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mihai_mail_ro

20 Sep 2023 14:20


test

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Cautand in cludynights, am gasit un sfat legat de testarea aberatiilor de sfericitale la refractoare, poate este util si altora

If you really want to know if the scope has spherical abreation, it is better to star test using a 30% obstruction. Make a cutout 30% of the diameter of the lens and suspend it in the front of the lens with some string (centered of course).

Use a 5mm eyepeice and defocus and watch for the point that you have a bright ring, a dim ring, and an inner brighth ring JUST starting to appear from under the inside black circle.

Measure the amount of travel back to best focus. Now, go past best focus an equal amount. If you once again see a bright ring, a dim ring, and another bright ring emerge at the exact same distance on the other side of focus, then the Spherical Abberation is well corrected.

If the inner ring breaks out from under the shadow earlier or later than at the exact same distance as your first measurement, then it is possible that some Spherical Abberation is present.

If the ratio is more than 3:1 (for example, 3mm on one side of focus vs 9mm on the other side of focus, a 3 to 1 ratio), then there may be more serious spherical abberation present. Anything smaller than 2:1 us pretty good.

