Jump to content

  •  

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

Photo

Eyepiece Safety Undercuts - a Bad Idea From the Start

  • Please log in to reply
121 replies to this topic

#51 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 78412
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 20 July 2019 - 05:44 PM

Note to self:

 

It's hot outside. Time for another "why I don't like eyepiece undercuts thread."

 

scratchhead2.gif

 

Thinking to self:

 

"I swap eyepieces a lot. Rarely have issues.. I wonder why?"

 

Jon


  • turtle86, Asbytec, Lenard and 2 others like this

#52 clivemilne

clivemilne

    Mariner 2

  • *****
  • Posts: 283
  • Joined: 13 Jun 2011
  • Loc: West Oz

Posted 20 July 2019 - 10:11 PM

~Tries to remember the last time owning a dobsonian with its focuser oriented in a downward gradient...

 

~ never

 

~Tries to recall the number of eyepieces passed over because their undercuts were incompatible (with focusers, eyepiece holders, etc)

 

errrrm... lost count.


  • Asbytec, TOMDEY, Peter Besenbruch and 2 others like this

#53 CrazyPanda

CrazyPanda

    Surveyor 1

  • *****
  • Posts: 1889
  • Joined: 30 Sep 2012

Posted 20 July 2019 - 10:23 PM

What is it that you (and others) find annoying about undercuts? When you say that the problem they exist to address is only a perceived one, are you saying that you've never had, in a long observing session, set screw loosen? 

 

I guess I'm an exceptio. I don't find undercuts particularly annoying. I've also found, during long observing sessions with a SCT, that set-screws on the compression ring holding the diagonal may become sufficiently loose that the undercut has "saved" my eyepieces during a change. 

Undercuts make it physically harder to remove the eyepiece from the focuser. These things frequently happen to me as a direct result of undercuts:

 

1. Moved the telescope out of position when the undercut got caught on a thumb screw or compression ring

2. Defocused the focuser when trying to remove the eyepiece (parfocal eyepiece, so I wanted focus to remain the same)

3. The undercut causing the eyepiece to catch in the focuser has made me lose my grip on the eyepiece, and I have almost dropped it as a result (which is ironic).

 

What has *NEVER* happened to me is being saved by a safety undercut. In all my years of observing, I have never once experienced a situation where the eyepiece has almost slipped out of the focuser and was saved by the safety undercut.

 

Quite literally 100.00% of my interaction with safety undercuts has involved cursing at them rather than thanking them.

 

Safety undercuts make sense on the nose piece of a diagonal since that is oriented in such a way that it could slip out of an SCT or refractor, and since you're infrequently removing that diagonal, it's not going to be cumbersome. But unless your scope is on a GIANT mount whereby the eyepiece has to be rotated downward to view through it, there is no need for safety undercuts on eyepieces. And in those cases where your mount is so tall that your eyepiece is rotated downwards (e.g. big SCT or Frac on a pier, or a big Newt on a  big GEM), then I would say you will be experienced enough to ensure your eyepieces are adequately clamped in place in the focuser.

 

I will say though that tapers are better than undercuts. The taper on the 17 ES92 has never caused me problems, and as long as it sits snuggly against the rim of the focuser, it doesn't tilt when clamping down on it. The hard undercuts of Tele Vue eyepieces though? Let's just say it's Tele Vue should count its blessings that its optics are good enough to make it worth the trouble of its undercuts...


Edited by CrazyPanda, 20 July 2019 - 10:37 PM.

  • russell23 and clivemilne like this

#54 TOMDEY

TOMDEY

    Skylab

  • *****
  • Posts: 4435
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 20 July 2019 - 10:27 PM

~Tries to remember the last time owning a dobsonian with its focuser oriented in a downward gradient...

 

~ never

 

~Tries to recall the number of eyepieces passed over because their undercuts were incompatible (with focusers, eyepiece holders, etc)

 

errrrm... lost count.

Excellent point! Just one more thing great about Dobsonians... eyepiece always comfy horizontal (or above)... and the eyepiece is never tyring to fall out.    Tom


  • Asbytec, CrazyPanda and 25585 like this

#55 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 78412
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 20 July 2019 - 11:09 PM

Safety undercuts make sense on the nose piece of a diagonal since that is oriented in such a way that it could slip out of an SCT or refractor, and since you're infrequently removing that diagonal, it's not going to be cumbersome.

 

It's not that the diagonal can slip out, it's that it can rotate. It's that the nose piece is threaded to the diagonal body and can possibly unscrew. 

