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Equipment Discussions >> Eyepieces

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SkyRanger
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Reged: 10/21/10

Loc: Prescott Valley, AZ
Delos 17.3---VERY Sad
      #5149478 - 03/30/12 10:33 PM

I had first light with my D17.3 tonight in my 8" F6 dob. To my great disappointment, it would NOT come to focus; I needed a mm or so more infocus I did not have. The D6 and 10 are close to parfocal and work fine in my little dob. Am I the only one who did not realize that the D17 was not even close to the other Deloi?

Gordon


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johnnyha
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Re: Delos 17.3---VERY Sad new [Re: SkyRanger]
      #5149487 - 03/30/12 10:37 PM

No Gordon I have experienced the same thing and a few others have reported it, you do need another 1/4" or so of backfocus. Have you tried screwing the collimation bolts in a little to move your mirror up and get the extra mm?

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johnnyha
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Re: Delos 17.3---VERY Sad *DELETED* *DELETED* new [Re: SkyRanger]
      #5149489 - 03/30/12 10:38 PM

Post deleted by johnnyha

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SkyRanger
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Reged: 10/21/10

Loc: Prescott Valley, AZ
Re: Delos 17.3---VERY Sad new [Re: johnnyha]
      #5149529 - 03/30/12 11:10 PM

I will try adjusting the collimation screws tomorrow night--might get just enough to make it work. Thanks for the suggestion!

Gordon


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BillP
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Reged: 11/26/06

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Re: Delos 17.3---VERY Sad new [Re: SkyRanger]
      #5149541 - 03/30/12 11:18 PM

According to the TV site's EP Specs sheet, the 17D needs about 1/2" infocus compared to the 6mm and 10mm. The field stop is located about 1/4" above the shoulder of the eyepiece.

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seryddwr
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Reged: 02/19/10

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Re: Delos 17.3---VERY Sad new [Re: BillP]
      #5149587 - 03/31/12 12:00 AM

If that doesn't work, ScopeStuff has a negative profile 2" to 1.25" adapter that might work.

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sniperpride
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Reged: 01/04/12

Re: Delos 17.3---VERY Sad new [Re: seryddwr]
      #5149654 - 03/31/12 02:11 AM

Here I came to this thread thinking something was wrong with the 17.3
false alarm...


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Scott in NCModerator
Mad Hatter
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Reged: 03/05/05

Loc: NC
Re: Delos 17.3---VERY Sad new [Re: sniperpride]
      #5149752 - 03/31/12 06:39 AM

Whew! Fortunately your situation can be fairly easily remedied. My first thought was that you had dropped it and rolled it down your driveway!

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Sgt
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Reged: 12/17/05

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Re: Delos 17.3---VERY Sad new [Re: Scott in NC]
      #5149766 - 03/31/12 06:57 AM

Yeah I thought you'd dropped it!
... Either that or TV decided to go with Double undercuts or something


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csa/montana
Den Mama
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Reged: 05/14/05

Loc: montana
Re: Delos 17.3---VERY Sad new [Re: seryddwr]
      #5149948 - 03/31/12 10:41 AM

Quote:

If that doesn't work, ScopeStuff has a negative profile 2" to 1.25" adapter that might work.




Greg; that might work!


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derangedhermit
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Reged: 10/07/09

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Re: Delos 17.3---VERY Sad new [Re: csa/montana]
      #5150413 - 03/31/12 04:06 PM

I'm actually quite steamed about this. Traditionally, all TeleVue 1.25" eyepieces - the Plossls, the Radians, the Naglers, the Panoptics - are parfocal. The exceptions are the 40mm Plossl and, evidently, the Ethos line.

Having parfocal eyepieces is a real convenience to me. This is one way the Delos line falls short of my expectations. I own the 17.3, and I'm surprised and disappointed.


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johnnyha
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Re: Delos 17.3---VERY Sad new [Re: derangedhermit]
      #5150459 - 03/31/12 04:39 PM

The Ethos line goes the other way - you have to rack the focuser out, sometimes a lot. The new Delos racks IN... so changing between 2" Ethos and Delos 17.3mm could require quite a bit of travel. Luckily bino-friendly scopes are becoming more popular, so achieving focus won't be an issue with most people. One potential problem I can see besides not achieving focus at all, is you might be normally using an extension with your other eyepieces in the bino-friendly scope, but the extension may have to be removed just for the Delos. In binoviewing there is a potential problem in that you may not be able to get the Delos 17.3mm to focus with your lowest power setup, it may require more barlow magnification to achieve focus.

I'll admit I am missing my svelte little 19mm Pans... parfocal with my Brandons...


