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Twist lock Centering Adapters?! Huh! Centered? Really!?

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#1 emflocater

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Posted 11 January 2017 - 04:15 PM

Hi Folks. I was looking at some of the Twist-Lock 2" to 1.25" adapters...just as an example the Antares Twist-Lock Adapter 2" - 1.25" among others. Anyways...the description says that it will center your eyepiece or other 1.25" attached equipment and lock it in with a simple twist, since it does not use a thumb screw which would cause the eyepiece to lean to one side. This appears to be the selling point...ease of use and centering the eyepiece.

*

Thinking deeper as I do and which always gets me in trouble...I said to my self "wait a minute here" ...

These adapters correct half the problem. What I mean by that is, when you install the 2" barrel end into your focuser and or 2" Diagonal, you then have to tighten the adapter with the focuser or diagonal thumb screw (s) or compression ring! Doesn't this push the Twist -Lock adapter slightly to one side?! So now you put your eyepiece in the Twist-Lock adapter which centers the eyepiece but your still half tilted at the barrel end! Am I thinking stupid here? If so it's not the first time nor will it be the last!

*

I feel a better design would be to have a Twist - Lock at both ends. In other words the 2" barrel end has something like the Hotech Adapter end and the 1.25" end has the Twist-Lock. Of course ideal would be to have 2" Diagonal with both ends like this too. Now your diagonal is centered in the focuser and your eyepiece is centered in the diagonal. I understand about backfocus issues possibly arising, but I am sure this can be minimized somehow as well in the design of the barrel lengths. I think I have too much time on my hands! :4

Cheers

Don 


Edited by emflocater, 11 January 2017 - 04:29 PM.

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#2 leveye

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Posted 11 January 2017 - 04:27 PM

Blue Fireball makes 2" and 1.25 twist lock self centering adapters. I just double stack them. Agena Astro sells them. Great product.


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#3 emflocater

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Posted 11 January 2017 - 04:34 PM

Blue Fireball makes 2" and 1.25 twist lock self centering adapters. I just double stack them. Agena Astro sells them. Great product.

But the barrel end still does not self center where ever you first install it in your optical train. Correct?

Cheers

Don


Edited by emflocater, 11 January 2017 - 04:35 PM.

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#4 csrlice12

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Posted 11 January 2017 - 04:52 PM

Get a Glatter paralyzer and remove all doubt.


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#5 slack

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Posted 11 January 2017 - 05:05 PM

 

Blue Fireball makes 2" and 1.25 twist lock self centering adapters. I just double stack them. Agena Astro sells them. Great product.

But the barrel end still does not self center where ever you first install it in your optical train. Correct?

Cheers

Don

 

I think you're arguing the obvious, predicated on marketing terminology. They are self-centering, which is just a byproduct of the twist-lock design. Your point seems to be, yeah, that's great, but unless everything else is perfectly centered, the claim is somewhat spurious. Of course, it's not. The claim is valid, it's just not particularly relevant. 

 

To your last question, quoted above, if you plop a self-centering 1-1/4" to 2" adapter into, for example, a Baader diagonal that features 2" Clicklock EP holder, then those two adapters should be self-centered.

 

Of course, to your underlying point, if the telescope focuser, where the nosepiece of the diagonal attaches, is also not a self-centering design, then everything being self-centering downstream may be irrelevant.

 

IME, with my refractors, outside of some issues with binoviewer collets/EP designs and merging, I've never noticed any issues or differences attributable to diagonals, adapters, or eyepieces being out of alignment due to set screws, compression rings, or self-centering parts. I have assembled scopes were everything should be in perfect alignment (Borgs, with threaded parts and all Baader Twistlock fittings), and my most used scope, in mono mode, incorporates two 2" extensions and a 2" diagonal (usually all installed with set screws), and 1-1/4" to 2" hi-hat adapter (with compression ring), and I regularly test EPs in it and have never discovered an aberration attributable to the alignment of the components or EPs.

 

Btw, I dislike the self-centering EP holders that I have owned (Baader Clicklocks). They have all imparted grease onto whatever component they are clamping (like EP barrels), weighed more than conventional options, and I've found I prefer the traditional use of a screw and that the lighter touch does not disrupt viewing (and target alignment) as much. Partly practical issues and partly personal preference. I've gone so far as to replace the 2" Clicklock on my Baader CCS Herschel Solar Prism with conventional EP holders. Likewise, I know there are applications where others find the Clicklock great. 


Edited by slack, 11 January 2017 - 05:08 PM.

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#6 junomike

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Posted 11 January 2017 - 05:06 PM

 

Blue Fireball makes 2" and 1.25 twist lock self centering adapters. I just double stack them. Agena Astro sells them. Great product.

But the barrel end still does not self center where ever you first install it in your optical train. Correct?

Cheers

Don

 

You are correct.  You can get perfectly centered by buying a Baader Click Lock VB

and a Baader Click Lock Diagonal. Then add the Twist lock for 1.25" Eyepieces.

Nice to have but IMO the slight off-centering of Compression rings has never had any effect I could see at the eyepiece.

 

Mike


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#7 emflocater

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Posted 11 January 2017 - 05:26 PM

 

 

Blue Fireball makes 2" and 1.25 twist lock self centering adapters. I just double stack them. Agena Astro sells them. Great product.

But the barrel end still does not self center where ever you first install it in your optical train. Correct?

Cheers

Don

 

I think you're arguing the obvious, predicated on marketing terminology. They are self-centering, which is just a byproduct of the twist-lock design. Your point seems to be, yeah, that's great, but unless everything else is perfectly centered, the claim is somewhat spurious. Of course, it's not. The claim is valid, it's just not particularly relevant. 

 

To your last question, quoted above, if you plop a self-centering 1-1/4" to 2" adapter into, for example, a Baader diagonal that features 2" Clicklock EP holder, then those two adapters should be self-centered.

 

Of course, to your underlying point, if the telescope focuser, where the nosepiece of the diagonal attaches, is also not a self-centering design, then everything being self-centering downstream may be irrelevant.

 

IME, with my refractors, outside of some issues with binoviewer collets/EP designs and merging, I've never noticed any issues or differences attributable to diagonals, adapters, or eyepieces being out of alignment due to set screws, compression rings, or self-centering parts. I have assembled scopes were everything should be in perfect alignment (Borgs, with threaded parts and all Baader Twistlock fittings), and my most used scope, in mono mode, incorporates two 2" extensions and a 2" diagonal (usually all installed with set screws), and 1-1/4" to 2" hi-hat adapter (with compression ring), and I regularly test EPs in it and have never discovered an aberration attributable to the alignment of the components or EPs.

 

Btw, I dislike the self-centering EP holders that I have owned (Baader Clicklocks). They have all imparted grease onto whatever component they are clamping (like EP barrels), weighed more than conventional options, and I've found I prefer the traditional use of a screw and that the lighter touch does not disrupt viewing (and target alignment) as much. Partly practical issues and partly personal preference. I've gone so far as to replace the 2" Clicklock on my Baader CCS Herschel Solar Prism with conventional EP holders. Likewise, I know there are applications where others find the Clicklock great. 

 

Very interesting info slack.

Thanks

Cheers

Don



#8 emflocater

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Posted 11 January 2017 - 05:28 PM

 

 

Blue Fireball makes 2" and 1.25 twist lock self centering adapters. I just double stack them. Agena Astro sells them. Great product.

But the barrel end still does not self center where ever you first install it in your optical train. Correct?

Cheers

Don

 

You are correct.  You can get perfectly centered by buying a Baader Click Lock VB

and a Baader Click Lock Diagonal. Then add the Twist lock for 1.25" Eyepieces.

Nice to have but IMO the slight off-centering of Compression rings has never had any effect I could see at the eyepiece.

 

Mike

 

Thank Mike seems you and slack have very similar observations on all this.

Cheers

Don



#9 Starman1

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Posted 11 January 2017 - 05:57 PM

Hi Folks. I was looking at some of the Twist-Lock 2" to 1.25" adapters...just as an example the Antares Twist-Lock Adapter 2" - 1.25" among others. Anyways...the description says that it will center your eyepiece or other 1.25" attached equipment and lock it in with a simple twist, since it does not use a thumb screw which would cause the eyepiece to lean to one side. This appears to be the selling point...ease of use and centering the eyepiece.

*

Thinking deeper as I do and which always gets me in trouble...I said to my self "wait a minute here" ...

These adapters correct half the problem. What I mean by that is, when you install the 2" barrel end into your focuser and or 2" Diagonal, you then have to tighten the adapter with the focuser or diagonal thumb screw (s) or compression ring! Doesn't this push the Twist -Lock adapter slightly to one side?! So now you put your eyepiece in the Twist-Lock adapter which centers the eyepiece but your still half tilted at the barrel end! Am I thinking stupid here? If so it's not the first time nor will it be the last!

*

I feel a better design would be to have a Twist - Lock at both ends. In other words the 2" barrel end has something like the Hotech Adapter end and the 1.25" end has the Twist-Lock. Of course ideal would be to have 2" Diagonal with both ends like this too. Now your diagonal is centered in the focuser and your eyepiece is centered in the diagonal. I understand about backfocus issues possibly arising, but I am sure this can be minimized somehow as well in the design of the barrel lengths. I think I have too much time on my hands! :4

Cheers

Don 

Yes, the focuser setscrew pushes the twist-lock adapter off center.  By maybe 0.002" or 0.003".

That amount of de-centering is inconsequential and cannot be seen.

Here's something to think on, though: your 2" collimation tools are also pushed off center by a similar amount.

Wouldn't you want the eyepiece to line up perfectly with the collimation tools?

Doesn't a centering adapter defeat that?

 

By the way, an adapter like the Howie Glatter Parallizer is shoved off-center in one direction and the eyepiece is shoved the opposite direction.

As a result, the eyepiece IS centered.  But I repeat my question above........

 

This is all an intellectual exercise, since it doesn't matter.

The primary advantage to a twist-lock is it's ability to allow easy removal of the eyepiece when loosened without catching on the undercuts.

Alas, they aren't particularly compatible with a conically-tapered eyepiece barrel undercut.  Mumble, mumble, mumble.


Edited by Starman1, 11 January 2017 - 08:39 PM.

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#10 emflocater

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Posted 11 January 2017 - 06:50 PM

 

Hi Folks. I was looking at some of the Twist-Lock 2" to 1.25" adapters...just as an example the Antares Twist-Lock Adapter 2" - 1.25" among others. Anyways...the description says that it will center your eyepiece or other 1.25" attached equipment and lock it in with a simple twist, since it does not use a thumb screw which would cause the eyepiece to lean to one side. This appears to be the selling point...ease of use and centering the eyepiece.

*

Thinking deeper as I do and which always gets me in trouble...I said to my self "wait a minute here" ...

These adapters correct half the problem. What I mean by that is, when you install the 2" barrel end into your focuser and or 2" Diagonal, you then have to tighten the adapter with the focuser or diagonal thumb screw (s) or compression ring! Doesn't this push the Twist -Lock adapter slightly to one side?! So now you put your eyepiece in the Twist-Lock adapter which centers the eyepiece but your still half tilted at the barrel end! Am I thinking stupid here? If so it's not the first time nor will it be the last!

*

I feel a better design would be to have a Twist - Lock at both ends. In other words the 2" barrel end has something like the Hotech Adapter end and the 1.25" end has the Twist-Lock. Of course ideal would be to have 2" Diagonal with both ends like this too. Now your diagonal is centered in the focuser and your eyepiece is centered in the diagonal. I understand about backfocus issues possibly arising, but I am sure this can be minimized somehow as well in the design of the barrel lengths. I think I have too much time on my hands! :4

Cheers

Don 

Yes, the focuser setscrew pushes the twist-lock adapter off center.  By maybe 0.002" or 0.003".

That amount of de-centering is inconsequential and cannot be seen.

Here's something to think on, though: your 2" collimation tools are also pushed off center by a similar amount.

Wouldn't you want the eyepiece to line up perfectly with the collimation tools?

Doesn't a centering adapter defeat that?

 

By the way, an adapter like the Howie Glatter Parallizer is shoved off-center in one direction and the eyepiece is shoved the opposite direction.

As a result, the eyepiece IS centered.  But I repeat my question above........

 

This is all an intellectual exercise, since it doesn't matter.

The primary advantage to a twist-lock is it's ability to allow easy removal of the eyepiece when loosened with catching on the undercuts.

Alas, they aren't particularly compatible with a conically-tapered eyepiece barrel undercut.  Mumble, mumble, mumble.

 

Thanks Don. 5 Star Excellent Points, especially the collimation thought! Wow how simple things become quite complicated when pondered. Great info and well appreciated Don

Cheers

Don


Edited by emflocater, 11 January 2017 - 07:18 PM.


#11 Starman1

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Posted 11 January 2017 - 08:40 PM

Oops, I meant to say "WITHOUT catching on the undercuts.

I've corrected post #9.



#12 Jon Isaacs

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Posted 11 January 2017 - 11:40 PM

Yes, the focuser setscrew pushes the twist-lock adapter off center.  By maybe 0.002" or 0.003".
That amount of de-centering is inconsequential and cannot be seen.
Here's something to think on, though: your 2" collimation tools are also pushed off center by a similar amount.
Wouldn't you want the eyepiece to line up perfectly with the collimation tools?
Doesn't a centering adapter defeat that?

By the way, an adapter like the Howie Glatter Parallizer is shoved off-center in one direction and the eyepiece is shoved the opposite direction.
As a result, the eyepiece IS centered.  But I repeat my question above........

This is all an intellectual exercise, since it doesn't matter.
The primary advantage to a twist-lock is it's ability to allow easy removal of the eyepiece when loosened without catching on the undercuts.
Alas, they aren't particularly compatible with a conically-tapered eyepiece barrel undercut.  Mumble, mumble, mumble.

 

 

:waytogo:

 

0.004" = 0.10 mm

 

Compare that to the field stop of your favorite high power eyepiece.  Does anyone think their optics are aligned axially to within 0.1mm?  That is about the thickness of a human hair.  

 

Jon


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#13 emflocater

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Posted 12 January 2017 - 08:40 PM

So is a compression ring less forgiving with tilting an eyepiece or inserted piece of equipment then say 1 or 2 thumb screws?

Cheers

Don



#14 nevy

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Posted 12 January 2017 - 08:50 PM

Using a self centring adapter means your 1 1/4" eyepiece will sit with the same tilt as 2" eyepieces, without the adapter your 1 1/4" eyepiece may tip twice. 



#15 Ain Soph Aur

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Posted 13 January 2017 - 05:17 PM

Taking the 'splitting hairs' idiom to an astronomical level! ;)




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