 

And if rotates and there happens to be an eyepiece in that diagonal, particularly a heavy one that caused it to rotate, that eyepiece can take a header.  

 

Now if that eyepiece had a safety under cut....

 

These threads always amaze me.  Observing is a peaceful experience, a calming, a mediation. Things just don't bother me, I deal with what happens and I figure out how to address the various issues that arise. I don't think it takes a genius to figure out to insert and remove eyepieces with undercuts with relative ease, without disturbing the telescope.  

 

YMMV

 

Jon


  • turtle86, bbqediguana, makeitso and 1 other like this

#56 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42373
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 20 July 2019 - 11:12 PM

Undercuts make it physically harder to remove the eyepiece from the focuser. These things frequently happen to me as a direct result of undercuts:

1. Moved the telescope out of position when the undercut got caught on a thumb screw or compression ring
2. Defocused the focuser when trying to remove the eyepiece (parfocal eyepiece, so I wanted focus to remain the same)
3. The undercut causing the eyepiece to catch in the focuser has made me lose my grip on the eyepiece, and I have almost dropped it as a result (which is ironic).

What has *NEVER* happened to me is being saved by a safety undercut. In all my years of observing, I have never once experienced a situation where the eyepiece has almost slipped out of the focuser and was saved by the safety undercut.

Quite literally 100.00% of my interaction with safety undercuts has involved cursing at them rather than thanking them.

Safety undercuts make sense on the nose piece of a diagonal since that is oriented in such a way that it could slip out of an SCT or refractor, and since you're infrequently removing that diagonal, it's not going to be cumbersome. But unless your scope is on a GIANT mount whereby the eyepiece has to be rotated downward to view through it, there is no need for safety undercuts on eyepieces. And in those cases where your mount is so tall that your eyepiece is rotated downwards (e.g. big SCT or Frac on a pier, or a big Newt on a big GEM), then I would say you will be experienced enough to ensure your eyepieces are adequately clamped in place in the focuser.

I will say though that tapers are better than undercuts. The taper on the 17 ES92 has never caused me problems, and as long as it sits snuggly against the rim of the focuser, it doesn't tilt when clamping down on it. The hard undercuts of Tele Vue eyepieces though? Let's just say it's Tele Vue should count its blessings that its optics are good enough to make it worth the trouble of its undercuts...


Wow!
You pulled the words out of my mouth.
One thing, though. A brass split ring can distort if tightened down on the conical section of the conical taper and stay distorted. The best binder for the conical taper is a simple thumbscrew pressing against the barrel. As you tighten the screw, the eyepiece is pulled into the focuser, and with even a loose thumbscrew, the eyepiece can't come out.

#57 TOMDEY

TOMDEY

    Skylab

  • *****
  • Posts: 4435
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 21 July 2019 - 01:10 AM

Saaaay...

 

QUESTION: Who is the original inventor of the ~undercut eyepiece~ ?

 

With my luck, it will turn out to be Galileo or Newton... >>>

 

Patent #0,000,001 Improved Astronomer Frustration Device and Method for Use

 

Abstract: A smoothie eyepiece is modified by machining material from the barrel in the form of a tangentially-symmetric negative belt. Naive competing astronomers will enthusiastically embrace the Trojan Horse as some sort of improvement. On the night of a next Grand Comet, the inventor will seamlessly discover the comet, because competing astronomers are fit to be tied, trying to get their improved eyepieces in and out.

 

Fig. 1 shows a prior art smoothie eyepiece, being fondled by a happy astronomer.

Fig. 2a shows an undercut in the form of a uniform negative belt.

Fig. 2b shows an undercut in the form of a negative belt comprising a tapered bottom.

Fig. 2c shows an undercut in the form of a negative belt comprising a tapered top.

Fig. 2d shows an undercut in the form of a negative belt comprising a tapered bottom and top.

Fig. 2e shows an undercut in the form of a negative belt comprising a substantially-tapered terminal end.

Fig. 2f shows an undercut in the form of a negative belt comprising a substantially-tapered top end.

Fig. 3 shows an improved eyepiece comprising an undercut, being smashed against a rock by an exasperated astronomer.

 

This, and other advantages are described in the teaching that follows.    Tom


Edited by TOMDEY, 21 July 2019 - 01:11 AM.

