Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Going to be trying Explore Scientific 92's

  • Please log in to reply
102 replies to this topic

#26 rowdy388

rowdy388

    Soyuz

  • *****
  • Posts: 3,567
  • Joined: 09 Apr 2013
  • Loc: Saratoga County, NY

Posted 14 November 2019 - 05:09 PM

I was worried the huge eye lens would be a dust/dirt/fog magnet but my 17mm has stayed 

very clean. 


  • John Huntley and 25585 like this

#27 25585

25585

    Fly Me to the Moon

  • *****
  • Posts: 6,409
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the UK.

Posted 14 November 2019 - 06:36 PM

If the night sky is music, a telescope an instrument, and eyepieces musicians, ES92s are a whole orchestral ensemble.    



#28 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 30,972
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 15 November 2019 - 08:33 AM

I have been tempted, but still have my Ethos 21mm, 17mm, 13mm and 10mm, plus a 31mm Nagler.   I don't need the extra eye relief. I find 10mm to 15mm of eye relief to be just fine.  Please give a full report on these 2 eyepieces when compared against he Ethos!

If you need more eye relief with the Ethos, just back off from the Ethos until you're at 92 degrees.  Then you'll have the eye relief and AFOV of the 92 ES at a smaller size and weight. shrug.gif

 

You always the option of moving your eye closer for the entire 100 degrees!  grin.gif

 

Yes, I've thought about buying a 92 ES, but so far this rationale has stopped me.

 

Mike


Edited by Sarkikos, 15 November 2019 - 10:31 PM.


#29 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 30,972
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 15 November 2019 - 08:34 AM

I've given up telextending big eyepieces !:

Cantilever!  https://www.google.c...HfUoBnkQ4dUDCAc

 

grin.gif

Mike


Edited by Sarkikos, 15 November 2019 - 08:36 AM.

  • John Huntley likes this

#30 rkelley8493

rkelley8493

    Apollo

  • *****
  • Posts: 1,216
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 15 November 2019 - 10:44 AM

Elephant trunk!

 

elephant trunk.jpg

 

grin.gif

RK


  • George N, Sarkikos, Peter Besenbruch and 1 other like this

#31 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 30,972
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 15 November 2019 - 10:52 AM

A prime example of why I avoid Barlows.

 

:grin:

Mike


  • Illinois, Neptune and rkelley8493 like this

#32 junomike

junomike

    Hubble

  • *****
  • Moderators
  • Posts: 17,310
  • Joined: 07 Sep 2009
  • Loc: Ontario

Posted 15 November 2019 - 01:09 PM

Elephant trunk!

 

attachicon.gif elephant trunk.jpg

 

grin.gif

RK

IMO ALL Focusers should be rated (1 - 10) on how they perform horizontally using this "Stack".

IME some would pass, but some would fail miserably.


  • Sarkikos and 25585 like this

#33 25585

25585

    Fly Me to the Moon

  • *****
  • Posts: 6,409
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the UK.

Posted 15 November 2019 - 01:30 PM

Elephant trunk!

 

attachicon.gif elephant trunk.jpg

 

grin.gif

RK

Do Barlows go under Paracorrs then?  



#34 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 43,361
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 15 November 2019 - 03:02 PM

Do Barlows go under Paracorrs then?  

The Paracorr has a focus point.  If the Barlow extends that focal point backwards, the eyepiece may require a lot of out travel to get the eyepiece to focus.

If the Barlow is parfocal with the eyepiece, it shouldn't require much change in focus position if inserted into the Paracorr between the eyepiece and Paracorr.

 

Say the eyepiece is adjusted to setting E, where the focal point of the Paracorr is equal to the top of the Paracorr.

Add a parfocal barlow that inserts into the Paracorr fully, and the eyepiece should still be in focus at setting E.

Add a short focal length barlow and the new focal plane might be several settings in.

Add a long focal length barlow and the setting required may be far out.

As to whether or not the system will come to focus is barlow-dependent.

 

A Telecentric device like the PowerMate provides magnification, but, after the lens, is essentially afocal.

Putting it in the Paracorr might preclude being able to achieve focus because the eyepiece will be pulled way out of the Paracorr.

