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Eyepiece Safety Undercuts - a Bad Idea From the Start

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#101 N3p

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Posted 22 July 2019 - 11:42 AM

I like the ES tapered barrels with an extension tube and nylon thumbscrews instead of metallic thumbscrews . I find them strong more then enough and they are not damaging the eyepiece. With my GEM mount I often need to position the eyepiece pointing the floor in order to pivot the tube, for that reason, I appreciate the security of the tapered barrel. (Very much)

 

ES eyepieces  +  a standard extension tube with nylon screws is waytogo.gif  for me.


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#102 Starman1

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Posted 22 July 2019 - 02:00 PM

Don, do you then recommend a Clicklock for collimating a Newtonian with a 2" HG laser & Tublug.

Only if the eyepieces will be used in it as well.  

It makes no sense to obsess over centering the collimation tools only to have the eyepieces be shoved off center.

BUT:

The collimation tools can be slightly off-center like the eyepieces with no issues.

The tiny amount of off-center error is not a problem for an eyepiece.

It is an issue for the coma corrector, but the degree of error introduced is not likely to ever be visible.

The tolerable error, with a coma corrector like the Paracorr II, at f/4 is in the neighborhood of 0.13mm (0.005"), and larger at longer f/ratios, and the amount the eyepieces and tools will get shoved off center are likely in the 0.002-0.0025" range with a loose fit.

So, not a problem.  Invisible in use, in other words.

What's the expression?: a mountain out of a molehill.

 

So, while I like the Baader Clicklock for many reasons, it is not essential to either collimation or coma corrector use.

 

Tilt is a different issue, but that is not what we are talking about in terms of centering.


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#103 Pezdragon

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Posted 22 July 2019 - 02:41 PM

The idea of a "sled" focuser, which moves the secondary and eyepiece back and forth, is not new, but dates back a long time.

Celestron had such a focuser on scopes in the '80s, and amateurs had used the idea on scopes decades before that.

The primary engineering problem is maintaining collimation as the sled moves back and forth.

That’s true. I was able to engineer/ build my sled to move with a silky smoothness with absolutely no wobble that could affect collimation. The secondary stalk is 1.5” wide and made from fired alumina ( Al2o3) that is crazy rigid. 


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#104 REC

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Posted 22 July 2019 - 03:03 PM

Well, at least ES did not use them, but why the tapered barrel. The one that got it right was Brandon. They fit my holder like a glove. Hardy have to tighten them.


Edited by REC, 22 July 2019 - 03:03 PM.

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#105 Starman1

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Posted 22 July 2019 - 03:28 PM

The tapered barrel offers 2 beneficial features for the thumbscrew that presses directly on the eyepiece:

--the thumbscrew can be loose, yet the eyepiece cannot fall out.

--the tightening of the thumbscrew actually forces the eyepiece down into the focuser for a flat contact.

See post #101.

 

The tapered barrel is not compatible with brass split-ring binders or twist lock or click lock binders

unless the pressure pieces inside the binding mechanism are wide enough to span the gap across the entire conical undercut

and press against the section of smooth barrel above AND below the conical taper.

This may or may not be the case.  If the split ring presses into the conical taper, it can distort permanently, which is why ES uses stainless steel in their split-ring binders.

Even then, this type of eyepiece is best used with a simple thumbscrew.

Again, see post #101.

This can be accomplished easily by simply removing the split ring and using nylon screws or metal screws with nylon tips.


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#106 Rustler46

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Posted 22 July 2019 - 03:38 PM

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.  

Yeah, Jon I've had that same experience with my Baader T2 diagonal rotating in a conventional compression ring visual back on a SCT. This is a particular problem with a bino-viewer turned to a convenient viewing angle. The little set screw just couldn't be tightened enough to hold against the imbalance. If it did then the visual back would just unscrew from the SCT rear port. The solution? - Baader ClickLock. Also I continue to tether my expensive BV with a nylon cord attached to a convenient tie point on the OTA. If all else fails, it won't fall all the way to the ground.

 

I also agree that one just does what's necessary to exchange eyepieces when there's an issue with undercut/tapercut, etc. The same holds true for lack of undercut/tapercut on an eyepiece barrel. The "genius" solution is to make sure you tighten the clamping device (set screw or brass clamp) enough to hold the eyepiece from dropping. Sure, YMMV.


Edited by Rustler46, 22 July 2019 - 03:40 PM.

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#107 Rustler46

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Posted 22 July 2019 - 03:57 PM

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, in retrospect I wish I had titled this thread Eyepiece Safety Undercuts - a Bad Idea From the Start??

 

Personally, I have little problem with eyepiece undercuts, definitely not frustrated. Why? Most of my eyepieces were purchased when all barrels were smooth. But the experience of others varies in dealing with the undercuts. 