  • Starman1, payner, eros312 and 2 others like this

#58 Asbytec

Asbytec

    Guy in a furry hat

  • *****
  • Posts: 15489
  • Joined: 08 Aug 2007
  • Loc: Pampanga, PI

Posted 21 July 2019 - 01:37 AM

 

Observing is a peaceful experience, a calming, a mediation. Things just don't bother me, I deal with what happens and I figure out how to address the various issues that arise. I don't think it takes a genius to figure out to insert and remove eyepieces with undercuts with relative ease, without disturbing the telescope.  

 

Where's the hammer on the nail head emoticon? That's the entire gist of it for me. I get much more kick out of the view than allowing a minor distraction of an eyepiece barrel take away from it. Sometimes I even let mosquitoes bite and worry about the scratching later. 


Edited by Asbytec, 21 July 2019 - 01:45 AM.

  • Jon Isaacs, Lenard, lsfinn and 3 others like this

#59 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 21 July 2019 - 05:05 AM

I have a physical disability in that my right arm and hand are now partially paralysed. As a consequence of this I have to use my left hand to insert and remove eyepieces or diagonals. I can hold things in my right hand for a limited time, but anything that requires a more complex dexterity or range has to be performed with my left (non-dominant) hand and arm.

 

Undercuts on eyepieces do not make my life easier. 


  • Asbytec likes this

#60 Ihtegla Sar

Ihtegla Sar

    Mariner 2

  • -----
  • Posts: 283
  • Joined: 02 Apr 2019
  • Loc: Pacific Northwest

Posted 21 July 2019 - 05:26 AM

It's not that the diagonal can slip out, it's that it can rotate. It's that the nose piece is threaded to the diagonal body and can possibly unscrew.

And if rotates and there happens to be an eyepiece in that diagonal, particularly a heavy one that caused it to rotate, that eyepiece can take a header.

Now if that eyepiece had a safety under cut....

These threads always amaze me. Observing is a peaceful experience, a calming, a mediation. Things just don't bother me, I deal with what happens and I figure out how to address the various issues that arise. I don't think it takes a genius to figure out to insert and remove eyepieces with undercuts with relative ease, without disturbing the telescope.

YMMV

Jon


You may have more manual dexterity/fine motor skills than many here cause it sounds like you don't experience the same frustration many of us do when dealing with undercut eyepieces. It's like penmanship or typing. No matter how much I practice I never improve and both are somewhat of a frustrating experience because of all the typos. I frequently confuse spell checker and even my handwriting has typos. So saying "just learn how to remove a tapered eyepiece" isn't really helpful.

#61 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 21 July 2019 - 06:41 AM

I think that the type of undercut and the material it is manufactured from can be a major factor.

 

gallery_249298_10131_270771.jpg

 

As soon as I obtained it I swapped the drawtube barrel on this 9mm Circle T orthoscopic for a smooth one from a borked Astro Hutech orthoscopic.

 

gallery_249298_10131_29998.jpg

 

AH drawtube threads can be weird though and I decided to change back to the original barrel seen in these pictures. The barrel itself is chromed-brass and very high quality. I've not had any filter compatibility issues and even Lumicon filters have no problems threading into it. Interestingly though, the undercut has never caused me any real problems. 



#62 luxo II

luxo II

    Apollo

  • -----
  • Posts: 1009
  • Joined: 13 Jan 2017
  • Loc: Sydney, Australia

Posted 21 July 2019 - 06:56 AM

A small lightweight eyepiece like that never needed an undercut.

 

IMHO the problem is complicated by both the individual eyepieces and the range of focusers we all use and there are several problems:

 

Some focusers have no compression rings, just a simple screw;

Some focusers have a compression ring with 1, 2 or 3 screws;

 

There is a huge issue with whether the compression ring fits into the undercut; if it does, there is a risk it will not fully expand and the eyepiece will be effectively locked in the focusser; when this happens extracting the eyepiece becomes exceedingly difficult. I had two items where this was a significant risk and I have sold them.

 

The second issue is that some eyepieces (or diagonals) are pushed off-centre when the screw is tightened; this again depends on the mechanical match/mismatch of the individual components.

 

But all of these issues would not exist if there were NO UNDERCUTS !


Edited by luxo II, 21 July 2019 - 06:57 AM.

  • russell23, CrazyPanda and BradFran like this

#63 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 21 July 2019 - 07:01 AM

A small lightweight eyepiece like that never needed an undercut.

