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Equipment Discussions >> Eyepieces

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SkyRanger
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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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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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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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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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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 NCAdministrator
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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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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
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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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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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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
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Re: Delos 17.3---VERY Sad new [Re: derangedhermit]
      #5150528 - 03/31/12 05:21 PM Attachment (136 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 NCAdministrator
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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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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 NCAdministrator
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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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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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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
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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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Starman1
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Re: Delos 17.3---VERY Sad new [Re: Richard Low]
      #5158556 - 04/06/12 01:53 AM

Quote:

Quote:

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.


There is a 0.63" delta of the focal plane position between T6N and the N31 while it is only 0.48" between the the T6N and the D17.3. Ergo using setting 5 on a Paracorr 1 will be closer to ideal for the D17.3 than it is for the N31. While not ideal, 5 still helps for the N31 and it should work a bit better for the D17.3 plus the latter isn't in need of as much help to begin with since the FOV is smaller.



You are forgetting that the 31 Nagler is 2" and inserts into the Paracorr a lot more than a 1.25" eyepiece, whereas the Delos and nagler 6's are 1.25" eyepieces.
Ergo, the setting 5 on the Paracorr 1 is only 1/8" away from the optimum setting--not much.
On the other hand Setting 5 is 3/8" shy of far enough in to optimize the 17.3 Delos. The paracorr I has an adapter which is .379" tall. If you can eliminate this height, then setting 5 may be OK for the 17.3 Delos. If the adapter I previously referred to works, it may allow another 3/8" inward movement due to its lower height in the first place and, possibly, a slight inward movement of the eyepiece from a simple shoulder.
The Nagler 6 eyepieces have a 0.48" greater out focus than the 17.3 Delos, which is approximately the whole range of the Paracorr I's tunable top. Unfortunately the Nagler 6's use the 1.25" adapter in setting 4, 1/8" shy of the in-most setting. But you need not one more inward setting, but 4 in order to optimize the 17.3 Delos.
Shortening the 1.25" adapter will help. Add that to moving the tunable top in some, and you will be about as far from optimum as the 31 Nagler and 21 Ethos in the same Paracorr--not very much and quite tolerable.

It doesn't surprise me that TeleVue would make an eyepiece not optimized by their own Paracorrs, either I or II. I think one of the reasons for the greater adjustment range on the Paracorr II was because TeleVue had eyepieces not optimized by the Paracorr I. It wouldn't surprise me if, in the future, there was even a Paracorr III to accommodate eyepieces not yet even in production. It's always a race to accommodate designs as they come out.


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ThreeD
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Re: Delos 17.3---VERY Sad new [Re: Richard Low]
      #5158562 - 04/06/12 01:58 AM

Thus creating a need for the Paracorr Type 3 that will be announced at NEAF much to the chagrin of those who invested in the Type 2 over the last year.

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ThreeD
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Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5158567 - 04/06/12 02:07 AM

Quote:


You are forgetting....


Yup I realised this a few short minutes after I did my post so I deleted it. Unfortunately you were on top of things and were already responding.

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Jeff Morgan
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Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5158943 - 04/06/12 10:44 AM

While I don't use a Paracorr, I find this interesting because I am building a truss scope. In the next month or two it is going to be time to start cutting aluminum, and I certainly want to accommodate my shiny new 17.3 Delos.

From what I gather, the infocus is quite similar (almost identical) to the 31 Nagler. Is this correct?


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Starman1
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Re: Delos 17.3---VERY Sad new [Re: Jeff Morgan]
      #5158975 - 04/06/12 10:59 AM

Quote:

While I don't use a Paracorr, I find this interesting because I am building a truss scope. In the next month or two it is going to be time to start cutting aluminum, and I certainly want to accommodate my shiny new 17.3 Delos.

From what I gather, the infocus is quite similar (almost identical) to the 31 Nagler. Is this correct?




Only if you ignore the thickness of the 1.25" adapter.

The 31 Nagler has its focal plane 0.38" above the seat of the barrel.
The 17.3 Delos has its focal plane 0.23" above the seat of the barrel.

IF your 1.25" adapter is 0.38 - 0.23 = 0.15" thick, then the two eyepieces would be parfocal.

However, most 1.25" adapters are quite a bit thicker than 0.15". A relatively thin one is about 0.25".

That means the "effective" distance the Delos focal plane is above the focuser is 0.23" plus the thickness of the adapter.

That is likely to exceed the 0.38" for the 31 Nagler, so the highest likelihood is that the 17.3mm Delos will require additional inward movement of the focuser to focus, compared to the 31 Nagler. How much additional in-focus will depend on the thickness of your adapter.

In a Moonlite focuser with a Moonlite adapter, the adapter's "lip" is so thin the 17.3mm Delos might require a bit more OUT focus compared to the 31 Nagler. But that is an exceptional situation.


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Deep13
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Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5160894 - 04/07/12 02:54 PM

Scratch this one off the list. Serious design flaw. So now the question is, 16 or 17 Nagler?

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Ava
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Re: Delos 17.3---VERY Sad new [Re: Deep13]
      #5160905 - 04/07/12 03:03 PM

Baader sells a 2"-1.25" adapter that would fit the bill, only 1mm optical path length (less than 0.04"). Part #15A, you can check it out here:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p767_Baader--15A-2--Steckhuelse-auf-1-25----nur-1mm-optische-Baulaenge.html

Can be used as adapter or permanent solution for a specific eyepiece. Should be available in any US shop that sells Baader adapters I guess.

