Sunday, September 6, 2009

As promised--continued

A short one. Due to some accidental keystrokes I published my last post on lens resolution while I was spell checking and otherwise editing it. Since I was still setting up my new laptop--I went with the accident and moved on to other tasks.

Eight X magnification--alas, twas but empty magnification. That means everything was bigger but there was no new detail. Even at 5X magnification I was pushing the ability of the 35mm Minolta lens to resolve detail. The finest 'hairs' on the moth's antenna were 5 pixels wide. This calculated out to be 7 microns wide or about 1/8 the diameter of the average human hair.

And if any of my hundreds of readers (humor, humor) ever want to do this at home the procedure is simple.

Use your version of my trusty machinist rule to see how big the spot you are imaging is. Convert to microns (1/1000 of a millimeter) if your part of the world never got the metric urge. Divide that number by the number of pixels in your sensor to give the micron per pixel number--1.4 in this image.

Then count the number of pixels in the tiny stuff to learn--
a--how big the fine stuff really is.
b--where your lens's resolution craps out.

And how do I know I ran up against case b? Looked at the slide with my microscope.

In an ideal world I'd now upload the microscope image. But the box of slides is buried--I suspect--under the mess of toys, books and other debris in Charlotte's bedroom/toyroom/storeroom. Time for a cleanup. But not today. The weather is too nice this weekend to waste on a cleanup.

So this post maybe continued again

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