Televue

[jetstream]

10 hours ago, markse68 said:

do people really buy eyepieces for the barrels?

Well from another post some dont, so apparently it is a consideration? I have a hard time believing we are talking about Ep barrels anyway lol! where ever the path wanders I follow- I actually do find this interesting.👍

[Deadlake]

6 minutes ago, jetstream said:

Well from another post some dont, so apparently it is a consideration? I have a hard time believing we are talking about Ep barrels anyway lol! where ever the path wanders I follow- I actually do find this interesting.👍

@JeremyS did start another post on this under cuts first world problem.

There is a large part of the APM EP zoom thread (even although it's not released) talking about the sky falling if it's got undercuts.... 

[jetstream]

Because of the way I use the PCII my favourite 1.25" eyepieces reside in 2" EP holders, so no possible undercut issues for the fracs as I have a 2" prism diag- another solution.

[globular]

I feel left out.  I have EPs with undercuts and I've never had a problem.   What am I doing wrong?

[John]

1 hour ago, globular said:

I feel left out.  I have EPs with undercuts and I've never had a problem.   What am I doing wrong?

Obviously you and I are doing things in a similar way !

 

[Highburymark]

1 hour ago, globular said:

I feel left out.  I have EPs with undercuts and I've never had a problem.   What am I doing wrong?

I was just about to say the same thing. In my third decade of stargazing. Probably owned 40/50 eyepieces over the years, at least 10 diagonals, and have never had a problem. 

[Don Pensack]

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.😆

 

[Highburymark]

55 minutes ago, Don Pensack said:

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.😆

 

Wouldn’t a Baader clicklock solve your problems Don?

[Louis D]

5 minutes ago, Highburymark said:

Wouldn’t a Baader clicklock solve your problems Don?

I have more problems with the 2" compression ring in the GSO CC and 2" 2x ED Barlow than with any 1.25" adapter.  I have toyed with the idea of getting a BCL with 47mm extension to replace the GSO CC eyepiece holder, but I've read of several horror stories of BCLs getting stuck in the lock position over the years.  There seems to be no agreed upon way to easily release it when that happens.

[globular]

I feel your frustration @Don Pensack.  I'm not making light of the very real issues you and others face.

It sounds like the design of the Paracorr holder has a) thumbscrews that compress a compression ring when tightened  and b) relies on the springiness of the compression ring to retract itself back into the housing as the thumb screws are loosened. 

Is that right?

If so, from your description above, it sounds like the compression ring in your Paracorr has lost some of it's spring and is not retracting itself fully when the thumb screws are loosened.

This only partially retracted ring does not snag on straight barrels because there is nothing to snag on.  But an undercut barrel needs the ring to retract at least as far as the extra diameter of the barrel verses the undercut or it might snag.  The latest tapered undercuts may snag less, as they help to retract the ring as the EP is removed, although I suspect they will have issues to from time to time too with faulty rings.

I can see how you would blame the undercuts for this... as it only happens on barrels with undercuts... but the real problem lies with the holder. i.e. straight barrels do not highlight the fault in your holder, but undercut ones do.

I suspect a nice new springy compression ring will fix the problem. 

Edited August 28, 2021 by globular

[Don Pensack]

3 hours ago, Highburymark said:

Wouldn’t a Baader clicklock solve your problems Don?

No, because all 4 of the eyepieces with problems are 2", so no adapter is used, and a Paracorr resides in the focuser 100% of the time.

The Baader Click Lock adapter isn't a cure, since it has an undercut on the outside, so it's no better than the TeleVue adapter.

Several other adapters have smooth sides and work great with the Paracorr, but the 6mm and 8mm Ethos need a "Hi-Hat" style adapter to safely use them as 1.25" eyepieces,

which means the TeleVue Paracorr adapter.

 

I could use a Twist-lock, smooth-sided, adapter for the 9mm, 12.5mm, 14mm Morpheus eyepieces, but the 17.5mm needs an in travel adapter, and I draw the line at 2 different adapters, not 3.

Plus, they work fine in the Paracorr adapter since they don't have undercuts.

I am leaning toward attaching 2" adapters to all the 1.25" eyepieces and just using them all as 2".  I would need a number of adapters, but it could be a permanent fix.

 

[Don Pensack]

2 hours ago, globular said:

I feel your frustration @Don Pensack.  I'm not making light of the very real issues you and others face.

It sounds like the design of the Paracorr holder has a) thumbscrews that compress a compression ring when tightened  and b) relies on the springiness of the compression ring to retract itself back into the housing as the thumb screws are loosened. 

Is that right?

If so, from your description above, it sounds like the compression ring in your Paracorr has lost some of it's spring and is not retracting itself fully when the thumb screws are loosened.

This only partially retracted ring does not snag on straight barrels because there is nothing to snag on.  But an undercut barrel needs the ring to retract at least as far as the extra diameter of the barrel verses the undercut or it might snag.  The latest tapered undercuts may snag less, as they help to retract the ring as the EP is removed, although I suspect they will have issues to from time to time too with faulty rings.

I can see how you would blame the undercuts for this... as it only happens on barrels with undercuts... but the real problem lies with the holder. i.e. straight barrels do not highlight the fault in your holder, but undercut ones do.

I suspect a nice new springy compression ring will fix the problem. 

I see you have your thinking cap on.  ES gave that some thought, too, and used stainless steel for the ring instead of brass.  Much springier.

My immediate cure was to remove the brass split ring and use delrin screws to press directly on the eyepiece barrel.

And to use a focuser drawtube with a smooth bore that has no brass split ring in it.

There is a cure with leaving the brass split ring in place, and it is a sanding of the split ring so its cross section is not || , but ().

I did that for a customer a couple years ago and it solved his problem.

 

But some eyepieces hang up on the top lip of the Paracorr, above the groove where the split ring resides.  Only a smooth internal bore on the top would solve that problem.

It just shouldn't be this much work to remove an eyepiece.

 

 

[globular]

May be then @Don Pensack your previous closing remark should have been:

"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 Paracorr eyepiece holders.😆"

[Don Pensack]

52 minutes ago, globular said:

May be then @Don Pensack your previous closing remark should have been:

"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 Paracorr eyepiece holders.😆"

Touché.

However, I have more than one scope and it is the same in the other scopes which do not use a Paracorr.

They do, though, use brass split ring binding systems.

I need to investigate other types of binding and compatibility with my focusers, though.

Maybe a Twist-Lock diagonal.

[Captain Scarlet]

I’ve removed the brass ring on my baader diamond steeltrak, because every time I unscrew and re-screw the grubs, with a laser fitted, secondary collimation would be completely different! Removing the brass ring solved it. I had the same with my baader click-lock adapters on different scopes, but I simply sold those in favor of a parallizer.

Magnus

Edited August 29, 2021 by Captain Magenta

[jetstream]

4 hours ago, Captain Magenta said:

I’ve removed the brass ring on my baader diamond steeltrak, because every time I unscrew and re-screw the grubs, with a laser fitted, secondary collimation would be completely different! Removing the brass ring solved it. I had the same with my baader click-lock adapters on different scopes, but I simply sold those in favor of a parallizer.

Magnus

Its amazing the lengths we go to with regard to collimation only to have tolerances sneak up on us- I tighten the focuser screws in the same order on the eyepieces as I do on the laser lol! My Moonlights are pretty good for consistency though.

[jetstream]

On 28/08/2021 at 15:53, Don Pensack said:

I am leaning toward attaching 2" adapters to all the 1.25" eyepieces and just using them all as 2". 

👍

I do this myself and focus with the PCII after setting it up on "A" and focusing the 21E after which I lock the focuser. Good enough for me.

[RT65CB-SWL]

I know many do complain and moan about the undercut on e/p's. But it is not only TeleVue that have them... I have them on my Circle-T 12.5 & 6mm Ortho's too. There is no escape from them. 

 

12 hours ago, Captain Magenta said:

I’ve removed the brass ring on my baader diamond steeltrak, because every time I unscrew and re-screw the grubs, with a laser fitted, secondary collimation would be completely different! Removing the brass ring solved it. I had the same with my baader click-lock adapters on different scopes, but I simply sold those in favor of a parallizer.

Magnus

Same here too! 

[Mr Spock]

One thing to note about undercuts. Some Skywatcher tubes have the screw very close to the top. This means the screw can land on the top of the undercut meaning the eyepieces doesn't go all the way in as the screw pushes against the undercut forcing the eyepiece outwards.

[Louis D]

4 hours ago, Mr Spock said:

One thing to note about undercuts. Some Skywatcher tubes have the screw very close to the top. This means the screw can land on the top of the undercut meaning the eyepieces doesn't go all the way in as the screw pushes against the undercut forcing the eyepiece outwards.

I've got that same situation with a $50 dielectric diagonal from Amazon.  It's a very nice diagonal except for the fact it pushes all 2" undercut eyepieces up and out of the holder because the compression ring is too close to the top.  I'll have to try removing the ring and replacing the screw with nylon one to see if that improves matters.

[Don Pensack]

16 hours ago, jetstream said:

Its amazing the lengths we go to with regard to collimation only to have tolerances sneak up on us- I tighten the focuser screws in the same order on the eyepieces as I do on the laser lol! My Moonlights are pretty good for consistency though.

If you have a Moonlite focuser, use only 2 screws to tighten something into the focuser--remove the 3rd screw and keep it in you spare parts kit.

Screw 1 presses against the other side of the drawtube but allows wiggle.

Screw 2 presses against the other side, making a 3-point contact--no wiggle possible.

Screw 3 presses the inserted accessory away from the drawtube wall, which is a negative for accurate registration.

This is because the 3 screws are at 120° apart.

 

[Don Pensack]

1 hour ago, Louis D said:

I've got that same situation with a $50 dielectric diagonal from Amazon.  It's a very nice diagonal except for the fact it pushes all 2" undercut eyepieces up and out of the holder because the compression ring is too close to the top.  I'll have to try removing the ring and replacing the screw with nylon one to see if that improves matters.

Ironically, this happens with TeleVue 1.25" eyepieces in TeleVue 1.25" star diagonals.

You have to press inward on the eyepiece as you tighten or the thumbscrew side lifts slightly.

[IB20]

Do the DeLites qualify as having an undercut? I’m looking at mine now and I wouldn’t say it looks that severe? I can’t say I’ve noticed it having any impact when changing it out of my scopes. 🤷🏼‍♂️

[Alan White]

15 minutes ago, IB20 said:

Do the DeLites qualify as having an undercut? I’m looking at mine now and I wouldn’t say it looks that severe? I can’t say I’ve noticed it having any impact when changing it out of my scopes. 🤷🏼‍♂️

It was the DeLites that unhinged me with my 1.25” TV diagonal.

The undercut is probably no deeper than older TV eyepieces, it’s the angled bit that was snagging, ironic as it’s designed or marketed to reduce snagging..... snagging that does not happen as I was told.

[John]