Jump to content


Photo

Who invented the barrel safety undercut?

  • Please log in to reply
69 replies to this topic

#51 Paul G

Paul G

    Fly Me to the Moon

  • *****
  • Posts: 5051
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 20 November 2012 - 09:06 AM

I think we can all blame Tele Vue for the continued use of the undercut whether or not they invented it. What I don't understand is why they continue to when well over 90% of their customers would like them to stop.


It's not even 90% in this thread, not sure where you are getting that idea. I agree with Jon, the undercut causes me no problems. Using an equatorial mount I often find the diagonal pointing at the ground after a slew so I can see its utility.

Not sure why you would blame TV; I've seen undercuts on a variety of premium and nonpremium brands, including Zeiss.

#52 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16698
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 20 November 2012 - 09:08 AM

Obviously not every eyepiece is for everyone, just as not every eyepiece is for every object or application. That's why I still hang on to my wide fields, my XO's, my bino pairs, and even my Huygens. I've only sold eyepieces that come close to duplicating another eyepiece's function and focal length ... or that didn't appeal to me for some reason.

For me, absolutely pristine sharpness to the edge is not always important for every object I'm observing. It just isn't. (Though the Baader Zoom is not bad.) And a wide field is not always necessary. I let the objects dictate the optics.

Also, I'm able to observe at my dark site only once or twice a month if I'm lucky. It just makes more sense - for my purposes - to avoid switching among eyepieces when I only have a limited amount of time to observe all the objects that I want to observe. Usually I only switch to another eyepiece when it makes sense in terms of that object, not in terms of what I expect out of the optics.

Mike

#53 JIMZ7

JIMZ7

    Apollo

  • *****
  • Posts: 1450
  • Joined: 22 Oct 2005
  • Loc: S.E.Michigan near DTW

Posted 20 November 2012 - 11:04 AM

Let's hear it for the smooth barrels! :choochoo: :applause:

Jim :refractor:

#54 Scott99

Scott99

    Mercury-Atlas

  • *****
  • Posts: 2890
  • Joined: 10 May 2007
  • Loc: New England

Posted 20 November 2012 - 12:09 PM

The occasional anti-undercut thread is welcome and always entertaining!

I often use under-mounted scopes and therefore have gone to great lengths to purge all undercut eyepieces out of my case - I once paid $150 to get a smooth barrel made for my 35mm Panoptic. It just takes a little extra commitment to beat this annoying problem.

By using some vintage and carefully selected modern ep's, I currently have around 25 eyepieces - the only ones with undercut are the 3 Pentax XW's. Unfortunately they have lenses in the barrels or I'd try to replace them too.

#55 dscarpa

dscarpa

    Gemini

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

Posted 20 November 2012 - 12:25 PM

I suspect differences in diagonals or focusers compression ring set up has an effect on hang up issues. I've got 2 OPT dialectric and one Meade dialectric diagonals all 2". So far I don't have any hang up issues getting eyepieces out of my newish Antares 1.25"-2" twist-lock adapters of which I have 3 and am using in place of the ones that came with the diagonals. As to eyepieces with a deep sharp edged undercut add the 31 Hyperion Aspheric to the list. David

#56 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 22873
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 20 November 2012 - 12:32 PM

I suspect differences in diagonals or focusers compression ring set up has an effect on hang up issues. I've got 2 OPT dielectric and one Meade dielectric all 2". As to eyepieces with a deep sharp edged undercut add the 31 Hyperion Aspheric to the list. David

Eyepieces vary in size and so do focusers and star diagonals, so some fits might be tight while others are loose.
And some brass ring inserts in focusers and star diagonals are rectangular in cross-section. They also work just as well if the brass ring is more lenticular in cross section. Try removing the ring and sanding down the edges to make them thinner than the centers and the hang up on eyepiece barrels is virtually eliminated.
Or, simply remove the brass ring and have the thumbscrew press directly on the eyepiece. It will mean marks on the eyepiece (who really cares?), but the "safety retention groove" won't be the issue it is when the brass ring is in place.

#57 dscarpa

dscarpa

    Gemini

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

Posted 20 November 2012 - 12:36 PM

Thanks for the tip! David

#58 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 43894
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 20 November 2012 - 12:38 PM

My Baader Zoom is good enough for 90% of what's up there. Optics or objects? I'm more concerned with the objects. :grin:

For the big stuff, I switch to my wide field ES eyepieces. For really dim stuff, I might try a good ortho, XW or XO.