 

Yeah, I'm sure this issue has been discussed many times before in various threads. My reason for starting this thread was not to beat a dead horse. BeatingADeadHorse.gif   

 

It was to help others have a more enjoyable experience with their telescope. Dobsonian.gif sct.png Telescope.gif  smile.gif

I'm sure that is a goal that we can all appreciate. Perhaps newcomers can benefit from a repeat discussion of the issues and the solutions that have been offered. Your own contributions are a good example of that. Yes, YMMV for sure!

 

Best Regards,

Russ


Edited by Rustler46, 22 July 2019 - 04:43 PM.


#108 Jon Isaacs

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Posted 23 July 2019 - 03:07 AM

Jon, in retrospect I wish I had titled this thread Eyepiece Safety Undercuts - a Bad Idea From the Start??

 

Personally, I have little problem with eyepiece undercuts, definitely not frustrated. Why? Most of my eyepieces were purchased when all barrels were smooth. But the experience of others varies in dealing with the undercuts. 

 

Yeah, I'm sure this issue has been discussed many times before in various threads. My reason for starting this thread was not to beat a dead horse. BeatingADeadHorse.gif   

 

It was to help others have a more enjoyable experience with their telescope. Dobsonian.gif sct.png Telescope.gif  smile.gif

I'm sure that is a goal that we can all appreciate. Perhaps newcomers can benefit from a repeat discussion of the issues and the solutions that have been offered. Your own contributions are a good example of that. Yes, YMMV for sure!

,

Best Regards,

Russ

 

Russ:

 

I had that same thought, if it had been posed as a question, it would have been better.

 

I believe starting such a thread with neutral or positive tone results in a more constructive.

 

"Your tricks for dealing with eyepiece undercuts"  or "Understanding undercuts and how to live with them."

 

I am not a big fan of undercuts but I think there's a place for them and they are a fail safe, they do not depend on sufficient friction/tightness to prevent an eyepiece or diagonal from falling. Tightening on a straight barrel is not necessarily enough.

 

Back when I had my 12.5 inch RG, sometimes to focuser would be pointed down and undercuts provided some sense of security.  With any scope on an equatorial mount, the eyepiece can end up aim at the ground.

 

This is discussion reminds me of discussions in biking forums about "lawyer lips."  Lawyer lips are little tabs on the front fork of a bicycle that prevent the front wheel from falling out if the wheel nuts or quick release is not tightened sufficiently.. The addition was reputedly made after a law suit over a front wheel that feel out.

 

A front wheel falling out is potentially more dangerous that trashing a Nagler 31 but some disliked the few added seconds it required to change the wheel..

 

Jon


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#109 Rustler46

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Posted 23 July 2019 - 04:01 AM

Russ:

 

I had that same thought, if it had been posed as a question, it would have been better.

 

I believe starting such a thread with neutral or positive tone results in a more constructive.

 

"Your tricks for dealing with eyepiece undercuts"  or "Understanding undercuts and how to live with them."

 

I am not a big fan of undercuts but I think there's a place for them and they are a fail safe, they do not depend on sufficient friction/tightness to prevent an eyepiece or diagonal from falling. Tightening on a straight barrel is not necessarily enough.

 

Back when I had my 12.5 inch RG, sometimes to focuser would be pointed down and undercuts provided some sense of security.  With any scope on an equatorial mount, the eyepiece can end up aim at the ground.

 

This is discussion reminds me of discussions in biking forums about "lawyer lips."  Lawyer lips are little tabs on the front fork of a bicycle that prevent the front wheel from falling out if the wheel nuts or quick release is not tightened sufficiently.. The addition was reputedly made after a law suit over a front wheel that feel out.

 

A front wheel falling out is potentially more dangerous that trashing a Nagler 31 but some disliked the few added seconds it required to change the wheel..

 

Jon, after I re-read my original post, I wish it had been written differently. My initial statement was certainly not neutral and didn't have a positive tone. So in that regard I see the wisdom of a more constructive start to a discussion. Not only that, my own experience has been quite limited with undercut eyepieces. So my original statements were colored by ignorance of the issues the undercuts addressed. But I've learned a lot from the contributions of those who responded. Yes, it has been interesting to see the different the experiences many have had.

 

Your mention of the "lawyer lips" on bicycles shows how well-intentioned laws can have unintended consequences. Some years ago there was a requirement that plastic gasoline containers had a "spill-roof" valve on the output nozzle. I soon learned that the design almost ensured that a spill of gasoline would occur. I have discarded all the government mandated "improved" versions and purchased aftermarket, straight output nozzles. With reasonable care, no spills occur. That has been my experience. Yet I wouldn't be surprised if others have found the "spill-proof" design works great. So go figure.

 

YMMV.

