Don Pensack

The amount the Parallizer is shoved sideways in the focuser matches the amount of sideways movement the other way by the thumbscrew in the Parallizer, so it is centered.

I wrote some illustrated instructions for the use of the Parallizer.

The Howie Glatter Parallizer.docx

Some, but not all, eyepieces or accessories with undercuts are a problem and some aren't.

My Paracorr's adapter was incredibly hard to remove from the Paracorr if tipped even an extremely small amount,

which proved to be a sure thing in the field.  The 2" eyepieces were not hard to insert or remove.

Neither were 1.25" eyepieces in the adapter.  But that adapter would sometimes need a lot of wiggling and pulling

to get it to come out, even with the thumbscrews backed out all the way.

I filled in the undercut with metal tape and the problem simply disappeared.  

Inserting and removing is now a matter of one second and there is no catching going in or coming out.

That is the difference a smooth barrel makes.

You guys who have no problems with undercuts are lucky--you just haven't gotten one of the problem fits that would cause you to curse.

I remember back when no eyepieces had undercuts, and inserting and removing eyepieces was incredibly easy.

You loosened the thumbscrew 1/32 turn and out slid the eyepiece.

Now, you do the same and, in the process of pulling the eyepiece out, it catches.  So you loosen the thumbscrew(s) some more, and try to remove the eyepiece and it STILL catches.

Now you've unscrewed the thumbscrews a full turn or more and the eyepiece STILL catches.  Finally, you loosen a screw so much it falls out on the ground

and the eyepiece is still stuck.  So you wiggle it back and forth a lot and you finally find a point where the eyepiece forces the brass split ring back in its groove

and the eyepiece starts sliding out, only to catch a tad on the opening of the focuser as the bottom of the safety groove catches on the lip at the opening.

I don't know why, but I always seem to get those problem children.  It's no better when inserting the eyepieces, either.  They tend to bump and slightly catch going in as well.

4 of my 12 eyepieces have undercut grooves (8 don't), and those 4 are always a problem putting in or taking out.

Here is something interesting: The Paracorr has a smooth side without an undercut. But the inside of the top has 4 grooves an eyepiece can bump on going in.

And though the 6mm and 8mm Ethos eyepieces have undercuts in their 2" skirts, their 1.25" barrels are smooth.  And, used as 1.25" eyepieces, they slide into and out of the adapter without issue.

I feel like Job.  My life has been filled with wars, economic chaos, a pandemic, cancers, and injury.  I just want to live out the few years I have left without the plague of undercuts on eyepieces.😆

Unfortunately, there are a lot of 1.25" eyepieces that don't work in the Parallizer adapter.

If the upper barrel protrudes sideways enough to stick out beyond the adapter, the eyepiece hits the thumbscrew,

which is angled up at a 45° angle.

There is at least one person here who machined off the top of the Parallizer to make it flat and installed his own thumbscrew 90° to the bore.

If the eyepiece does not hit the thumbscrew, though, there is no better adapter.

No, it's not a collet, merely a mechanical way to press the brass split ring into the eyepiece.

5 hours ago, Louis D said:

Brass is barely heavier than SS, especially as either compared to aluminum or delrin.  However, SS could be made with thinner walls than brass to yield similar strength characteristics.  In that case, it would definitely be lighter overall than brass.

I guess you haven't seen all the nice SS jewelry coming out of China lately.  I've bought quite a few bands and faux gemstone rings through ebay for cheap, and the SS they're using takes a very high polish and doesn't seem to tarnish at all in my experience.  It's a different "whiteness" from sterling silver, but still quite mirror-like.

Interesting.  My wedding ring is made from Silicon Carbide and is heavier than gold.

I have a couple other rings made from titanium and they, too, have a high polish.

There are a lot of materials that eyepiece barrels could be made from, but aluminum is still the most practical because of low weight and low cost.

Speaking of lightweight, imagine beryllium or magnesium as a material--talk about light.

1 hour ago, Louis D said:

It appears that the TV Apollo 11 also comes with a 2" sleeve:

Maybe it would have been $50 cheaper without it?

Possibly, since only 300 were made (no economy of scale).

It points out that a dual-size eyepiece should have a removable skirt if the eyepiece can be used as a 1.25".

6 hours ago, markse68 said:

why don’t premium eps use stainless steel for the nose piece instead of the traditional plated brass? would be much more durable.

Mark

Stainless steel doesn't have that shiny chrome look, though.

The Stellarvue Optimus eyepieces do have stainless steel lower barrels, and they are not unique.

