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Development of an Ultimate Combination Tool F/4 to F/6

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#1 MellonLake

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Posted 09 June 2021 - 06:01 PM

All;

I have been working in my spare time for the last 6 months developing a better combination tool.  I think I am now at the point where I can share this with the community.  There have been many hundreds of hours spent on the tool and more than 30 revisions of this tool have been manufactured and tested.  I would like to thank CN member Kipper-Feet for his input and help testing multiple revisions of my collimation tools.  Note: the results of collimation with this tool have been checked against a well aligned laser (Farpoint), Cheshire (Farpoint), Combo tools (Orion USA, Celestron), and other tools.  The tool will meet the focuser axis error requirements and primary axis error requirements for telescopes between F/4 and F/6 (it is recommended that those using coma correctors get an accurate laser for alignment of the secondary mirror).   

 

This tool combines the features of a variable length sight tube, combination tool (crosshairs), Cheshire, and collimation cap.   While it has some of the features of each of these tools, it combines all of the best features of each tool.   In its current form, the tool is 3D printed with an aluminium 1.25" barrel.  Why do you ask does it have an 1.25" barrel?  It is intended to be used on telescopes having a 1.25" focuser.  It is also intended to be used with a centring adapter like the Glatter Parallizer such that, in 2" focusers, it will well centred and aligned to the focuser axis by the adapter (I have an adapter tool in development that achieves similar centring and alignment) making a 2" version unnecessary.   As such, it is intended to be universal for both 1.25" and 2" focusers.

 

NOTE: There are slight errors visible in the collimation images below due to the photography technique.

 

The sight tube portion of the tool is extendable.  

Long (F/6 Telescope)

Ultimate Combo Tool Long - small.jpg

 

Short (F/4 Telescope)

Ultimate Combo Tool Short - small.jpg

 

This variable length is achieved through a movable tube that includes the cross hairs.  The tube is held in place at any length by friction with the outer body.

Ultimate Combo Tool Sight Tube 2 - Small.jpg

 

The tube can be removed at which point the upper portion becomes a Cheshire/Collimation Cap.  The reflective ring in the Cheshire can be manufactured with a 19mm diameter for triangular mirror markers and with a 14mm ring for standard telescope manufacturer's round mirror markers (triangular version below).  Because the surface is also printed in light grey and the pupil is small, the tool can also be used as a collimation cap.  A flashlight can be used to illuminate the Cheshire ring via the cut-out. 

Ultimate Combo Tool Cheshire 2 - small.jpg

 

With the sight tube in place, the peephole view is as shown in the image below.  With the sight tube portion in place, it is easy to see that the secondary mirror physical outer diameter edge is concentric to the tool inner diameter (concentric to the focuser) and the primary reflection is concentric to the secondary.   By changing the overall length of the tool and varying the position of the peep hole to a position slightly below the apex, the tool can be set to be used for telescopes from F/4 to F/6.  Additionally, the crosshairs will allow for alignment of the secondary mirror by aligning the crosshairs to the middle of the primary mirror marker using the secondary alignment screws.

Ultimate Combo Tool Crosshair - small.jpg

 

 

With the sight tube portion removed and a flashlight shining in the cut-out, the mirror marker and reflective ring of the Cheshire are clearly visible.  Additionally the black dot of the eye's pupil through the tool peep hole is also visible.  The primary mirror can be aligned using the inner diameter of the reflective Cheshire ring to centre the mirror marker or by centring the black dot of the peep hole/pupil in the centre circle of the mirror marker.

 

Ultimate Combo Tool Cheshire - small.jpg

 

In summary this Ultimate Combination Tool can be used for all steps in collimation for telescopes with focal ratios from F/4 to F/6:

1) Centre and round the secondary as a sight tube,

2) Align the secondary as a combination tool,

3) Align the primary mirror as a combination tool, Cheshire, or collimation cap.

 

 

Thanks for reading. 

 

All the best    

 

Rob

 

 

 

 


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#2 Asbytec

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Posted 11 June 2021 - 06:05 AM

Rob, I am surprised no one commented. I confess being short of words. But, I know you and Richard put a lot of time and effort into making a nice tool. It's an interesting concept to put all (most) of the tools into a single package. I am sure they will all agree with each other, too, well except for maybe a laser. smile.gif


Edited by Asbytec, 11 June 2021 - 06:06 AM.


