Eyepiece/Adapter Catches

[Stargezzr]

I am a new member to SGL, but I have haunted your posts for many years, extracting valuable knowledge when it was posted.  I recently concluded a study of eyepiece barrel and adapter types to determine causes and possible solutions to the annoying catch that sometimes occurs during insertion or extraction of an eyepiece.  I think it might be helpful to some members here who have suffered with this issue.  The report is quite detailed and includes 4 tables of data and several images.  It is lengthy, but represents many hours of testing/reporting.  This was my opportunity to give back to your community.  I hope you find it of benefit.
 Cheers!  Ray... otherwise known as StargezzrE:A Compatibility Study PDF:S.pdf

[RT65CB-SWL]

Hi Ray and welcome to SGL. 

Downloaded and will have a read later. 

[John]

Welcome to the forum Ray

Thats got to be the most comprehensive piece on that topic that I've ever read !

Thanks for posting it.

[YKSE]

Welcome to SGL Ray   I've followed your comments on undercuts with great interest on CN, thanks very much for sharing your valuable work.

[laudropb]

Hello and a warm welcome to the SGL. That is a very full and comprehensive report you have prepared. You have put a lot of work into it and I found it very useful. Thanks for posting.

[Mak the Night]

Looks like this is a scoop for Skygazers as there is a waiting list to publish on CN from what I can gather. I am pleased to say that I contributed a little bit to your research when I replied to some of your questions on CN, although my username there is 'Shorty Barlow'. 

[John]

The CN forum have a very long thread running on this topic though - 300+ posts and some pretty strong views expressed.

[Stargezzr]

Thank you.  It's nice to be welcomed to another forum.  The report is going through the submission process at CN.  So it will be published in "User Reviews" after approval.  But that can take several weeks for an overburdened volunteer staff.  

The problem of catches plagued my observing for many years.  But having switched some components, I have eliminated frustrations associated with metal compression rings.  Catches that do occur with my 2" eyepieces and ClickLock equipped Baader diagonal are not nearly as severe as when using a diagonal with metal compression ring.  But all of my 1.25" eyepieces now slide in and out without a single catch... ever.  I previously considered using only 1.25" eyepieces for that very reason... if only my 2" eyepieces weren't so great!  But I also own an old, original style TV Everbrite dielectric diagonal with an aluminum, captive thumbscrew and no metal compression ring.  It also solves all problems with catches.  I'm grateful that I still own it.  

Manufacturers who read the study may decide to offer a high quality adapter with a single, non-maring thumbscrew and no compression ring... if there is a demand for it.  It seems like the perfect solution.  The eyepiece barrel undercut would actually serve a purpose again.  Eyepieces of all types could be used in a single adapter and there would be no catch during insertion or extraction.  It's a very simple and inexpensive remedy to the problem of catches.  Other solutions only relieve half of the problem or they complicate matters.  

[John]

I've not had problems with this myself during the 30+ years I've been observing but I read enough comments from others to realise that others do. If the manufacturers can come up with a simple and low cost solution or option then thats great.

[Stargezzr]

Hi, Shorty Barlow.  Yes you DID contribute.  I decided to complete the study because of postings on the very long CN thread.  I have put a link to this thread referencing the study... since SGL allows direct attachments.  I saw that there is possibility of a poll in certain areas of SGL.   It would be quite remarkable to add a 2-3 question poll to this thread, so that people who read the study could respond:

     1.  Have eyepiece insertion/extraction catches ever been a problem for you?

     2.  Is this a problem that manufacturers should address?

The CN forum has no polling mechanism.  So SGL could lead in gathering the needed information to prompt a manufacturer response.  Just a thought!

[Mak the Night]

Hi, Shorty Barlow.  Yes you DID contribute.  I decided to complete the study because of postings on the very long CN thread.  I have put a link to this thread referencing the study... since SGL allows direct attachments.  I saw that there is possibility of a poll in certain areas of SGL.   It would be quite remarkable to add a 2-3 question poll to this thread, so that people who read the study could respond:

     1.  Have eyepiece insertion/extraction catches ever been a problem for you?

     2.  Is this a problem that manufacturers should address?

The CN forum has no polling mechanism.  So SGL could lead in gathering the needed information to prompt a manufacturer response.  Just a thought!

Hi, GG. I've had a quick look through your PDF. It looks very comprehensive, I'm sure it will produce something positive with regards to the current situation. I think you've accurately assessed and identified the problems inherent with both compression rings and undercuts, and especially combinations of the two, that many experience. I wouldn't hold my breath for manufacturer responses quite yet though lol. Good luck. 

Shorty Barlow aka Mak the Night

[Mak the Night]

I've not had problems with this myself during the 30+ years I've been observing but I read enough comments from others to realise that others do. If the manufacturers can come up with a simple and low cost solution or option then thats great.

