculating of course, as the market is limited, and I think they will probably stop at the 30 and market it as an uberwide for the APOs with big focusers.


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