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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   44 downloads



#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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