looking through lenses
|Dad died and left him his old compact binoculars, known as field glasses.
Attached to it was a piece of paper in dad’s handwriting.
‘If you want to see something in the distance, you can use two convex lenses, placed one in front of the other. The first lens catches light rays from the distant object and makes a focused image a short distance behind the lens. This lens is called the objective because it's nearest to the object you're looking at. The second lens picks up that image and magnifies it, just like a magnifying glass magnifies an image on paper. If you put the two lenses in a closed tube you have a telescope.
Binoculars are simply two telescopes side by side, one for each eye. But there's a catch. When light rays from a distant object pass through a convex lens, they cross over. That's why distant things sometimes look upside down if you look at them through a magnifying glass. The second lens doesn't sort out that problem. So binoculars have a pair of prisms (large wedges of glass) inside them to rotate the image through 180 degrees. One prism rotates the image through 90 degrees (flips it onto its side), then the next prism rotates it through another 90 degrees (flips it onto its side again), so the two prisms effectively turn it upside down. The prisms can either be arranged in a back-to-back arrangement or at 90 degrees.
The prisms explain why binoculars are heavy and why they are sometimes quite chunky in the middle. Field glasses, which are compact binoculars, flip the incoming images using only lenses. There are no prisms, so field glasses are smaller, lighter and more compact—but the image quality is poorer.’
He smiled at the precision of the description. In life, he had been just as precise, his dad.
A little black case came with the pair of binoculars so no dust could creep up on it, damaging the glasses, ruining its capacity to look close by or far away.
He took home the pair of binoculars and forgot about it immediately.
One morning, he was sipping his coffee in the garden, trying to understand the situation in the world reading the newspaper, he heard a sound so he looked up and spotted a little bird.
He recognized the Saxicola rubicola, the European stonechat, a variety of the snowbird, a small passerine bird with the bright colors red, brown, and white. Its chirping and singing brought tears to his eyes. How wonderful this creature was, hiding in his back yard.
He suddenly remembered the pair of binoculars of his late dad. Thinking it would take him a minute or two to fetch the device he slowly stood up from his chair, entered the house, and started looking.
He looked everywhere, in the drawers, in the side table, yes even in the kitchen although he knew it could not have been there. He was thorough. Of course, it took him too long, and by the time he went back into the garden, the bird was gone.
He could not find the pair of binoculars.
Where could he have put it? He didn’t know and searched the house without any result. Finally, he gave up the search.
Walking downstairs again to relax in the garden once more he suddenly heard a scratching sound. It came from upstairs. What is that sound in the attic? He turned and walked up to investigate.
His attic was a spooky place, and he rarely came up there. It had been 20 years since he last cleaned it so a lot of dust cobs as he entered the four by four wooden room.
A small window at the back let some light in but apart from that, it was dark. The switch did not work either and he stumbled inside, almost breaking his neck on a fluffy toy, a little dog that once belonged to his daughter.
He squinted his eyes.
There on a side table lay the pair of binoculars. Some white dust covered its dark top. It looked like it had been there for ages.
He slowly moved towards the table and his hand touched the coated surface. It felt warm as if somebody had held it for a long time, had touched it, had used it.
It felt strange, this sensation from his hand to his arm. The sudden numbness startled him.
Adjusting the lenses he looked into the pair of binoculars. In the far distance, he spotted a figure, slowly approaching.
“Son”, the familiar voice said. “It’s time to see for yourself”.
Throwing the pair of binoculars as far away as he could, he looked up, staring into the darkness.
No one was there.
Word count: 793
google search on prisms and lenses.