What's A Megapixel, And Why Should I Care?

Some of us are technogeeks. We like reading up about the latest gewgaw, gadget and gizmo, and if possible, possess it for ourselves. Our use of jargon is often so convoluted and esoteric it evolves into it's own dialect, or at least a pidgin. We wax rhapsodic about the pros and cons of various models, knowledgable about all the differences between different manufacturers and even the conditions in the factories where our favorite toys are made. Occasionally, we become so enthralled with the bundled features of a given device that we forget to actually use the device for its intended purpose.


Some of us are, instead, rather more luddite when it comes to technology. We don't really care about the latest innovations if what we're using now suits our needs. We prefer to master the technology we have on hand than to constantly have to update ourselves on current developments. We openly scoff and sneer at the early adopters of new technology, especially when the shortcomings of that technology becomes more apparent over time. Although we sometimes wake up to discover that the world has moved on without us and we have a steep learning curve ahead of us in order to catch up, we believe it's worth the occasional paradigm shift in order to avoid wasting time shopping for new gear every week when we could be using what we've already got.


I think most of us fall somewhere between the two extremes, and when it comes to photography, the technology advances in such fits and starts that sometimes you do discover that there is technology out there that really is measurably better than what you've got. So you decide it's time to buy yourself a new camera, but you haven't paid much attention to what's been happening in the market the past decade or so and don't really know what to look for. That's okay; if you haven't immersed yourself in the lore and jargon of the photographic world, it can get pretty confusing. Even for those of us who are in a deeper section of the pool can sometimes get a little turned around when it comes to the technical aspects of the field, and some photographers find experts to advise them in the kinds of gear they need so they can concentrate more on just shooting photos, rather than studying journals to find out the latest and greatest toys on the market.


So today, we're going to focus on that one word that shows up in the description of every digital camera, but that not everyone really understands: megapixels. Before we get to the real nitty gritty of the topic, however, it might be instructive to back up a bit and discuss how a camera works in general, before getting into the digital stuff.


At it's most basic, a camera is just a light-sensitive media (celluloid film, digital sensor, silver-coated tin or copper plate, etc.) encased in a housing that protects it from light until the moment you want to expose it to the scene you'd like to photograph. That's really pretty much it; everything else on the camera is a bonus feature that either makes it easier to take the photo or improves the quality of the image. There is a mechanical shutter on most modern cameras that serves as the means to let light in (you've probably seen old 19th-century cameras in the movies with the photographer under a cloth hood and sliding a piece of wood out from in front of the camera -- that piece of wood was essentially the shutter, and they could get away with it because their daguerrotype plates weren't very sensitive and required as much as eight minutes to expose properly, so a few seconds on either end while the photographer fiddled with the shutter really didn't matter). The shutter works in conjuction with an iris, which limits the amount of light that can enter when the shutter opens, and these two work together to determine the exposure you get in the final image (much, much more on that in another article). The lens brings the image into sharper or softer focus, and is a means of collecting the light coming into the camera; with telephoto zoom capability, the lens can also bring subjects closer. Flashes illuminate the subject when lighting is not optimal at the time you take the picture. And so on.


All technologies prior to the digital age relied on chemical mixtures that underwent a reaction when exposed to light. Films were coated with layers of photosensitive compounds such as silver oxide, treated to react to different colors of light. Once exposed, the film was processed with solutions that developed the film and fixed the final image to the film. The image could then be transferred to photosensitive paper and finally developed as a positive print.


A digital camera replaces film with a sensor called a charge-coupled device (CCD). It works like this: the surface of the CCD is an array of photosensitive capacitors, often made of silicon doped with boron, that develop a charge relative to the intensity of light which hits each capacitor. The capacitor is then allowed to pass its charge on to its neighbor, and at the end of each row is a connection to an image processor which measures each of those charges, calculates which charges came from which capacitors, and then converts and saves this information as digital data.


The capacitors are grouped into trios that are able to sense red, green and blue light (the primary colors of the  visible light spectrum), and these trios are what are referred to as pixels (if you look very close to an older CRT television screen, you'll probably see tiny squares or rectangles that are either red, green or blue -- those are pixels, too; the modern 1080P HD plasma screen you just bought means that it can disply 1080 pixels across the width of your screen.) So when you see a camera that says it has 8 megapixels (MP), they're saying that the CCD inside the camera has a total of eight million pixels on the surface of that sensor. Very generally speaking, the more pixels there are on the sensor, the better the camera's resolution. If you take the exact same picture with two different cameras, one with 3 MP and one with 18 MP, you'll end up with the same basic image but the 18MP camera takes a picture that you can zoom in on many more times without loss of image quality because it can capture more data in that image.


Okay, you say, so a digital camera with more megapixels is better. So I should go out and buy one with the most megapixels I can afford, right?


Well, no, not necessarily. I think photographer and teacher John Greengo explained it best with a little visual aid.

