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Solar Orientation in Refractors

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#1 cptbobrfh

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Posted 20 January 2021 - 01:40 PM

Hello-

 

Does anyone use a 2" ERECT IMAGE DIAGONAL to visually see the Sun in the CORRECT up/down,left/right orientation? 

 

Such as Baader 2" ERECT IMAGE DIAGONAL? 

 

Thanks to all,

 

Bob



#2 sg6

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Posted 20 January 2021 - 02:47 PM

Oddly it may be irrelevant.

The "top" and so "bottom" of the sun alters as you move North and South on the earth. Moon is the same.

Although the Sun remains "upright" the observer could be considered upright at the North Pole and "upside down" at the South Pole, and so the orientation of the sun appears to switch.

 

The old question of: Is the Moon upside down in Australia, No, but the observer is.


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#3 Couder

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Posted 20 January 2021 - 03:19 PM

To tell which way I'm viewing the sun, I lightly tap the tube up and see which way it moves in the image, then I know which way is up.


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#4 dhkaiser

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Posted 20 January 2021 - 03:37 PM

To answer your question, no I do not use a correct image right angle (cira) diagonal.  Those would have to be used with a objective solar filter.  I use either a Herschel Wedge or a dedicated solar scope, neither of which is cira.  I'm sure your aware that the sun's tilt will vary throughout the year, so it is more than using a cira to determine solar north in the telescope.

 

To find the correct solar orientation in my telescopes I use the Tilting Sun software.  Using your location, time, date, mount type and diagonal use it gives the proper eyepiece view.

 

http://www.atoptics.co.uk/tiltsun.htm


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#5 BYoesle

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Posted 20 January 2021 - 03:55 PM

 

Does anyone use a 2" ERECT IMAGE DIAGONAL to visually see the Sun in the CORRECT up/down,left/right orientation?

 

Such as Baader 2" ERECT IMAGE DIAGONAL?

 

None that I know of. After all, there is no advantage other than orientation, and for astronomical objects, this is traditionally considered irrelevant.

 

sun orientation.jpg

A: Eyeball, B: Telescope, C: Telescope with diagonal mirror / prism.

 

On the other hand I sort of like the idea of eliminating the reversed mirror image shown in diagram C. If you have enough in-travel, a good alternative would be a pentaprism:

 

https://www.telescop...al/p/130301.uts

 

https://www.omegon.e...ab_bar_0_select

 

The standard Baader Amici prism diagonal is intended for terrestrial viewing at "low power." If you intend to use this for astronomical viewing, I'd recommend the more expensive version with BBHS coatings w Zeiss prisms.

 

These would be for use with front mounted solar filters.

 

A pentapism version of the Herschel wedge could also be employed as seen on right below:

 

Solar Prisms.jpg

 

And there's an interesting post on one being used here.

 


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#6 chemman

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Posted 20 January 2021 - 08:45 PM

To answer your question, no I do not use a correct image right angle (cira) diagonal.  Those would have to be used with a objective solar filter.  I use either a Herschel Wedge or a dedicated solar scope, neither of which is cira.  I'm sure your aware that the sun's tilt will vary throughout the year, so it is more than using a cira to determine solar north in the telescope.

 

To find the correct solar orientation in my telescopes I use the Tilting Sun software.  Using your location, time, date, mount type and diagonal use it gives the proper eyepiece view.

 

http://www.atoptics.co.uk/tiltsun.htm

Great program Dan, Thanks.  


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#7 chemman

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Posted 20 January 2021 - 08:59 PM

Visually I am unconcerned about the Sun's orientation.  After all I am always looking at from a perpendicular angle when using a diagonal, If I wanted the orientation correct I  should be viewing it from a position of the Earth 3 months from now or 3 months ago, lol.  I typically assume when I am viewing straight through I am looking at it like it would look with solar binoculars, probably not so but it  is what runs through my head.  When I put a camera on the image plane sometimes I go to GONG and orient the camera to match it, I don't think that works either, lol.    It does seem to help me navigate when I am using the soda straw Barlow magnification though.  

 

 

Nice discussion of this dilemma Bob.  Thanks

 

Chuck


Edited by chemman, 20 January 2021 - 09:00 PM.


#8 cptbobrfh

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Posted 20 January 2021 - 09:16 PM

As a strictly visual solar observer,I would like to see the Sun as is pictured on GONG,SOLARHAM.COM,DAYSTAR WEBSITE,as the Sun surface features come from behind,and rotate from the left(east) and move towards the right(west) as per the rotation of the Sun.


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#9 viewer

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Posted 24 January 2021 - 07:49 AM

I have an erecting prism on my WL telescope, like it that way as OP. My HA PST telescope flips the image left/right and vertically, so after sketching I turn the sketch upside down for "correcting" directions. For getting the directions fine tuned I compare to SDO/GONG.


Edited by viewer, 24 January 2021 - 08:11 AM.


#10 rocketsteve

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Posted 24 January 2021 - 12:57 PM

You can also get correctly-oriented views of the sun online:

 

http://jsoc.stanford.../images/latest/

 

https://sohowww.nasc...me/hmi_igr/512/



#11 viewer

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Posted 24 January 2021 - 01:39 PM

Yes, I think all of them have the sun's north pole up and south pole down. Not exactly how it looks when viewed from earth's northern hemisphere, but in the ballpark.


Edited by viewer, 24 January 2021 - 01:49 PM.



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