#3 sixela

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Posted 11 June 2021 - 09:18 AM

If I'd change one thing, it's to make the Cheshire ring retro-reflective and to ditch the cutout (you can illuminate that area through the primary anyway if needed, and that also illuminates the centre spot).

 

But well thought out and executed!


Edited by sixela, 11 June 2021 - 11:47 AM.


#4 Vic Menard

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Posted 11 June 2021 - 10:04 AM

If I'd change one thing, it's to make the Cheshire ring retro-reflective and to ditch the cutout...

waytogo.gif



#5 MellonLake

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Posted 11 June 2021 - 05:31 PM

All;

I actually tested many retroreflective designs with several different retroreflective materials both with and without a cut-out.  As I noted, above there have been many many versions of this tool.  Below is the reasoning for not using a retroreflective surface and incorporating the cut-out:

  1. Unlike conventional Cheshires where the reflective ring is external to the tube, the internal retroreflective ring (within the tube) is difficult to fully illuminate from the front of the tube this is because the light must be shone into the tube coaxially to the tube.  This is increasingly difficult as the focal ratio increases.  I actually tested this with three different retroreflective tapes and a retroreflective 3D printed ring.  None of the retroreflective surfaces proved to be better than the cut-out. With the ring inside the tube, the cut-out is needed.  
  2. Unless the mirror marker is also retroreflective the mirror marker is difficult to detect unless retroreflective surfaces of different colours are used for the Cheshire ring and the circle inscribed by the Cheshire ring.  Thus a retroreflective ring will not work well with a standard mirror marker from Orion, Celestron, Zhumell, etc.  This is addressed in my tool by cut-out, the ring, and the light grey tool surface.  Extensive testing was done.  Thus unlike other Cheshires, this tool is easy to use with existing mirror markers.  No replacement of the mirror marker is required unlike for other Cheshire tools.
  3. The light reflected down the tube by the cut-out helps illuminate the crosshairs for alignment of the secondary.   Without the cut-out, the light shining down the tube to illuminate the mirror marker and Cheshire ring ends up making seeing the crosshairs difficult and the crosshairs themselves are not illuminated.  The illumination of the crosshairs via the cut-out helps with visible during alignment of the secondary.  

I used a glow in the dark material for the 3D printed Cheshire ring.  This ring can be "charged" through the cut-out with the intense glow lasting for about 60 seconds.  For those who want to illuminate via the tube, the Cheshire ring can be "charged" and will glow and then a flashlight can be shone onto the mirror maker.   The mirror marker can then be centred in the glowing Cheshire ring.  However, I found simply illuminating the with the cut-out much preferable.  In the pictures above you can see how easy it is to centre the mirror marker in the illuminated ring (it is actually much brighter than shown). 

 

This tool has been tested extensively vs. other tools like the Farpoint Cheshire (which has the retroreflective ring) and laser and high quality Orion USA combo tool.   

 

Rob   


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#6 MellonLake

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Posted 11 June 2021 - 06:34 PM

Rob, I am surprised no one commented. I confess being short of words. But, I know you and Richard put a lot of time and effort into making a nice tool. It's an interesting concept to put all (most) of the tools into a single package. I am sure they will all agree with each other, too, well except for maybe a laser. smile.gif

Thanks Norme!  A good laser is still better for aligning the secondary, really can't beat the Farpoint (I have made a few laser collimators of my own and boy they are hard to align well, still working on a few laser designs).  An autocollimator is still a better tool for those with really fast telescopes (less than F/4).  This tool really fills a gap for those who own Newtonian reflectors with 1.25" focusers and for users who want a "all in one" tool.

 

Rob


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#7 Jon Isaacs

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Posted 11 June 2021 - 07:38 PM

Thanks Norme!  A good laser is still better for aligning the secondary, really can't beat the Farpoint (I have made a few laser collimators of my own and boy they are hard to align well, still working on a few laser designs).  An autocollimator is still a better tool for those with really fast telescopes (less than F/4).  This tool really fills a gap for those who own Newtonian reflectors with 1.25" focusers and for users who want a "all in one" tool.

