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TAK Doublet or Stellarvue Triplet?

refractor astrophotography
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#51 edif300

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Posted 16 September 2020 - 09:53 AM

I'm not entirely certain as the Japanese is all Greek to me, but I imagine the 1.000 on the vertical graph could represent the diameter of the Airy disk. All colours are within that diameter on the DZ, and just one colour barely outside on the DL. I doubt this would be visible visually, and I haven't found a similar graph so far for the FS. Of course I could be wrong!



1.000 means edge of the lens, 50% of diameter from the center. There is no the other half plotted from -1.000 to 0.000.

0.000 means center of the lens. In fact the graph is simetrical so you can sometimes find it as 0 to 100% too. X axis means the “defocusing” of the given wavelenght ray.

#52 StarAlert

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Posted 16 September 2020 - 10:14 AM

1.000 means edge of the lens, 50% of diameter from the center. There is no the other half plotted from -1.000 to 0.000.

0.000 means center of the lens. In fact the graph is simetrical so you can sometimes find it as 0 to 100% too. X axis means the “defocusing” of the given wavelenght ray.

So what would a "bad" graphic look like? 



#53 Hesiod

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Posted 16 September 2020 - 10:47 AM

In a "bad" graph you would see the lines less straight and close; as an example, in the case of the common "Cde" achromat correction, you would see those lines somewhat close each other, while the g and F going for their own way.



#54 aa6ww

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Posted 16 September 2020 - 11:01 AM

This is nothing youre eyes can visually detect when you are out with your scope  in the dark.

Of course in these forums, even the smallest changes are easily detected visually.

 

...Ralph

 

 

The FC100DZ technically has better colour correction than the FS and the DL, but I suspect the difference would only be detectable, with a critical eye as regards the FS and not at all with the DL.

 

attachicon.gif2020-06-09 18.33.37.png

attachicon.gif2020-09-16 15.09.07.png


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#55 StarAlert

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Posted 16 September 2020 - 11:43 AM

This is nothing youre eyes can visually detect when you are out with your scope  in the dark.

Of course in these forums, even the smallest changes are easily detected visually.

 

...Ralph

lol.gif



#56 TNmike

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Posted 16 September 2020 - 12:26 PM

This is nothing youre eyes can visually detect when you are out with your scope  in the dark.

Of course in these forums, even the smallest changes are easily detected visually.

 

...Ralph

This might be the best one of the year! roflmao.gif roflmao.gif roflmao.gif



#57 payner

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Posted 16 September 2020 - 03:54 PM

SA is what one definitely doesn't want to see in their refractor. I see very little hint in my FS-102N. A keeper (for me). Oh, and don't forget about a well figured lens. One that controls scatter and holds (already accounted for SA) aberrations to a minimum--adds to the overall clean definition of the object in view.


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