Mike


Mike:

It all depends on your mind set... If one limits the objects to those that are visible with a 8-24mm zoom, then yeah... but that doesn't work for me.

Jon Isaacs

#59 dscarpa

dscarpa

    Gemini

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

Posted 20 November 2012 - 12:46 PM

I like my Hyperion Zoom a lot but on very good nights the difference in image quality between it and my XWs, Delos, Ethos and LVW is not subtle. David

#60 csrlice12

csrlice12

    Voyager 1

  • *****
  • Posts: 10817
  • Joined: 22 May 2012
  • Loc: Denver, CO

Posted 20 November 2012 - 12:51 PM

A good way to avoid hanging up on the undercuts is to keep a nice Zoom eyepiece in the focuser for most of the observing session. Less changes, less hangups. Sigmund Freud would be proud. Sehr gut! :ubetcha:

My Baader Zoom sees so much sky time, I can't even recall if it has an undercut... :thinking:

:grin:
Mike


When they finally get the prototype 31mm-1.75mm, 82degree AFoV Zoom that is well corrected at F/4 into production, it would be of interest. Until then, I'll be swapping eyepieces... :ubetcha:

Jon


and if they could do it for the same $50 price as the Zhummel 8-24mm zoom, that would be a best seller....everybody would want one.....

#61 SteveG

SteveG

    Skylab

  • *****
  • Posts: 4311
  • Joined: 27 Sep 2006
  • Loc: Seattle, WA

Posted 20 November 2012 - 01:01 PM

I think we can all blame Tele Vue for the continued use of the undercut whether or not they invented it. What I don't understand is why they continue to when well over 90% of their customers would like them to stop.


It's not even 90% in this thread, not sure where you are getting that idea. I agree with Jon, the undercut causes me no problems. Using an equatorial mount I often find the diagonal pointing at the ground after a slew so I can see its utility.

Not sure why you would blame TV; I've seen undercuts on a variety of premium and nonpremium brands, including Zeiss.


FWIW, I ran a poll here on CN a couple of years ago. The Like/Don't Like was about 2 to 1 in favor of no undercuts or tapered barrels (66%).

#62 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16698
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 20 November 2012 - 01:24 PM

Jon,

My Baader Zoom is good enough for 90% of what's up there. Optics or objects? I'm more concerned with the objects. :grin:

For the big stuff, I switch to my wide field ES eyepieces. For really dim stuff, I might try a good ortho, XW or XO.

Mike


It all depends on your mind set... If one limits the objects to those that are visible with a 8-24mm zoom, then yeah... but that doesn't work for me.

Jon Isaacs


Now, did I say that I limit myself to objects that are visible with a 8-24mm zoom? In the very post that you quote here, I state that I will switch to other eyepieces if the object warrants it ... but only if the object warrants it. That's my whole point. I let the objects dictate my mind set, not the optics.

Mike

#63 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 43894
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 20 November 2012 - 01:45 PM

Now, did I say that I limit myself to objects that are visible with a 8-24mm zoom? In the very post that you quote here, I state that I will switch to other eyepieces if the object warrants it ... but only if the object warrants it. That's my whole point. I let the objects dictate my mind set, not the optics.

Mike



You did say that 90% of the objects you view reasonable in an 8mm-24mm Zoom. 90% of the objects I view would not be optimal in an 8-24mm Zoom.

I don't mind swapping eyepieces, the night is long, there are many clear nights in a year and I am not in a hurry.

Jon

#64 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16698
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 20 November 2012 - 03:00 PM

90% reasonable? Yes. 90% optimal? Maybe not. Objects, not optics, have higher priority for me.

There are not so many nights for me at a dark site! I'm always doing a cost/benefit analysis.

:grin:
Mike

#65 Jeff Morgan

Jeff Morgan

    Fly Me to the Moon

  • *****
  • Posts: 5681
  • Joined: 28 Sep 2003
  • Loc: Prescott, AZ

Posted 21 November 2012 - 09:17 AM

The occasional anti-undercut thread is welcome and always entertaining!


Yes, it is kind of a pointless venting since TeleVue seems so intent on ignoring what the majority of their customers want in this matter.

Perhaps if a competitor (ES?) went smooth sides they would learn the error of their ways very quickly.

#66 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 22873
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 21 November 2012 - 10:19 AM

Every time I pull the Paracorr out of the focuser to put a filter on the bottom, I appreciate the smooth side and the easy slide out of the focuser.
Then I change the eyepiece in the Paracorr and start mumbling about compression rings and undercuts.
Put me down as a smooth side lover.

#67 Doug Culbertson

Doug Culbertson

    Skylab

  • *****
  • Posts: 4110
  • Joined: 06 Jan 2005

Posted 21 November 2012 - 10:40 AM

Every time I pull the Paracorr out of the focuser to put a filter on the bottom, I appreciate the smooth side and the easy slide out of the focuser.
Then I change the eyepiece in the Paracorr and start mumbling about compression rings and undercuts.
Put me down as a smooth side lover.


+1 I keep thinking about taking every single compression ring out of my focusers, diagonals, and 1.25" adapters and replacing the screws with nylon screws. Fortunately, the 2" tube on my Moonlight has no compression ring, and uses a nylon setscrew. I like that.

#68 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16698
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 21 November 2012 - 11:32 AM

When I asked about "compression rings" earlier, what I meant was the twist-lock type of adapter, such as this:

Baader Planetarium 2 Inch Deluxe Clicklock Eyepiece Extension

... or this:

Antares 2" Twist-Lock Eyepiece Adapter

... or this:

Orion 2" Precision Centering Extension Adapter

I like these twist-lock gizmos. Now these DO keep your eyepieces and such securely in the focuser. I'd like to see all undercuts done away with and instead twist-locks put on all focusers and any adapters which accept eyepieces and other accessories.

So do undercut eyepieces get hung up on these twist-lock fittings? If so, that's a real shame. :p More reason to hate the undercuts. :flame:

Being forced to retrofit nylon screws in focusers seems like a step backward to me. :ohgeeze:

Mike

#69 Sarkikos

Sarkikos

    Hubble

  • *****
  • Posts: 16698
  • Joined: 18 Dec 2007
  • Loc: Per sylvam ad astra

Posted 21 November 2012 - 11:39 AM

My old-school Burgess Binoviewer came with nylon set screws. I was able to upgrade to twist-lock fittings. Much, much better! IME, the eyepieces are still easy to insert and remove. And there is a huge improvement in centering the eyepieces and ease in merging the images. Now I can bump the power up to 600x if I want! I don't want to do that very often, but if I do, I can enjoy a clean, merged image.

Mike

#70 Doug Culbertson

Doug Culbertson

    Skylab

  • *****
  • Posts: 4110
  • Joined: 06 Jan 2005

Posted 21 November 2012 - 12:59 PM

When I asked about "compression rings" earlier, what I meant was the twist-lock type of adapter, such as this:

Baader Planetarium 2 Inch Deluxe Clicklock Eyepiece Extension

... or this:

Antares 2" Twist-Lock Eyepiece Adapter

... or this:

Orion 2" Precision Centering Extension Adapter

I like these twist-lock gizmos. Now these DO keep your eyepieces and such securely in the focuser. I'd like to see all undercuts done away with and instead twist-locks put on all focusers and any adapters which accept eyepieces and other accessories.

So do undercut eyepieces get hung up on these twist-lock fittings? If so, that's a real shame. :p More reason to hate the undercuts. :flame:

Being forced to retrofit nylon screws in focusers seems like a step backward to me. :ohgeeze:

Mike


Mike,

We are referring to the standard ubiquitous flexible brass compression ring that tightens when you turn the setscrew. you know, the ones that come standard on almost every focuser and diagonal in existence today.

I don't believe that the twist lock type of adapter that you are talking about will hang up on the undercuts. I have one 1.25" adapter that I bought from someone on CN a couple of years ago, and it's a collette type that tightens on the eyepiece when you turn the top; sort of like the twist locks. I have no trouble when using an eyepiece with this adapter.

FWIW, I have ordered a 2" Baader Click-Lock adapter for my EON 120, to replace the compression ring adapter that comes on the focuser drawtube. Hopefully it will be an easy replacement, and will end that dreaded star diagonal flip when slewing the mount.






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics