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Has anyone built one of these collimators or...?

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#51 Philip Levine

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Posted 30 March 2019 - 08:59 PM

To SMark,

Thank you for these instructive and informative posts on collimation.

Phil



#52 SandyHouTex

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Posted 31 March 2019 - 08:30 AM

This has been one of the best threads ever on CN.  I have learned so much.


Edited by SandyHouTex, 31 March 2019 - 08:30 AM.


#53 Mergurt

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Posted 31 March 2019 - 04:24 PM

I started on making one of these after Bill's first book came out - needless to say it's still an ongoing project. The new book fills in some gaps. As Matt said, the auxillary telescope is the "secret sauce". Finding a rhomboid prism long enough to give a decent offset and give a line of sight which clears the intervening binocular body was not so easy. I managed to find a supplier who sells individual pieces to the public, and picked up a couple uncoated 42mm ones: https://www.knightoptical.com/  The main hold up is just the fine mechanics of mounting the prism, without having access to a well equiped workshop. If (when!) I ever get it finished, I'll post some pictures.

 

For the collimator itself, I intend just using a telescope - a good reason to buy an SCT I think, so I can collimate my binos ;-)

 

For those who missed it, Foss had a Mk V up for sale in the CN classifieds, and had a short video describing it.


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#54 vietspace

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Posted 06 April 2019 - 03:06 AM

Hi all,
I'm setting a 11in SCT for a collimator as shown in the picture.

But I still haven't figured out how to correct the reticle screen exactly at the focal plane position. I see in this topic that many people have plan to use SCT to setup a collimator, can you help me know how to do it?

 

SCT_collimator.jpg



#55 Ant1

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Posted 06 April 2019 - 06:48 AM

Hi

 

https://www.cloudyni...plane-question/

 

If you are using an SCT you don't need green light, any light will do

 

Regards

Ant1


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#56 vietspace

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Posted 06 April 2019 - 07:40 AM

thank you Ant1, I will try it

#57 vietspace

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Posted 06 April 2019 - 11:04 AM

Hi

 

https://www.cloudyni...plane-question/

 

If you are using an SCT you don't need green light, any light will do

 

Regards

Ant1

 

Tonight I did follow your process but I used a bahtinov mask to make sure the reticle screen in focus



#58 shredder1656

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Posted 11 April 2019 - 04:06 AM

This should help!

 

Attached File  CN Collimation Manifest 4.0 190409.pdf   205.26KB   66 downloads


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#59 Gordon Rayner

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Posted 16 April 2019 - 12:43 AM

In  this thread,  it was  stated that the Suddarths use a C8 and a C14,  and  USN  Mk 5.    Do they  transfer  the 2-angular axes  adjustable  fixture from the Mk. 5  to  the C 8 and/or the C14,  when using  those Celestron scopes as  parallel light sources?   Or  are  other   2- angular axes adjustable   fixtures  used  with the Celestrons?  

 

My fixture is now   based upon  a Swedish   2- angular axes    adjustable  support  for a  geodetic  tellurometer.  I formerly used  a modified   artillery panoramic  scope,  Goerz,  WW II.   But it  had some lost motion ( for which I learned to compensate)

 

Mad Matt  re. #25,  #28:  I  tried the  2 Porros  cemented  to made a rhomboid  experiment  years ago.    The peek-around ray  goes through the prisms,   and the ray through  the binocular half  just clears the edge  of the lower Porro  prism. 

Image rotation  can  happen  if the Porros  are not square when  the cement hardens.    

 

The errors of such a glued up  rhomboid prism   made of two  Porros    could be corrected with wedge  windows  housed in rotatable  mounts.  

 

The  JTII   "hand collimator"   used   an inaccurate rhomb  ( to lower cost).  corrected by  two  rotatable  wedge windows, located   just  ahead of  each of the two   ray  entries  to the rhomboid.   the exit end of the rhomboid  has  a 45 degree  prism  attached to its reflective  face,  to make  that end a beam combiner.  Appropriate  coatings  or semi-reflecting  silver of aluminum  at the  glued  junction  of the two prisms  act  to make   one   ray  slightly yellow,  and the  other  slightly blue-green.  The color difference  allows the operator to  see   the origins  of  each part of the combined  images.  That is,  Left , or Right,  or  Peek-Around  vs.  through  one half of the binocular.  

 

The JTII  can work as a  comparator  L vs R,   or  as a peek-around  comparator  WITH OR  WITHOUT  AN AUXILIARY TELESCOPE.    The magnification  of an auxiliary    handheld  scope  is helpful,  at 2x to perhaps  5X,  but   a  JTII   can be used alone.   I have  done ( tiring) work  on a dockside  boat  with just  a JTII  and braced elbows ,in the 1980's or early '90's.   I saw similar activity  at  sometime Bushnell  subcontractor   Oriental  Optical   in Pasadena.  Yoshi  was working  on  binocs  which were  not the finest,   and handheld   was good enough,  particularly with his  long experience on similar  specimens. 

 

See  Hanna   or Gardner   in ATM II or III   to make small Navy  style  peek-around rhomboids 

 

See my posts  via  searching  older  CN   via   Nuer  and /or Dinka   as   search  words, to   see  some   comparators and adaptation of  JTII  to auxiliary  scopes.    I have  Navy  comparators  with rhomb attachments,   1923 vintage.  They   had lots of use  in the 1970's and 1980's.  Distant terrestrial  targets were the parallel light sources. 

 

What  sort  of  handheld comparator did Hans Seeger  use  ?



#60 Mad Matt

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Posted 16 April 2019 - 05:05 AM

Just an FYI, I ordered a 220mm/600mm Fresnel lens off ebay and it looks like they should work well enough. I have initial tested with my Swarovski 8.5x42 EL and I believe the image quality should be good enough for collimation. I don't have a periscope aux. telescope (yet) so this was a simply naked eye collimation check. Of course the CA is pretty bad but a monochrome light source will take care of that. The image was perfectly collimated and I could not detect that the distortion was falsifying the collimation.

 

If you cant find a "long" focal length Fresnel locally then you can also try combining a positive and negative Fresnel into a doublet to get a usable focal length. 



#61 Gordon Rayner

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Posted 16 April 2019 - 02:36 PM

FF  #'s   25, 28, 59:

 

Three   Porro  prisms,  cemented  to each other   on   what are normally their reflecting  faces,   conceivably   may  serve  as a  beam combining  pseudo  rhomboid  prism.    Where the second prism   interfaces   the third  prism,   that  surface of the   second prism    could be   50/50%    half silvered   , to make   that interface a beamcombiner   of the image through  the binocular  half with the    image   via  the peek-around path.   

 

Flash silvering   kits   are used   by pro optical   fab shops    for   intermediate   tests . 

 

The mentioned   wedge  window  /weak wedge    "prisms",   in rotatable  mounts,   would  be needed for  undoubted  error

correction   of such a three-Porro   assembly.   



#62 MartinPond

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Posted 17 April 2019 - 01:04 AM

It's exhausting just reading the various tries..


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#63 shredder1656

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Posted 20 April 2019 - 07:18 AM

The "JTII Hand Collimator" is covered in Binoculars Fact and Fallacy.  Also, I think it only works for conditional alignment, and not actual collimation. 

 

Both of these books have a ton of good info.  Probably much more info than can be gleaned here, but seeing some color pics of a completed homemade collimator would be great.  Hopefully, eventually enough people will have read through THE book, since it is very informative, and one of the group of students will have completed it AND the project.

 

In the meantime, the pics that SMARK and others have posted are awesome.  I wish I lived close enough to attend a class conducted by Suddarth Optical with Bill Cook and Cory Suddarth.  That would be outstanding. 



#64 MartinPond

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Posted 21 April 2019 - 07:09 PM

The class might help you finish one?



#65 Gordon Rayner

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Posted 01 May 2019 - 12:27 AM

Re: #63   and my #59:

 

The peek-around  rhomb  , Navy with an auxiliary scope, or   a    JTII  " hand collimator",    with or without  an auxiliary scope,  can be used   to obtain   parallelism of the hinge  with the two optical axes.    So, 
#63 is  not correct  in  its guess that  a JTII  is  only useful for   checking the parallelism of the two optical axes.   

 

With a two axis angularly adjustable fixture,   the JTII   can act as a peek-around  beam combiner,  with or without  an attached auxiliary scope,   to  mutually parallelize   the three axes of the binocular,   using the Navy method.  

 

Freehand or braced   elbows use of the JTII,  can be used to obtain   3-axis parallelism.   However,  such use   is likely to be tiring and confusing   to a beginner.    With experience  using the Navy method  with a  two angular axes  repeatable adjustable fixture  or the Fuji  UBBM   or similar,     or  lacking those,  but with  lots of  understanding and thought,   a JTII or   equivalent  comparator  has been seen  to  be used   by  experienced Japanese  pros,   and by your servant personally  on a  docked but  slowly  slightly moving   100 plus foot boat boat, to obtain  3-axis parallelism.   

 

As always   the key is    mental visualization   of   the position    at infnity of the  hinge axis,   after swinging  the hinge  to form  an isosceles  triangle  whose apex  is the hinge  axis,   and whose  other two  corners are  first  , the fused  images of the  direct image   from peek-around   view of the target,   superimposed  (by the fixture, or  freehand or semi-freehand) on the   target image though one barrel of the binocular,   and   second,  the  image of the target  through   the barrel   after  a swing.

 

DEJA VU



#66 Gordon Rayner

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Posted 05 May 2019 - 11:08 PM

The    included angle   between   the two legs  of the isosceles  triangle,   which is the angle   adjacent to the   apex , is the angle through which the  binocular's  hinge  has been rotated.  

 

By  repetition   of the   described   process,   the    triangle   shrinks   to a point .    
That point is  the projection of the   hinge   axis  to infinity.     Thus,  the hinge axis and the two optical axes    are  then parallel.    The instrument is  thus   suitable for   use  by  persons with   any   interpupilary  distance.  

 

Absence of image  rotation, L vs. R.,   is a diffferent topic.  



#67 dries1

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Posted 06 May 2019 - 06:10 AM

"The "JTII Hand Collimator" is covered in Binoculars Fact and Fallacy.  Also, I think it only works for conditional alignment, and not actual collimation.

 

Both of these books have a ton of good info.  Probably much more info than can be gleaned here."

 

shredder1656

 

 

Agreed.

 

 

Andy W.


Edited by dries1, 06 May 2019 - 06:12 AM.


#68 Gordon Rayner

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Posted 08 May 2019 - 07:55 PM

Re   # 63 and # 67.     The mentioned  "thinking"   is guesswork and is  fallacious.    It seems that the "Fallacy"   book does not  mention  several applications of the JTII  or an equivalent  comparator  

 

I suggest that you get a JTII  or equivalent comparator,   and  use  it   in the   Navy   Peek -Around  One Barrel mode,  with or without attaching it to an auxiliary  telescope. 

 

Such a comparator   can also be use to   view fused images via the L and R  barrels.   Freehand,  ( unless one  has four hands),   hinge axis information  would be  difficult  /laborious/impossible  to  obtain  in that mode, and  thus parallelism of   the two optical axes with the hinge axis  , "collimation", is not to be   easily found via that route.  

 

However,   if the   comparator   is  rigidly   fixed,   and  the  binocular  wiggled via   swinging the  hinge  while the  instrument   points at the target, perhaps by  being   rested upon a  window, as in the Fuji  UBMM,   the technician   can  observe  the motion  of both target images  simultaneously, at least  through a swing range  which will be greater  with larger  exit pupils.  He/she can  thus mentally construct  two  isosceles triangles  , each to be shrunk  to a   single point  via  adjustment  of the eccentrics  or the  push-push   or push-pull   screws   or other (?)  available mechanisms.    

 

In a projection system such as the Fuji UBMM,  there  is   no such   limitation  from exit pupil  sizes.   



#69 Gordon Rayner

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Posted 11 May 2019 - 04:08 PM

What are the answers  to  the question I raised   in #59 about    what   2-axis  angularly adjustable fixture do the Suddarths use  with the  C-8  or the C-14 (  or  with some suitably   distant terrestrial target)?

 

Do they   move the Navy   fixture   from   the Mk. 5   to some other base?

 

My fixture is now  based  upon a   AGA (Sweden)   precise, repeatable ,  2-angular axis adjustable  base  originally used   to point  a geodetic   tellurometer.  

 

In # 40 or #41,  SMark  emphasized  that the graph  should be clockwise.   That is true if the swing was CW.   If it was  CCW,   the graph should proceed   CCW. 

 

Graphs  are  are useful tool   to understand   construction of the   triangles  to be iteratively shrunk  to  a point.    But with   some experience,   one can dispense  with the graphs  and proceed  via mental visualization   of   the apex of   the triangle  generated via  a rotation of the hinge , a "swing". 

 

Note that use of  a   projection  Fuji   UBMM   involves   bidirectional    CCW-  CW   swing wiggles   while the front of the binocular  is supported  upon a window   which  keeps the  hinge pointed  at the simulated  infinity target.   The implicit assumption is that  the  plane of the front of the binocular  is perpendicular to  the hinge axis,   which   will be true  of any decent  mechanical   production  factory.



#70 SMark

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Posted 11 May 2019 - 11:49 PM

Here's another great pic and description from Cory...

 

This shows the error of approximately 25 minutes step and 20 minutes convergence on the Mark 5 as seen thru the auxiliary scope. The thin line is the 3x auxiliary thru the Rhomboid Prism, and the thick lines are looking thru the binocular. If the glass is 7x, the total magnification is 21x.

Attached Thumbnails

  • IMG_1738.JPG


#71 Gordon Rayner

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Posted 12 May 2019 - 12:56 AM

That   will   tell   errors.     Another way is to use a transit or a theodolite  to   measure the  angular dimensions of  features  in a suitably distant terrestrial target,  such as a large smokestack,  statue,  power  line support,  tree,   advertising or traffic sign, etc.  

 

"thin line"=  the dark  lines ?    Thick lines =  the  green  lines  out of focus  or otherwise aberrated?

 

But why  worry about quantitative  errors?   A better policy, unless one is in  a big hurry,  is to work to  the most  precise  result   available  with  the equipment ,  operator,  and  reasonable   expenditure of  time ,  depending upon the   likelihood   of the   binocular's adjustments   remaining  correct  over time.  That is: cheapo  mechanisms  vs.  quality, stable mechanisms.

 

Incidentally, the only  firsthand use  by me  of a Mk.  5  or a Mk. 3  was  during a  courtesy visit to a  Navy tender  in  late 1969 or early  1970,  when I had  only a spanner  , and was preparing a WW  II Flak 10 x 80  for the March 1970  long eclipse in Oaxaca  and  first views of Crux,  southern Vela and Centaurus, etc.   I saw  Apollo 13  take off  in Florida later that spring.     There is no hinge on those  Flaks, hence  no swinging is involved.   They lent to me, for use in their shop,    one of the Navy   "  Stereo Comparator".   The JTII  is similar in principle, but more versatile. 
      I never saw any   Mk. 5   for sale   in   official  government surplus,  nor in secondary   sales with that source.   But I have  seen and been prospectively offered   such  by  presumably cumshaw   primary or secondary sources.    But I do have a Mk. 13  from a secondary source.   I suspect that its primary source was Mare Island.  I saw no such equipment  at the second  disposal  auction there.   I missed attending the first  auction at the time that base was being permanently closed.    My secondary source is RIP, and has been so for   about a decade  .

 

What about  my question concerning  transfer   of the  Mk. 5  adjustable fixture  to use with the C8 or C14,  or the  use of   some other 2- angular axes  adjustable   fixture   for application with the  reversed   Celestrons  as sources  of artificial  infinity targets?  


Edited by Gordon Rayner, 12 May 2019 - 01:03 AM.


#72 shredder1656

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Posted 12 May 2019 - 06:15 AM

Mad Matt, did you buy one of the Fresnel lenses from China?  Care to post any pics of your kit?

 

I finally have the auxiliary scope, so I think the Fresnel is the last component I need.  Should be soon.


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#73 Mad Matt

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Posted 12 May 2019 - 08:30 AM

Mad Matt, did you buy one of the Fresnel lenses from China? Care to post any pics of your kit?

I finally have the auxiliary scope, so I think the Fresnel is the last component I need. Should be soon.



I still have not gotten around to building a prototype yet but as I posted above, based on my initial test, it should work with monochromatic light.

The trick is to find one with as long a focal length as possible. Mine is 600mm and it may prove to be too short. I believe the Mk V has a focal length of about a meter.

#74 shredder1656

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Posted 16 May 2019 - 03:58 AM

More helpful info, here: Attached File  CN Collimation Manifesto 190515.pdf   116.01KB   37 downloads

 

 



#75 vietspace

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Posted 19 May 2019 - 11:49 AM

IMG_0168.JPG

 

I almost finished my collimator
Today I received a 3-9x40 rifle scope to make the auxiliary telescope, but it’s too long and heavy so it's too difficult to stabilize behind binoculars eyepiece

Anyway, I think I have all things to complete my collimator. In the next few days I will complete the test stand and consider whether I can replace a lighter auxiliary telescope.

 

I use a Celestron CPC 11in for collimator tube with a reticle at focal plane
Rhomboid prism ~ 50 usd from a Vietnamese optical company
A Vixen Az-Alt adjustment for Test stand


Edited by vietspace, 19 May 2019 - 11:57 AM.

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