//Anders


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ed_turco
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Re: Delos 17.3---VERY Sad new [Re: ThreeD]
      #5161076 - 04/07/12 05:08 PM

Quote:

Thus creating a need for the Paracorr Type 3 that will be announced at NEAF much to the chagrin of those who invested in the Type 2 over the last year.




It is a very clever business model that plans for incremental improvements over the years. Does this mean that the designer didn't get it right the first time?

Why?

Surprised this hasn't come up before.



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helpwanted
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Re: Delos 17.3---VERY Sad new [Re: ed_turco]
      #5161245 - 04/07/12 07:18 PM

Great, TV is going to mimic Apple and get us to but a new Paracorr every year with our iPads & iPhones?
I agree with skipping this 17.3 and just wait and hope for a parfocal 12.


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derangedhermit
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Re: Delos 17.3---VERY Sad new [Re: helpwanted]
      #5161636 - 04/08/12 02:01 AM

TV should offer a 1.25"-2" adapter designed to make the 17mm parfocal with all the other 1.25 eyepieces (except Ethos), when the others are used with some "standard height" (TV I'm sure) adapter. And maybe not charge the typical startling amount for it, as a way to show some goodwill. Actually they should start putting it in the box with the eyepiece.

I'll check their return policy. I've decided maybe I just don't want to mess with the thing, over this one issue.


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Jeff Morgan
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Re: Delos 17.3---VERY Sad new [Re: derangedhermit]
      #5161843 - 04/08/12 08:56 AM

Quote:


I'll check their return policy. I've decided maybe I just don't want to mess with the thing, over this one issue.




Perspective.

I seem to have an instinctive need to play with focus whenever I change eyepieces. Since I have a nice focuser, parfocal has never been an issue for me.

OTOH, getting a great eyepiece is of great importance to me. Less than 3/16" more infocus than the 31 Nagler? I can manage that. I'll just make my Newtonian truss poles a little bit shorter, and of course no issue at all on the refractor. I can't imagine SCT owners will have any issues at all.


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helpwanted
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Re: Delos 17.3---VERY Sad new [Re: Jeff Morgan]
      #5162193 - 04/08/12 01:29 PM

It's not the parfocal for me, it the fact that it doesn't have a Paracorr position.
If I have to settle with "close enough" in the paracorr, I'll just keep my XWs.


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sniperpride
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Re: Delos 17.3---VERY Sad new [Re: helpwanted]
      #5162392 - 04/08/12 03:59 PM

I dont use paracorr for my Delos, I find it well corrected, and at 72* fov I dont detect coma in my f4.5

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Pollux556
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Re: Delos 17.3---VERY Sad new [Re: SkyRanger]
      #5162808 - 04/08/12 10:07 PM

I am reminded that some Speers Waler serie 1 ep had this problem in some Dobs

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Richard Low
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Re: Delos 17.3---VERY Sad new [Re: Pollux556]
      #5162892 - 04/08/12 11:10 PM

I am keeping my XWs. I also have the Ethos to fill in the focal length at 17mm. Sometimes when i observed through the Ethos with my glasses on, the Afov is around 70 degrees, so this make up for the Delos 17.3

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johnnyha
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Re: Delos 17.3---VERY Sad new [Re: Richard Low]
      #5163713 - 04/09/12 02:35 PM

There is a very real chance if you have a short-tube "bino-friendly" refractor and you normally employ an extension to reach focus, that you may have to remove the extension for this one eyepiece. I did not have this problem but the increasing distance between the focal point of the Ethos and the 17.3 Delos is worrisome.

Frankly I had minor problems with blackouts (maybe its my eyes getting older) but primarily I did not like the weight in my binoviewers compared to my 19mm Pans. The 19mm Pans won out for me. Of course they only have 13mm eye relief but I don't view with my glasses on and I find the Pan most comfortable for me.


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dscarpa
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Re: Delos 17.3---VERY Sad new [Re: SkyRanger]
      #5163760 - 04/09/12 03:11 PM

I've had a 17.3 Delos for a couple of weeks and it's already one of my favorites up there with my Ethos and XWs. Barlowed it's very easy to use with images of the Moon, Mars and Saturn being truly excellent. I have cats and a refractor. I did notice it wasn't parfocal with my 24 Pan. The Delos and Pan do make a very nice DSO team well worth a bit of refocus for me.David

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mark8888
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Re: Delos 17.3---VERY Sad new [Re: dscarpa]
      #5164045 - 04/09/12 07:12 PM

Quote:

I have cats and a refractor. I did notice it wasn't parfocal with my 24 Pan.




With your refractor, could you estimate how much you had to turn the focuser to go from the 24pan to the 17.3 Delos?


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Scanning4Comets
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Re: Delos 17.3---VERY Sad new [Re: Richard Low]
      #5164061 - 04/09/12 07:23 PM

As I stated in the beginning of this thread, I was kinda bummed out, but parfocalizing eyepieces is simple! Go see my pic on page one of this thread! I said I wouldn't get the 17.3mm Delos because of the extra focus travel needed, but after some thought, it is a really easy fix!

First, you put the eyepiece in your focuser that needs the most "in" travel on your focuser. After that, remove that eyepiece and just leave the focuser exactly where it is. Now, take your other eyepieces and slowly put them into the focuser until you get a good focus and use the set screws, or compression ring to lock the next eyepieces in place and use a thin erasable marker to mark the eyepiece barrel just above the lip of your focuser. All you have to do now is use strong rubber gaskets to put just above the mark you made on your other eyepiece barrels!!!....Now when you use your eyepieces, they will all focus at the same distance in your focuser !!!