So it's easier to put it under the Paracorr.

 

As you can see in the picture, though, the Paracorr does not insert fully into the PowerMate, but gets pulled back a lot.

In order to return the Paracorr to its nominal position in the light cone from the primary, a lot of in travel might be required.

I remember doing this with a Paracorr 1 which was a lot shorter and, more or less, inserted into the PowerMate fully.  It did not require more than a smidge of addition inward travel, IIRC.

I don't know about the Paracorr 2.  It looks like it would require a lot of in travel of the focuser.

Maybe someone else could report on that.


  • 25585 and rkelley8493 like this

#35 John Huntley

John Huntley

    Vanguard

  • *****
  • topic starter
  • Posts: 2,215
  • Joined: 16 Jul 2006
  • Loc: Portishead, SW England - mentioned in the Domesday Book.

Posted 15 November 2019 - 08:35 PM

Then again, a long stack does have it's uses grin.gif

 

 

Attached Thumbnails

  • longepuse.jpg

Edited by John Huntley, 15 November 2019 - 08:35 PM.

  • George N, noisejammer, Jaimo! and 6 others like this

#36 rkelley8493

rkelley8493

    Apollo

  • *****
  • Posts: 1,216
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 15 November 2019 - 08:51 PM

Then we have the other extreme...

 

or9pm.jpg


  • George N, John Huntley, Sarkikos and 1 other like this

#37 Ihtegla Sar

Ihtegla Sar

    Ranger 4

  • -----
  • Posts: 367
  • Joined: 02 Apr 2019
  • Loc: Pacific Northwest

Posted 15 November 2019 - 11:07 PM

Elephant trunk!

elephant trunk.jpg

grin.gif
RK


And here I thought my HRCC + ES 17mm 92 made for a long stack but it's a shorty compared to your elephant trunk. :)
  • rkelley8493 likes this

#38 rkelley8493

rkelley8493

    Apollo

  • *****
  • Posts: 1,216
  • Joined: 19 Jan 2019
  • Loc: Southeast USA

Posted 15 November 2019 - 11:56 PM

Having read so much about the ES 92 degree eyepieces, I could not pass up a chance to get hold of the 12mm and the 17mm pre-owned for a pretty good price for the pair. Reading about eyepieces is one thing but trying them for yourself is even better smile.gif

 

My mainstay eyepieces in my 12 inch F/5.3 dob have been my 21, 13, 8 and 6mm Ethos for the past 3-4 years but I'm happy to see what the ES 92's are all about for a few months before deciding what stays and what goes.

 

I'm not expecting the ES 92's to beat the Ethos in pure optical performance but I'm interested to see how their overall presentation, as it's often termed, compares. As a confirmed "occularholic" I have to say that the prospect of gazing into those expansive ES eye lenses is very intriguing smile.gif

 

Anyone else been though a similar process recently with these hyper wide giants ?

To get back on topic, I actually preferred the 12/92º & 17/92º over the 13 & 17 Ethos due to its larger eye lens, longer eye relief, viewing comfort, and presentation. You made a good point mentioning the Ethos probably being better in "pure optical performance", which may be true, BUT it was outdone by the 92º in all other categories. 

 

12:92 13E.jpg


  • John Huntley, Illinois, Neptune and 1 other like this

#39 StevenYood

StevenYood

    Explorer 1

  • *****
  • Posts: 94
  • Joined: 29 Jan 2010
  • Loc: Suwanee, GA

Posted 16 November 2019 - 05:58 AM

When I compared an 18 Ethos to a 17 ES 92, I felt that the transparency of the 92 was ahead on the Ethos and that sealed the deal for me. I sold the Ethoi and use the 92s happily. Now, if they would just expand the line.
  • John Huntley likes this

#40 25585

25585

    Fly Me to the Moon

  • *****
  • Posts: 6,409
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the UK.

Posted 16 November 2019 - 06:32 AM

To get back on topic, I actually preferred the 12/92º & 17/92º over the 13 & 17 Ethos due to its larger eye lens, longer eye relief, viewing comfort, and presentation. You made a good point mentioning the Ethos probably being better in "pure optical performance", which may be true, BUT it was outdone by the 92º in all other categories. 

