Jump to content


Photo

Delos and the plastic disk

  • Please log in to reply
52 replies to this topic

#26 dscarpa

dscarpa

    Gemini

  • *****
  • Posts: 3006
  • Joined: 15 Mar 2008
  • Loc: San Diego Ca.

Posted 12 October 2012 - 03:13 PM

I use my 17.3 Delos with a 1.5X Siebert barlow, 2X and 3X TV barlows, 2.5X and 5X Powermates. I can get all the FLs I need from my 17.3 Delos with them. The Delos barlows very well. David

#27 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 23417
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 13 October 2012 - 03:17 PM

AFAIK, the plastic disc is NOT a field stop--that's further up inside the eyepiece. I believe it was a baffle added to catch a reflection from part of the barrel, probably in Moon viewing. Alvin can confirm that.
I think there were a couple eyepieces affected and TV has taken steps to prevent anyone else from ever having that issue.
I think the presence of the disc, whatever material it is made from, represents TeleVue's attempt to achieve as close to perfection in the design as they can--otherwise, it would simply have been left off.
And Alvin can testify that its presence or absence under dark skies isn't critical, obviously.

By the way, most of my Ethos eyepieces have a black plastic disc glued to the bottoms in between the 2" skirt and 1.25" barrel. It's there to prevent reflection back from the bottom of the eyepiece.

#28 Starman81

Starman81

    Vanguard

  • *****
  • Moderators
  • Posts: 2118
  • Joined: 06 Mar 2008
  • Loc: Metro Detroit, MI, USA

Posted 13 October 2012 - 06:11 PM

I use my 17.3 Delos with a 1.5X Siebert barlow, 2X and 3X TV barlows, 2.5X and 5X Powermates. I can get all the FLs I need from my 17.3 Delos with them. The Delos barlows very well. David


Having one great eyepiece and using barlows to get the rest of the focal lengths always tempts me. But there usually ends up being some magnification gaps unless you have like 5 barlows (like you do). Maybe 2 great eyepieces and a series of 3 barlows would be a little more versatile of a lineup. Like the 17.3mm and 10mm Deloi with 2x, 2.5x and 3x barlows yielding:

17.3, 10, 8.7, 6.9, 5.8, 5, 4, 3.3
for
70x, 120x, 138x, 174x, 207x, 240x, 300x, 360x in a 1200mm FL 8" or 10" dob. But I digress...

#29 Binojunky

Binojunky

    Mercury-Atlas

  • *****
  • Posts: 2930
  • Joined: 25 Dec 2010

Posted 14 October 2012 - 11:24 AM

Worth remembering that if you have the manufacturer making his profit, TeleVue making theirs plus the retailer getting his cut, shipping half way around the world, any import tarrifs then the $300+ eyepice may start its life out at about a third of that ??? DA.

#30 Mike B

Mike B

    Starstruck

  • *****
  • Posts: 10334
  • Joined: 06 Apr 2005
  • Loc: shake, rattle, & roll, CA

Posted 14 October 2012 - 12:32 PM

Maybe 2 great eyepieces and a series of 3 barlows would be a little more versatile of a lineup.


Well, it all looks so tidy on paper... the real stumper is that Barlows are notoriously variable in their amplifying effects- depending on the EP they're mated with.

I was just out yesterday afternoon, a tape-measure hangin' on a streetlight ~80 feet away, trying three different EPs in three diff Barlows, plus NO Barlow. Got x-factors like:
TV 2x: 1.95x -to- 2.39x
Dakin 2.4x: 2.23x -to- 2.61x
UO Klee 2.8x: 2.33x -to- 3.07x

Then last night (well, 3-5:00 ayem ;)) i used these same EPs & Barlows to watch the last 25% of Io's dance across Jupiter... spent a nice li'l while fiddling with EP+Barlow combo's until i found the view i liked... whatever the heck its magnification was!

Yes, i'd made myself a cheat-sheet of the various combos & their x-factors, as a guide, but this was merely a "guide". But i still hunt-'n-pecked my way thru using my eye... was much more fun than sittin' at a calculator.
:grin:

#31 The Ardent

The Ardent

    Apollo

  • *****
  • Posts: 1240
  • Joined: 24 Oct 2008
  • Loc: Virginia

Posted 14 October 2012 - 03:43 PM

+1

I tried the 10 and 6 this weekend at Staunton River and was very impressed. I had them next to each other in a TEC turret so was able to compare quickly. Looked at doubles and some showpiece DSO for about two hours.
I dont use the entire 82* of the Nagler type 6 and I like the longer eye relief, so the Delos are on my shopping list.