 

All the Best,

Russ


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#110 John Fitzgerald

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Posted 23 July 2019 - 09:45 AM

We could start a heated oto discussion on lawyer lugs and gas cans.

 

Last night I changed eyepieces a few times between WO Uwan, Pentax, and TMB, and did not disturb the scope if I was careful, backed out the ring pushing screw extra, and wiggled the eyepiece slightly.  I did end up a few times with the eyepiece upside down when slewing the scope around (by hand).  I still carefully tighten all the screws even with the undercuts.   Most of my eyepieces have them in some form or other.  I use a TV heavy brass 2 inch to 1.25 adapter most of the time and it seems to hang less than most.   I got it from Agena.



#111 Jeff Morgan

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Posted 23 July 2019 - 10:37 AM

I wish it had been written differently. My initial statement was certainly not neutral and didn't have a positive tone. So in that regard I see the wisdom of a more constructive start to a discussion. 

 

You shouldn't lose too much sleep over it. Wherever it originated, it was a poorly conceived idea that has turned out to be deeply unpopular with a majority of users. The dislike comments were inevitable.

 

On the brighter side, the techniques needed to remedy the defect did come out. While many think this is yet another re-hash (certainly several dozen by now), us old-timers need to remember that as newer people come into the hobby they will encounter this problem for the first time, making it a new problem to them.

 

I don't recall it mentioned, but there was a lengthy CloudyNights article on this topic:

 

https://www.cloudyni...s-a-catch-r3022


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#112 csrlice12

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Posted 23 July 2019 - 10:58 AM

While I prefer smooth barrels.....if the thought of eyepieces falling out of your focuser bothers you....use superglue and experience the eyepiece hangup others describe....or, maybe its a conspiracy by diagonal and focuser manufacturers to get you to buy more equipment?

 

OR...use alt/az mounts and skip the superglue...at least then the most that will happen is needing to cut the diagonal off the eyepiece.


Edited by csrlice12, 23 July 2019 - 11:03 AM.


#113 nicoledoula

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Posted 23 July 2019 - 12:29 PM

GSO has responded to consumer demand and all GSO accessories with undercuts have been replaced with smooth barrels, from plossl's to diagonals. Now I wish they'd make some corrected widefield's and maybe jump (back) into the refractor market.


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#114 REC

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Posted 23 July 2019 - 12:39 PM

Yeah, Jon I've had that same experience with my Baader T2 diagonal rotating in a conventional compression ring visual back on a SCT. This is a particular problem with a bino-viewer turned to a convenient viewing angle. The little set screw just couldn't be tightened enough to hold against the imbalance. If it did then the visual back would just unscrew from the SCT rear port. The solution? - Baader ClickLock. Also I continue to tether my expensive BV with a nylon cord attached to a convenient tie point on the OTA. If all else fails, it won't fall all the way to the ground.

 

I also agree that one just does what's necessary to exchange eyepieces when there's an issue with undercut/tapercut, etc. The same holds true for lack of undercut/tapercut on an eyepiece barrel. The "genius" solution is to make sure you tighten the clamping device (set screw or brass clamp) enough to hold the eyepiece from dropping. Sure, YMMV.

Yeah, tapers can be an issue win BV/s as you mention. That is why I never paired up and of my ES eyepieces.  Good idea on the tether cord!



#115 CounterWeight

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Posted 23 July 2019 - 01:05 PM

Just saw this thread, i was one of the original complainers about it.  When needed, I just use a layer of paper and wrap foil tape to fill the undercut.  The first ones I did with just foil tape but then when selling it took too long to remove the sticky, so decided on present solution.  Not perfect but does the job.


Edited by CounterWeight, 23 July 2019 - 01:06 PM.

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#116 Scott99

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Posted 04 September 2019 - 11:39 AM

Here is a company that has switched from undercut barrels to smooth ones - and they offer smooth barrels for owners of older ones - bravo!  Now why do the other companies charging 3x the money refuse to listen to their customer base?   

 

https://agenaastro.c...?q=gso eyepiece



#117 Starman1

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Posted 04 September 2019 - 01:20 PM

Simple math:

1) More inexpensive eyepieces are sold, so there is faster turnover.

2) An inexpensive eyepiece made in China has a lower cost to the barrel than an expensive eyepiece from Taiwan or Japan,

so scrapping a number of barrels has a lower effect on the profit margin.

3) American distributors have a significantly lower inventory of the inexpensive eyepieces, both in units and dollars, so maintaining a dual inventory 

doesn't increase the inventory costs significantly.

4) Changing the barrels would not please a number of the current or future owners of the eyepieces and high-end companies cannot afford to alienate potential customers.

It's my feeling that there are a small number of intensely vocal critics but that we don't represent the majority of the marketplace.