 

Rob

 

In my situation, I like the Tublug because I can adjust the primary while looking at the Tublug. I really don't know how people use collimation caps and autocollimators when they can't adjust them in real time.  

 

If there's someone to help then I can see it but doing it alone when it's several feet from the adjustments to the focuser and may require climbing up a ladder, the Tublug is a god send.

 

Jon



#8 MellonLake

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Posted 11 June 2021 - 09:33 PM

Jon... got that covered too.  Works with cheap lasers and 1.25" Barlow cells too.    

 

Laser Barlow 3 small.jpg

 

laser barlow - smaller.jpg

 


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#9 sixela

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Posted 12 June 2021 - 04:08 AM

Below is the reasoning for not using a retroreflective surface and incorporating the cut-out:


I’m not against the cut-out per de; I’m just wondering if on all scopes it’s length will still allow you to put the top of the tool at the focal plane (which Ishtar makes the Cheshire reading tolerant of small residual errors in tilting the secondary).
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#10 Asbytec

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Posted 12 June 2021 - 05:35 AM

Jon... got that covered too.  Works with cheap lasers and 1.25" Barlow cells too.    

 

attachicon.gifLaser Barlow 3 small.jpg

 

attachicon.giflaser barlow - smaller.jpg

Rob, how have you incorporated this method in the all in one tool shown in the OP? 



#11 MellonLake

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Posted 12 June 2021 - 06:20 AM

Rob, how have you incorporated this method in the all in one tool shown in the OP? 

smile.gif   Wish I could!  But alas nothing is perfect.

 

Rob


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#12 MellonLake

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Posted 12 June 2021 - 06:42 AM

I’m not against the cut-out per de; I’m just wondering if on all scopes it’s length will still allow you to put the top of the tool at the focal plane (which Ishtar makes the Cheshire reading tolerant of small residual errors in tilting the secondary).

Yep, thought of that too and tested many many tools like the Telecat as well.  However, with the cut-out removed, the tube becomes too short at F/4 and the crosshairs become unusable because they are too close to the eye with a 1.25" focuser.  There is no perfect tool for every telescope.  However, I would rather have the crosshairs present than worry as much about being able to see the entire primary reflection.  Most users cannot centre their secondaries well enough to use the three circles to confirm alignment of the secondary and will always have the primary reflection a bit out of position.  I would rather they have usable crosshairs, a tube that can be used for centring/rounding, and if their focal plane is too low, not be able to see the entire primary reflection.  Also if the primary reflection is not perfect, it only means there is a minor illumination issue which will not grossly affect the view.  The tool is really for the beginner/intermediate astronomer.  If you are doing astrophotography with a fast Newtonian with an oversized secondary, you probably want so high end tools anyway and this tool is not for you. 

 

Maybe I should retitle as "Ultimate Beginner/Intermediate Combination Tool".  I really envision this tool for those who have mass produced Newtonians and want to be able to do all the steps of collimation including centring/rounding.  Also, there is no tool on the market that works well for centring and rounding for 1.25" focusers at F/4.  

 

In summary, you are right, some telescopes where the focal pane is too low in the drawtube, will not work perfectly with this tool because the entire primary reflection will not be visible.  However, this is a drawback I am willing to accept given all the other useful features of the tool (i.e. it can centre and round secondary on a wide range of focal length, very accurately align the primary as a Cheshire, and provide secondary alignment via the crosshairs). 



#13 Jon Isaacs

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Posted 12 June 2021 - 10:28 AM

smile.gif   Wish I could!  But alas nothing is perfect.

 

Rob

Is that a copy of the TuBlug?

 

I suspect Howie patented the TuBlug concept and that's why there are no copies out there.

 

Jon



#14 MellonLake

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Posted 12 June 2021 - 11:08 AM

Jon;

 

The Blug is patented but my device does not violate the patent because it does not incorporate the divergent lens (Barlow).  The essence of the patent is that the device incorporates the Barlow to make the tool "shorter".   My tool does not incorporate the lens and hence is significantly longer.  The large Barlow cell is user supplied and not part of the tool.  

 

"While Barlowed laser collimation of primary mirrors has several advantages over standard laser collimation, the combined collimating apparatus of the laser collimator and conventional telescope Barlow lens presents a long, bulky, and somewhat heavy burden to the usual telescope eyepiece holder or focuser drawtube that the combination must be mounted in. This disadvantage was overcome with this author's innovation of the self-Barlowed laser collimator, disclosed in an item entitled “Critical Collimation”, published in the New Product Showcase section, page 108, of the September 2004 issue of Sky and Telescope magazine. Although the self-Barlowed laser collimator significantly eases application of the Barlowed laser collimation technique, it shares a difficulty of conventional Barlowed laser collimation."

 

Also, the patent does not appear to cover the "Tublug".  The Glatter patent covers only the Blug design:

"The body is preferably, although not necessarily made cylindrical in form, and of somewhat greater diameter than the inside diameter of the focuser drawtube or eyepiece holder that the device is intended to attach to. The end of the body that faces the laser collimator is made square with the body's cylindrical axis. A short length of this end is made slightly smaller in diameter than the inside diameter of the focuser drawtube into which it is intended to fit. This reduced diameter portion ends at a shoulder...In a preferred embodiment, a resilient rubber or plastic o-ring 3 is installed in groove 4, formed on the reduced diameter portion of the device. The groove depth and o-ring thickness are chosen so that compression of the o-ring will provide secure retention when the device is inserted in the open end of the drawtube."

 

My tool is, not "self barlowed" and as a result is much longer than the Tublug.  It also does not go into the drawtube.   This tool is simply an adaptation of Nils Olaf Carlin's design that places the laser and target above the focuser.   In my opinion this device does not violate the patent primarily because it is not "self-barlowed" which is the essence of the Glatter Blug patent.  

 

Rob


Edited by MellonLake, 12 June 2021 - 11:18 AM.


#15 Vic Menard

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Posted 12 June 2021 - 11:39 AM

...However, with the cut-out removed, the tube becomes too short at F/4 and the crosshairs become unusable because they are too close to the eye with a 1.25" focuser.

I don't understand why the tube length would be shorter--if the tool is designed to be usable from f/4 to f/6 (whatever that means), the length should not change and, assuming the cross hairs are usable as currently designed, should still work. A simple solution would be to keep everything the same and eliminate the tool shoulder (or place it at the very top). This would allow the tool to be inserted fully into the focuser. While the cutout would be unusable fully inserted, the tool could be used at the apex for secondary mirror placement (which is rarely (never?) assessed after dark anyway) and pulled out of the focuser to expose the cutout for axial alignment. 

 

...However, I would rather have the crosshairs present than worry as much about being able to see the entire primary reflection.

Since the tube insert with cross hairs can be removed, you've already made this accommodation, yes?

 

...Most users cannot centre their secondaries well enough to use the three circles to confirm alignment of the secondary and will always have the primary reflection a bit out of position. I would rather they have usable crosshairs...

You lost me here. Most users use the three circles for secondary mirror placement (rotation and/or offset), and then the secondary mirror tilt for fine adjusting the focuser axis (sight tube cross hairs or thin beam laser). This fine adjustment always happens at the expense of rotation and/or offset--so the alignment of the three circles needs to be close if you want both alignments (placement and focuser axis) to be corrected. And for what it's worth, "usable" cross hairs is also a function of the user's eyesight--something you have no reasonable control over.

 

...Also if the primary reflection is not perfect, it only means there is a minor illumination issue which will not grossly affect the view.

If the primary reflection is not centered, the focal plane will be tilted relative to the eyepiece axis, impacting focus and image performance. Centered and rounded secondary mirror placement delivers centered and balanced field illumination (which has minimal impact on visual performance)--but if the secondary mirror minor axis is optimized for minimal obstruction, and the secondary mirror edge correction is suspect, placement errors can impact visual image performance.

 

...The tool is really for the beginner/intermediate astronomer.  If you are doing astrophotography with a fast Newtonian with an oversized secondary, you probably want so high end tools anyway and this tool is not for you.

A 1.25-inch adjustable length sight tube will likely attract a broader group than you're thinking (including many classic Newtonian collectors). Most imagers will have a 2-inch focuser, so you'll have competition there.

 

...there is no tool on the market that works well for centring and rounding for 1.25" focusers at F/4. 

I recently collimated an old Cave 6-inch f/4 with an equally old Tectron Cheshire* (about f/3.2). I was able to get nice discrete incremental steps between the three circles (I used a laser for the axial alignments). Omegon makes a knockoff with similar measurements--and that's what I've (recently) recommended.

 

(FYI--My Tectron 1.25-inch sight tube is 5.25-inches long with a 1.1-inch clear aperture, so, about f/4.8. And even with my glasses, I still can't get the cross hairs to focus. But my TeleCat XL (6.125-inches long) cross hairs will almost come to sharp focus.)

 

...some telescopes where the focal pane is too low in the drawtube, will not work perfectly with this tool because the entire primary reflection will not be visible.

I would be more concerned about scopes with the focal plane a half inch or so above the drawtube--pretty common with "mass produced" economy Dobs that use smaller secondary mirrors (to save $)--and the recent arrival of mass produced photo/visual Dobs with visual use drawtube extensions. Ideally, the pupil should be able to reach the focal plane with the focuser almost fully retracted, although most apex viewpoints will place the pupil some distance above the focal plane (typically, not much above the focal plane with smaller apertures, unless the scope is configured specifically for imaging). 


Edited by Vic Menard, 12 June 2021 - 12:17 PM.


#16 Jon Isaacs

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Posted 12 June 2021 - 12:12 PM

My tool is, not "self barlowed" and as a result is much longer than the Tublug.  It also does not go into the drawtube.   This tool is simply an adaptation of Nils Olaf Carlin's design that places the laser and target above the focuser.   In my opinion this device does not violate the patent primarily because it is not "self-barlowed" which is the essence of the Glatter Blug patent. 

 

Rob

 

 

The essence of the TuBlug and Blug is that the Barlow and is placed before 45 degree viewing window so that the diverging beam only passes through the Barlow one time. That was the stroke of genius that made the TuBlug so effective.

 

Are you using a Barlow-telenegative to diverge the beam that is placed prior to the viewing window so that the diverging beam passes through the Barlow only once? 

 

Note that neither the TuBlug nor the Blug is self-Barlowed in the sense of Howie's Self-Barlow, it was an attachment with a Barlow that threads on to the laser itself.

 

The TuBlug with the external 45 degree viewing port was not part of Nils' original design.. 

 

I'm not so concerned about the patent, I'm concerned about the fundamental principle and whether this is based on the TuBlug concept or not. 

 

Jon



#17 MellonLake

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Posted 12 June 2021 - 01:14 PM

Vic... Your input is great.  See my comments below.

 

 

I don't understand why the tube length would be shorter--if the tool is designed to be usable from f/4 to f/6 (whatever that means), the length should not change and, assuming the cross hairs are usable as currently designed, should still work. A simple solution would be to keep everything the same and eliminate the tool shoulder (or place it at the very top). This would allow the tool to be inserted fully into the focuser. While the cutout would be unusable fully inserted, the tool could be used at the apex for secondary mirror placement (which is rarely (never?) assessed after dark anyway) and pulled out of the focuser to expose the cutout for axial alignment. 

 

Your right, if I get rid of the shoulder it would work better, but with the 3D printer I currently cannot achieve this.  I currently need the aluminum barrel (due to slight ovality in the 3D print which makes registration in the focuser an issue, I chased this issue for months).  I would need to make the tool in aluminium to do this (which is costly and I don't have the capacity to do right now).   The machining to match the OD of the sliding portion to the outer barrel ID would be critical and make the tool cost the same as the Telecat which I am trying to avoid.     

 

Since the tube insert with cross hairs can be removed, you've already made this accommodation, yes? Yes.  

 

You lost me here. Most users use the three circles for secondary mirror placement (rotation and/or offset), and then the secondary mirror tilt for fine adjusting the focuser axis (sight tube cross hairs or thin beam laser). This fine adjustment always happens at the expense of rotation and/or offset--so the alignment of the three circles needs to be close if you want both alignments (placement and focuser axis) to be corrected. And for what it's worth, "usable" cross hairs is also a function of the user's eyesight--something you have no reasonable control over.  Agreed, we must be miscommunicating on this.  I had though in your first post in the thread that you meant the the secondary alignment could be achieved simply adjusting the secondary and making the primary circle concentric to the other circles (i.e. not using the crosshairs). 

 

If the primary reflection is not centered, the focal plane will be tilted relative to the eyepiece axis, impacting focus and image performance. Centered and rounded secondary mirror placement delivers centered and balanced field illumination (which has minimal impact on visual performance)--but if the secondary mirror minor axis is optimized for minimal obstruction, and the secondary mirror edge correction is suspect, placement errors can impact visual image performance.  Agreed, which is why I used "minor".  

 

A 1.25-inch adjustable length sight tube will likely attract a broader group than you're thinking (including many classic Newtonian collectors). Most imagers will have a 2-inch focuser, so you'll have competition there. Interesting! 

 

I recently collimated an old Cave 6-inch f/4 with an equally old Tectron Cheshire* (about f/3.2). I was able to get nice discrete incremental steps between the three circles (I used a laser for the axial alignments). Omegon makes a knockoff with similar measurements--and that's what I've (recently) recommended.  I have come across this tool a couple of times on the web but did not know if it has crosshairs.  I will now assume that it does!

 

 

(FYI--My Tectron 1.25-inch sight tube is 5.25-inches long with a 1.1-inch clear aperture, so, about f/4.8. And even with my glasses, I still can't get the cross hairs to focus. But my TeleCat XL (6.125-inches long) cross hairs will almost come to sharp focus.)  Yeah, I am starting to have that problem too. The only solution is a laser (either laser vision to correct the eye or a laser collimator)!  

 

I would be more concerned about scopes with the focal plane a half inch or so above the drawtube--pretty common with "mass produced" economy Dobs that use smaller secondary mirrors (to save $)--and the recent arrival of mass produced photo/visual Dobs with visual use drawtube extensions. Ideally, the pupil should be able to reach the focal plane with the focuser almost fully retracted, although most apex viewpoints will place the pupil some distance above the focal plane (typically, not much above the focal plane with smaller apertures, unless the scope is configured specifically for imaging). Yes, there are always going to be telescopes where certain tools will not work well.  If I can eventually do this in aluminium it would work.     



#18 MellonLake

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Posted 12 June 2021 - 02:02 PM

The essence of the TuBlug and Blug is that the Barlow and is placed before 45 degree viewing window so that the diverging beam only passes through the Barlow one time. That was the stroke of genius that made the TuBlug so effective.  This is Nils' invention the beam only passing through the Barlow once.  45 degree targets had been used on laser collimators prior to the Barlowed laser technique being developed. 

 

Are you using a Barlow-telenegative to diverge the beam that is placed prior to the viewing window so that the diverging beam passes through the Barlow only once?  Yes, as Nils described prior to the Howie's Blug patent and which Howie acknowledges in the patent.  

 

Note that neither the TuBlug nor the Blug is self-Barlowed in the sense of Howie's Self-Barlow, it was an attachment with a Barlow that threads on to the laser itself.  I disagree.   They are the same tool only the angled face is different.  

 

The TuBlug with the external 45 degree viewing port was not part of Nils' original design.. Agreed but this is not the novel part of the patent.  

 

I'm not so concerned about the patent, I'm concerned about the fundamental principle and whether this is based on the TuBlug concept or not. The tool was in part inspired by the Tublug as well as Nils, and conventional laser collimators (i.e. SVbony).  

 

Jon

Both the Tublug and Blug are "Self Barlowed" in the sense of the patent and Howe's invention.  Look at the drawings in the patent.  The stroke of genius is Nils Olaf Carlin's not Howie's.  Howie acknowledges this in the Patent,

 

"This weakness has been largely eliminated by another advance in the art, disclosed in the article “Collimation with a Barlowed laser” by Nils Olof Carlin, published on pages 121 to 124 of the January 2003 issue of Sky and Telescope magazine. The Barlowed laser technique eliminates compounding of secondary mirror misalignment error when adjusting primary mirror alignment, and it is also relatively insensitive to alignment errors of the laser collimator within the eyepiece holder."

 

Nils' webpage describes his invention,

"A Barlowed Laser Collimator... You need to put a target over the lens end of the Barlow: Cut a circle of cardboard, large enough to fit over the lens end of the Barlow, and make a center hole to let through the laser beam. Attach it to the Barlow (make it a tight fit to the lens cell, but make a tab to let you lift it off afterwards).Do step 4 the usual way without the Barlow. For step 5, put the Barlow in the focuser and the laser in the Barlow. You should now see the wide return spot illuminate the target, and also the shadow of the main mirror spot. Now collimate the main mirror to center this shadow.

(The laser light now appears as if coming from a virtual point source, for a 2x Barlow this is near the upper end of the barrel. If used in the normal focuser position, it is well balanced for 1B error)."

 

A Blug or Tublug without the "diverging lens" or Barlow is not patented.  The only novel component of the Tublug (and Blug) in the patent is internal Barlow lens that shortens the device. Tublugs without lens are just common everyday laser collimators, you can buy a SVbony one from Amazon for $25.  

 

The Patent actually get's pretty close to Nils' technique, it notes: "Although the preferred embodiment has this face angled, it may also be square with the body cylindrical axis". With the face square to the body, this is Nils' device except for the internal Barlow lens in the device.  If not for the "self barlow" the Howie Patent would be Nils' invention. I actually find this patent far too close to Nils' invention for comfort. 

 

The Tublug was part of the inspiration for this tool (as were conventional laser collimators with 45 degree windows) and playing with Nils design with the paper on the end of the Barlow.  I also played with putting a plug in the bottom of the drawtube and then placing a Barlowed laser in the focuser (kind of a cross between Nils' design and the Blug).  The tool I show above works very much like the Tublug but is just a different adaptation based on Nils' Barlowed laser technique.  It works based on the principles developed by Nils.  I chose not to incorporate the tiny Barlow lens into the tool and to allow for the tool to be very long as opposed to short with internal Barlow as described by Howie in the Patent. 

 

 

Rob  


Edited by MellonLake, 12 June 2021 - 02:06 PM.


#19 Jon Isaacs

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Posted 12 June 2021 - 02:22 PM

Rob:

 

I had privilege of knowing both Nils and Howie via the internet and had many conversations with each of them. I've been using Howie's collimators more than 20 years, I remember when Nils first published in Sky and Telescope. 

 

There is no doubt that Nils was a genius and that the Barlowed laser a stroke of genius.

 

But Howie was a genius in his own way and the Blug and TuBlug were both important contributions to collimating with a laser.  You weren't around back then. 

 

You and I are both engineers. We respect previous art. The TuBlug represents previous art and it is something I'm sure you were aware of when you came up with your design. 

 

Please give Howie the respect he deserves, don't claim your design is solely based on Nils' Barlowed laser..  

 

This is not about any patents.. 

 

Jon



#20 MellonLake

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Posted 12 June 2021 - 02:50 PM

Sorry, I did not mean to take anything away from Howie. The tool is very effective. Credit is due to Howie for sure, the incorporation of the lens into the target is novel and achieves a very elegant design that is better than I can achieve without violating the patent.
Howie's patent is novel and this is why I won't violate it. Howie's parallizer is a stroke if genius, I have yet to be able to even approach something as effective after months of trials. He was an amazing engineer and for this reason I was careful not to tread on the patent, I take these things very seriously.

Unfortunately I don't know either of these two gentlemen and wish I did. I appreciate that Howie acknowledged Nils in the patent, that is very classy and not always done. But none the less the Glatter patent gets very close to being the same as Nils' invention in certain aspects.

I am sorry that I took offense to your comments but I strongly considered my design in light of both Nils' invention and Howie's patent. You can see this from my comments above I carefully considered the patent and scrutinized it because I did not want to tread on the patent.

Edited by MellonLake, 12 June 2021 - 02:50 PM.

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#21 Jon Isaacs

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Posted 12 June 2021 - 03:14 PM

Rob:

 

In my mind, the important aspect of the TuBlug is the outward placement of the viewing 45 degree window with the Barlow placed between the laser and the window.

 

That's what made it so effective, the Barlowed laser could be viewed easily while adjusting the collimation.

 

Jon


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#22 Vic Menard

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Posted 12 June 2021 - 03:33 PM

Your right, if I get rid of the shoulder it would work better, but with the 3D printer I currently cannot achieve this.  I currently need the aluminum barrel (due to slight ovality in the 3D print which makes registration in the focuser an issue, I chased this issue for months).  I would need to make the tool in aluminium to do this (which is costly and I don't have the capacity to do right now).

It seems to me that all you would need to do is to make the current 1.25-inch aluminum barrel about twice as long and drill a hole (illumination aperture) in the side (close to the shoulder), then 3D print the Cheshire/cap head, and use your current inner extension barrel. Would that be significantly different from your current materials/assembly?

 

If the primary reflection is not centered, the focal plane will be tilted relative to the eyepiece axis, impacting focus and image performance. Centered and rounded secondary mirror placement delivers centered and balanced field illumination (which has minimal impact on visual performance)--but if the secondary mirror minor axis is optimized for minimal obstruction, and the secondary mirror edge correction is suspect, placement errors can impact visual image performance.  Agreed, which is why I used "minor".

Just to be clear, I'll respond again: it's not an illumination issue, and it's not minor. The primary mirror reflection centering (usually fine tuned using the secondary mirror tilt adjustment) has an error tolerance, the secondary mirror centering does not.

 

Omegon makes a knockoff with similar measurements--and that's what I've (recently) recommended.  I have come across this tool a couple of times on the web but did not know if it has crosshairs.  I will now assume that it does!

The Omegon Cheshire is a knockoff of the Tectron "Cheshire"--neither have cross hairs (neither are combination tools). But the barrel length is suitable for f/4 secondary mirror placement (with access to the apex and incremental steps). As I mentioned, I used a laser for the axial alignments.


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#23 MellonLake

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Posted 12 June 2021 - 04:53 PM

It seems to me that all you would need to do is to make the current 1.25-inch aluminum barrel about twice as long and drill a hole (illumination aperture) in the side (close to the shoulder), then 3D print the Cheshire/cap head, and use your current inner extension barrel. Would that be significantly different from your current materials/assembly?  Great point!   I will see if I can find something.

 

Just to be clear, I'll respond again: it's not an illumination issue, and it's not minor. The primary mirror reflection centering (usually fine tuned using the secondary mirror tilt adjustment) has an error tolerance, the secondary mirror centering does not.  I see what you are saying now.  Sorry I misinterpreted.

 

The Omegon Cheshire is a knockoff of the Tectron "Cheshire"--neither have cross hairs (neither are combination tools). But the barrel length is suitable for f/4 secondary mirror placement (with access to the apex and incremental steps). As I mentioned, I used a laser for the axial alignments.  Probably because it is so short and does not extend.  



#24 Bob4BVM

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Posted 13 June 2021 - 12:52 AM

In my situation, I like the Tublug because I can adjust the primary while looking at the Tublug. I really don't know how people use collimation caps and autocollimators when they can't adjust them in real time.  

 

If there's someone to help then I can see it but doing it alone when it's several feet from the adjustments to the focuser and may require climbing up a ladder, the Tublug is a god send.

 

Jon

Electric collimation. Real-time  That is the real God-send.



#25 Starman1

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Posted 13 June 2021 - 12:05 PM

In my situation, I like the Tublug because I can adjust the primary while looking at the Tublug. I really don't know how people use collimation caps and autocollimators when they can't adjust them in real time.  

 

If there's someone to help then I can see it but doing it alone when it's several feet from the adjustments to the focuser and may require climbing up a ladder, the Tublug is a god send.

 

Jon

Not accurate enough unless your vision is a lot better than most people.  I found using a small monocular from down below allowed me to get within the  (effective)1' distance I needed to do a good job

centering the primary marker shadow in the tublug.  Otherwise, you're not accurate enough unless you do what I ended up doing--sitting between the tublug screen and the bottom of the scope,

reaching around to turn a knob by leaning one way, and leaning toward the tublug to check.

Autocollimators are used for secondary adjustment, so you make a tweak, look, make a tweak, look, etc.

A collimation cap or Cheshire can be easy tools to use even when you have to go back and forth.  Once you've collimated a thousand times, you know which knob to turn and in which direction to make a positive change.




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