I've not had many real problems and wasn't too sure what all the invective was about. I think the problems arise with non-standardised undercut and compression ring combinations from different manufacturers. As virtually all of my eyepieces and Barlows are either Celestron or TeleVue, and only one of my diagonals has a compression ring, I just haven't really had any of the terrible hang ups and problems others have. 

[Stargezzr]

There is no debate that some equipment combinations produce smooth operation, free of catches; but some combinations produce really bad results.  I also found that ergonomics do play a role in catches.  I was able to produce catches intentionally; unfortunately, I could not eliminate them intentionally during the test.  physical limitations, depth perception, using gross muscle or fine motor skills, the angle of insertion all play into the number of catches that can distinguish the experience of one observer compared to another using the exact same equipment.  But my study really dealt with the physical/mechanical structure of catches during insertion or extraction... why they result and what can be done to eliminate them for all types of equipment and all observers, whether they are able bodied or physically disabled.  

If you are using a GEM mount, a catch does not create much of a problem because the telescope is held firmly.  Extracting an eyepiece, even if it takes extra seconds to remove, is OK because when you do insert the next eyepiece, the target is still in the FOV.  But if you are using a push-to Dob or manual Alt/Az mount, a catch can move the scope off target.  Or, it can take so long to get the eyepiece removed and another eyepiece inserted and re-focused that the target is lost.  When this happens repeatedly, frustrations grow exponentially.  I believe that is why opinion on this matter ranges from "not too interested" to "passionate."  If you use an alt/az mount that locks quickly to change eyepieces, the topic may be of little interest.  But my experience in using astronomy equipment leads me to believe that the issue of catches is one that deserves attention and a suitable remedy for those who are annoyed by catches.   And my years of service to my community taught me that what effects one member of a community today, can effect other members tomorrow.  Change focusers or telescopes, mounts or eyepieces, and the curse of the catch might fall upon you.  Or, as you age and lose coordination that blessed your youth, depth perception or motor skills because of illnesses like strokes or tragedy like accidents, the non-problem of a catch could become a more menacing factor.

I solved my problems with catches.  The study I conducted was designed to help others... to identify the problem, explain it, explain what others have done, including manufacturers who have tried to eliminate catches by modifying their equipment offerings, and by testing how those modifications actually perform.  I do not believe it impossible that a manufacturer might receive a link to this thread, read the study and decide that they should create a new, high quality adapter that performs perfectly with all eyepieces.  One of them might even be looking for this information.  After all, they are in business to make money, and a new, universal adapter designed to work with all styles of eyepiece barrels/undercuts would certainly be useful to us all. The study shows that some adapters do perform without catches on each of the eyepiece barrel types that were used in the testing process.  A successful adapter could be the first step in creating an industry standard.  A few standards have been established in the past; eyepiece barrel sizes went from .965" to 1.25"... what, only 40 years ago?       Maybe it's time for a few more standards in the industry.  

[cs1cjc]

Very thorough and useful.  

Many Thanks!

[Roy Challen]

Thank you for a fantastic study of this irritating problem, Ray. I fully agree that this is something that can be resolved and standardised by the manufacturers, solutions already exist- Baader ClickLock, spotting scopes use bayonet fittings, threaded barrels etc. That is actually what annoys me most about this, the solution already exists but manufacturers still insist on using silly little thumb screws and so called 'compression rings'.

As for marking barrels, well I for one buy equipment for use so over time it is inevitable that marks occur. So what? A few marks on the barrel really don't mean a thing as long as it was well looked after in general.

[alan potts]

Hi and a belated welcome.

I have had this problem and commented on it a few times. I now find no issues what so ever with my eyepieces being all Televue and diagonals and reducers likewise. The only place I find a problem now is with the Williams Optic diagonal and reducer I have in the piggyback scope on my 12 inch Meade. I don't tend to change the eyepiece in this very much so can live with it.

Chinese reducers and Televue don't seem to get on well so I have dumped them, Moonlite also work without problems.

Alan

[YKSE]

Ray,

I've just finished reading your study, very extensive tests with many well-known eyepieces and adapters, very insightful findings about causes of catches and bumps, and many doable solutions to resolve the catches. Many thanks again.

[Mak the Night]

Oddly, my Williams Optics diagonal works well with my TeleVue eyepieces and my TeleVue Barlows work well with my Williams Optics eyepieces. But many of my Celestron Plossls hang up in the WO diagonal and the TV gear. They all have older style undercuts. The hang ups can mostly be alleviated by techniques of insertion/extraction though.

[John]

..... The hang ups can mostly be alleviated by techniques of insertion/extraction though.

Yes, thats what I've found. I tend to use a gentle twisting motion as I remove an eyepiece. It's almost 2nd nature now.

[Mak the Night]

Yes, thats what I've found. I tend to use a gentle twisting motion as I remove an eyepiece. It's almost 2nd nature now.

Yes, I know what you mean. I didn't really think about dexterity/manipulation on insertion and extraction until reading some of Ray's thoughts on the matter before he posted his PDF here. Ray noticed that the way the eyepiece is held contributes a lot to the ease (or not) of insertion/removal. Grasping the eyepiece from its side (as opposed to its top) with thumb and multiple fingers as it is manipulated contributes hugely to successfully removing or inserting a particular eyepiece. It had become an adaptation that had virtually become second nature for me. Holding/grasping the eyepiece from its side most probably enables greater dexterity control, such as the gentle twisting motion you have described. For me, anyway, the only problems arise with combinations of eyepieces that have old-style 90° undercuts and adaptors (Barlow/diagonal) that have compression rings. 

[alan potts]

Mak the Night,

Having read what you have said I have checked out the WO diagonal on top of my Meade and found it has a Chinese reducer on it, I will get it switched back. I used the word dumped rather badly, they are infact in a box, dumped in the barn, not the bin.

Alan

[RT65CB-SWL]

After thoroughly reading this article, (best read off-line), it was good see that some manufacturers have taken note. As someone that has a mixed bag, (OK, mixed case), of eyepieces and accessories with or without the undercut does not seem to bother me at the present time.

That said though, on one of my TeleVue diagonals, I did over tighten the locking screw and the head of the thumbscrew came off much to my surprise when changing my 6mm Radian for my Nagler 3-6mm zoom. I had to wait until I returned home/indoors and find my mole-grips and carefully clamp them on to the thread without stripping it, (with the e/p still in situ), for when I replaced the thumbscrew head. I succeeded in freeing the e/p and not stripping the thread. I found my tube/bottle of superglue and applied a small drop to the female thread of the thumbscrew head and tightened it as far as it would go by hand before the superglue set. And today it is still secure.

message/note to self: DO NOT OVERTIGHTEN!

[Mak the Night]

Mak the Night,

Having read what you have said I have checked out the WO diagonal on top of my Meade and found it has a Chinese reducer on it, I will get it switched back. I used the word dumped rather badly, they are infact in a box, dumped in the barn, not the bin.

Alan

Tapered barrels, such as this WO eyepiece or gentler angles machined into the undercut as in the TeleVues below, seem to fair much better with compression rings.

But when the undercut has a more or less 90° angle as in these Celestron Omni eyepieces below, I find that there can be hang-ups with compression rings.

[Stargezzr]

There are many variables regarding catches or hang-ups caused during insertion or extraction.  A user's dexterity, how they grasp or manipulate the eyepiece, the angle of the focuser or diagonal, the brand of eyepiece and style of undercut, the brand of diagonal or adapter... or even the year of production within a given model... the list of variables is very long.  We all have different tolerance levels for small niggles like this; for some they just don't matter.  But if catches do bother a user, there are remedies/solutions, and that was the point of the study.  I think it was the details of the various parts involved in the testing that caught my attention.  Very small differences, such as the width of the exposed shoulders on a metal band compression ring adapter, revealed that tenths of a millimeter can make the difference between many or few catches.  Other details such as Tele Vue's switch from a captive thumbscrew to a removable thumbscrew has a bearing on the effectiveness of the bevel that they employ on new models.  The longer, steeper bevels on the ends of Pentax eyepieces certainly played a role in reducing insertion catches.  I did not consider the bevel at the end of the barrel much of an advantage until I completed the tests.  

I use a home built portable pier and alt/az mount to support my 5.5" refractor, so catches do effect my viewing when they occur.  I observe usually 2x weekly during 9 months of the year, less often when it gets colder during our rainy season (when we actually have rain here in drought-stricken California).  Eliminating catches for me was a pretty significant issue.  It didn't cost much and it has made my viewing so much more pleasant... similar to having a really good observing stool that suits my needs.

The adapter I had made of stainless steel was CAD designed to be a specific weight.  So it eliminated catches AND provides the perfect weight so that my 4 large 100* eyepieces used in 2" format and my 2-3 oz. orthos used with the adapter all fall within 4 oz. of each other... so, I am no longer concerned with scope balance on my alt/az mount.  

One thing I discovered on my adapter is that I preferred a synthetic thumbscrew.  They don't look particularly elegant, but they work really well.  I prepared a really nice stainless steel thumbscrew for use in the adapter, but it will probably never get used.  The plastic thumbscrew is a nice fit in the threads, offering just a tiny bit of resistance.  It works very smoothly, but it does not loosen on its own... it only loosens when I actually rotate it.  And if it ever does loosen from wear, it is very easily replaced at a hardware store or on-line (10 plastic thumbscrews for $3.50 or 100 for $8.90).  Making this small alteration also makes my viewing more enjoyable.. which means I'm more likely to observe.  

A slightly modified version of my report may be available on CN User Reviews as early as this week.  It will be titled, "There's a Catch!" 

Thank you all.  I intend to spend a little more time on SGL.