Here is the world's simplest digital camera CCD: a four pixel camera. Let's say you bought this four pixel camera a few years back and have gotten a lot of use out of it, but you're considering getting a new one. So what about doubling the number of pixels? Well, it's hard to arrange eight pixels in anything other than a rectangle, like this:

So you've doubled the resolution in only one direction while leaving the other dimension the same (two pixels high). This is fine if you're buying a panoramic camera; coupled with a wide-angle lens, you could take really wide landscape photos at the same basic image quality of your old camera, but if you want to improve overall resolution, you're going to need to increase it in both the vertical and horizontal directions.

This nine-pixel camera accomplishes that: you go from two to three pixels in both dimensions, for a 50% increase in resolution overall. But to get that 1.5X increase in resolution, you actually had to have 2.25X the number of actual pixels on the sensor. This leads us to our rule of thumb: a given increase in digital resolution requires the square of that increase in pixels.

So going back to our four pixel camera, in order to double the resolution, we actually need four times as many pixels, so you'd need to buy a sixteen pixel camera.

So let's apply this to the real world. The Canon EOS 50D digital SLR camera features a 15.1 MP sensor, and you're thinking of upgrading to a Canon EOS 5D with its 21.1 MP sensor. Well, 21.1/15.1 is 1.397x the number of pixels. Take the square root of that, and you see that it's 1.182X the resolution, i.e. you get an 18.2% increase in resolution. Will you notice the improved image quality? Maybe you will, maybe you won't; it kind of depends on what subjects you like to photograph. If you do a lot of close-up work of really detailed subjects, then you might notice the difference. If you do a lot of really broad landscape photography, you might not.

Here's where the difference lies: the sensor is smaller in the 50D, less than 3/4 the area of the sensor in the 5D. There are physical issues involved with trying to cram ever more pixels into a limited amount of sensor real estate, principal among which is noise. At high ISO or long exposures, all cameras are subject to a certain amount of noise (in film cameras, this was known as grain or graininess), but with a sensor that is smaller relative to the aperture you're shooting through, there is a higher probability that the light that is sensed by each individual capacitor or pixel will either be a slightly different shade from the actual absorbed photon due to variations in the charge developed for a given photon energy level, because the individual pixels are crammed in closer to one another and may have a tendency to bleed charges into one another. So although you might not notice the 18.2% increase in resolution, if you add in the reduction in noise from having a sensor that is 25% larger, it might be worth it, if you plan on doing a lot of long exposures or photography requiring a high ISO (frequently in underlit environments, for instance)

Therefore, it might still be a tough decision if you wanted to upgrade from a 50D to a 5D, but at least you have one bit of information: There will be an improvement in image quality based on a larger sensor with more pixels available. The question is whether that improvement in image resolution is worth paying an extra $1400 (the difference in price between a 50D and a 5D on Amazon at the time of this writing). For the casual vacation photographer, it's almost certainly not worth it; for the $1400 you save, you can be happy with a really good consumer camera and spend that money on jetski lessons and umbrella drinks.

For the semi-professional or professional photographer, a little more research is required; the sensor offers a somewhat better image, in terms of increased resolution and decreased noise, but what may provide as good an improvement in image quality as a better CCD might be better quality lenses. So while you grapple with the decision whether or not to upgrade your camera body, you also need to ask yourself if you need better glass. That will be the topic of my next article.



Gear, Part II

On the subject of equipment upgrades, I know every photographer struggles at least some of the time with the question of whether or not you need a new camera, new lenses, or a new tripod or head mount. And for every photographer who asks the question, the answer is always a solid, definite, “It Depends.”

In very general terms, for the casual vacation photographer, the answer is almost always no, unless your camera is so antiquated that it lacks the functionality you require, or is no longer supported by the manufacturer, or no longer performs as it once did (I’ve discovered dropping a camera onto a marble floor does not improve its operation one bit). For someone like you, a reasonably inexpensive digital camera can be yours for under $100 that will do just about anything you’re going to need it to do, and software is available for your computer that can accomplish in post editing what your camera cannot do in the field. My current phone possesses photo and video capabilities that actually exceed those of my first digital camera, so you don’t have to buy an expensive rig to take decent photos. If you insist on shooting with film, you can probably go even cheaper by buying a gently-used one, but just realize that there are fewer and fewer companies making film these days, and it may make better sense from a long-term investment standpoint to bite the bullet and go digital.

For the amateur photographer or hobbyist, and anyone above that level, you may or may not require better gear. It really depends on the kind of photography you plan on doing. For $300-$500, there are some really excellent digital point-and-shoot cameras out there with good enough resolution to print clear 8x10’s, with different shooting modes that take most of the guesswork out of taking photos under different lighting conditions and a variety of subjects. I’ve even sold a few prints of shots I took with my old Olympus C300, so you’re already getting into the area where your current camera may be good enough.