In fact, I wholeheartedly recommend the entire Delos series if you want the ultimate in performance in deep sky or planets in any widefield eyepiece.



#32 Starman81

Starman81

    Vanguard

  • *****
  • Moderators
  • Posts: 2118
  • Joined: 06 Mar 2008
  • Loc: Metro Detroit, MI, USA

Posted 14 October 2012 - 05:03 PM

Maybe 2 great eyepieces and a series of 3 barlows would be a little more versatile of a lineup.


Well, it all looks so tidy on paper... the real stumper is that Barlows are notoriously variable in their amplifying effects- depending on the EP they're mated with.

I was just out yesterday afternoon, a tape-measure hangin' on a streetlight ~80 feet away, trying three different EPs in three diff Barlows, plus NO Barlow. Got x-factors like:
TV 2x: 1.95x -to- 2.39x
Dakin 2.4x: 2.23x -to- 2.61x
UO Klee 2.8x: 2.33x -to- 3.07x

Then last night (well, 3-5:00 ayem ;)) i used these same EPs & Barlows to watch the last 25% of Io's dance across Jupiter... spent a nice li'l while fiddling with EP+Barlow combo's until i found the view i liked... whatever the heck its magnification was!

Yes, i'd made myself a cheat-sheet of the various combos & their x-factors, as a guide, but this was merely a "guide". But i still hunt-'n-pecked my way thru using my eye... was much more fun than sittin' at a calculator.
:grin:


Haha, yes I am sure we all get a little overboard with our spreadsheets and calculators making sure we have every possible observing scenario covered! It makes for a fun activity while the nights are cloudy and if it was clear, I would have been out there with you!

#33 BillP

BillP

    Voyager 1

  • *****
  • Posts: 12044
  • Joined: 26 Nov 2006
  • Loc: Vienna, VA

Posted 14 October 2012 - 05:27 PM

Maybe 2 great eyepieces and a series of 3 barlows would be a little more versatile of a lineup.


Well, it all looks so tidy on paper... the real stumper is that Barlows are notoriously variable in their amplifying effects- depending on the EP they're mated with.


All depends where that field stop is located in the eyepiece which is what is doing it. If it is offset from the shoulder of the eyepiece any, then the Barlow magnification will vary according to the particular Barlow's offset sensitivity. Klee is one of the more sensitive ones so adding a little distance gives a fairly large change.

Attached Files



#34 Mike B

Mike B

    Starstruck

  • *****
  • Posts: 10334
  • Joined: 06 Apr 2005
  • Loc: shake, rattle, & roll, CA

Posted 14 October 2012 - 06:17 PM

Ooo- nice chart- thanks Bill!

All depends where that field stop is located in the eyepiece which is what is doing it.


Interestingly, the EP that ran on the top end of my spread, and for each Barlow considered, was a 10mm CZJ Ortho... i suspect its 1-1/4" adapter was jacking it up in the saddle a bit, leading to the greater magnifications.

The other two EPs were Olympus micro's, coverted to astro by Gerd Neumann... they, too, had 1-1/4" adapters, but for whatever reason still tracked consistently & notably LOW for amplification- each about the same for each Barlow.

Checking each EP & Barlow out, sighting on a tape measure, has been my practice for a while now... has been interesting to see the variations, plus it helps my cheat-sheet guide choices at the scope.

However, no plastic discs were seen in any samples...
:whistle:

#35 GeneT

GeneT

    Ely Kid

  • *****
  • Posts: 12841
  • Joined: 07 Nov 2008
  • Loc: South Texas

Posted 14 October 2012 - 07:08 PM

I agree. I have the 6 and 10 Delos. Fantastic eyepieces. I have on pre-order the 8 and 14.
GeneT

#36 Alvin Huey

Alvin Huey

    Mercury-Atlas

  • *****
  • Posts: 2761
  • Joined: 17 Oct 2005
  • Loc: Greater Sacramento region

Posted 15 October 2012 - 02:21 PM

AFAIK, the plastic disc is NOT a field stop--that's further up inside the eyepiece. I believe it was a baffle added to catch a reflection from part of the barrel, probably in Moon viewing. Alvin can confirm that.
I think there were a couple eyepieces affected and TV has taken steps to prevent anyone else from ever having that issue.
I think the presence of the disc, whatever material it is made from, represents TeleVue's attempt to achieve as close to perfection in the design as they can--otherwise, it would simply have been left off.
And Alvin can testify that its presence or absence under dark skies isn't critical, obviously.

By the way, most of my Ethos eyepieces have a black plastic disc glued to the bottoms in between the 2" skirt and 1.25" barrel. It's there to prevent reflection back from the bottom of the eyepiece.


Yes, that is correct Don regarding the purpose of the disk.

And I have not noticed a difference without the disk versus with the disk under dark skies. I can verify when I get the replacement disk from TV...I can somehow temporarily put it on and pull it off for A vs B comparison, but I won't spend much time doing that.

#37 Mike B

Mike B

    Starstruck

  • *****
  • Posts: 10334
  • Joined: 06 Apr 2005
  • Loc: shake, rattle, & roll, CA

Posted 15 October 2012 - 02:37 PM

Yes, clearly not a job for us amateurs... perhaps someone knows a good chiropractor who can evaluate these disks?
:whistle:

#38 dscarpa

dscarpa

    Gemini

  • *****
  • Posts: 3006
  • Joined: 15 Mar 2008
  • Loc: San Diego Ca.

Posted 18 October 2012 - 10:07 AM

I got my Antares twist-lock adapter a few days ago. I put it on my 1.5X Siebert barlow with the 17.3 Delos-which is excellent on Jupiter and the Moon with my cats-all of which fit in a large bolt case. I was using the combo in my IM-715 and C-9.25 back to back with my 13 Ethos and 20 ES100. It was a lot easier just to pop the Delos-Siebert barlow into the cats without having to put the diagonal's stock thumb screw-compression ring adapter on. I've got two more adapters on the way. Thanks for the tip! David

#39 Geoff M

Geoff M

    Explorer 1

  • -----
  • Posts: 51
  • Joined: 08 Mar 2012
  • Loc: Tahoe, CA

Posted 31 January 2013 - 07:42 PM

The first minute I received my 10mm Delos, I was appalled to see this cheap, retrofitted piece of plastic on my $370 eyepiece. The only reason I didn't return it immediately was because of Astronomiccs' 15% re-stocking fee(I have now vowed to never again buy anything sight-unseen from any dealer who charges this draconian restocking charge-most major dealers do not.) As far as I know, the 10mm is the only Delos with the plastic disk.(I just bought an 8mm and 12mm.) The plastic ring is much smaller than 1/2 way in between the diameters of the outer(metal) rings of the 8 and 12, so my best take is that a portion of the light cone is being blocked by the plastic offender. In A-B testing against a Pentax XW 10mm (2 observers), the Delos 10mm very obviously showed lower light transmission (from a partially blocked light cone?). However, stars are very sharp right to the edge of the field, markedly better than the XW. The Televue support team's evasive comments on other forums-they refuse to put any reason in print why this cheap ring is there (to avoid a recall) or justify why this and no other TV ocular has had this modification after design completion (obviously in a blind rush to get it to market) makes me smell a rat-Anyway, I'm very happy with the 8 and 12 Delos offerings.
Geoff M

#40 Jim Romanski

Jim Romanski

    Vanguard

  • *****
  • Posts: 2257
  • Joined: 02 Jan 2005
  • Loc: Guilford, Connecticut

Posted 01 February 2013 - 10:44 AM

Have you tried calling Televue to ask if they still use the "cheap and nasty disk" on any of their Delos?

#41 Starman81

Starman81

    Vanguard

  • *****
  • Moderators
  • Posts: 2118
  • Joined: 06 Mar 2008
  • Loc: Metro Detroit, MI, USA

Posted 01 February 2013 - 03:12 PM

Is this the disk or has it been changed already? I did some A/B tests with the 10 Delos and XW 10 (along with the Baader Hyperion 10) over the course of a couple months on a variety of objects and the Delos had excellent 'transmission'; everything that could be seen in the XW was seen in the Delos.

Attached Files



#42 Geoff M

Geoff M

    Explorer 1

  • -----
  • Posts: 51
  • Joined: 08 Mar 2012
  • Loc: Tahoe, CA

Posted 01 February 2013 - 07:10 PM

Hi Starman,
Yep, that plastic looks like mine, bought last Aug., I think...As far as I know, this feature has not changed. I was in L.A. at a local vendor(WHCT) and their 10mm in stock had the ring. That's why I bought my 8mm and 12mm Delos oculars there(I think visual and tactile inspection before purchase is becoming a higher priority to me. It's tough, though, living 4-8 hours from the nearest vendor.) As far as observing goes, there was no scientific study or measurement done in our A-B's. Also, no comparison was done with the disk removed. All of the objects we saw just seemed brighter through the XW(12.5 inch f5 dob, fairly fast- which could be a factor in any possible light path issues, which vary with telescope f/ratio). Faint stars and Nebulae just seemed to stand out a bit more in the XW than the Delos. I still thought the views were really great in the Delos 10- very sharp to the edge-sharper than the XW at the edge(I'm super happy with my 8 and 12's Delos' too, and fully intend to get the 17.3, 6 and maybe 4.5). My main issue with the whole thing is that plastic thing. After reading of another user's experience of it falling off, being familiar with the properties of many adhesives in the sub-freezing weather I observe in, and knowing my luck, it would fall off and land perfectly, adhering itself to the $2400 primary on my 16. For the money I paid, I just expected a little bit better fit and finish.

