Space is a Landscape

Apr 28, 2009

For as long as I can remember, I have been fascinated with photography, though my early recollections of it had more to do with clicking a button on a box and watching a piece of “plasticky” paper come out.  The reward came after a minute of flapping the paper from side to side and then hesitating long enough to see a ghostly image gradually gaining in opacity and strength, soon turning into a fully-realized picture of some inartistic, yet heart-felt object of my affection.  Probably just a picture of my icky little sister.

My Polaroid camera soon gave way to dreams of my first “real” camera.  These were dreams that began when I first saw “it” in some of my uncle’s mid-70s “Popular Photography” magazines.  In fact, my first association with “sexy,” despite my prepubescence, would have been that awesome Nikon F2 that graced those pages.  Of course, back then, that camera cost more than a couple of my parents’ monthly paychecks - and I was smart enough not to ask for one.  Though I did manage to score a 110-format “brick” with disposable flash cubes.

It would be 25 years later when I would acquire that dream Nikon camera, and with that camera came my first real successes at imaging the stars.

But for some reason - I don’t know if it’s the darkness of space, the “fixed-lens” aspect of a telescope, or the inefficiency of film when taking such lengthy exposures - but the wisdom of the time eschewed the thought that my photography experience during the day would help very little on my imaging efforts at night.  So I was indoctrinated into the idea that astrophotography bears no resemblance to real-life, terrestrial photography in almost every traditional aspect of the discipline.

So for several years, I learned to image the heavens by studying the new ways of this most challenging hobby.  Concerns about composition were replaced by equal parts of persevence and luck.  Shutter speed was made obsolete by the camera’s “bulb” mode, bypassing a light meter entirely.  Focus was less important because all I needed was a manual focus camera with a lens set to infinity.  Depth of field?  No longer applicable.  Notions of reciprocity failure and spectral range danced in my head, which were concepts that most certainly no real photographer had ever heard of.  And then, I went digital, which meant a whole new vocabulary, a whole new set of rules would be necessary: signal-noise ratios, dynamic range, photon flux, calibration frames, shot noise, sky-limited imaging - most certainly, we are in a whole new kind of imaging.

Is this all there is?  Like many in this hobby, I began my imaging by working my way through progressively longer focal length lens with my film camera to the current prime focus images taken with some of the best tools available to amateur imagers, namely cooled astronomical CCD cameras on high dollar scopes and mounts.  But my early efforts in digital astroimaging gave rise to thoughts that their must be something more, especially in light of some of the results I began to see from my contemporaries.  Most of my early CCD efforts looked like most astrophotos you might expect to see - stars, and various other areas of color and brightness, against a massive backdrop of dark space.  If we look at the percentage of a range of brightness values in most such images, you might expect upwards of 70% of featureless pixels.  And thus, a histogram of such images would be heavily concentrated to the left side of the graph, which is in direct contrast to that of a landscape image as it would appear to have a much more equal distribution of pixel values (illuminations). If exposed correctly, it will yield the full dynamic range of the camera, where there is aesthetic value and meaning within all brightness “zones.” So I began to lift the blackpoint in my images, seeking for other niceties that lurked just barely undetected in the shadows.  I sought to master Curves in Photoshop, or other one-touch methods of logarithmic “stretches” of my data such as digital development (DDP). And after a while, all of my images began to yield entire array of pixels containing meaningful photons of light, much like an Ansel Adams photograph or one of my own shots of something like the Grand Canyon.  Of course, it is easy with large, extended nebulae and Milky Way areas, but when I shot smaller, isolated targets such as galaxies and star clusters, I began to explore ways to infuse the same “landscape” philosophy into even those images.  So, for me, the question becomes, “How might we render astronomical images in such a way to match terrestrial values, with a higher percentage of pixels in an image actually showing something of interest?  Or, if we now have the technology to see deeper into space, then why should our images continue to look like old film images?  And what practices can we develop in our techniques that can optimize pixel values to yield greater dynamic range and make for more interesting and impactful images?