Resolution Revelation

Gary Hart Photography: Winter Sunset, Wanaka Willow Tree, New Zealand

Winter Sunset, Wanaka Willow Tree, New Zealand
Sony a7RIII
Sony 24-105 G
30 seconds
F/9
ISO 200

For years I’ve been pleading with camera manufacturers to stop giving us more resolution, and instead concentrate on things like improving dynamic range and high ISO performance. And while I still think that would be a better approach, I have to admit that I’m loving having all these pixels to play with.

Red Sunset, Lake Wanaka, New Zealand

The catalyst for my resolution revelation was this New Zealand sunset image. A couple of months ago I decided that I wanted to hang a large, vertical print in a space on a wall in my office. I really like this image, but it wasn’t vertical, and the vertical versions I captured that evening weren’t during peak color. In the olden days I’d have just moved on to a different image, but advancing sensor technology has caused me to rethink my position on the resolution race.

Let’s review

In digital photography, light passing through a lens is focused onto a sensor packed with an array of microscopic electronic light-catchers called “photosites.” Each photosite reports information about the incoming photons to the camera’s microprocessor, which interprets the light’s color and intensity at that location on the sensor. That information is digitized and stored with the information from all the other photosites. Voila, a digital image is born.

Digging deeper, we see that not all photosites are created equal, and that (on most sensors, depending on the technology) each photosite measures a specific color, either red, green, or blue. But for simplicity sake, it’s enough to know that one photosite equals one pixel—that is, a 42 megapixel camera has 42 million photosites, and a 50 megapixel camera has 50 million photosites, and so on.

Any digital camera, whether it be a smartphone, a full-frame 35mm mirrorless camera, or whatever, has a fixed amount of sensor real estate upon which to place its photosites. Fortunately, as sensor technology evolves, not only are we getting more photosites, the image quality is improving with it.

But improving sensors can’t change the fact that a larger photosite collects more light than a smaller one, making it more efficient. Think of a bucket: the bigger the bucket, the more water it holds before overflowing. Another undeniable truth is, the farther apart the photosites are, the less each photosite interferes with its neighbors, and the cooler they remain (heat is the enemy of pretty much all things electronic). And while they could solve these problems by just making the sensors bigger whenever they increase the resolution, larger sensors would require different lenses. So there are really only two practical ways to increase a sensor’s resolution: shrink its photosites, and/or cram the photosites closer.

For any given sensor technology, the fewer the photosites (lower megapixel number), the better the image quality. We can define image quality in a number of ways, but as a landscape photographer, the two quality factors that matter most to me are dynamic range (the range of light a sensor can “see,” from the darkest shadows to the brightest highlights) and high ISO capability (light sensitivity). That’s why I’ve always hoped that camera manufacturers would stop adding resolution and instead concentrate on dynamic range and sensitivity.

A little history

My first DSLR camera was 6 megapixels, and I was happy. But as sensor technology improved, cameras were able to add photosites without sacrificing image quality, and I was happier. At around 24 megapixels I reached the point where I was pretty convinced I didn’t need any more resolution, and would gladly sacrifice more resolution to get even more quality.

But the manufactures kept going. When I got the Sony a7RIII that I used to capture this New Zealand winter scene, I though surely its 42 megapixel sensor would be the end of the resolution road. Silly me.

Back to the present

Today, not only does my 61 megapixel Sony a7RIV have more resolution than I ever dared dream would be possible, all that resolution has come without sacrificing my coveted dynamic range and high ISO performance. And lately, I’ve actually started to appreciate having resolution horsepower to spare.

First, I’ve come to realize that for the vast majority of scenes I shoot, my Sony Alpha bodies have more than enough dynamic range—so much that I virtually never use the graduated neutral density filters that I once considered essential for managing extreme dynamic range. And for those rare times I need to test my camera’s ISO limits, I have my 12 megapixel Sony a7SIII (12MP sounds small compared to most of today’s sensors, but it’s more than adequate for most uses), that seems to be able to see in the dark. In other words, I rarely find myself longing for more performance.

And more and more, I find myself appreciating the extra resolution. Of course it’s important to get the framing right at capture, but sometimes that’s not possible. For example, when I photograph lightning, the best I can do is loosely frame a nice composition to ensure that I get the lightning somewhere in the frame. At 50 megapixels, I have plenty of resolution to crop in tighter on the bolt, wherever in my frame it fired. Also, a magazine will ask if I have a vertical version of a horizontal image to put on their cover. 50 megapixels is more than big enough to crop a vertical version from the original file, confident that I’ll still have plenty of resolution for even the highest quality publication.

How much resolution? Reversing the original 2/3 crop of my Sony 61 megapixel Sony a7RIV, gives me nearly 27 megapixels. And even my Sony a7RIII, with its “measly” 42 megapixels gives a nearly 19 megapixel file when I crop a horizontal to a vertical (or vice versa).

So when I wanted a vertical print for my office, I didn’t hesitate open the horizontal original of my New Zealand sunset and find a vertical crop that I liked. I ended up going with a 24×36 print of the vertical (taken from the horizontal original) you see at the top of this blog post. And you know what? It looks marvelous.