 

 

Oddly, the most problematical eyepiece undercuts for me have been using small Plossls with aluminium drawtube barrels. A few years ago I had a 'Celestron' 17mm Plossl caught in a TeleVue 3x Barlow for well over an hour. It was then that I realised the undercut was not my friend lol.



#64 Asbytec

Asbytec

    Guy in a furry hat

  • *****
  • Posts: 15489
  • Joined: 08 Aug 2007
  • Loc: Pampanga, PI

Posted 21 July 2019 - 07:08 AM

Wow, some of you have had real problems with stuck eyepieces. I guess I've been lucky. Most I've ever had to do is turn the set screw a little more, if I set it at all. 


  • bbqediguana and makeitso like this

#65 TOMDEY

TOMDEY

    Skylab

  • *****
  • Posts: 4435
  • Joined: 10 Feb 2014
  • Loc: Springwater, NY

Posted 21 July 2019 - 08:06 AM

Saaaay... INVENTION: How's about an eyepiece shoehorn ?

 

It would look a lot like a regular shoehorn, but be called a focuserhorn.

 

So, for inserting and extracting your eyepiece past those gnarly brass rings... you just hammer the horn in there, using a hefty ball-peen hammer. >>>

Attached Thumbnails

  • 255 eyepiece focuser undercut shoehorn hammer.jpg

  • Jeff Morgan, Scott99, Asbytec and 2 others like this

#66 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 78412
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 21 July 2019 - 09:18 AM

You may have more manual dexterity/fine motor skills than many here cause it sounds like you don't experience the same frustration many of us do when dealing with undercut eyepieces. It's like penmanship or typing. No matter how much I practice I never improve and both are somewhat of a frustrating experience because of all the typos. I frequently confuse spell checker and even my handwriting has typos. So saying "just learn how to remove a tapered eyepiece" isn't really helpful.

 

I don't think I'm any more dexterous than average, I'm a guy with big hands and short, fat fingers. Typing on a virtual keyboard is a problem for me because my fingers are too big to cover just one key.

 

I think there's a number of factors but attitude is probably one that's relatively important.

 

Figuring out solutions, figuring out the best way to do something has been something I've been good at, whether it's getting a wrench on a bolt that can't be seen or working out a complicated experimental procedure in the laboratory, I seem to be good at optimizing repetitive tasks.

 

I'm not afraid to experiment, to think outside the box. Don points out that the real problem is not the undercuts, it's the combination of the compression rings with the undercuts. The obvious solution is to remove the compression ring and just use set screws. I have a collection of brass and nylon thumb screws for just that purpose. I wish aluminum thumb screws were readily available because they're the best.

 

And too, practice does help. I change eyepieces at lot and I observe a lot, an average year is 500-600 hours observing. 

 

But I think patience and a positive attitude are factors. Consider the title of this thread. It could have have been:

 

"I'm FRUSTRATED with eyepiece undercuts, what are your tricks to make it easy?"

 

I think first step is removing any compression rings if they're part of the problem. For Shorty Barlow who has physical difficulties, I don't know if this would help. But getting past our frustration and trying to understand his specific issues could help him deal with them.

 

YMMV

 

Jon


  • 25585 likes this

#67 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42373
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 21 July 2019 - 09:27 AM

A small lightweight eyepiece like that never needed an undercut.

 

IMHO the problem is complicated by both the individual eyepieces and the range of focusers we all use and there are several problems:

 

Some focusers have no compression rings, just a simple screw;

Some focusers have a compression ring with 1, 2 or 3 screws;

 

There is a huge issue with whether the compression ring fits into the undercut; if it does, there is a risk it will not fully expand and the eyepiece will be effectively locked in the focuser; when this happens extracting the eyepiece becomes exceedingly difficult. I had two items where this was a significant risk and I have sold them.

 

The second issue is that some eyepieces (or diagonals) are pushed off-centre when the screw is tightened; this again depends on the mechanical match/mismatch of the individual components.

 

But all of these issues would not exist if there were NO UNDERCUTS !

I have a TeleVue 24mm Panoptic.  When a thumbscrew is tightened on the eyepiece, the screw lifts the side of the eyepiece it presses against because the thumbscrew hits the upper lip of the undercut on the eyepiece barrel.

This tips the eyepiece at an angle.  No amount of inward pressure on the eyepiece when tightening the thumbscrew prevents the lifting of that side of the eyepiece when the thumbscrew is tightened.

So, you say, there is an incompatibility between the (in this case) star diagonal's adapter and the eyepiece, and you would be right.