If you use a paracorr, well, I guess that maybe another story, LOL!





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Mr. Bill
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Re: Delos 17.3---VERY Sad new [Re: Scanning4Comets]
      #5165329 - 04/10/12 02:27 PM

Just a reminder....TV website ep specs page gives fieldstop location referenced from the ep shoulder for all their current eps.

Use it and there will be no more surprises after ordering TV eps.



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SkyRanger
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Re: Delos 17.3---VERY Sad new [Re: Richard Low]
      #5166057 - 04/10/12 10:48 PM

NO luck getting the D17 to focus in my 8" dob. There is just no way to get more infocus other than shortening my poles- which I am not willing to do. With only a 1.25 focuser there is no way to play tricks with adaptors. Next time I will check the stats and not assume!

Gordon


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John Rhodes
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Re: Delos 17.3---VERY Sad new [Re: SkyRanger]
      #5166257 - 04/11/12 01:49 AM

Quote:

NO luck getting the D17 to focus in my 8" dob. There is just no way to get more infocus other than shortening my poles- which I am not willing to do. With only a 1.25 focuser there is no way to play tricks with adaptors. Next time I will check the stats and not assume!

Gordon



Gordon,
Try re-collimating the mirror with it as forward toward the focuser as possible that you can get good collimation... this often works.


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Richard Low
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Re: Delos 17.3---VERY Sad new [Re: John Rhodes]
      #5166339 - 04/11/12 05:32 AM

Quote:

Quote:

NO luck getting the D17 to focus in my 8" dob. There is just no way to get more infocus other than shortening my poles- which I am not willing to do. With only a 1.25 focuser there is no way to play tricks with adaptors. Next time I will check the stats and not assume!

Gordon



Gordon,
Try re-collimating the mirror with it as forward toward the focuser as possible that you can get good collimation... this often works.




looks like i really wont be able to try out this eyepiece in my dobs as i may not have enough in-focus and Paracorr issues...sigh...


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SkyRanger
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Re: Delos 17.3---VERY Sad new [Re: Richard Low]
      #5166362 - 04/11/12 06:16 AM

John, Thanks for the tip, but I have tried moving the mirror forward already--just not quite enough slack with the PB8. I am disappointed since I really enjoy the D6 and D10. At least for now, I will stick with the N17 in my scopes with 2" focusers.

Gordon


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sniperpride
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Re: Delos 17.3---VERY Sad new [Re: SkyRanger]
      #5167554 - 04/11/12 08:39 PM

Gordon, does it work with your 12.5?

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Pingu
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Re: Delos 17.3---VERY Sad new [Re: sniperpride]
      #5167564 - 04/11/12 08:43 PM

Thankfully, I haven't a problem at all with my D17 in my XT8.

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SkyRanger
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Re: Delos 17.3---VERY Sad new [Re: Pingu]
      #5167566 - 04/11/12 08:49 PM

Snipe, my 12.5 is loaned out to a friend. It has a 2" focuser, and I predict the D17 would work in the larger Portaball. I love the Nagler 17 in that scope and at this point I am sticking with the Nagler. The D17 sold quickly on a site we all know of, and I am sending it out with tear drops on its huge eye lens.

Gordon


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jeffdetweiler
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Re: Delos 17.3---VERY Sad new [Re: Richard Low]
      #5541108 - 11/26/12 09:38 PM

Astro Systems makes a 2" - 1 1/4" adapter in which a 1 1/4" eyepiece drops about 1/2" down into the adapter to give you an extra 1/2" of in focus

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Sarkikos
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Re: Delos 17.3---VERY Sad new [Re: Jeff Morgan]
      #5541213 - 11/26/12 10:39 PM

Jeff,

Quote:

I seem to have an instinctive need to play with focus whenever I change eyepieces. Since I have a nice focuser, parfocal has never been an issue for me.




I agree. I never got this preoccupation with parfocality - is that a word? - in eyepieces. That factor flies well below my radar. I don't give a fig if my eyepieces are parfocal or not. I just don't get it. What's a focuser for?

On the other hand, it is not a good thing if an eyepiece needs more focus or less focus than my focuser will allow. I'd rather not deal with extensions and low-profile adapters.

Mike


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Deep13
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Re: Delos 17.3---VERY Sad new [Re: Sarkikos]
      #5541402 - 11/27/12 12:34 AM

If it doesn't come to focus, it is not really an eyepiece. Swing and a miss from TV.

And as far as moving the mirror forward a tiny bit with collimation, 1. what does the scope's manufacturer say about that? 2. why should have screw around with that? Shouldn't the eyepiece work with commercially produced scopes as they are? I can see mickey mousing it with an eyepiece made from spare lenses you got from Surplus Shed or with a DIY scope, but not a "premium" "EP" on a Newt that works with ever other EP.


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ThreeD
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Re: Delos 17.3---VERY Sad new [Re: Deep13]
      #5541444 - 11/27/12 01:38 AM

Quote:

If it doesn't come to focus, it is not really an eyepiece. Swing and a miss from TV.

And as far as moving the mirror forward a tiny bit with collimation, 1. what does the scope's manufacturer say about that? 2. why should have screw around with that? Shouldn't the eyepiece work with commercially produced scopes as they are? I can see mickey mousing it with an eyepiece made from spare lenses you got from Surplus Shed or with a DIY scope, but not a "premium" "EP" on a Newt that works with ever other EP.


