Showing posts with label science and math. Show all posts
Showing posts with label science and math. Show all posts

Wednesday 6 November 2013

Halo and chameleon

Saw two somewhat unusual things today. The first, a halo around the Sun, which I photographed from two different sides of a building, trying to keep direct sunlight out of the lens:



And then, a few hours later, found this little fellow clinging to the curtains in my apartment:


Presumably my cat brought it in, and then, for some reason, decided not to dissect it as she usually does with her wildlife specimens (she makes Hannibal Lecter look like Gandhi by comparison). So I took the lucky survivor outside and put it in a tree densely overgrown with creeping jasmine - not perfect, but probably better habitat than my apartment:


Chameleons were common around here when I was a child, but I haven't seen one in many years. Perhaps they are making a comeback.

Wednesday 19 December 2012

And another anthotype

A very busy schedule effectively prevented me from doing much for two months. But here is another anthotype from some time ago. This time round I cut a design from cardboard, and used beetroot juice to print it. Beetroot juice turned out to be very sensitive and I got a very clear print within a few days. Here's the setup:



And here is the print:




Monday 3 September 2012

More anthotypes

Some further attempts at making anthotypes, as described in a previous post.

I used turmeric for this one, with a five-day exposure:


It's very sensitive, and I think even a day or two of exposure would result in a good image.

For this one I used red wine again, with a ten-day exposure; it is rather dim and I think twenty days or even more would have been better:


The long exposure required may be a result of the process I used here. I printed the image from a computer, then applied cooking oil to its reverse side in order to make it transparent. Last time I tried this, the oil leaked through onto the red wine emulsion, making a big mess and virtually no image. So this time I covered the light-sensitive paper with a plastic transparency, put the oiled paper on top of that, and then put a glass plate on top of the whole setup. The glass and plastic may have cut down the amount of UV light, thus requiring a long exposure.

On the bottom right you can see a big blotch where some oil somehow leaked onto the paper despite the transparency; it quite thoroughly messes up the image.

Sunday 12 August 2012

Anthotypes

I have been trying my hand at making anthotypes - basically making prints using photosensitive chemicals from plants. An description of what it entails can be read in Wikipedia here:

http://en.wikipedia.org/wiki/Anthotype

And here are two articles describing how to do it in some detail:

http://www.alternativephotography.com/wp/processes/anthotypes/anthotype-process

http://www.alternativephotography.com/wp/processes/anthotypes/anthotypes-making-print-using-plants

For my first attempt, I used the purple berries of a privet bush (Ligustrum sp.). I mashed up a handful with a mortar and pestle, added a bit of water and methylated spirits to create a thin, watery paint (because the pulp was rather too dry to brush on its own) and then brushed two or three layers onto cartridge paper (letting layers dry before brushing on the next one). When the liquid dried it turned brownish.

I then put the paper onto a piece of Masonite, put a few leaves from a carob tree (Ceratonia siliqua) on top, and then covered it with a plastic transparency, and fastened the whole thing together with clips:


As you can see, the transparency did not work very well: instead of pressing the leaves flat against the paper, it buckled a bit, allowing sunshine to get partly under the leaves. I left the setup out in the sun for about five days, after which a clear print had formed on the paper:


It looks rather out of focus for reasons explained above: the leaves did not press down firmly onto the paper, so as the sun shifted position through the days, its rays got in under the sides of the leaves, exposing bits of paper that should have remained in shade.

For my next attempt I got hold of a piece of plate glass, and I used three layers of cheap red wine as photosensitive pigment. For the rest I simply repeated the procedure as above:


As you can see, the leaves were pressed down more firmly against the paper this time. I used carob leaves again, plus a few leaves from a garden shrub I can't identify. I once again left it in sunshine for about five days. This time round, the print came out more crisply and clearly:


Perhaps not exactly great art or photography, but there is something rather magical about it.

Friday 3 August 2012

A simple pinhole camera

Every now and then, I cobble together some or other thing I really should have done when I was twelve and gotten it out of my system. I never did then, so now I am doomed to remain twelve all my life. I'm not sure that is necessarily a bad thing.

Anyway, here's one of those impromptu experiments:


A simple shoe box, with a pinhole in one side and a viewscreen made of piece of white paper glued inside, on the side opposite the pinhole. An image of whatever the pinhole is facing will be cast onto the viewscreen. In order to see it, I cut a peephole into the box, as shown. You close the lid to make the inside dark, look through the peephole, and there you have it: an upside down image of the world behind you.

To photograph it, I simply poked the front of my point-and-shoot camera into the peephole. The photo came out even dimmer than my subjective experience of the image:


Here's the same picture, turned right side up:


And here is the same photo, brightened up a bit with the help of Gimp:


Rather out of focus! My pinhole was a bit too large, I think. With a smaller pinhole, the image will be in sharper focus, but also more dimly lit, which would likely make photographing it impossible without a time exposure.

Short of keeping silkworms in it, I can't think of a cooler use of an old shoe box.

Friday 23 December 2011

A homemade rainbow

It has been a while since I have had time to post anything here. Well, rather late than never. Here is a photo of the sun's light falling through water in a wine glass and in the process being broken up into a spectrum of its constituent wavelengths:


And here is a closeup of a part of the rainbow:


Finally, a photo of a "real" rainbow I took some weeks ago:


My simple point-and-shoot camera is not the best tool with which to capture the rich colours. All seven, er, six, er... how many colours are there in a rainbow anyway? At school, we are usually taught that there are seven. Precisely seven, no more and no less, and the clever kids, none of whom have ever taken the time to look - really look - at a rainbow, can even name them for you: red, orange, yellow, green, blue, indigo and violet. Or something like that. I can never quite remember, and I don't think I have ever seen more than six clearly defined colours in a rainbow. Because the colours smoothly flow into one another, one can perhaps see more than seven. Or, depending on your culture and language, fewer than six.

Next time you see a rainbow, take note of how many colours you see. You may be surprised.

Edit, 24/12/2011:
There is a good article in Wikipedia about rainbows, that explains quite a lot about them, here.