However, as a result, they are a lot heavier than the all-aluminum APM versions of the same eyepieces.

6 hours ago, John said:

The Ethos SX 4.7 and 3.7 use just that approach as well. I was using my 4.7 last night and it's a great high power eyepiece with my 12 inch dob

I could see that a smooth 2 inch barrel option could be provided at a reasonable cost.

For 1.25 inch eyepieces (eg: the Panoptics that @JeremyS pictures it's more difficult unless folks simply add a smooth sided 1.25 - 2 inch adapter and leave it on the eyepiece. Something like this:

https://www.firstlightoptics.com/adapters/moonlite-2-to-125-low-profile-eyepiece-adapter.html

 

 

There are a number of smooth-sided adapters out there, some of which don't require the slit in the focuser like the Moonlite.

The new 7mm APM XWA eyepiece has a threaded on 2" adapter with smooth sides, and the 1.25" barrel underneath is also smooth sided.

But that could be done because it was a new eyepiece and was ordered that way.

6 hours ago, JeremyS said:

Thank Don. I was thinking I’d be prepared to pay 10% extra for another barrel, or £50, which I would fit if they were simply screw fit

Do you know when and why they changed the design of the barrel undercuts?

Also, I notice the barrel of my Pan 24 has tarnished a little. I’ve noted other people make this comment (can’t remember which TV EP). Do you know why this is? All stored in same way in same case. The Pan is the oldest.

The tapered edge to the bottom lip of the undercut was several years ago, though I couldn't tell you exactly when.

They did so to get the eyepiece to remove a little easier by shoving the brass split ring aside on removal and to get around the lip above the brass split ring.

TeleVue lower barrels have been chrome plated brass for a long time, and chrome is usually put on top of nickel to adhere better.  Nickel will dull with time, and, if the chrome plating is very thin,

may cause the surface to dull, perhaps irregularly.  You might try a little jeweler's polishing rouge (aka Simichrome polish) to buff it up if you want.

TeleVue said that they had a few reasons for not wanting to offer smooth barrels for the eyepieces as an option:

--the barrels were expensive--about $50 at their cost in the volume they contemplated

--a large number of different barrel sizes and shapes

--they didn't have enough manpower in the office to do the switch--especially if it proved popular

--it would be a marketing admission that not everyone liked the undercuts

--it might result in more damaged eyepieces, which could tarnish their reputation (though, I would argue, not any more than the undercuts in the first place)

Reasons 3 and 4 are why they couldn't switch back, either, in addition to:

--making old stock, a lot of which is at the dealers, obsolete or less desirable

--meaning they would have to have double inventory if the smooth barreled versions came from the factory, which they couldn't afford

--meaning the dealers would have to carry dual inventory as well if some people preferred the undercuts (and some people do).

So, we aren't going to see the disappearance of undercuts in eyepiece barrels.  But at least an attempt was made to modify the undercuts to make the eyepieces easier to remove.

That still leaves the incompatibility problem.  Brass split rings, collets, et al.  are designed to hold smooth barrels securely.  Undercuts (cylindrical or conically tapered) are designed to work best with thumb screws.

If you see the issues, then you can do what I did--simply use thumbscrews and leave marks (or use nylon or nylon tipped thumbscrews), or look for smooth barrels (not many of them, though).

16 hours ago, Louis D said:

And your point is what?  I never claimed they were.  Besides, the AF70 is available under other brands in Europe.  The B&L eyepieces were long since discontinued when I bought them off ebay 15 years ago, so the point is moot with them.  They're probably 1960s or 1970s vintage.  The 17mm NT4 was just discontinued and is still listed as in stock a few places.

Sorry, the only point was that comparing discontinued eyepieces for edge sharpness that are not available for purchase is useful information only to the purchaser of used eyepieces.

You're right, though, that there are probably 17mm Naglers still in stock at various places, and that the 17mm Astrotech is available under other labels.

44 minutes ago, johninderby said:

One of the newer type of click lock adaptors solves the undercut problem by using a nice wide clamping band. Similar wide bands used on some 2” diagonals now as well.

That's great, because the collet comes up all the way to the opening of the orange aluminum. It needs to grab the skinny little 1.25" section above the eyepiece's undercut to properly align the eyepiece

with the bore of the adapter, and on that one it does.  On this one, also, the internal collet comes up all the way to the opening:

https://www.cloudynights.com/topic/182290-new-redesigned-twist-lock-adapter-from-antares/

The Celestron one is very close, though:

https://agenaastro.com/celestron-2-to-1-25-twist-lock-eyepiece-adapter-93668.html

Some collet style adapters do not, so they can tip:

https://www.highpointscientific.com/baader-clicklock-2inch-to-1-25inch-adapter-t2-15b?utm_source=google&utm_medium=cse&utm_term=BAD-T2-15B&gclid=CjwKCAjwmqKJBhAWEiwAMvGt6AskBk8OqRTcxNGFBH7EoNEHB3a3oJr9vtaDY0obQwvjOTP1qLrtfxoCFi4QAvD_BwE

With that one, the fit depends solely on tolerances of fit of barrel through the opening.

6 hours ago, markse68 said:

is there a danger that by effectively removing the upper 1.25” part that when you tighten the clamp screw the ep will be pushed over at an angle in the focuser? I guess if you’re using a click lock type band clamp it wouldn’t be and would depend on clearance in focuser tube otherwise.

Mark

The answer to your question is yes.  The small 1.25" section at the top is necessary to be inserted in the focuser so the eyepiece doesn't tip.

And your assumption about Click-Lock and Twist-Lock attachments is correct.

3 hours ago, JeremyS said:

 Wonder if anyone has considered interchangeable barrels. Order with or without undercut -or supply both - and screw in the one you prefer. Obviously an increase in cost but probably ok for pricier EPs like TVs.

TV looked into this and over a decade ago the barrels were about $50 apiece at TeleVue's cost.

Then there is the labor of changing the barrel.

This might be a solution for a machinist who can make his own, but it's not commercially viable.

6 hours ago, Louis D said:

My favorites are a pair of vintage 15x wide field B&L microscope eyepieces I originally bought for my AO Series 10 microscope.  At f/18 with the 3x Barlow nosepiece on the binos, they are super comfy and sharp.

All those eyepieces are discontinued except the ES.

I can't say because I don't know your scope.

In an 8" f/6, the 25mm..12mm..8mm..5mm can be a fairly complete set.

In a 102mm f/7 refractor,  the same 4 work out fairly well.

In an 8" SCT, though, you need something longer than 25mm as a low power, and 8mm might be a highest normal power eyepiece.

There, a different brand of eyepiece might do better.

If the undercuts are somewhat of a problem in your equipment, then filling the undercuts with metal tape is an easy fix, and it can be undone to sell them.

Personally, I prefer smooth barrels and a focuser drawtube that is smooth with no compression ring or collet, just thumbscrews to tighten down on the inserted item.

It leaves marks.  Oh, horrors?  Who cares?  I don't buy eyepieces thinking I'm going to resell them anyway.

The newer tapered edge undercuts TeleVue uses are less of a problem than the earlier sharp-edged ones.

The conically-tapered undercuts on a lot of recent eyepieces (ES, et.al.) are a real problem for the split ring binders found in most focusers and star diagonals.

The metal band is twisted, often permanently, by tightening down on the slanted surface.  ES went to stiff stainless steel split rings instead of brass in their focusers and star diagonals.

Collets (as in many adapters) that tighten uniformly around the perimeter can solve some undercut problems, but they don't tighten on the barrel at the bottom of the undercut

and, if they are the type with small metal rods, can actually get caught in the undercuts.

However, face facts.  Almost no modern eyepieces lack undercuts of one sort or another, so limiting your purchases only to smooth barrels is only hurting yourself.

So figuring out how to deal with undercuts is part of the hassle of using contemporary astronomy equipment.

I deal with it by filling the undercuts with metal tape, eliminating the split ring binders (remove them if they're there) in favor of thumbscrews or collets, and having a few eyepieces without

the safety undercuts and using a focuser with a smooth bore, a combination of all 4 solutions.

I had one adapter that had an undercut that always caught, and it had a tapered cylindrical undercut.  I taped it and it slides in an out without issue.  

So I wouldn't remove the tape if its presence make the item work well.  You might regret it.

Get the Starguiders.  The wider, more open, apparent fields are well corrected and more enjoyable to use for general viewing.

https://www.lifehacker.com.au/2014/08/whats-the-difference-between-a-reticle-and-a-reticule/

https://www.yourdictionary.com/reticule

https://www.collinsdictionary.com/us/dictionary/english/reticule

https://www.merriam-webster.com/dictionary/reticule

https://www.lexico.com/en/definition/reticule

My dictionaries in the house refer to the drawstring bag first and a variant spelling of reticle second.

Spellings are listed as variant, the index states, when they are not as common and are used, usually, only in specific geographical areas.

I at first thought this must be a British spelling, like colour/color or honour/honor, but the dictionaries convinced me otherwise.

It is possible, I speculate, that reticle became the dominant spelling to differentiate it (and avoid confusion for the reference) from the word reticule used commonly to describe a bag.

4 hours ago, Geoff Barnes said:

I've often wondered what eyepieces are used in professional observatory telescopes and are they available to mere mortals like us? 

Would they be likely to use Televue ep's?

No, most of those big scopes, if ever used visually, use 4" or larger eyepieces of 80mm and longer focal lengths.

In the 60" at Mt. Wilson, a 50mm eyepiece is 488x.

4 hours ago, jetstream said:

This is a very high standard. Congrats for this fine acquisition! Maybe Televue can buy the design and start producing them, its a shame they are no more. Mind you the 13E wouldnt like this! LOL!

Not everyone thinks the 12.5mm Noblex was all that great an eyepiece.  It's angular magnification distortion made it unusable for me.

The 12.5mm APM Hi-FW is better in that regard and equally sharp, but has edge of field brightening, another issue I can't live with.

I find the 12.5mm Morpheus better than both of them.  However, I don't use that much, preferring the TeleVue Apollo 11.

4 hours ago, jetstream said:

Good post Don, those pesky orthos still go a bit deeper than my Delos, which is a deep eyepiece IMHO. Totally agree about aperture- my 24" is much deeper than my 15" etc etc. I would not spend a grand on an eyepiece to go deeper but throw the cash at a bigger scope or ways to get to a darker site.

Speaking of skies and transparency- the thunder yesterday started more fires and the smoke just billowed in an hour ago across the lake. No aperture or eyepiece punches through this.

 

That difference would be invisible in smaller scopes.

1 minute ago, John said:

Really detailed testing - we so rarely see that in astro eyepieces.

 

You're right.  It would be great to get some in-depth lab testing, but there isn't enough money in it to pay for the lab equipment.

If such occurs, it is usually an amateur astronomer working for a large optical lab doing government work.

The answer to your question is no.  It is a threaded-on eyepiece and not 1.25".

The likely focal length is 22-23mm to yield 9x in a 200mm focal length front lens.

Reticle (note spelling--reticule is a seldom-used variant and usually refers to a small drawstring bag) eyepieces in 1.25" are available quite cheaply on eBay and Amazon.

Stellarvue produces a small finderscope with a 1.25" eyepiece, as does Antares, but they are rare birds.  Most dedicated finder scopes (not 50mm refractors repurposed as a finder) do not use 1.25" eyepieces.

2 hours ago, jetstream said:

I have a few Zeiss optics- all superb- an old Zeiss T coating rangefinder monocular type has better glass and views than a set of Pentax binos I had. The Zeiss T coating zoom 25.1-6.7 also has "zero" (not detectable to me) scatter and is one of my few truly sharp eyepieces, my 2" Zeiss prism is also beyond compare. Then there is the Docter 12.5 UWA (no longer produced).

Question- if there are already glass types, polish levels and coating technologies out there that only a very few use what chance do we have of ever getting the newest latest techno glass out there in astro eyepieces coming up?

I wonder if there are any widefields that go deeper than Delos? any Pentax XW users experience?

The difference in transmission is likely to be on the order of 2%, if that much.  That is ~0.02 magnitudes.  It would take a spectrophotometer to see that difference.

Both Delos and XW are BBAR coated on all surfaces, even the cemented ones.

There is a difference in correction of astigmatism at the edge in faster f/ratios, and in the spectrum of transmission (the XWs were a tad yellower in my color test), and in flatness of the field.

Those differences are unlikely to matter for something on axis in a tracking scope.

If you are looking to see deeper, eyepieces are not the place to look for that.  Larger aperture is.

As for the latest technology in lens materials and surface polishes, unless suddenly the eyepiece market is willing to cough up $1000 or more for every eyepiece, we aren't going to see it.

High end camera lenses for professional use are mostly above $10K.  Most of the posts here on SGL are arguing about whether this $100 eyepiece or that one is better.

A Nikon engineer told me they can get 99% transmission through a 20 element lens, but the coating on each lens surface costs about $300.

We will never see that.

Still, there are differences in eyepieces that can be measured.

Here are a couple links to peruse:

https://web.archive.org/web/20110622011950/http://cieletespace.fr/files/InstrumentTest/201102_test_oculaires.pdf
https://web.archive.org/web/20130829052725/http://www.cieletespace.fr:80/files/InstrumentTest/201306__6_oculaires_10mm.pdf

15 hours ago, mtminnesota said:

 

Delites are also Japan.