I've read of premium dob buyers cutting trusses to the proper length upon arrival of their scope. Loosening the collimation bolts a turn or two is nothing...

Are you sure the scope works with *every* other EP? Do you own every other EP and have you tried them all? I'm sure there are a few others out there that won't work in that scope too unless the mirror is moved forward -- and the numbers will be even larger if you want to use a barlow or a Paracorr as they both require more in-focus.

I know that to use my 31T5 Nagler with a Paracorr and have it achieve focus in my LB I need to make sure the mirror isn't pulled all the way back. I prefer to have my cell pulled back as it stiffens the cell and ensures it won't shift. However, I do need to run it relaxed just a bit to make that combination work. Luckily it's not enough to make it to where cell shift is a problem. Would you also claim that a Terminagler/Paracorr combination is a swing and a miss??


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Stellarfire
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Re: Delos 17.3---VERY Sad new [Re: Mr. Bill]
      #5541461 - 11/27/12 02:30 AM

Quote:

Just a reminder....TV website ep specs page gives fieldstop location referenced from the ep shoulder for all their current eps.

Use it and there will be no more surprises after ordering TV eps.







Yes. By the way: According that TeleVue spec page, the new 14mm Delos will have the same field stop location like the 17.3mm Delos. All other Delos models are parfocal.

Stephan


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Sarkikos
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Re: Delos 17.3---VERY Sad new [Re: Stellarfire]
      #5541582 - 11/27/12 07:16 AM

If there is not enough in-focus for an eyepiece, and you have an old-style tall focuser, you could upgrade to a low-profile. Or if you have a truss scope, you could shorten the trusses. Or you could raise the mirror in a tube scope. But then you might need to buy extensions for your other eyepieces...

Or you could return the eyepiece or sell it to someone else. Cut your losses, don't shorten the scope.


Mike


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Jeff Morgan
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Re: Delos 17.3---VERY Sad new [Re: Deep13]
      #5541760 - 11/27/12 10:01 AM Attachment (22 downloads)

Quote:

If it doesn't come to focus, it is not really an eyepiece. Swing and a miss from TV.

And as far as moving the mirror forward a tiny bit with collimation, 1. what does the scope's manufacturer say about that? 2. why should have screw around with that? Shouldn't the eyepiece work with commercially produced scopes as they are? I can see mickey mousing it with an eyepiece made from spare lenses you got from Surplus Shed or with a DIY scope, but not a "premium" "EP" on a Newt that works with ever other EP.




A relevant topic for me, since I just finished focus testing (trimming truss tubes) on my new project. Daylight focus on a distant hill works, star test is next.

Firstly, trimming tubes is not a big deal. Even if you have no tools a trip to the hardware store for a hacksaw, mitre box, and file will set you back about $25 and do an acceptable job. And if you have a table saw, it is a trivial job. I would prefer this solution over using the collimation screws or moving the mirror cell up the tube (for solid tube scopes).

A swing and a miss on the Delos 17.3 and 14? Hardly! They both appear to require just a bit less in-travel than the 31 Nagler, which is perhaps the most common maximum field sweepers you will find on Dobs today. If you can make the 31N focus, the 17.3/14 Delos should also focus.

As far as focus travel, most of us inflict that pain upon ourselves by selecting focusers with minimum travel distance. I just did it to myself also, buying a 1-1/2" travel focuser instead of the 2" travel I have used in previous builds. I can reach with the 31 Nagler and 14 Delos, and most of the rest of my eyepieces will reach focus within my focuser range, with one exception - the 48 Brandon. It requires an extension tube. Annoying, but not a show stopper. Had I chosen the 2" travel focuser, they would all reach with no extension tube but that is the nature of choices, no?

What would the manufacturer would say about moving the mirror forward? There is a reason those collimation screws are left that long ....


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Sarkikos
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Re: Delos 17.3---VERY Sad new [Re: Jeff Morgan]
      #5541780 - 11/27/12 10:12 AM

Quote:

Firstly, trimming tubes is not a big deal. Even if you have no tools a trip to the hardware store for a hacksaw, mitre box, and file will set you back about $25 and do an acceptable job. And if you have a table saw, it is a trivial job. I would prefer this solution over using the collimation screws or moving the mirror cell up the tube (for solid tube scopes).




Trimming truss tubes should not be a problem. Resizing a solid tube - or moving a mirror up in tubes where the cell attaches directly to the tube end - can be a problem. Well, IS a problem for me with my lack of metal-working skills, metal-working equipment and the space for metal-working.


Mike


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Starman1
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Re: Delos 17.3---VERY Sad new [Re: Sarkikos]
      #5541838 - 11/27/12 10:43 AM

Quote:

Jeff,

Quote:

I seem to have an instinctive need to play with focus whenever I change eyepieces. Since I have a nice focuser, parfocal has never been an issue for me.




I agree. I never got this preoccupation with parfocality - is that a word? - in eyepieces. That factor flies well below my radar. I don't give a fig if my eyepieces are parfocal or not. I just don't get it. What's a focuser for?

On the other hand, it is not a good thing if an eyepiece needs more focus or less focus than my focuser will allow. I'd rather not deal with extensions and low-profile adapters.

Mike



One of the great things about the Paracorr, other than eliminating coma and flattening the field, is that it makes every eyepiece parfocal.
If one presets the Paracorr's tunable top before the next eyepiece is inserted, the amount of focuser travel to get to perfect focus is negligible.
All my eyepieces focus in +/- 1mm.
Or, one can insert the new eyepiece and focus using the tunable top.
Either way, each eyepiece will have its correct setting and the amount of focuser shift from one eyepiece to the next will be negligible.
The only reason it might not have been wise for me to use a focuser with <1/2" travel is that there may be accessories I don't yet have that wouldn't focus in that range. If I used binoviewers, for example, they are typically used without a Paracorr, and the focal position could be well away from where the Paracorr is positioned.

Oh, that and the Delos 17.3 and 14 require a little more in-travel of the Paracorr's tunable top than is allowed in the Paracorr design. There are a couple adapters that could work
to mitigate this.
However, this may not be enough in the Paracorr I. There, some experimentation would be necessary.
But, you'll be closer to parfocal than not using a Paracorr at all.

Edited by Starman1 (11/27/12 10:50 AM)


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dcoyle
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Re: Delos 17.3---VERY Sad new [Re: Jeff Morgan]
      #5541853 - 11/27/12 10:54 AM

An OT moment, please.

Jeff, That is an amazing scope! What size and f/ is it?

Thanks,

Dan


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Scanning4Comets
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Re: Delos 17.3---VERY Sad new [Re: Sarkikos]
      #5541862 - 11/27/12 10:57 AM

When I received my new crayford focuser I thought I needed an extension tube to reach focus for all of my eyepieces, but it turns out that the one I got can go outwards about another 1/4" so I was in business. Someone on here mentioned moving my mirror back a bit, so that helped as well.

I can now use ALL of my eyepieces without the extension tube and I was also awarded with another added bonus:

I can use my two extension tubes with filters attached to them, so when I need to use my 2" filters, I just plop the extension tube with Orion Ultrablock or 2" Polarizer, then add the eyepiece into the tube and I can still reach focus!

No more fumbling in the dark screwing filters onto eyepieces !!! I DESPISE doing that because half the time I try that, the threads don't catch or they will try to cross-thread. I have almost dropped the filters so many times when trying to screw them onto the barrels of my adapters.

I will never go back to screwing filters onto barrels ever again!

So, in relation to the original poster here, and others who think it is a bummer if you need to fiddle a bit in order to actually REACH FOCUS, consider yourselves lucky! Sometimes you can't get focus at all. A few twists of the collimation screws, or truss adjustments is half the fun in achieving focus sometimes!



Cheers,


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Sarkikos
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Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5541869 - 11/27/12 11:06 AM

Don,

Quote:

One of the great things about the Paracorr, other than eliminating coma and flattening the field, is that it makes every eyepiece parfocal.
If one presets the Paracorr's tunable top before the next eyepiece is inserted, the amount of focuser travel to get to perfect focus is negligible.
All my eyepieces focus in +/- 1mm.
Or, one can insert the new eyepiece and focus using the tunable top.
Either way, each eyepiece will have its correct setting and the amount of focuser shift from one eyepiece to the next will be negligible.




I have not done this yet but it sounds like a worthy experiment for next New Moon at my dark site. So far, I haven't kept the Paracorr in the focuser consistently, but only use it now and then for specific eyepieces.

One problem that I've found when setting my Paracorr I for different eyepieces, is that the tuning knob sticks. Often I need to loosen both the tuning knob and the set screw that detains the 1.25" adapter in order to turn the tuning top. This is a PITA at a dark site.

Mike


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Sarkikos
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Re: Delos 17.3---VERY Sad new [Re: Scanning4Comets]
      #5541915 - 11/27/12 11:33 AM

Mark,

Quote:

I can use my two extension tubes with filters attached to them, so when I need to use my 2" filters, I just plop the extension tube with Orion Ultrablock or 2" Polarizer, then add the eyepiece into the tube and I can still reach focus!

No more fumbling in the dark screwing filters onto eyepieces !!! I DESPISE doing that because half the time I try that, the threads don't catch or they will try to cross-thread. I have almost dropped the filters so many times when trying to screw them onto the barrels of my adapters.

I will never go back to screwing filters onto barrels ever again!




Yep, I use that trick for 2" filters, too. It also allows you to keep the same filter on the scope and change eyepieces. A friend had a 2" filter wheel I thought about buying, but I thought again and decided not to. In a Dob, you'd probably need an OCA to come to focus, thereby halving the effective focal length of the eyepiece. That would ruin the whole idea of using low power eyepieces with a 2" filter. (The extra weight would also be a bear to deal with.)

But for medium-to-high power, a wheel for 1.25" filters is great. I have a wheel permanently loaded with DSO filters for trips to the dark site. Nothing like viewing M42 with a Baader Zoom on a filter wheel. You can immediately vary the image scale and the DSO filter as you wish.

That's one of the main reasons I don't have a Paracorr permanently installed in my focuser!


Mike


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Starman1
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Re: Delos 17.3---VERY Sad new [Re: Sarkikos]
      #5542191 - 11/27/12 01:55 PM

Quote:

Don,

Quote:

One of the great things about the Paracorr, other than eliminating coma and flattening the field, is that it makes every eyepiece parfocal.
If one presets the Paracorr's tunable top before the next eyepiece is inserted, the amount of focuser travel to get to perfect focus is negligible.
All my eyepieces focus in +/- 1mm.
Or, one can insert the new eyepiece and focus using the tunable top.
Either way, each eyepiece will have its correct setting and the amount of focuser shift from one eyepiece to the next will be negligible.




I have not done this yet but it sounds like a worthy experiment for next New Moon at my dark site. So far, I haven't kept the Paracorr in the focuser consistently, but only use it now and then for specific eyepieces.

One problem that I've found when setting my Paracorr I for different eyepieces, is that the tuning knob sticks. Often I need to loosen both the tuning knob and the set screw that detains the 1.25" adapter in order to turn the tuning top. This is a PITA at a dark site.

Mike



There are 2 versions of the Paracorr 1 I see in the field: one has a thumbscrew you loosen and that is the only alignment screw between the tunable top and the Paracorr body. The newer version of the Paracorr 1 had 3 screws aligning the top to the body, and only one was loosened to turn the top. The second version is better able to hold its alignment and turn smoothly. The earlier version was sometimes difficult to turn with an eyepiece in place because the weight of the eyepiece could tilt the tunable top when the thumbscrew was loosened.
I got around that by simply supporting the weight of the eyepiece with my hand as I was turning the top and eyepiece together.
I can't think of why the setscrew in the adapter would have to be loosened, however. That's a mystery.


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Jeff Morgan
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Re: Delos 17.3---VERY Sad new [Re: dcoyle]
      #5542273 - 11/27/12 02:49 PM

Quote:

An OT moment, please.

Jeff, That is an amazing scope! What size and f/ is it?

Thanks,

Dan




Thanks. The scope is obviously not complete, this photo was taken last week during focus testing. As you can see, I had quite a few tubes to trim But it does reach focus with the 31 Nagler and the 14 Delos. I start the ServoCAT install after lunch today and hope to have it operational by Thursday night. Finishing touches and debugging should take another month, but that can be accomplished between observing sessions.

The original concept was a 12.5" f/9 to replace a 12.5" f/6. I approached Carl Zambuto to do the mirror and he suggested that considering effort and investment I really should go up in aperture too. After some thought and reflection, I agreed. Based on cost, nightly temperature variation, and weight a 16" aperture was about the maximum I wanted. (Well, I want a 30" but we all know how that goes.) However the preliminary design on the 16" f/9 was rather ... intimidating.

Since 112" of focal length was about the most I was prepared to deal with, Viola! a 16" f/7.

Edited by Jeff Morgan (11/27/12 02:51 PM)


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Sarkikos
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Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5542456 - 11/27/12 04:43 PM

Don,

Quote:

There are 2 versions of the Paracorr 1 I see in the field: one has a thumbscrew you loosen and that is the only alignment screw between the tunable top and the Paracorr body. The newer version of the Paracorr 1 had 3 screws aligning the top to the body, and only one was loosened to turn the top. The second version is better able to hold its alignment and turn smoothly. The earlier version was sometimes difficult to turn with an eyepiece in place because the weight of the eyepiece could tilt the tunable top when the thumbscrew was loosened.
I got around that by simply supporting the weight of the eyepiece with my hand as I was turning the top and eyepiece together.
I can't think of why the setscrew in the adapter would have to be loosened, however. That's a mystery.




My Paracorr has one thumbscrew in the tuning slot and one thumbscrew which secures the 2" eyepiece or 1.25" adapter inside the Paracorr. That's all. I know for a fact that if I only loosen the tuning slot thumbscrew, the tuning top will become tight and hang up about mid-range. This does not happen if an eyepiece or 1.25" adapter is not in the Paracorr.

However, if I also loosen the thumbscrew which secures the 2" eyepiece or 1.25" adapter, the tuning top can be turned easily. But then you have be aware that the eyepiece is not tightly secured in the Paracorr.

Other than this, the Paracorr works beautifully. But it definitely gets too tight to turn - or turns only with difficulty - if only the tuning slot thumbscrew is loosened. The thumbscrew which secures the eyepiece also needs to be loosened a little. I have no idea why. That's just the way it is.

Mike


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csrlice12
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Re: Delos 17.3---VERY Sad new [Re: Richard Low]
      #5542462 - 11/27/12 04:53 PM

My 13mmT1 had the opposite Problem. Too little outfocus unless i use the 1.25" adapter. Kind of scary holding that eyepiece with a single set screw on the end of the 1.25" barrel. But, it did work. putting it all the way in with the 2" barrel, I could not come to focus. I did later discover that if I put the "notch" in the 2" eyepiece where one of the two 2" focuser set screws are, it will "rest" on the set screw; and I tighten the other set screw and I can bring it into focus, but it is still at almost the max outfocus.

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Starman1
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Re: Delos 17.3---VERY Sad new [Re: Sarkikos]
      #5542616 - 11/27/12 06:45 PM

Quote:

Don,

Quote:

There are 2 versions of the Paracorr 1 I see in the field: one has a thumbscrew you loosen and that is the only alignment screw between the tunable top and the Paracorr body. The newer version of the Paracorr 1 had 3 screws aligning the top to the body, and only one was loosened to turn the top. The second version is better able to hold its alignment and turn smoothly. The earlier version was sometimes difficult to turn with an eyepiece in place because the weight of the eyepiece could tilt the tunable top when the thumbscrew was loosened.
I got around that by simply supporting the weight of the eyepiece with my hand as I was turning the top and eyepiece together.
I can't think of why the setscrew in the adapter would have to be loosened, however. That's a mystery.




My Paracorr has one thumbscrew in the tuning slot and one thumbscrew which secures the 2" eyepiece or 1.25" adapter inside the Paracorr. That's all. I know for a fact that if I only loosen the tuning slot thumbscrew, the tuning top will become tight and hang up about mid-range. This does not happen if an eyepiece or 1.25" adapter is not in the Paracorr.

However, if I also loosen the thumbscrew which secures the 2" eyepiece or 1.25" adapter, the tuning top can be turned easily. But then you have be aware that the eyepiece is not tightly secured in the Paracorr.

Other than this, the Paracorr works beautifully. But it definitely gets too tight to turn - or turns only with difficulty - if only the tuning slot thumbscrew is loosened. The thumbscrew which secures the eyepiece also needs to be loosened a little. I have no idea why. That's just the way it is.

Mike



You have the original version, and the adapter tilts slightly when the tunable top thumb screw is loosened. That's why you have to loosen the adapter's set screw. It has to be able to "float" in the tunable top, which is now slightly off angle.
I would suggest you adjust the tunable top before you put the eyepiece into the Paracorr. I couldn't remember the settings for every eyepiece and didn't want to have a crib sheet by the scope (back when I had a hundred eyepieces), so I put a label-maker label on the side of each eyepiece with the correct setting for that eyepiece (which I had determined by focusing with the tunable top earlier) so I wouldn't have to remember at all.


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Starman1
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Re: Delos 17.3---VERY Sad new [Re: SkyRanger]
      #5542618 - 11/27/12 06:49 PM

Quote:

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



There are other 1.25" eyepieces (like the Parks Gold Series 35) that require even MORE inward focuser movement. The answer is a thinner 1.25" adapter if you have a 2" focuser.
But if you have a 1.25" focuser, the answer is a little more complicated and either involves installing a lower-profile focuser or moving the primary mirror upward. Just about any solution will involve a slight change of balance in your scope.


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Starman1
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Re: Delos 17.3---VERY Sad new [Re: csrlice12]
      #5542624 - 11/27/12 06:53 PM

Quote:

My 13mmT1 had the opposite Problem. Too little outfocus unless i use the 1.25" adapter. Kind of scary holding that eyepiece with a single set screw on the end of the 1.25" barrel. But, it did work. putting it all the way in with the 2" barrel, I could not come to focus. I did later discover that if I put the "notch" in the 2" eyepiece where one of the two 2" focuser set screws are, it will "rest" on the set screw; and I tighten the other set screw and I can bring it into focus, but it is still at almost the max outfocus.



When using a skirted 1.25"/2" eyepiece, that's how you're supposed to do it: the 1.25" adapter's thumbscrew fits in the slot in the 2" skirt and the screw on the 2" skirt tightens down on the adapter from outside the 2" barrel. Plenty of support that way.
You can tighten both screws, actually, making the fit quite solid.


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Sarkikos
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Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5542786 - 11/27/12 08:48 PM

Don,

Quote:

You have the original version, and the adapter tilts slightly when the tunable top thumb screw is loosened. That's why you have to loosen the adapter's set screw. It has to be able to "float" in the tunable top, which is now slightly off angle.




Just this evening I've solved this problem (= Televue design defect) for the most part by taking the tunable top off and carefully rubbing Super Lube on the opposing surfaces. Now the tunable top turns much more smoothly without having to loosen the set screw that secures the adapter/eyepiece. It also helps to pull up a bit on the tunable top as I turn it.

Quote:

I would suggest you adjust the tunable top before you put the eyepiece into the Paracorr.




That would defeat the purpose of setting each eyepiece on-the-fly by using the tunable top to focus, as you were suggesting.

Quote:

I couldn't remember the settings for every eyepiece and didn't want to have a crib sheet by the scope (back when I had a hundred eyepieces), so I put a label-maker label on the side of each eyepiece with the correct setting for that eyepiece (which I had determined by focusing with the tunable top earlier) so I wouldn't have to remember at all.




I hardly ever use the Paracorr at home. Here I usually have a binoviewer in the focuser instead. When I go to my dark site, I take along "only" about 30 eyepieces. I have the Paracorr settings for them on a cheat sheet, which I look at when I need to.

I never put any labels on my eyepieces. My sites tend to very dewy, and I don't want any labels sliding off and onto optical surfaces! Whenever I buy eyepieces, the first thing I do is take off all those "helpful" labels that previous owners have put on. I do put labels on filter cases, though.


Mike


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sixela
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Re: Delos 17.3---VERY Sad new [Re: ThreeD]
      #5543281 - 11/28/12 05:05 AM

Quote:

Thus creating a need for the Paracorr Type 3 that will be announced at NEAF much to the chagrin of those who invested in the Type 2 over the last year.




New 'enhanced' 2"-1.25" adapter:
http://www.sciencecenter.net/hutech/prices/borgparts/html/7396.htm

Been using it for years in similar situations.

Although in this case I'd possibly prefer to use this from Baader and turn the 17.3mm Delos into a 2" eyepiece:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p767_Ba...

You can remove the long set screw and use the recessed set screw (and a small hex wrench) instead. The length of the adapter is then just 1mm.


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Mirzam
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Re: Delos 17.3---VERY Sad new [Re: jeffdetweiler]
      #5543391 - 11/28/12 08:17 AM

I have recent experience with the Astrosystems negative adapter and can offer a few observations.

1. The adapter has an internal compression ring rather than a bare set screw. This holds tall eyepieces like the D17.4 more securely. Not all negative adapters have this.

2. The D17.4 DOES fit into the recessed hole in the astrosystems adapter. My Pentax XWs also fit.

3. My version of the adapter seems to have a bit longer snout (50 mm) than the one shown in the earlier link. I bought mine from OPT a couple weeks ago. This is an issue for using the adapter in a Paracorr in that the adapter may not seat all the way into the Paracorr (it depends on the Paracorr setting if the tunable top is all the way out then it's okay).