The star diagonal in question is a TeleVue, as is the adapter, and it is the brass split ring of the TeleVue 1.25' adapter that is hitting the upper lip of the undercut and lifting that side of the eyepiece.

!!!!!!!!!!!!!!!!!!!!!!!!

And, removing the brass split ring and using the screw directly on the eyepiece has exactly the same problem.

 

So I removed the adapter with the brass split ring, and I use a twistlock adapter instead.  The twistlock has a smooth outer side so it doesn't get tipped by any binder that presses on its exterior, and it

compresses evenly around the eyepiece (unlike a brass split ring) and binds it.  In addition, the internal collet is a lot longer than the length of the undercut on the eyepiece, so the undercut causes no issue in removal of the eyepiece, since

the bottom of the undercut cannot catch on anything.


  • 25585 likes this

#68 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42373
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 21 July 2019 - 09:32 AM

I don't think I'm any more dexterous than average, I'm a guy with big hands and short, fat fingers. Typing on a virtual keyboard is a problem for me because my fingers are too big to cover just one key.

 

I think there's a number of factors but attitude is probably one that's relatively important.

 

Figuring out solutions, figuring out the best way to do something has been something I've been good at, whether it's getting a wrench on a bolt that can't be seen or working out a complicated experimental procedure in the laboratory, I seem to be good at optimizing repetitive tasks.

 

I'm not afraid to experiment, to think outside the box. Don points out that the real problem is not the undercuts, it's the combination of the compression rings with the undercuts. The obvious solution is to remove the compression ring and just use set screws. I have a collection of brass and nylon thumb screws for just that purpose. I wish aluminum thumb screws were readily available because they're the best.

 

And too, practice does help. I change eyepieces at lot and I observe a lot, an average year is 500-600 hours observing. 

 

But I think patience and a positive attitude are factors. Consider the title of this thread. It could have have been:

 

"I'm FRUSTRATED with eyepiece undercuts, what are your tricks to make it easy?"

 

I think first step is removing any compression rings if they're part of the problem. For Shorty Barlow who has physical difficulties, I don't know if this would help. But getting past our frustration and trying to understand his specific issues could help him deal with them.

 

YMMV

 

Jon

Aluminum thumb screws:

https://www.mcmaster.com/thumb-screws

Click on thumb screws, then pick aluminum thumbscrews.


Edited by Starman1, 21 July 2019 - 09:33 AM.


#69 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 78412
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 21 July 2019 - 09:53 AM

Aluminum thumb screws:

https://www.mcmaster.com/thumb-screws

Click on thumb screws, then pick aluminum thumbscrews.

 

Don:

 

Thanks. I have seen them but I guess I'm just too lazy to deal with McMaster-carr personally. Before i retired, I used them a lot, they were my goto supplier. If I ordered before 10:30 am, they offered same day delivery to San Diego.

 

Regarding the 24mm Panoptic, it occurred to me a parfocal ring or O-ring could respace the eyepiece and potentially resolve the issue.

 

Jon



#70 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42373
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 21 July 2019 - 10:45 AM

Don:

 

Thanks. I have seen them but I guess I'm just too lazy to deal with McMaster-carr personally. Before i retired, I used them a lot, they were my goto supplier. If I ordered before 10:30 am, they offered same day delivery to San Diego.

 

Regarding the 24mm Panoptic, it occurred to me a parfocal ring or O-ring could respace the eyepiece and potentially resolve the issue.

 

Jon

Nope.

Jon, there is a small section of 1.25" barrel above the undercut.  When you install an o-ring on the eyepiece to lift the eyepiece up enough to have the brass ring press directly into the undercut, the top section of 1.25" barrel above the undercut no longer gets pressed against the other side by the thumbscrew.

Instead, the undercut is pressed against the other side and the tilt in the eyepiece is worse.

The short section of 1.25" barrel above the undercut MUST be pressed against the other side of the adapter or focuser for the eyepiece to maintain registration.

 

Yet ANOTHER disadvantage of undercuts--you cannot parfocalize the eyepieces if the section of eyepiece barrel that would then press against the other side when tightened happens to be the undercut, whether cylindical or tapered.

The top section above the undercut MUST still be exposed and MUST still press against the other side of the adapter or focuser.



#71 hoof

hoof

    Surveyor 1

  • *****
  • Posts: 1557
  • Joined: 07 Apr 2005
  • Loc: Monroe, WA

Posted 21 July 2019 - 11:35 AM

For me it's not the undercuts, it's the blasted compression ring craze that popped up a few decades ago.