#43 Geoff M

Geoff M

    Explorer 1

  • -----
  • Posts: 51
  • Joined: 08 Mar 2012
  • Loc: Tahoe, CA

Posted 01 February 2013 - 07:35 PM

Hi Jim,
The "cheap and nasty disk", henceforth to be named "Little Nasty":(kind of a catchy moniker, actually)was still on the shelf stock 10mm Delos of a local dealer(not sure of mfg. date, though). Ironically, I did have a lengthy conversation with Al Nagler the day I bought this eyepiece. It was also the day before Televue released the additional Delos focal lengths available. If Al had given me a ballpark idea of the new products focal length range, or that they were releasing this info the next day, my purchase would have been a different one 17.3/12/8/6 and maybe 4.5 is the set for me. (I did ask Al about the focal lengths, and about pacorr positions-he suggested I buy a paracorr type II-not necessary(salesmanship?), since there are eyepiece adapter work-arounds to parfocalize the longer Delos', but that's off topic, I guess). After this and after reading accounts of Televue's responses to the disk issue, I just got that "sales above all" feeling. I was kind of shocked. I'm still a loyal TV user, though, just a bit more wary.

#44 BillP

BillP

    Voyager 1

  • *****
  • Posts: 12044
  • Joined: 26 Nov 2006
  • Loc: Vienna, VA

Posted 01 February 2013 - 08:40 PM

...and knowing my luck, it would fall off and land perfectly, adhering itself to the $2400 primary on my 16. For the money I paid, I just expected a little bit better fit and finish.


I agree...but in your case to protect your investment would recommend you purchase an inexpensive color filter, unscrew the retaining ring and remove the filter glass, then use the now filterless housing and screw onto bottom of Delos. That will keep the plastic disk in place and also let you to continue to use filters if needed.

#45 tomcody

tomcody

    Surveyor 1

  • *****
  • Posts: 1798
  • Joined: 06 Jul 2008
  • Loc: Titusville, Florida

Posted 01 February 2013 - 09:08 PM

...and knowing my luck, it would fall off and land perfectly, adhering itself to the $2400 primary on my 16. For the money I paid, I just expected a little bit better fit and finish.


I agree...but in your case to protect your investment would recommend you purchase an inexpensive color filter, unscrew the retaining ring and remove the filter glass, then use the now filterless housing and screw onto bottom of Delos. That will keep the plastic disk in place and also let you to continue to use filters if needed.

Makes one wonder why Telvue just does not use a screw in metal disk and avoid all the bad comments?
EDIT What I am asking is; why are they installing a plastic glued-in disk instead of making a metal disk with threads that is screwed into the filter threads? Or am I not seeing something correctly in the pictures? ( I have not yet looked at a 10mm Delos in person). Perhaps There would be a market for such a machined disk made by Precise Parts or the like? Anyone care to comment?
Rex

#46 Scanning4Comets

Scanning4Comets

    Markus

  • *****
  • Posts: 13905
  • Joined: 26 Dec 2004
  • Loc: Canada

Posted 01 February 2013 - 10:30 PM

Someone did a test with and without the disc and noted no difference.

#47 Scanning4Comets

Scanning4Comets

    Markus

  • *****
  • Posts: 13905
  • Joined: 26 Dec 2004
  • Loc: Canada

Posted 13 December 2013 - 02:59 AM

I'm going to resurrect this thread, since I just ordered the 10mm TV Delos !!!! :jump:

#48 Pinbout

Pinbout

    Cosmos

  • *****
  • Posts: 8260
  • Joined: 22 Feb 2010
  • Loc: You can't see me...

Posted 13 December 2013 - 07:29 AM

I just ordered the 10mm TV Delos !!!!



I got him to admit it was infamous... :lol:

http://www.youtube.c...h?v=MFMRk-Hhic0

#49 Jim Romanski

Jim Romanski

    Vanguard

  • *****
  • Posts: 2257
  • Joined: 02 Jan 2005
  • Loc: Guilford, Connecticut

Posted 13 December 2013 - 11:23 AM

:beat:

#50 csrlice12

csrlice12

    Voyager 1

  • *****
  • Posts: 11491
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 13 December 2013 - 11:41 AM

:beat: :beat:

It ain't quite dead yet.....






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics