Re: Phaco for Nikon SE? 20x oculars?
- From: Kevin Cunningham <smskjc@xxxxxxxxxxxxxx>
- Date: Thu, 6 Mar 2008 12:56:31 -0800 (PST)
On Mar 6, 2:27 am, Richard J Kinch <ki...@xxxxxxxxxxx> wrote:
Pincopallino writes:
What's the main drawback of using 20x oculars instead of higher
magnification objectives?
20X is much more expensive than 10X for equal optical quality.
You also loose tons of field size.
Now for the tough one, total mag will be beyond NA. At 1000 times the
NA the image quality starts to fall apart. Think of a 100X Achromat,
its NA is 1.25 so a thousand times is 1,250. Thats were the
degradation starts and it gets worse from there.
The core point is NA shows you the resolution of the objective,
magnification is just an add on , its the least important number out
there. A Nikon S series is hard to buy for since it uses short
barrels. You might want to look at a good quality used instrument.
Thanks,
Kevin Cunningham
SMS
.
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