Numerical Aperature 40x

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microscopeboi
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Numerical Aperature 40x

#1 Post by microscopeboi » Thu Apr 16, 2020 2:21 am

hey, im wondering if anyone knows a good NA for a 40x plan apochromatic objective? which NA is sufficient for a crystal clear image and what NA is the minimum for good resolution. Thanks!

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Wes
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Re: Numerical Aperature 40x

#2 Post by Wes » Thu Apr 16, 2020 3:26 pm

Typical NA for a 40x planapo is 0,95. Keep in mind that for a crystal clear image you want the specimen you're looking at to be as close as possible to the coverslip and you also have to adjust the coverslip correction colar. Otherwise the image will lack contrast and sharpness.
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apochronaut
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Re: Numerical Aperature 40x

#3 Post by apochronaut » Thu Apr 16, 2020 5:39 pm

A lower N.A. apochromat will not theoretically have any better resolution than an achromat of the same N.A. However, achromats lack some of the higher corrections that apochromats feature, so certain aberrations such as chromatic aberration will distort the resolution of the achromat. Thus the apochromat would have a cleaner more defined image. Low or medium N.A. apos are unusual but the idea appeals to me. Sometimes with high N.A. apos, the requirement for high precision in slide preparation can be annoying, especially for quick sampling, so I quite often use achromats for that task. A .65 apo might be nice.

Scarodactyl
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Re: Numerical Aperature 40x

#4 Post by Scarodactyl » Thu Apr 16, 2020 5:56 pm

Of course when you get into industrial dry long working distance objectives you can spend an awful lot for a very thoroughly engineered objective with a much lower NA. But you are unlikely to end up with one of these without knowing what you're getting and exactly what you want to use it for.

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