Monday, July 6, 2009

Why are three cameras hanging from my neck?

Last Sunday I went on one of our monthly flickr walks--this time to the Allen Centenenial Gardens on the UW campus. It's a public garden that for some reason had failed to register in this photographer's brain cells. Not only had I never photographed there, until recently I didn't know the garden existed.

We flickr-walkers weren't the only ones with cameras. It's that sort of place. So after I had stepped away from the group to take a series of reflected images, I returned to the group to find ones of the orher flickrwalkers explaining to a non flickrwalker what she would need to take macro flower photos.

In rough order of expense, she would have to buy at least one:
1--set of closeup lenses
2--set of extension tubes
3--macro prime lens
4--macro zoom lens.

A mini tutorial, well explained--but with one unspoken and wide spread assumption. After you paid all those big bucks for your DSLR the rules demand that you use it to take all your pictures. Big bucks > better camera> photographic masterpieces. Right??

Not necessarily, or so I believe. When I joined the conversation, I lifted the Canon S3IS that was hanging around my neck, and added a fifth option. She could buy a highish end Canon non-DSLR like mine. Then, after she downloaded the totally free CHDK firmware extension she would have all the goodies like RAW mode that the Canon marketing folks stripped out of their non-DSLRs. Plus a whole pile of extra goodies like scripts that the Canon engineering folks never managed to invent.

The best of all worlds and for only a fraction of the price of a macro lens. Or as it turned out, totally free. Her boyfriend owned an S3IS that was gathering dust somewhere.

A wild unusual idea, I know. Carrying more than one camera around your neck. So wild and unusual I was asked to pose for a series of photos of my three cameras to document the concept.

OK, what is going on here. One of the holdovers from 35 mm film days is that 24 mm lens is a wide angle lens, a 50 mm lens is a normal lens (whatever that means) and a 200 mm lens is a telephoto lens. Correct if you are shooting 35mm format. Wrong if your sensor dimensions are not 35mm by something less mm.

Since the vast majority of digital cameras use a smaller sensors we now have the "35 mm equivalent" spec. By the way this is not a new invention of the digital age. With larger and smaller film formats the focal lengths are also different.

Very different, for instance, if you are shooting with a 8 by 10 inch view camera. If you study the history of photography, you would be very hard pressed to come up with any 19th century telephoto images. Except for a few images of the moon shot through astronomical telescopes long enough lens weren't available.

And to jump off topic for a moment, why is 8 by 10 inches such a common print format. First reason--in the 19th century you could only make contact prints and 8 by 10 inches makes for a very viewable size. Second reason, you could wander in to the local general store and buy your glass plates--8 by 10 inches was also the standard window pane of the time.

Which brings up an interest question--how many masterpiece of photograph were lost when some frugal farmer scrapped off the emulsions of a stack of worthless glass negative to repair his greenhouse after a hailstorm. A common practice in years gone by.

But back to the point of this blog (Yes there is one)

Instead of talking about "35 mm equivalents' we could talk about fields of View, Like how wide an angle the photo will take in using a a 1/2.5 (5.75 X 4.31mm) sensor-- which happens to be the sensor size on my S3IS. Then we would easily see (with the help of a little geometry) that the 6 to 72 mm zoom lens of the S3IS had a field of view that ranges from from ~62 degrees to ~4 degrees. If you insist on doing it the old way, the chart--found in a garage sale book-- shows that 35 mm eqivs range from 36 mm to 432 mm.

So what! Little cameras have little sensors and little lens and don't cost much. DSLR have big sensors that cost lots and lots more but they are always better because_______!


Short focal length lens have a much greater longitudinal Depth of Field (DOF). That's optics talk for saying that more of the flower or bug you pointed your camera point at is now in focus. Many of the so called Internet gurus will tell you different but optics is optics and the shorter the focal length the greater the DOF.

So there, all you DLSR-with-zoom-lens lovers!!! My S3IS with a 6mm super macro mode will always have a greater DOF. Ain't just cheaper. It is always--well sometimes always--better.

Here's proof for the doubters.

The top image was taken with a new 90 mm Tamron zoom at f8 in my local camera store . From top to bottom the artificial flower is about 1 inch tall

And this image was taken with my S3IS, again at f8.

To quote the friendly salesman after I showed him the two images. "Looks like you just saved yourself five hundred and fifty bucks."

And to show how the S3IS works in the field. The flower was about 3/4 inch in diameter. The love bugs--they were too busy and preoccupied to be measured

Macros are fun. So expect more posts about them.

You have been WARNED !

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