Televue

[John]

4 minutes ago, Stu said:

.... I was just making what I had work together…

Yep - it's great to share these little tips and wrinkles

 

[jetstream]

Over on another place it was brought up that there was no way the 32mm/25mm TV plossls/under cuts would work with the Binotron 27 eyepiece holder design. They would twist/cant preventing a merge or good views at the least... yeah- I bought them ,put them in, instantly merged and got extremely good views. No snagging on removal either. They stay right in the binoviewer case.

If I had a diagonal that caused issues with vg eyepieces, the diagonal would go...

I check my scopes straight through and with the TSA120 I use the superb extension system with their EP holder- zero issues with Televue or any other eyepiece.

Edited August 26, 2021 by jetstream

[Louis D]

I had one eyepiece holder/eyepiece undercut mismatch so bad that I almost couldn't retrieve the eyepiece from the holder because the brass compression ring got snagged and pulled up out of its groove where it jammed against the eyepiece above its normal position.  I was pretty panicked.  I'm not sure how I eventually got it freed (it's been years), but I'm more careful now.  If there's any snagging, I don't try to brute force the eyepiece out of the holder.

The real issue is that compression rings and narrow collet bands don't interact well with eyepiece undercuts.  Either by themselves don't generally cause issues.

Edited August 26, 2021 by Louis D

[jetstream]

3 minutes ago, Louis D said:

The real issue is that compression rings and narrow collet bands don't interact well with eyepiece undercuts.  Either by themselves don't generally cause issues.

Yeah, I dont crank the screws down on the holder really distorting the band- I just snug them. I wonder if some give a "robust" turn of the screw(s)?

[jetstream]

One more thing as I enjoy a dark roast, I think if a diagonal has one screw then that one screw can force the band the whole distance into the undercut which can cause multiple issues if nor careful. A diag with 2 screws will "split" this distance if used right so that the band is not forced into the undercut all on one side.

[Louis D]

17 minutes ago, jetstream said:

Yeah, I dont crank the screws down on the holder really distorting the band- I just snug them. I wonder if some give a "robust" turn of the screw(s)?

You kind of have to with stiff zooming zoom eyepieces, or you have to grab the lower part of the eyepiece to zoom, which is a pain in binoviewers with two of them to zoom.

[jetstream]

1 minute ago, Louis D said:

You kind of have to with stiff zooming zoom eyepieces, or you have to grab the lower part of the eyepiece to zoom, which is a pain in binoviewers with two of them to zoom.

My Binotrons design allows truly tight connection if desired- honestly I couldnt be happier with these, Russ hit a winner with the design all way round IMHO.

[Louis D]

My basic Arcturus binos' collets tend to tip eyepieces with undercuts.  I have to really mash them down in the holders while tightening them to avoid this.  However, once tightened, they're solidly in there.

However, since there is no way to lock the diopter setting except to snug it all the way up or down, I have to sometimes fight with it while zooming stiff zoom eyepieces.

[jetstream]

1 minute ago, Louis D said:

My basic Arcturus binos' collets tend to tip eyepieces with undercuts.  I have to really mash them down in the holders while tightening them to avoid this.  However, once tightened, they're solidly in there.

However, since there is no way to lock the diopter setting except to snug it all the way up or down, I have to sometimes fight with it while zooming stiff zoom eyepieces.

Thats what I like to hear- making things work!

If I get lazy with my 3 screw Moonlight on the dobs I just use one screw to hold stuff- this can pop the band out of its groove, my bad.

Its amazing the views that almost any binoviewer can give if a few things are followed like not "fighting" the merge with low fl eyepieces etc. My TV plossls are so good in the binos I use nothing else really. I bought double sets of Tak orthos etc and they are just sad- never getting the nod to play.

[Louis D]

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.

[jetstream]

3 minutes ago, Louis D said:

15x wide field B&L microscope eyepiece

Excellent!

I just about got into Zeiss micro eps after reading Denis Levacic posts on them, but I just styed with the TV plossls

[Alan White]

I knew mentioning undercuts would keep folks busy for a while.
Yes you have to adapt some items, but when spending good money, why should you?

I still have undercuts on most of my eyepieces by the way, just not a fan, but I olny use alt az mounts,
if I were a equatorial user, then my liking might be proportionaly higher.
 

[jetstream]

16 minutes ago, Alan White said:

I knew mentioning undercuts would keep folks busy for a while.
Yes you have to adapt some items, but when spending good money, why should you?

I still have undercuts on most of my eyepieces by the way, just not a fan, but I olny use alt az mounts,
if I were a equatorial user, then my liking might be proportionaly higher.
 

Again I just say to each their own, lots of eyepieces to choose from, no big deal. My Nikon HW has great glass but the total design leaves much to be desired. Its design doesnt stop me from using it though- unless I want to use it in the PCII... the 17E is much better all round with very similar views.

[John]

1 hour ago, Alan White said:

I knew mentioning undercuts would keep folks busy for a while.
Yes you have to adapt some items, but when spending good money, why should you?

I still have undercuts on most of my eyepieces by the way, just not a fan, but I olny use alt az mounts,
if I were a equatorial user, then my liking might be proportionaly higher.
 

Fair enough Alan.

I'm an "alt-az only" person as well so the security aspect is not as high a priority for me.

Maybe an acceptable compromise would be undercuts on eyepieces over a certain weight but smooth barrels on the smaller ones ?

 

 

[JeremyS]

 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.

[Louis D]

I was just about to suggest it, but then realized many premium eyepieces have lenses in the lower barrel, so this would only work with an interchangeable 2" skirt on 1.25" eyepieces or on 2" eyepieces that don't need the entire ~46mm inner diameter for lenses.  It would be a simple solution for eyepieces that have no lenses in the lower barrel, though.

[jetstream]

7 minutes 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.

Excellent!

Someone who offers solutions not just identifying problems!

We think the same in this regard Jeremy.

Edited August 26, 2021 by jetstream

[JeremyS]

I posted a potential solution to the dreaded undercuts that I am trialling

 

[jetstream]

2 hours ago, John said:

Fair enough Alan.

I'm an "alt-az only" person as well so the security aspect is not as high a priority for me.

Maybe an acceptable compromise would be undercuts on eyepieces over a certain weight but smooth barrels on the smaller ones ?

 

 

You know, I think that if the undercut saved a , well, lets say a 21E when the diag/eyepiece spun around from leverage that many might be worshipping the machinist who cut, it avoiding broken glass on the ground?

[Louis D]

35 minutes ago, jetstream said:

You know, I think that if the undercut saved a , well, lets say a 21E when the diag/eyepiece spun around from leverage that many might be worshipping the machinist who cut, it avoiding broken glass on the ground?

I had something similar happen when a diagonal tried to unthread itself in a similar manner.  All I could do was grouse that this would never happen with a Dob that has it's focuser angled upward.

Edited August 26, 2021 by Louis D

[Don Pensack]

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.

[Don Pensack]

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.

 

[Louis D]

12 minutes ago, Don Pensack said:

All those eyepieces are discontinued except the ES.

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.

[Louis D]

15 minutes ago, Don Pensack said:

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.

 

That "discontinued" 17mm AF70 shown above in my pic has a removable 2" barrel without an undercut.  I seriously doubt it added $50 to the cost of that eyepiece.  Was TeleVue considering having Starlight Instruments CNC machine them at that price?

[John]

43 minutes ago, Louis D said:

That "discontinued" 17mm AF70 shown above in my pic has a removable 2" barrel without an undercut.  I seriously doubt it added $50 to the cost of that eyepiece.  Was TeleVue considering having Starlight Instruments CNC machine them at that price?

That works fine where a 2 inch barrel is added to a fixed 1.25" barrel.

For 1.25 inch eyepieces the replacement barrel would also have to contain the lower optical set which many of the Tele Vue ranges use. Either that or a complete re-design of the lower half of the eyepiece would be needed to provide a lower optical element housing and a 1.25 inch sleeve to fit (and lock) over that, either undercut or not according to the owners preference.

 

 

Edited August 26, 2021 by John