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helpwanted
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Loc: Phoenix, AZ
Re: Delos 17.3---VERY Sad new [Re: johnnyha]
      #5150506 - 03/31/12 05:08 PM

This disappoints me! I wanted to use all of the Delos, because they would all use the same focus setting in my Paracorr 1. Now I find out the 17.3 will not even come to an optimal setting in the Paracorr. This is just like using an XW in the Paracorr, you GUESS at the sharpest point.

With all the 1.25 eps that TV makes, and this is the only one that is not parfocal with the rest, it just seems like a rush to get to market, without any thought.
Would it have not made more sense to find the longest focal length that would work, and be parfocal? Maybe a 16.5, or an even 17.
I would rather have that, and all my eps parfocal, not to mention able to work in my Paracorr without guessing on the sharpest point.


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Scanning4Comets
Markus
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Reged: 12/26/04

Re: Delos 17.3---VERY Sad new [Re: derangedhermit]
      #5150528 - 03/31/12 05:21 PM Attachment (135 downloads)

I was kinda bummed when I found this out too! I WAS going to grab a 17.3mm Delos, but not after finding out you need 1/2" more in travel compared to the 10mm and 6mm Delos eyepieces.

I parfocalized three eyepieces just last week.

The 6mm Delos and 28mm Meade 5000 SWA are super close to being perfectly parfocal while I have my Antares twist lock adapter on the 6mm Delos. All I needed to make the 28mm 5000 SWA and 6mm Delos with antares twist lock adapter parfocal, was use a thin rubber gasket on the 28mm SWA!

The 12mm Nagler T4 just needed one thin rubber gasket and another rubber ring just above it! Thanks to JunoMike, he gave me the idea to use the rubber gasket rings! I looked in my junk drawer and there were a whole bunch in there from a while back just sitting there! Great thing is that they don't mark up the eyepieces like a 2" metal parfocal ring does with the small set screw.

Here are pics of my three eyepieces which are now all parfocal with each other....zero refocusing needed!

Cheers,


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Scott in NCModerator
Mad Hatter
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Reged: 03/05/05

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Re: Delos 17.3---VERY Sad new [Re: Scanning4Comets]
      #5150576 - 03/31/12 05:52 PM

Hey Mark--nice pic. I seem to recognize one of those 2" adapters; glad it came in handy for you! Seriously though, I wouldn't have thought to use rubber gasket rings. Where did you find them (and no, I don't mean in your junk drawer, I mean originally)?

Edited by ssatko (03/31/12 05:55 PM)


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Scanning4Comets
Markus
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Reged: 12/26/04

Re: Delos 17.3---VERY Sad new [Re: Scott in NC]
      #5150589 - 03/31/12 06:00 PM

Hi Scott! yes indeed! Thanks!!! That is your adapter you sent to me! It sure did come in handy! As you can see, there isn't much 2" barrel space left on my 12mm Nagler T4 when parfocalizing comes into play! The black barrel extender makes it all good now!

Thanks to you Sir!
Now back to the 17.3mm Delos thread peeps! I have to admit, the 17.3mm Delos looks rather sexy.

Cheers,


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Scott in NCModerator
Mad Hatter
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Reged: 03/05/05

Loc: NC
Re: Delos 17.3---VERY Sad new [Re: Scanning4Comets]
      #5150601 - 03/31/12 06:07 PM

I'd like to express my apologies to the OP. I just realized that my comment and question to Mark could be construed as thread hijacking, and that was not my intention at all. I'll let you return to the subject at hand re: the 17.3mm Delos, and will conduct any further non-Delos commentary via PM. Sorry!


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Starman1
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Reged: 06/24/03

Loc: Los Angeles
Re: Delos 17.3---VERY Sad new [Re: Scanning4Comets]
      #5150619 - 03/31/12 06:25 PM

If you use a Paracorr, all your eyepieces will be parfocal--only the tunable top goes in and out.

But, I understand the 17.3 is like the 31 Nagler and 21 Ethos in a Paracorr I--the tunable top simply doesn't move in far enough to find the optimum position for the eyepiece.

It would if it were a 2" eyepiece--it's the massive amount of pull-back that occurs in the eyepiece because it's 1-1/4".

It needs about 1/2" more in-travel on the tunable top than the Type 6 Naglers.

Since the Type 6 Naglers use setting 4 on the original Paracorr, you have only 1/8" additional you can move the Paracorr in from there--3/8" shy of the full 1/2" you need to move in but far from bad. Being 3/8" away from the optimum setting is more than the Nagler 31 and Ethos 21.

In the Paracorr II, the Type 6 Naglers use setting D on the Paracorr, and setting A is the farthest in position, another 0.3" in from the D setting, so still 0.2" shy of moving far enough in to get to the optimum position.

The obvious answer is a 1.25" adapter that's thinner than the one in the Paracorr. Since it's already a very thin adapter, the following would be a good possibility as a solution:
http://www.astrosystems.biz/eyepieceadapter.htm

Though the large diameter eyepiece wouldn't insert in this adapter all the way to the sunken shoulder, it WOULD move in closer than the top of a normal 1.25" adapter.
And since what you really need is 3/8" on the original Paracorr and a smaller amount on the Paracorr II, I'm sure this adapter would help to provide some extra amount of inward focuser travel.

And, there's no reason this adapter wouldn't work in any 2" focuser to gain inward focuser travel if you don't use a Paracorr.

NOTE: I do not know what the bottom of the fat barrel diameter is on the 17.3 Delos. It is larger than the 6mm and 10mm. If it does NOT insert into the deep-set adapter far enough for the 1.25" barrel on the eyepiece to insert into the 1.25" hole in the adapter, THEN THIS ADAPTER WILL NOT WORK. I would measure the outside diameter of the 17.3mm Delos just above the 1.25" barrel and compare it to the inside diameter of the deep-set adapter BEFORE I bought the adapter just to be sure it would work.
If the eyepiece body inserts into the adapter even a millimeter, that would be enough to help out the problem of inward focuser travel.

If you use a 1.25" focuser, though, the 17.3mm will focus nearly 1/2" further in than a lot of 1.25" eyepieces.

Edited by Starman1 (04/03/12 10:18 AM)


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derangedhermit
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Reged: 10/07/09

Loc: USA
Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5158258 - 04/05/12 08:40 PM

I'm not very happy when the solution to a product problem starts like this:
1. Buy a lathe that can turn aluminum
2. Learn to use it.
3. Make your own product to solve the problem.
To get the reported 1/2" infocus, you would need a 2-1.25" adapter that accepted 1.9" wide eyepieces down to that .5" level. More than 0.5" cannot be done in a 2" adapter or focuser, the eyepiece gets wider than 2" after just over 0.5". I guess you can make a 1.25-2" adapter with 0.05 walls, or add rings 0.5" up on the other Delos. But I have not yet found parfocal rings that fit the inletted ("safety") part of the eyepiece chrome section, only the standard 1.25" diameter ones.


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Richard Low
professor emeritus
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Reged: 11/27/05

Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5158464 - 04/05/12 11:51 PM

Quote:

If you use a Paracorr, all your eyepieces will be parfocal--only the tunable top goes in and out.

But, I understand the 17.3 is like the 31 Nagler and 21 Ethos in a Paracorr I--the tunable top simply doesn't move in far enough to find the optimum position for the eyepiece.

It would if it were a 2" eyepiece--it's the massive amount of pull-back that occurs in the eyepiece because it's 1-1/4".

It needs about 1/2" more in-travel on the tunable top than the Type 6 Naglers.

Since the Type 6 Naglers use setting 4 on the original Paracorr, you have only 1/8" additional you can move the Paracorr in from there--3/8" shy of the full 1/2" you need to move in but far from bad. Being 3/8" away from the optimum setting is more than the Nagler 31 and Ethos 21.

In the Paracorr II, the Type 6 Naglers use setting D on the Paracorr, and setting A is the farthest in position, another 0.3" in from the D setting, so still 0.2" shy of moving far enough in to get to the optimum position.

The obvious answer is a 1.25" adapter that's thinner than the one in the Paracorr. Since it's already a very thin adapter, the following would be a good possibility as a solution:
http://www.astrosystems.biz/eyepieceadapter.htm

Though the large diameter eyepiece wouldn't insert in this adapter all the way to the sunken shoulder, it WOULD move in closer than the top of a normal 1.25" adapter.
And since what you really need is 3/8" on the original Paracorr and a smaller amount on the Paracorr II, I'm sure this adapter would help to provide some extra amount of inward focuser travel.

And, there's no reason this adapter wouldn't work in any 2" focuser to gain inward focuser travel if you don't use a Paracorr.

NOTE: I do not know what the bottom of the fat barrel diameter is on the 17.3 Delos. It is larger than the 6mm and 10mm. If it does NOT insert into the deep-set adapter far enough for the 1.25" barrel on the eyepiece to insert into the 1.25" hole in the adapter, THEN THIS ADAPTER WILL NOT WORK. I would measure the outside diameter of the 17.3mm Delos just above the 1.25" barrel and compare it to the inside diameter of the deep-set adapter BEFORE I bought the adapter just to be sure it would work.
If the eyepiece body inserts into the adapter even a millimeter, that would be enough to help out the problem of inward focuser travel.

If you use a 1.25" focuser, though, the 17.3mm will focus nearly 1/2" further in than a lot of 1.25" eyepieces.




From what i am reading, it seems that Televue did not make the Delos 17.3mm work at the optimum position on the Paracorr II because there is not enough in-travel focus (beyond "A" setting). This is not something I would expect of two products from the same leading company. I can understand the disappointment. I am sure Televue will sort this out.

Thankfully my whole XW series work at the Paracorr II's "A" setting together with the ZAO-IIs.


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