I trimmed 3/8" off of the end of my adapter to allow it to seat all the way in. This is easily done with a hacksaw.

JimC


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Starman1
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Re: Delos 17.3---VERY Sad new [Re: sixela]
      #5543536 - 11/28/12 10:11 AM

Quote:

Quote:

Thus creating a need for the Paracorr Type 3 that will be announced at NEAF much to the chagrin of those who invested in the Type 2 over the last year.




New 'enhanced' 2"-1.25" adapter:
http://www.sciencecenter.net/hutech/prices/borgparts/html/7396.htm

Been using it for years in similar situations.

Although in this case I'd possibly prefer to use this from Baader and turn the 17.3mm Delos into a 2" eyepiece:

http://www.teleskop-express.de/shop/product_info.php/language/en/info/p767_Ba...

You can remove the long set screw and use the recessed set screw (and a small hex wrench) instead. The length of the adapter is then just 1mm.



TeleVue has designed an adapter for the 17.3 and 14 Delos that makes them parfocal in the Paracorr with all the other Delos eyepieces (which use the standard Paracorr adapter) and nearly all their 1.25" eyepieces. It might not make it into production unless we push them to do so (I gave a nudge), but it would end the discussion except for those scopes with 1.25" focusers with insufficient in-travel.
Alexis' 2nd link comes close, but to make the 17.3/14 Delos parfocal in the Paracorr, the adapter has to have a negative height, like the GSO or Astrosystems adapters.


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Starman1
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Re: Delos 17.3---VERY Sad new [Re: Mirzam]
      #5543540 - 11/28/12 10:13 AM

Quote:

I have recent experience with the Astrosystems negative adapter and can offer a few observations.

1. The adapter has an internal compression ring rather than a bare set screw. This holds tall eyepieces like the D17.4 more securely. Not all negative adapters have this.

2. The D17.4 DOES fit into the recessed hole in the astrosystems adapter. My Pentax XWs also fit.

3. My version of the adapter seems to have a bit longer snout (50 mm) than the one shown in the earlier link. I bought mine from OPT a couple weeks ago. This is an issue for using the adapter in a Paracorr in that the adapter may not seat all the way into the Paracorr (it depends on the Paracorr setting if the tunable top is all the way out then it's okay).

I trimmed 3/8" off of the end of my adapter to allow it to seat all the way in. This is easily done with a hacksaw.

JimC



When the adapter is trimmed, does the setting selected come close to other 1.25" eyepieces?


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Mirzam
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Re: Delos 17.3---VERY Sad new [Re: Starman1]
      #5543549 - 11/28/12 10:18 AM

It works fine now at the middle setting of the tunable top, which is where I usually leave the Paracorr.

There was a link way up the thread though that showed an Astrosystems adapter that looked shorter than mine. So maybe there is another version that does not need to be trimmed.

JimC


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Mirzam
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Re: Delos 17.3---VERY Sad new [Re: Mirzam]
      #5543563 - 11/28/12 10:27 AM

Looking at the Paracorr settings guide it appears that the lowest setting is recommended for the Delo 17.4. In any case, I've been using mine at the middle setting without obvious problems.

This makes sense I guess since the adapter recesses the eyepiece, much like having the Paracorr at a low setting.
JimC

Edited by Mirzam (11/28/12 10:29 AM)


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dcoyle
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Re: Delos 17.3---VERY Sad new [Re: Mirzam]
      #5543582 - 11/28/12 10:37 AM

When I ordered an astrosystems negative adapter, they informed me that the tall adapter was the old style and that they were now producing the short adapter.

Dan


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Scanning4Comets
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Re: Delos 17.3---VERY Sad new [Re: dcoyle]
      #5543656 - 11/28/12 11:11 AM

Quote:

Yep, I use that trick for 2" filters, too. It also allows you to keep the same filter on the scope and change eyepieces. A friend had a 2" filter wheel I thought about buying, but I thought again and decided not to. In a Dob, you'd probably need an OCA to come to focus, thereby halving the effective focal length of the eyepiece. That would ruin the whole idea of using low power eyepieces with a 2" filter. (The extra weight would also be a bear to deal with.)

But for medium-to-high power, a wheel for 1.25" filters is great. I have a wheel permanently loaded with DSO filters for trips to the dark site. Nothing like viewing M42 with a Baader Zoom on a filter wheel. You can immediately vary the image scale and the DSO filter as you wish.

That's one of the main reasons I don't have a Paracorr permanently installed in my focuser!


Mike




I also came up with another idea! I just bought a 2" Lumicon Polarizing filter. What I do with that is unscrew one side of the filter and screw it onto the bottom of my 2" Antares Twist Lock adapter of whatever eyepiece I am using. I leave the other side of the 2" Polarizing filter on my 2" Blue Fireball extension tube.

To use the filter, I insert the extension tube with 1/2 of the 2" Lumicon polarizing filter, and then insert my eyepiece with the other 1/2 of the Lumicon Polarizing filter which is on the bottom of my Antares Twist Lock adapter, into the extension tube and all I need to get the desired brightness is turn the eyepiece in the focuser!

Works great! The only thing one needs to remember is to NOT turn the eyepiece counter clockwise because the one half of the 2" filter can unscrew resulting in that not-so-desired "tinkling" sound of gear falling onto the mirror.

Cheers,


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