 

The issue with undercuts is with compression rings, undercuts were invented and gained traction largely before compression rings.  Compression rings came about because people worried about their eyepiece barrels getting scratched.  So now I have issues inserting and removing eyepieces because most of the available eyepiece holders have those things.

 

I'm not opposed to the compression ring itself.  It's the groove in the holder required to hold the ring.  I can't count how many times I've struggled to get an eyepiece into the holder because it catches on the groove *while inserting*.   For some reason, for example, my Lunt 60mm is really difficult to get my no-undercut plossls into, and constantly frustrates me as it catches on the compression ring groove.

 

I don't care about scratches on my eyepiece barrels.  Heck, we observe in the dark, right? :)  However, because some do, we have compression rings, and thus the double-whammy of eyepieces getting caught while inserting into a holder, as well as the undercuts catching on the way out.  

 

IMO, blame the compression ring craze, not the undercuts,  Set screws work just fine, but everybody seems to offer primarily compression rings these days, for what is arguably an aesthetics issue.


  • Starman1, Jon Isaacs, turtle86 and 1 other like this

#72 turtle86

turtle86

    Mr. Coffee

  • *****
  • Posts: 5149
  • Joined: 09 Oct 2006

Posted 21 July 2019 - 11:42 AM

 

 

These threads always amaze me.  Observing is a peaceful experience, a calming, a mediation. Things just don't bother me, I deal with what happens and I figure out how to address the various issues that arise. I don't think it takes a genius to figure out to insert and remove eyepieces with undercuts with relative ease, without disturbing the telescope.  

 

YMMV

 

Jon

 

waytogo.gif   Well said.  Sure, undercuts aren’t really needed with reflectors but are good to have with SCT’s and refractors, and it’s just not practical for manufacturers to sell eyepieces in two versions.

 

I personally have experienced little or no problems with undercuts.  To be, much bigger issues to deal with when observing are dew, light pollution, thermal management, and mosquitoes. lol.gif


  • Jon Isaacs, Albie, alnitak22 and 1 other like this

#73 turtle86

turtle86

    Mr. Coffee

  • *****
  • Posts: 5149
  • Joined: 09 Oct 2006

Posted 21 July 2019 - 11:50 AM

For me it's not the undercuts, it's the blasted compression ring craze that popped up a few decades ago.

 

The issue with undercuts is with compression rings, undercuts were invented and gained traction largely before compression rings.  Compression rings came about because people worried about their eyepiece barrels getting scratched.  So now I have issues inserting and removing eyepieces because most of the available eyepiece holders have those things.

 

I'm not opposed to the compression ring itself.  It's the groove in the holder required to hold the ring.  I can't count how many times I've struggled to get an eyepiece into the holder because it catches on the groove *while inserting*.   For some reason, for example, my Lunt 60mm is really difficult to get my no-undercut plossls into, and constantly frustrates me as it catches on the compression ring groove.

 

I don't care about scratches on my eyepiece barrels.  Heck, we observe in the dark, right? smile.gif  However, because some do, we have compression rings, and thus the double-whammy of eyepieces getting caught while inserting into a holder, as well as the undercuts catching on the way out.  

 

IMO, blame the compression ring craze, not the undercuts,  Set screws work just fine, but everybody seems to offer primarily compression rings these days, for what is arguably an aesthetics issue.

 

I agree. Just want to add that if nylon set screws are used, there are no worries about getting marks on the barrel.


  • Jon Isaacs likes this

#74 bbqediguana

bbqediguana

    Viking 1

  • *****
  • Posts: 887
  • Joined: 28 Feb 2015
  • Loc: Canada

Posted 21 July 2019 - 12:11 PM

Four of my six eyepieces have undercuts, yet I have never noticed any difference using any of them - and I have a compression ring eyepiece holder on my diagonal.

 

I have never experienced any issues or frustrations with undercuts. I am sure if I did, I would spent 5 minutes in my garage and figure out a solution.


  • turtle86 likes this

#75 Shorty Barlow

Shorty Barlow

    Viking 1

  • -----
  • Posts: 812
  • Joined: 15 Sep 2015
  • Loc: Lloegyr

Posted 21 July 2019 - 12:16 PM

I would spent 5 minutes in my garage and figure out a solution.

Be sure to patent it if you do. waytogo.gif


  • bbqediguana likes this


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


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics