Friday, March 29, 2013

Catching Light

Frozen Land and Rays of Light

I have to say I'm finding it very difficult to stay committed to picture-making these days. It has been one of the cruellest months of March that I can recall, and I'm glad it's coming to a sweet end on Easter day, when finally there is some warm sunny weather in the forecast. Not to mention that my so called Canadian ruggedness to brave the elements has been seriously cut down by the fact that I've had a miserable cold all month.

But enough moaning. The weather is finally turning, and I'm starting to feel better. I will soon be out enjoying the click of my shutter(s) again. Meanwhile, I'm going back to a picture I did over a year ago, in the dead of winter, when this kind of weather is at least appropriate, and therefore to be enjoyed. I was using the EOS 40D at the time, well before it broke. It was a great picture maker, considering it's vintage - a DSLR over five years old is considered ancient, given all the "progress" that modern digital cameras are undergoing  year after year. This particular shot is one that I had set aside as having some potential, but I am only now getting back to it.

As I was working it up in Photivo, it dawned on me (again) just how dark and lifeless this scene was, out of the camera. I finally gave in to the plain truth  that a digital camera is in fact, a computer with a lens on it, and it is only capable of doing exactly what you're telling it to do. In this case, I was using Aperture Priority with Evaluative Metering (as I usually do), which is an automatic exposure mode which is meant to provide the best overall exposure throughout the entire scene. In this scene, I was shooting directly into some very glorious natural outdoor lighting, and I had yet to learn that when using a computer with a lens on the front, you cannot rely on the computer's evaluative metering to make the right evaluations. So, naturally, the computer measured most of the light as being concentrated in the clouds and atmospheric sun-rays, and set the exposure for the entire scene based on that. I've finally learned that "evaluative metering" does not necessarily evaluate the entire scene coming at it through the lens. No. Rather, it evaluates the sum-total of the light in the entire scene, regardless of where that light is located, and then compensates the overall exposure to fit within the dynamic range of the computer's image sensor, resulting in this:

JPEG Straight Out Of Camera

You can see exactly why I decided to set this one aside - this should've been a good picture straight out, and if I had been using a real camera, and not a computer with a lens, it would've been glorious. But instead, all the computer with a lens managed to do was "evaluate" the rays of light in a way it deemed to be correctly, and then compensate the rest of the scene to suit the limits of it's image sensor. A true camera (the kind you put film into) would've managed this differently, because it doesn't have to make decisions based on such limits. Film, especially modern print film, is extremely generous with light range, and the built in metering does not "evaluate" or make decisions. It doesn't have to, nor does it even know how to - in a real camera, there is no such thing as "evaluative metering". Rather, it simply sets a shutter speed that is appropriate to the amount of light the lens aperture is letting into the camera as measured in the middle of the frame, and that light, all of it, gets "captured" by the film. I've proven this to myself time and time again, and is the biggest reason I've come to prefer film cameras.

How then did I manage to get the almost acceptable result as seen in the top picture? I did it with lot's of post-processing of the RAW file. Just a reminder for those who may be new to my Blog - I almost always set my DSLR to RAW + JPEG. On rare occasions when the JPEG comes out OK, I just go with it, but more often than not, I have to post-process the RAW file with my computer (that is, the big box with the keyboard and mouse attached, not the computer with a lens on it, more commonly called a digital camera.) The RAW file contains all the data about the picture - it's not really a finished picture file. It can only be "seen" by a computer, which in turn does you the courtesy of providing you with a preview of what the final result would look like once you convert it into a standardized graphic (picture) file. The saving grace of RAW Data Files is that every bit of data they contain can be changed - and because they are from 12 to 16 bit uncompressed files, as opposed to JPEG's compressed 8-bit, there is far more adjustment capability contained in a RAW file. Essentially, having a RAW file at hand allows you to completely re-expose a picture using your big computer, after it was taken with your little computer with the lens on the front. In the case of this shot, here's what I did, using "Photivo" (which is a free Opensource "clone" of Lightroom):

  • Brighten the shot by two full stops, using the Reinholdt algorithm, but with a "film curve" turned on so as to not blow out the highlights (I always use Reinholdt because it has some smarts built into it; I find it far better than merely turning the EV up)
  • Increase the Gamma, to get rid of that hazy cast, and increase overall contrast
  • Compress the Dynamic Range, which is actually a means of "fooling" the picture data into allowing what is perceived by the human eye as a wider range from the lightest to the darkest values
  • Everything I've mentioned so far creates noise in the image, seen as "speckles", because it's all trickery, and noise is the price that is paid for it. The software gives you several options of noise reduction, which really only give you plenty of ways to "smudge" the pixels together. The noise I had generated so far wasn't too bad, so I opted out of Noise Reduction
  • Sharpen the picture by applying "local contrast" as needed. Local contrast, as opposed to overall contrast, actually increases the contrast at a micro level, between one pixel and each of it's neighbouring pixels. It can selectively be applied to shadows, mid-tones and / or highlights. I think in this case I did it to the shadows and highlights, leaving the mid-tones alone.


There might have been a couple of other minor tweaks I applied, but I don't remember everything I did.

I should point out that I actually enjoy post-processing, but there's quite a learning curve to doing it. I'm teaching myself through experimentation - what works for me may not be the same as what works for you. Experimentation and observation is my learning style - the downside of it is that you are left with a lot of holes in your knowledge, because after a few tries you tend to gravitate only toward what works best for you. and don't bother learning the other stuff. If you'd rather learn from someone else, there are plenty of online tutorials, or local Photoshop and Lightroom classes. Another way of getting the results you want is to use a real camera - that is, shoot film. You can then avoid most, if not all of the post-processing required to make a picture look great.

Making a great picture, whether through Photography or Painting, is all about creating contrasts - the capture of light versus non-light, or the interesting contrasts that are visible within nice textures. Sometimes, a computer with a lens on it doesn't do this very well, unless you know how to program it to suit the scene you're shooting. Real (film) cameras do a much better job of it of course, but it is just as much an "art" to use a digital camera, and make those programming choices both before and after the fact.


No comments:

Post a Comment

Reader's comments are welcome, and are subject to moderation by the author.