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We need new nomenclature



 
 
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  #1  
Old April 15th 18, 12:35 AM posted to sci.astro.amateur
RichA[_6_]
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Default We need new nomenclature

I read a review of the ugly Baader Morpheus eyepieces on cloudynights and
something stuck me. The reviewer used the term, "diffraction rings" (of a star)when describing the view through a 65mm Pentax refractor using the 17mm Morpheus. Problem is, that's 22x on that scope with that eyepiece. So he was describing the intra and extra-focal rings shown when a star is thrown out of focus and not the in-focus diffraction rings seen at powers of 30x per inch and up. We should call the rings formed by out of focus star images something other than diffraction rings since they are definitely not that.

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  #2  
Old April 15th 18, 07:39 AM posted to sci.astro.amateur
Chris.B[_3_]
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Default We need new nomenclature

On Sunday, 15 April 2018 01:35:56 UTC+2, RichA wrote:
I read a review of the ugly Baader Morpheus eyepieces on cloudynights and something stuck me. The reviewer used the term, "diffraction rings" (of a star) when describing the view through a 65mm Pentax refractor using the 17mm Morpheus. Problem is, that's 22x on that scope with that eyepiece. So he was describing the intra and extra-focal rings shown when a star is thrown out of focus and not the in-focus diffraction rings seen at powers of 30x per inch and up. We should call the rings formed by out of focus star images something other than diffraction rings since they are definitely not that.


Dunno, Mate. They all look like inverted coke bottles to me.
I'm amazed Choker-Color hasn't sued them yet.
Must be chronic cough "sugar" overload in their ambulance chaser's rest room.
Snorting lines of "the white stuff" can't be good for you in the long run.
I suppose they are just compensating for never doing a decent day's work in their entire lives?
I bet they can afford "real" coke bottle eyepieces! ;-)
  #3  
Old April 17th 18, 01:37 AM posted to sci.astro.amateur
Razzmatazz
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Default We need new nomenclature

On Saturday, April 14, 2018 at 6:35:56 PM UTC-5, RichA wrote:
I read a review of the ugly Baader Morpheus eyepieces on cloudynights and
something stuck me. The reviewer used the term, "diffraction rings" (of a star)when describing the view through a 65mm Pentax refractor using the 17mm Morpheus. Problem is, that's 22x on that scope with that eyepiece. So he was describing the intra and extra-focal rings shown when a star is thrown out of focus and not the in-focus diffraction rings seen at powers of 30x per inch and up. We should call the rings formed by out of focus star images something other than diffraction rings since they are definitely not that.


In the optical world they are known as Fresnel rings. Diffraction rings are only visible when the star is in focus - they surround the Airy disc. Many amateurs also confuse the out-of-focus disc of a star and call that the Airy disc.

Razz
 




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