 

attachicon.gif 12:92 13E.jpg

Both eyepieces have their eye lenses near the top. What makes the Ethos have so much less eye relief than the ES92? 



#41 F.Meiresonne

F.Meiresonne

    Fly Me to the Moon

  • *****
  • Posts: 5,069
  • Joined: 22 Dec 2003
  • Loc: Eeklo,Belgium

Posted 16 November 2019 - 07:07 AM

I only have 5 eyepieces of 80° AFOV or over, 2 of those are the 92s, the other 3 80° 31mm Axiom LX  14 & 20 Orion LHDs. My 92s show the whole FoV with greater ease than any of the others. Kudos to the JOC opticians, & to Scott Roberts of ES if he envisioned the ES92s as to what they are. 

I have a bit trouble with that, it is difficult for me to oversee the whole 82° off an eyepiece...i don't have that with a 70° eyepiece.

 

The Morph i have now i can just see i barely...

 

I have a fellow observer (more experienced) who has no issue with the 82° FOV though...



#42 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 43,361
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 16 November 2019 - 10:42 AM

Both eyepieces have their eye lenses near the top. What makes the Ethos have so much less eye relief than the ES92? 

There is a direct relationship between the diameter of the eye lens and the eye relief.

The ES92s have a much larger eye lens than the corresponding Ethos.

The depth of the eye lens can change the "effective" eye relief of the eyepiece, but the actual eye relief, measured

from the lens, is related to the lens diameter.


  • George N, John Huntley, Neptune and 2 others like this

#43 Sarkikos

Sarkikos

    ISS

  • *****
  • Posts: 30,972
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 16 November 2019 - 12:13 PM

To get back on topic, I actually preferred the 12/92º & 17/92º over the 13 & 17 Ethos due to its larger eye lens, longer eye relief, viewing comfort, and presentation. You made a good point mentioning the Ethos probably being better in "pure optical performance", which may be true, BUT it was outdone by the 92º in all other categories. 

 

attachicon.gif 12:92 13E.jpg

I wonder how much effective eye relief the Ethos has when the observer backs off enough to see only 92 degrees?  About as much eye relief as the 92 ES?  thinking1.gif

 

This possibility, combined with the smaller size and weight of comparable Ethos, pretty much quashed my interest in the 92 ES.

 

Here are the weights and dimensions of the 13 and 17 Ethos compared to the 12 and 17 92 ES:

 

13 Ethos:  1.3 lbs, 4" x 2.4"

12 92 ES:  2.4 lbs, 6" x 2.8"

 

17 Ethos:  1.6 lbs, 4.5" x 2.4"

17 92 ES:  2.4 lbs, 6" x 2.8"

 

In my case, though, I don't have the 17 Ethos.  Instead, I have a 17/14 NAV-HW.  It's specs are 2 lbs, 6.2" x 2.5".  The eye relief is 16mm, compared to 15mm for the Ethos and 20mm for the 92 ES.  I'm still wondering whether I should sell the 13 Ethos.

 

Mike


Edited by Sarkikos, 16 November 2019 - 12:32 PM.

  • Neptune and 25585 like this

#44 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 43,361
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 16 November 2019 - 12:53 PM

Weights on my gram scale:

 

12mm 92° 1017g 2.24 lbs

13mm Ethos 590g 1.30 lbs

 

17mm 92° 1159g 2.56 lbs

17mm Ethos 704g 1.55 lbs

 

1 lb = 453.6g

 

If your focuser can handle the weight of a 31mm Nagler (2.2 lbs) or 21 Ethos (2.25 lbs), then it can handle the ES 92° series.

That weight difference partially is explained by the larger lenses needed to yield a long eye relief on the ES 92s.

The rest is a combination of heavier build materials and thicker walls.


  • John Huntley, Sarkikos, StarDust1 and 1 other like this

#45 25585

25585

    Fly Me to the Moon

  • *****
  • Posts: 6,409
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the UK.

Posted 16 November 2019 - 01:25 PM

Weights on my gram scale:

 

12mm 92° 1017g 2.24 lbs

13mm Ethos 590g 1.30 lbs

 

17mm 92° 1159g 2.56 lbs

17mm Ethos 704g 1.55 lbs

 

1 lb = 453.6g

 

If your focuser can handle the weight of a 31mm Nagler (2.2 lbs) or 21 Ethos (2.25 lbs), then it can handle the ES 92° series.

That weight difference partially is explained by the larger lenses needed to yield a long eye relief on the ES 92s.

The rest is a combination of heavier build materials and thicker walls.

Why I am puzzled rocketride wrote sbout the ES92s,  "Note that these are particularly large and heavy eyepieces in their class and they are over a limit we would not exceed. It’s why we limited the Ethos eye-relief to 15mm.  Understand that the sizes and weights of the 92° series eyepieces are inevitable given the design choices Jing Jua made"

 

But TV has in the past (eg 20mm T2) & does currently (31T5, 21E, 41 Pan.) make large and heavy eyepieces, so the "limit" claim is puzzling. 


Edited by 25585, 16 November 2019 - 01:25 PM.


#46 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 43,361
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 16 November 2019 - 01:41 PM

Why I am puzzled rocketride wrote sbout the ES92s,  "Note that these are particularly large and heavy eyepieces in their class and they are over a limit we would not exceed. It’s why we limited the Ethos eye-relief to 15mm.  Understand that the sizes and weights of the 92° series eyepieces are inevitable given the design choices Jing Jua made"

 

But TV has in the past (eg 20mm T2) & does currently (31T5, 21E, 41 Pan.) make large and heavy eyepieces, so the "limit" claim is puzzling. 

Yes, but TeleVue's heaviest eyepiece, the 21mm Ethos, is the same weight as the 12mm 92° ES.

Extrapolating, a 21mm ES 92 would be about 3.7 lbs (why we're unlikely to see one in that long a focal length).

It's generally true than shorter focal lengths are lighter.

And, it looks like TeleVue doesn't want to exceed about a kilogram (they have 2 at about that weight, while ES has a couple near a kg and 3 more exceeding it).

Judging from the CN online complaints about weight, it seems that keeping eyepieces smaller and lighter make good business sense.


  • Sarkikos likes this

#47 25585

25585

    Fly Me to the Moon

  • *****
  • Posts: 6,409
  • Joined: 29 Aug 2017
  • Loc: In a valley, in the UK.

Posted 16 November 2019 - 02:02 PM

Have to wait on JOC I guess. Do you think a <12mm is more likely than >17mm if they make any more? 



#48 Neptune

Neptune

    Apollo

  • *****
  • Posts: 1,205
  • Joined: 16 Apr 2007
  • Loc: Georgia

Posted 16 November 2019 - 02:47 PM

Have to wait on JOC I guess. Do you think a <12mm is more likely than >17mm if they make any more? 

What about the ES 25mm 100 Deg?  Whoops I forgot this is about 92 Deg.


Edited by Neptune, 16 November 2019 - 02:48 PM.


#49 Tyson M

Tyson M

    Soyuz

  • *****
  • Posts: 3,880
  • Joined: 22 Jan 2015
  • Loc: Alberta, Canada

Posted 16 November 2019 - 03:52 PM

What about the ES 25mm 100 Deg? Whoops I forgot this is about 92 Deg.


I thought about trying one but the 31N fits better with the 17mm ES.

I have to admit I am curious though.
  • Neptune likes this

#50 noisejammer

noisejammer

    Fish Slapper

  • *****
  • Posts: 3,666
  • Joined: 16 Sep 2007
  • Loc: The Uncanny Valley

Posted 16 November 2019 - 07:36 PM

Have to wait on JOC I guess. Do you think a <12mm is more likely than >17mm if they make any more? 

The plan - at least as I was informed by the ES folk - was to offer one around 8-9 mm. I'm somewhat sceptical of this because it would cull the remaining possible sales of the 9/120o. On reflection, this may be exactly why nothing has reached the market.

 

As an owner of the 9/120o, a higher mag 92o isn't really of much interest but I would buy a 20-22 mm model in a heartbeat. It's waiting for one of these that has largely kept me off the Ethos bandwagon. The sale may finally end my never-used-an-Ethos status.


  • 25585 likes this


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics