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Eyepiece Safety Undercuts - a Bad Idea From the Start

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#1 Rustler46

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Posted 19 July 2019 - 04:53 PM

Most experienced observers will agree that the ubiquitous "safety undercuts" on eyepieces are a poor solution to a perceived problem. The best solution to an eyepiece possibly falling out if one forgets to tighten it in the eyepiece holder is simple - don't forget to secure your valuable eyepiece. 

 

So now that virtually all eyepieces are supplied with some form of this bad idea, we are all dealing with its consequences. I suspect that few manufacturers would risk losing the beginner's eyepiece purchases by doing away with the undercut or tapered cut on the barrel.

 

Does anyone recollect when this bright idea first began to be offered? Once that was started it seems like all manufacturers were compelled to join in the parade.

 

Russ


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#2 John Fitzgerald

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Posted 19 July 2019 - 05:12 PM

Most experienced observers will agree that the ubiquitous "safety undercuts" on eyepieces are a poor solution to a perceived problem. The best solution to an eyepiece possibly falling out if one forgets to tighten it in the eyepiece holder is simple - don't forget to secure your valuable eyepiece. 

 

So now that virtually all eyepieces are supplied with some form of this bad idea, we are all dealing with its consequences. I suspect that few manufacturers would risk losing the beginner's eyepiece purchases by doing away with the undercut or tapered cut on the barrel.

 

Does anyone recollect when this bright idea first began to be offered? Once that was started it seems like all manufacturers were compelled to join in the parade.

 

Russ

I think, to my recollection, it began about 25 years ago.  I don't think manufacturers are interested in going back to smooth barrels.

 

Personally, I do not like undercuts or tapers either.


Edited by John Fitzgerald, 19 July 2019 - 05:13 PM.

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#3 lsfinn

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Posted 19 July 2019 - 05:19 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. 


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#4 Conaxian

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Posted 19 July 2019 - 05:28 PM

 The annoying part is how many turns of the thumbscrew it takes to change the eyepiece.

You unscrew it some, try to remove the EP, hit the screw and turn it some more...then the thumbscrew falls out.

I vote for straight barrels.  Dropping an eyepiece is the fault of the butter-fingered themselves. Don't do dat!


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#5 markb

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Posted 19 July 2019 - 05:38 PM

That time frame sounds right.

People loved barrel cuts when they came out. I think things really soured when the compression band eyepiece holders and so called centering clamp focusers started to show canting problems, particularly with the 'improved' taper cuts (absolutely the worse in my experience).

Compression band holders work extremely well in increasing eyepiece safety even with smooth barrels, without the safety-cut caused canting and multiple turns of thumbscrews for removal of eps with cuts.

Compression band holders on smooth barrels were a far better solution, but the timing of the innovations clashed.

Thank goodness the cuts are disappearing, but manufacturers need to spend a couple of bucks and eliminate thumbscrew-only visual backs too.

Incidentally, the Baader grooved-semi-smooth barrels appear problem free, and still offer some thunbscrew safety. See Short Barlow's great photos of the 'Safety Kerfs' in post #16, below.


Edited by markb, 20 July 2019 - 10:13 AM.

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#6 oldstargazer

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Posted 19 July 2019 - 05:47 PM

Best part about working with my C8. My camera is my EP and it along with everything else in the visual train screws together, not one undercut or setscrew to deal with. When I do use an actual EP, rare these days, mine are like me, they are old and they don't have any undercuts either. Some of my 2 inch to 1.25 inch adapters do have it, thankfully those just get installed on whatever scope I am using and doesn't have to be dealt with again.

 

I would hate to have all EPs with that on them, glad I won't be buying any, whatever I have is all that I am going to have.


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#7 TOMDEY

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Posted 19 July 2019 - 06:03 PM

Yeah, the undercuts were the stupidest idea since unsliced bread. Indeed, depending on the design of the undercut and of the eyepiece holder (most always different makes, models, brands...) the geometry matches wrong... worst case, literally capturing the eyepiece in there so it can't come out! Or the compression dingus doesn't properly index to the indeterminate eyepiece, etc. etc. Part of the problem is that a.r. amateurs don't want the slightest little mar in the chrome finish on their precious eyepieces. That cascaded forward to the plethora of focuser and eyepiece designs and no one (manufacturer of astronomer) knows what to design or expect.

 

So we practical guys put tape over the undercuts --- pretty much like permanently duct-taping the ~dead man bar~ to the handle of your lawn mower, the moment you pull it outa the box. The eyepiece designer genius who came up with the idea probably never even used a telescope, and assumed that amateur astronomers are idiots!    Tom

Attached Thumbnails

  • 248 Stupid Eyepiece Undercuts.jpg

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#8 lsfinn

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Posted 19 July 2019 - 06:18 PM

 The annoying part is how many turns of the thumbscrew it takes to change the eyepiece.

You unscrew it some, try to remove the EP, hit the screw and turn it some more...then the thumbscrew falls out.

I vote for straight barrels.  Dropping an eyepiece is the fault of the butter-fingered themselves. Don't do dat!

 

I guess I'm not as sensitive to a few more "turns of the screw" and have never had a set screw pop-out on me (at least, not for that reason). To the extent that I'm do find it occasionally annoying to have to loosen the screw a bit more, it is much less annoying to me than (the prospect of) an eyepiece or diagonal falling out onto the ground. I certainly wouldn't take any pleasure in seeing it happen to someone else, either. 

 

(At one point I look at the Baader quick-lock solution; however, I was a bit concern that its use would lose me too much in-focus in my 9.25 SCT.)



#9 Asbytec

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Posted 19 July 2019 - 06:31 PM

Yea, sometimes an eyepiece get's snagged on the undercut, so it makes me almost remove the set screw to ensure the undercut clears it. In reality, it's not like I storm off in a hussy because of those darn undercuts. I really pay them no mind. I do not always tighten the set screw, anyway. Maybe I should, but I don't. I have not dropped an eyepiece as far back as I can remember (but I did lose a set screw a few years ago, had a spare thankfully). No biggie, never understood the hatred for undercuts. Well, I understand, but I don't really understand why all the angst. I just use the eyepiece as is and kind of got used to pulling it out once or twice. Dumb idea, yea, maybe...to a perceived problem. 


Edited by Asbytec, 19 July 2019 - 06:34 PM.

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#10 payner

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Posted 19 July 2019 - 06:42 PM

That time frame sounds right.

People loved barrel cuts when they came out. I think things really soured when the compression band eyepiece holders and so called centering clamp focusers started to show canting problems, particularly with the 'improved' taper cuts (absolutely the worse in my experience).

Compression band holders work extremely well in increasing eyepiece safety even with smooth barrels, without the safety-cut caused canting and multiple turns of thumbscrews for removal of eps with cuts.

Compression band holders on smooth barrels were a far better solution, but the timing of the innovations clashed.

Thank goodness the cuts are disappearing, but manufacturers need to spend a couple of bucks and eliminate thumbscrew-only visual backs too.

Incidentally, the Baader grooved-semi-smooth barrels appear problem free, and still offer some thunbscrew safety.

Absolutely agree, collet holders and smooth barrels are the best solution.  Centers and tightly holds the eyepiece.  Now Takahashi has always (since I've been doing this anyway) implemented those designs into their eyepieces and prism diagonal.  Yet, the diagonal is the bane of never-ending complaints here. Why? Because people try to use them on "foreign" oculars, not because of poor prism quality.  In fact, the prism gets praised, yet the system just doesn't play nice with defective eyepieces.  

 

Stick with Tak eyepieces and diagonal and you'll have an experience as it was meant to be. <g>

 

Randy



#11 Scott99

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Posted 19 July 2019 - 06:54 PM

There IS interest from manufacturers in going back to smooth barrels - Takahashi eyepieces, Brandons, Masuyamas have them.  2nd run of Zeiss orthos was made with smooth barrels after the 1st run had grooves


Edited by Scott99, 20 July 2019 - 03:39 PM.


#12 csa/montana

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Posted 19 July 2019 - 07:15 PM

Moved to Eyepieces.


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#13 Stardust Dave

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Posted 19 July 2019 - 07:43 PM

Safety undercut + compression sleeves in paracorr barlow or focuser = a real nuisance.

I would say the undercut was as poor idea as the "instajust" feature.  



#14 213Cobra

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Posted 19 July 2019 - 07:43 PM

Truly a First World problem in the extreme. The world is on fire and this little corner of it obsesses over undercuts and tapers on eyepiecesrolleyes.gif

 

I've never had a problem with smooth barrels nor undercuts on eyepieces. It's just not that difficult to handle. I have both and use them with collets, click-locks and set screws. It's all the same to me.

 

Phil


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#15 Jon Isaacs

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Posted 19 July 2019 - 07:51 PM

Yea, sometimes an eyepiece get's snagged on the undercut, so it makes me almost remove the set screw to ensure the undercut clears it. In reality, it's not like I storm off in a hussy because of those darn undercuts. I really pay them no mind. I do not always tighten the set screw, anyway. Maybe I should, but I don't. I have not dropped an eyepiece as far back as I can remember (but I did lose a set screw a few years ago, had a spare thankfully). No biggie, never understood the hatred for undercuts. Well, I understand, but I don't really understand why all the angst. I just use the eyepiece as is and kind of got used to pulling it out once or twice. Dumb idea, yea, maybe...to a perceived problem. 

 

I am with Norme (and Phil) on this.  I rarely have difficulties swapping eyepieces with undercuts. I generally prefer nylon, brass or aluminum setscrews to a compression ring. I think the mix of a compression ring and an undercut is the real problem.. 

 

The only situation when I dislike undercuts is when I am using a finder scope without a focuser.  In this situation, I have some slight load on the set screw, I rotate and slide the eyepiece to focus,.. The edge of the undercut can really mess with focusing this way. The other night, I was able to split the double-double with my 70mm F/4.5 finder by slip-sliding the 3.5mm Nagler but that undercut made it extra tricky.

 

Jon



#16 Shorty Barlow

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Posted 19 July 2019 - 07:55 PM

GSO are slowly replacing their undercuts with smooth tubes. Which is odd, as their undercuts have lower lip tapers like TeleVue. I find these no problem. There is a trend away from undercuts.

 

Tapers or flares have their own problems, principally they can distort compression rings.

 

gallery_249298_10131_60034.jpg

 

Baader have introduced a new variation known as 'safety kerfs'.

 

gallery_249298_10131_691330.jpg

 

Although I was originally apprehensive about these barfs, sorry, kerfs they are surprisingly effective in use. 



#17 Migwan

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Posted 19 July 2019 - 07:59 PM

Yeah, the undercuts were the stupidest idea since unsliced bread. Indeed, depending on the design of the undercut and of the eyepiece holder (most always different makes, models, brands...) the geometry matches wrong... worst case, literally capturing the eyepiece in there so it can't come out! Or the compression dingus doesn't properly index to the indeterminate eyepiece, etc. etc. Part of the problem is that a.r. amateurs don't want the slightest little mar in the chrome finish on their precious eyepieces. That cascaded forward to the plethora of focuser and eyepiece designs and no one (manufacturer of astronomer) knows what to design or expect.

 

So we practical guys put tape over the undercuts --- pretty much like permanently duct-taping the ~dead man bar~ to the handle of your lawn mower, the moment you pull it outa the box. The eyepiece designer genius who came up with the idea probably never even used a telescope, and assumed that amateur astronomers are idiots!    Tom

The taped out undercut is waytogo.gif.  Going to try that.   But I love unsliced bread.  It always homemade and sometimes, fresh and warm.

 

jd



#18 alnitak22

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Posted 19 July 2019 - 08:12 PM

Truly a First World problem in the extreme. The world is on fire and this little corner of it obsesses over undercuts and tapers on eyepiecesrolleyes.gif

 

I've never had a problem with smooth barrels nor undercuts on eyepieces. It's just not that difficult to handle. I have both and use them with collets, click-locks and set screws. It's all the same to me.

 

Phil

Agree. Perhaps the largest tempest in the smallest teapot ever. Sheesh.


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#19 Jon Isaacs

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Posted 19 July 2019 - 08:40 PM

Safety undercut + compression sleeves in paracorr barlow or focuser = a real nuisance.

I would say the undercut was as poor idea as the "instajust" feature.  

Here is a story that could be worth reading:

 

My 13mm and 8m Ethos's are equipped with the TV extensions so they're 2 inchers.  This is all fine and dandy but the eyepiece barrels themselves have the notch for the setscrew. 

 

Exit the Paracorr type 1, Enter the Paracorr type 2.  

 

The Paracorr 2 allows the eyepiece to inserted somewhat deeper, deep enough that the compression ring rides on the eyepiece barrel and not the extension. In fact, it is exactly the right depth so it lines up perfectly with that cutout notch.  

 

Well, that is what happened the very first night I was using my new Paracorr 2.  

 

And when that happens, tightening down the set screw deforms the compression ring into the notch.. and brass, being relatively ductile, it does not spring back.. 

 

That eyepiece was stuck, the brass had the eyepiece trapped.  At first I didn't understand what had happened but when I got the whole shebang under a bright light, I realized what the problem was and I realized the solution, unscrew the eyepiece from the extension tube, this releases the eyepiece. 

Then remove the deformed compression ring and toss it in the trash.  This releases the extension tube.  

 

Final step, replace the setscrews with either brass or nylon.  I had some 10x32 brass thumb screws in my spare parts so I used those for about 2 years. I recently found a surplus store that had thousands of 10x32 nylon thumb screws and I was able to buy about 18 of them for a dollar so now I've got Nylon Thumbscrews in my Paracorr 2.  

 

If the eyepieces hang up on the thumbscrews, I know what has happened and I just back the screws out.

 

Jon


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#20 TOMDEY

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Posted 19 July 2019 - 09:13 PM

The taped out undercut is waytogo.gif.  Going to try that.   But I love unsliced bread.  It always homemade and sometimes, fresh and warm.

 

jd

Actually... me too! I refuse to buy sliced bread, get the warm loaf and pay up for the privilege of cutting it myself... (actually, telling my wife to cut it, precisely 3/4-inch thick).    Tom


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#21 TOMDEY

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Posted 19 July 2019 - 09:33 PM

Truly a First World problem in the extreme. The world is on fire and this little corner of it obsesses over undercuts and tapers on eyepiecesrolleyes.gif

I've never had a problem with smooth barrels nor undercuts on eyepieces. It's just not that difficult to handle. I have both and use them with collets, click-locks and set screws. It's all the same to me.

Phil

Hi, Phil; you'd be surprised! When I was roaming the jungles of Panama (Atlantic side) collecting insects. The friendly care-free locals actually started complaining about... of all things... eyepiece undercuts?! That quite startled me, but sometimes we don't credit these folks with being as ~advanced~ as we rich Americans. Here's the set-up: You're out in the field, eyepiece in there nice... observing... and decide to go a step up in magnification. Only to find that the eyepiece is hopelessly stuck in the hole?! That particular eyepiece in that particular focuser... and the compression ring is hung up under the undercut and just no way to extract it. So, out comes the flashlight and tool kit and have to dismember the tail end of the telescope to destructively remove it. At that point... I, you, anyone --- would tape up all of his undercut eyepieces and never look back. And, the natives agreed, "fuerte malo" or some such exclamation.    Tom


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#22 Jeff Morgan

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Posted 19 July 2019 - 10:28 PM

Most experienced observers will agree that the ubiquitous "safety undercuts" on eyepieces are a poor solution to a perceived problem. The best solution to an eyepiece possibly falling out if one forgets to tighten it in the eyepiece holder is simple - don't forget to secure your valuable eyepiece. 

 

So now that virtually all eyepieces are supplied with some form of this bad idea, we are all dealing with its consequences. I suspect that few manufacturers would risk losing the beginner's eyepiece purchases by doing away with the undercut or tapered cut on the barrel.

 

Does anyone recollect when this bright idea first began to be offered? Once that was started it seems like all manufacturers were compelled to join in the parade.

 

Russ

 

Ah yes, the Undercut Defect ... a Solution in desperate search of a Problem.

 

Worse yet a Solution that was obviously not tested to any meaningful degree.

 

But we are stuck with it for another generation at least, so we have make the best of it.

 

Tape can be effective to correct the Undercut Defect. Tape is subject to wear, and will have to be replaced with a frequency that depends upon how heavily the eyepiece is used. Maybe once a season for a workhorse eyepiece. I have used TrimBrite automotive tape. It has a mylar substrate. There are also metallic tapes available.

 

Recently I bought a Baader BBHS diagonal with ClickLock and I must say it is an incredible design (leave it to the Germans to put a real mechanical engineer on the problem and get it right).

 

I un-taped my 27 Panoptic for testing, and the Undercut Defect does not appear to snag in the ClickLock. I tried to make it snag, it just doesn't want to. The ClickLock was also effective on my tapered barrel 40mm Paragon. And as you might expect, flawless with a smooth barrel device (my Starlight Instruments Leica adapter).

 

The ClickLock is very secure too. When locked it takes a large effort (as in adult male strength) to pull an eyepiece free from the mechanism. And even then, no wear marks on diagonal or eyepiece. In hindsight, I am lucky my rapidly escalating impromptu test did not separate the ClickLock collet from the diagonal body. I am quite satisfied as to the security of the device - and not taking that chance again.

 

I was so impressed with the ClickLock I ordered one for the drawtube on my Astro-Physics focuser, one for my Takahashi Epsilon, and the ClickLock adapter for my 1.25" eyepieces. Two FeatherTouch focusers left to go in next months budget ...


Edited by Jeff Morgan, 19 July 2019 - 10:30 PM.

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#23 Peter Besenbruch

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Posted 19 July 2019 - 10:53 PM

Count me in with the people who dislike these undercuts. So I tape them. Time to re-post this:

 

eyepiece-tape.jpg


Edited by Peter Besenbruch, 19 July 2019 - 10:54 PM.


#24 Asbytec

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Posted 19 July 2019 - 11:12 PM

...and brass, being relatively ductile, it does not spring back.

 

 

...and the compression ring is hung up under the undercut and just no way to extract it.

 

 

So far, no jammed compression rings here. Keeping my dedos cruzados. smile.gif


Edited by Asbytec, 19 July 2019 - 11:16 PM.


#25 NorthernlatAK

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Posted 19 July 2019 - 11:21 PM

I like the Morpheus solution, the "safety kerf". It locks in nice with the screw and doesn't snag. The ep is very secure in the focuser.
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