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10" Binos giving optical Illusion

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#1 Scopeman61

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Posted 16 July 2020 - 06:32 AM

Hello all -

 

I have a real issue that Im trying to figure out what is going on with the optical alignment of my homemade pair of 10" Starfinder Binos. the tubes are 10" f4.5 scopes that I married up as binos. At one time they rocked to say the least!

I normally use a pair of 2" 22mm TV eyepieces. I attached at CAD dwg I thru together and try to explain what going on. I had completely reworked the mounting structure of the tubes to be more durable when transporting. I collimate each tube separate form one another. the pic shows the two tubes (top view) the one of the top is fixed and the bottom tube has a 3 point adjustment  for aligning to the other tube.

 

Behind the eyepieces, My view (Fig A) a star centered,  When the binos are moved left or right (Figs B & C) that star becomes two stars and the more you continue moving the scope the further the two stars split apart! note all background stars do the same. Makes for a good headache!!

 

Does anyone know why this maybe happening? I've tried about everything I can think of, ie; measuring the primary and sec mirror ends of the tubes for distance.

 

** I really would love to get these boys working for NEOWISE !!

 

Thanks -

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#2 JoeInMN

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Posted 16 July 2020 - 07:58 AM

Sounds like the same or a very similar issue to what came up in this thread.



#3 Scopeman61

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Posted 16 July 2020 - 09:23 AM

Thanks for the feed back JoeInMN, I will go thru and read all in details, I can add,  I bought the two new Meade 10" Starfinders at the same time and same with the Televues EPs 

I do suspect something got out of wack in the 2" mirror diags but I know at one time she performed very well. BTW in that thread - those 16s are look awesome @@

 

Thanks again



#4 Rich V.

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Posted 16 July 2020 - 09:30 AM

Sounds like the same or a very similar issue to what came up in this thread.

I'm no expert on reverse binoscopes but try turning the eyepieces/diagonals 90° so they are perpendicular to the main tube axes.  You need to look down into the diagonals, not with them aligned straight with the tubes.  You have a 180° reversal of images L/R with the diagonals pointed the way you show.

 

Rich


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#5 Albie

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Posted 16 July 2020 - 09:49 AM

Sounds like the same or a very similar issue to what came up in this thread.

Or this thread .  https://www.cloudyni.../#entry10341417


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#6 Rich V.

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Posted 16 July 2020 - 10:40 AM

On further thought after my morning coffee, there's a reason why the JMI RB scopes are "reverse" binoscopes; you look behind you with the diagonals turned not 90° but a full 180° from the way you've pictured.  Deviation from that orientation determines the degrees of image rotation away from identical, matching images.  Multiple mirrors are fun, huh?   wink.gif

 

Rich


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#7 salico

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Posted 16 July 2020 - 11:43 AM

why do those scary threads pop up, shortly after I got my new 12" Binotoy?;-) it's a complex machinery and I hope to get mine running on my second try of First light - the first try failed because on the three places we ve been where people and lots of light,,,


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#8 Rich V.

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Posted 16 July 2020 - 01:55 PM

My 3D thinking is cloudy today and I've been preoccupied with other thoughts, Scopeman.  Eyecrazy.gif  I misinterpreted your drawings.  Sorry to be confusing about this.

 

Your mirrors are situated OK just the way they are as you are merely creating a mirror "rhomb" that makes an offset to reach a normal IPD range.  It's the same as a JMI RB BT.  What's critical is that those diagonals are perfectly parallel with the primary optical axes.  Any tilt of the diagonals in unison up or down from that parallelism will create that rotation effect.  As you tilt them, one image rotates CW and the other CCW so your situation appears to be just like Tom Duncan's in the thread linked above.

 

3D thinking is hard enough to get my head around in the first place and it gets harder for me the older I get.  gramps.gif

 

Rich


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#9 Mr. Bill

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Posted 16 July 2020 - 04:42 PM

It's the 4D thinking that's got me.....scratchhead2.gif


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#10 Scopeman61

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Posted 16 July 2020 - 04:58 PM

Thanks all - 

 

I hear ya.. 3D 4D thought with optics can get twisted the longer I fool with them the more it can turn you around I may want focus on the secondary's (pardon the pun) as this may be my culprit!




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