5) If the inventory maintained in the US is large, then the labor cost of switching the barrels, coupled with the cost of the barrels themselves, might be prohibitive.

High end companies are fighting for market share anyway.  They don't want to raise the price $100 to offer a smooth barrel.

6) If some of the high end companies switched, it would be an admission the older design was inferior.  That would plummet the value of the company's products,

both in the used and new markets.

7) A significant portion of the market, most notably the low end of scopes, does not have any type of eyepiece binder other than a thumbscrew.

This portion of the market is quite compatible with undercuts, whether cylindrical or conical.  Switching for this part of the market would be undesirable.

 

It is really easy to see why some companies can't switch back to smooth barrels.  Indeed. modifications to the undercuts can help.

But, that doesn't excuse those companies for introducing new lines of eyepieces, especially small, lightweight eyepieces, with the same undercuts as their older and larger eyepieces.

TeleVue could have eliminated undercuts in the Delite line.  ES could have eliminated the undercuts in the 52° series.

That isn't admitting there is a problem with undercuts; merely an acknowledgement they aren't needed for all eyepieces.

 

In the meantime, a collet style holder that is wide enough to span across the undercut and engage enough eyepiece barrel on each side is probably a reasonable solution.

I used eyepieces with undercuts in just such an adapter, and they slide in and out easily with no snags.


Edited by Starman1, 04 September 2019 - 01:20 PM.

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#118 Jeff Morgan

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Posted 04 September 2019 - 03:21 PM

I'll second the collet recommendation. I have been using the Baader ClickLock and it virtual eliminates snags on my 27 Panoptic. I picked up the 1.25" collet adapter and tested it on a Pentax 3.5 XW, zero snags.

 

Collets may not be for everyone, but I'm really liking the Baader approach. Fast. Secure. And most importantly, it works.

 

I still have two FeatherTouch focusers that are unable to use ClickLock, I'll be talking with Wayne at Starlight over the winter about correcting that. 


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#119 CrazyPanda

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Posted 04 September 2019 - 03:44 PM

I've wanted to see something like a tension lever similar to this:

 

https://i.ytimg.com/...xresdefault.jpg

 

Put the eyepiece in, flip the tab down, and it engages a full-length compression sleeve. The compression sleeve would be analogous to a compression ring, but would be approximately 1.5" long so as to ensure that there is nothing for the undercut to be caught on, ever.

 

The lever would make it very easy to engage/disengage, such that when disengaged, it would be *guaranteed* that there is no more force being applied to the barrel, and it can be removed easily.

This would only really work as an adapter in a 2" focuser, but a premium focuser company could either build an oversized 2.5" focuser and then sell adapters that can do this, or just build it directly into the focuser drawtube.

 

Alternatively, if you're going to go with a larger focuser, that company could just sell simple smooth adapters designed to slip over the barrels of your 2" eyepieces to permanently correct the undercut.


Edited by CrazyPanda, 04 September 2019 - 06:11 PM.

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#120 Scott99

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Posted 04 September 2019 - 03:55 PM

So the list for smooth barrels currently in production has grown - did I miss any??  You can find just about any type of eyepiece for all budgets now....progress!

 

All of these companies make at least some of their ep's without the notch:

 

Takahashi

Masuyama

GSO

APM

Brandon

KK/Fujiyama orthos

Edmund RKE

Seibert Optics

ATC (EU only)

Explore Scientific*

 

* - tapered barrel (not quite smooth but at least it won't move your alt-az scope off the target)


Edited by Scott99, 04 September 2019 - 04:03 PM.


#121 Starman1

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Posted 04 September 2019 - 05:31 PM

And Vixen (SLV)

Baader (Morpheus)

 

The tapered undercut of the ES/William Optics/APM et al. is not compatible with brass split ring binding

or shorter collets.  It's still an undercut, though it works very well with 1-2 thumbscrews pressing directly on the barrel.



#122 Jeff Morgan

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Posted 04 September 2019 - 10:25 PM

I've wanted to see something like a tension lever similar to this:

 

https://i.ytimg.com/...xresdefault.jpg

 

Put the eyepiece in, flip the tab down, and it engages a full-length compression sleeve. The compression sleeve would be analogous to a compression ring, but would be approximately 1.5" long so as to ensure that there is nothing for the undercut to be caught on, ever.

 

The lever would make it very easy to engage/disengage, such that when disengaged, it would be *guaranteed* that there is no more force being applied to the barrel, and it can be removed easily.

 

In my experience so far, the lever is not strictly necessary (on the Baader).

 

The ring has a pretty grippy ring on it. About half the time I use it, the other half I use the lever. (Often I am reaching without looking directly at it.) No preference has developed yet. Time will tell.

 

The motion is rotation, very short too.


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