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+--- Thread: Eyeballs vs digital microscopy imaging (/showthread.php?tid=173)
Eyeballs vs digital microscopy imaging - grepper - 09-15-2017
I was thinking about digital image microscopy and wondered what the resolution of the human eye is and how that compared to a 20mp digital camera image sensor.
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Of course it’s nowhere near that simple because the human eye does not have pixels, but rather rods for low light and cones that are color sensitive which are not evenly distributed over the retinal area. There are about 120 million rods and 6 – 7 million cones. Additionally, we don’t actually see individual pixels, but rather move our eyes around and assemble a more highly detailed mental image than simply the total of rods and cones.
I found this on the web: http://www.clarkvision.com/articles/eye-resolution.html It is an interesting read.
“So the megapixel equivalent numbers below refer to the spatial detail in an image that would be required to show what the human eye could see when you view a scene. 90 degrees * 60 arc-minutes/degree * 1/0.3 * 90 * 60 * 1/0.3 = 324,000,000 pixels (324 megapixels). 120 * 120 * 60 * 60 / (0.3 * 0.3) = 576 megapixels.”
My little 5 mp digital microscopy really doesn’t cut it, and I think Apple has a ways to go before any of their iThings truly have a retina display.
RE: Eyeballs vs digital microscopy imaging - Mark Reich - 09-25-2017
Sometimes I wish I could show pictures of edges, but the USB microscopes are not very easy to use while you're sharpening.
I have a bunch of inexpensive little microscopes from Amazon. They're so easy to use that I use them constantly, sometimes after each pass. That makes them the most used, if not the most important, pieces of sharpening gear I own.
At 60x it's very easy to see things I can't feel at all. It's so cool to be able to see Why a BESS measurement is off in either direction, and then be able to fix it.
RE: Eyeballs vs digital microscopy imaging - grepper - 09-25-2017
+ 1 for microscopy & edges.
What scopes are you using Mr. Mark?
RE: Eyeballs vs digital microscopy imaging - Mark Reich - 09-26-2017
I've tried nearly every type of little magnifier Amazon carries, but I have a dozen of These now (better hurry if you want them for $3 each).
There are a couple things that make these my favorite by a wide margin. You don't have to use the light! They have a larger objective lens so they're able to be used with good overhead lighting. That's huge to me. I don't have to worry about turning the light on and off, so it never gets left on. Batteries never go bad, but if they do, they are still perfectly serviceable.
They also have adjustable focus, so I put the objective shield on the blade and focus. A judicious drop of superglue will keep it focused for that distance, which is pretty handy too.