Tag Archives: digital images


Ralph Waldo Emerson, a daguerreotype

I attended a short lecture tonight at the Mount Auburn cemetary in Cambridge, MA on – of all things – daguerreotype.  Not your usual bill of fare for a Thursday night, but hey, it was really interesting.

The speaker was Melissa Banta who is the Program Officer for the Harvard University Library.  Apparently, Harvard has a substantial collection of daguerreotypes – more than 3,500 of them – and they are all reproduced digitally in an impressive, searchable web site freely available to the public.

But what is a daguerreotype?  Well, thanks to Melissa, I can now answer that. Daguerreotypes were the first photographic process – invented by Louis Jacques Mande Daguerre (pronounced “Dagair”), a French inventor (1787 – 1851), who also, on a side-note, came up with the concept of the diorama.  The chemistry that Daguerre and his colleagues figured out is to expose silver-coated copper plates to iodine, obtaining silver iodide in the process.  Then the plates are exposed to light for several minutes, then coated with mercury vapor which amalgamated the mercury with the silver and, finally, the image is fixed with salt water.  The image was then, typically housed under glass, framed and put inside a leather-bound case (a sort of portfolio folder), as you can see in the example at the top of Ralph Waldo Emerson (one from the Harvard Collection).  I just love the detail in that image – the shadows and contrast – not to mention Emerson’s winning smile.

Apparently, Daguerre (and others) had figured out how to make an image using these chemicals, but it wasn’t until he figured out how to fix them (in 1837) that the “daguerreotype” (the process) was born.

A little sniffing around online pulls up all sorts of intriguing resources.  For instance, The Daguerreian Society (who knew?) and the fact that, after Louis Daguerre published his manual on how to create the plates, the phenomenon known as “daguerreomania” erupted in England and France.

But here’s what I found totally fascinating.  Unlike traditional photographs that pixellate and degrade as you magnify them, daguerreotype get more precise the closer you get.  They are perfect recreations of the image, in all of its astonishing detail.



Filed under Reflections

The Digital Camera Reconsidered for Classroom Use


At the National Association of Biology Teachers (NABT) conference this year I caught the tail end of a workshop about using digital cameras in teaching, given by Brian Gross, Mike Kittel, and Brian Heeney (all from Delcastle Technical High School in Wilmington, DE). They had some terrific ideas for using digital cameras in the classroom.  Here were a few gems:

– Taking pictures of students on the first day of class

– Photo record of a field trip of lab experience.

– Pictures of models or maps that students create.

– Photo a day project.

– Five-Photo Stories.


The New Eye-Fi

One of my favorite tips of theirs was a new piece of hardward I’d never heard of called the Eye-Fi. This is an SD memory card (for your camera), companioned with a USB wireless device that allows you to automatically and wirelessly download photos from your camera to your computer. No more cables, no more fussing around. It means instant access to the photos on your camera. There’s a range of options – these guys recommnded the Eye-Fi Pro (which is $140) which functions without a router (the others, that are less expensive must traffic through a router). With this technology, you can use the pictures you take in class and instantly have them up there on the screen – “Look at Suzy’s concept map!” or “Everyone look up here to see what group 3 figured out.”

As for digital camera recomendations – Brian says it’s hard to go wrong these days. You can get a perfectly good camera for $99. If your camera is capable of taking photos at 8 or 10 megapixel resolution, they recommend reducing the resolution to 3-4 mega pixels as that is perfectly sufficient for most classroom or web use and the photos download much faster. If you are buying a bunch of cameras for student use, they do recommend getting cameras that take double A batteries, so that it’s easy to replace them (without having to recharge). Tiger Direct is a web site they recommend for good deals on electronic equipment. They also provided the link to their wiki site that is chock-full of helpful teaching resources related to the use of digital cameras in the classroom.  Good stuff.

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Filed under Project ideas, Teaching with Technology, Uncategorized