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Takes cognitive psych to fix a view

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#1 MartinPond

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Posted 13 December 2019 - 03:58 PM

It always seemed  to make sense that if I had

one star diagonal to correct up/down and then

another to fix left/right, the image should be

fully corrected...right?
 

DSC_0141.JPG

 

So I built the simple arrangement,

and the test fonts read true, but the

way the image moved when I moved the scope

was disorienting...I even got dizzy/woozy.

Things did not move the way they should..

Maybe that's why you don't see people using this scheme.

 

 

I revisited this, months later (today).

I thought of it as a POV problem...if I changed

my point of view, maybe my brain would connect.

So...I stepped to the >>side<< of the scope and looked down

into the EP.   Now things moved the way they should!

And it was just my POV that was messed up.

There is a virtual field to the side of the scope

that is the projection of the front view.

Feels natural, even though my mind has to

see something that is 90 degrees away.

And it only took standing to the side to feel right!

 

So...yes, you can use two star-diags to fully  fix the view

  (with no star spikes or phase hassle!)..

But....you have to change  (physically) your point of view!


Edited by MartinPond, 13 December 2019 - 03:59 PM.

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#2 wrnchhead

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Posted 13 December 2019 - 04:10 PM

Haha this is excellent. And Mr Pond, I know scant little about optics but your posts about eyepieces make me want to order a bunch of lenses from surplus shed and just play around with stuff
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#3 Peter Besenbruch

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Posted 14 December 2019 - 02:55 PM

I used that arrangement with a 60mm, 700mm fl telescope. I used a hybrid diagonal as the first one, and a standard 1.25" as the second. A 32mm Jaegers special (we don't need no stinking field stop) gave me 22x. I used it for several years as a spotter.

 

The most memorable event was traveling in Germany, and birding at Hauke Haien Koog on the North Sea coast. There was a bird in the distance. My uncle thought it was a Grey Heron. I said it was a flamingo. He said I was crazy. It was a good spotter and, yes, you had to stand sideways to the scope.



#4 MartinPond

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Posted 14 December 2019 - 05:26 PM

Birds do drift around.....with the storms.

Cattle egrets did not exist in the new world,

  but found their way to South and North America and

  the US where they are thriving.  

 Instead of following cattle they follow farming equipment.

 

Of course, flamingos have a huge traveling capacity..

Maybe if the weather suits them in a particular year

  they go where the conditions are good..

 

You can get disoriented looking up from the scope, too..

Best to stay at the eyepiece a good long time!


Edited by MartinPond, 14 December 2019 - 05:27 PM.


#5 25585

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Posted 15 December 2019 - 05:57 PM

Hope & mirrors. I'll stick with a single Amici. https://www.astrosho...wE&utm_content=



#6 MartinPond

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Posted 15 December 2019 - 06:12 PM

That's probably the priciest Amici!

But Baader says if the meeting angle is precise (very),

     there is no spike.  For that price..it should be awesome..

 

I once looked through an ordinary Amici with the edge cut and blackening..

    it was pretty good.  The phase thing isn't a huge issue though..

 

There used to be Porro pairs available...those are quite nice!

Maybe the extra weight was an issue, or maybe the travel. 


Edited by MartinPond, 15 December 2019 - 06:14 PM.


#7 wrnchhead

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Posted 15 December 2019 - 06:15 PM

I keep seeing this diagonal in CN threads. I think I must have one.

#8 MartinPond

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Posted 15 December 2019 - 08:07 PM

Make sure you have extra travel for it...

 

I am totally messed up with no correction,

but I'm really comfortable with just left-right reversal..

 

I have a strangely big .Amici from a "Galileo" brand telescope...

the spiking is very reduced....probably just coincidence and

easier positioning (with a larger chunk of glass) during manufacture..

Switching to a regular star diagonal, I have to put in an extender

to make up the difference with the Amici gone.  Better problem

than running out of travel the other way..


Edited by MartinPond, 15 December 2019 - 08:09 PM.


#9 25585

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Posted 16 December 2019 - 09:19 AM

That's probably the priciest Amici!

But Baader says if the meeting angle is precise (very),

     there is no spike.  For that price..it should be awesome..

 

I once looked through an ordinary Amici with the edge cut and blackening..

    it was pretty good.  The phase thing isn't a huge issue though..

 

There used to be Porro pairs available...those are quite nice!

Maybe the extra weight was an issue, or maybe the travel. 

Pricey it is but my main diagonal, and its correct image with BBHS coating & I have not noticed anything bad in stars. Not quite as good, but cheaper is APM's roof prism correct image diagonal  http://apm-telescope...em/333632303635


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#10 Ernest_SPB

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Posted 16 December 2019 - 01:32 PM

The mirror represented by you rotate image on 90 deg. comparing to original. 

 

So when scope axis is raised up, image in eyepiece moved left side (if observer face see ahead - toward observed object). If scope axis turns right image in FOV goes up. 

 

If observer stays sideway (his left hand toward observed object) image orientation and movement becomes more natural (agreed to scope movement).  


Edited by Ernest_SPB, 16 December 2019 - 01:36 PM.


#11 MartinPond

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Posted 16 December 2019 - 08:50 PM

Pricey it is but my main diagonal, and its correct image with BBHS coating & I have not noticed anything bad in stars. Not quite as good, but cheaper is APM's roof prism correct image diagonal  http://apm-telescope...em/333632303635

One central argument for finer accessories is that

  you share that diagonal among many eyepieces.

That was my logic for getting a focal extender...it's worth it.

The Crayford focuser was way overdue. 

 

I don't know why my Galileo 'big chunk' Amici works so well. 

  Just lucky, perhaps..


Edited by MartinPond, 16 December 2019 - 08:50 PM.

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