Okay, I hear you ask, if my current camera is good enough, why do professional photographers buy cameras for thousands or even tens of thousands of dollars? Are they really that much better? Do they really need to spend that much for what they do?

Yes… and no. Great photography is a synthesis of technology, talent, skill, planning and a dash of good, old-fashioned luck (more on that in another post). I know photographers who regularly take gallery-worthy photos with their iPhones. I have also witnessed snobbish dilettantes whip out their $30,000 Hasselblads and their 1:1.2 Swarovski crystal lenses, train them on the mountains at the first hint of sunrise and take a series of stunningly bad blurry photos of their thumbs.

Think of some of the pioneering photographers in history and the gear they had to work with. Some of the first cameras were little more than a piece of film in a wooden box, with a simple glass lens and a sliding shutter, that you then mailed back to the manufacturer to develop. Imagine waiting a week to get a print of your single photo, and you can see the kind of planning and forethought that a photographer had to do before ever taking a photo. (Don’t believe me? Look up “Box Brownie” on Google or Wikipedia sometime). Ansel Adams lugged a sheer mass of bulky, awkward equipment up Half Dome that seems positive ludicrous by today’s standards. Yet look at the powerful images they created with a level of technology we simply don’t have the patience to fiddle with today. The tech does not an instant masterpiece create.

That being said, there is also a place for better tools. If I handed you a section of tree stump, a handful of stone hand-axes from 5000 BC, and a box of modern surgical steel chisels and said, “I’d like you to carve me a salad bowl,” you would probably choose the steel chisels over the stone tools, wouldn’t you?” (Okay, you’d PROBABLY turn and point at the Ikea catalog, but work with me here)

A master wood carver would know how to use the stone tools to hollow out the stump and eventually create the salad bowl for me, but he would probably do it faster and with less swearing with better tools. You’d end up with the same masterfully carved bowl, but the woodworker might not actually hate you when he’s done if you gave him the right tools for the job to begin with. The same goes for a camera rig: You can spend a lot of money on the fanciest cameras and lenses, but if you don’t know how to take a good photo to begin with, chances are pretty good you’re still going to be disappointed with the results.

So the results you get from your photography really depend more on your abilities as a photographer than on the gear you bring with you. A better camera and higher quality glass won’t make you a better photographer, in other words, but once you start to improve your skills, better gear could make it easier to achieve the same results.

I experienced this this past weekend, at a shoot I did at a dressage show in western Washington. I did a few sessions at this indoor arena before, but because the lighting was dim on all but the brightest days, my lower-end rig just wasn’t up to the task much of the time. My telephoto lenses tended toward vignetting and chromatic aberrations, and didn’t have the light-gathering capabilities I really needed. My camera was prone to a good deal of noise at high ISO, due in no small part to the manufacturer trying to cram so many megapixels onto a ¾-frame CMOS, so many of the images turned out grainy. Since I was dealing with large, live animals, I didn’t feel comfortable using much flash, because I didn’t want the liability or guilt arising from killing some innocent rider because I spooked their horse right out from under them.

Yesterday, though, I cranked the ISO as high as 4000 in the early morning and dropped it to 1600 as the day wore on. This let me keep the shutter speed between 1/250 and 1/400 sec most of the time, and got great depth of field with the aperture as wide open as it would go. No flash required, I could keep the shutter speed fast enough that I didn’t get motion blur unless I wanted it, and no noise or graininess that I could see in the final images. Before, I would have to process my photos through Photoshop to try to adjust for the exposure and attempt to remove the noise, and many shots came out okay in the end, but now I can get shots that are just as good without having to retouch them at all. Now I can worry a lot less about how it’s going to look and focus more on getting what I want in the frame, because I know the camera is actually capable of capturing what my eye sees and my artistic sensibilities envision.

There is, of course, the final extreme end of the spectrum. Are there fancier cameras out there than mine? You bet. There are medium- and large-format cameras that have the luxury of placing 60 megapixels or more on their sensors due to roomier real-estate (more on that in another post, if you’re interested), higher shutter speeds to catch bullets in flight or hummingbird’s wings in motion, hand-ground crystal lenses from fifth-generation jewelers, lenses that are so large they look like artillery and require the help of two grown men and a small boy to carry around. Are they actually better than I have right now? Overall, no – they’re overkill for my daily use, even on a professional level. I rarely run into a situation where I think to myself, “Darn, if only I had a 1200mm lens with me, I’d be able to get this shot of something a mile away;” I just try to get a little closer to my subject, and I'm thankful I don't have to haul a 35-pound lens around. Until I’m actually asked to shoot something for a mural or billboard-sized print, I’m probably not going to need a medium- or large-format camera, either, nor can I afford one anyway (and besides, there are ways to blow up images through digital processing that promise to preserve detail even as you expand the image). And let's be brutally honest: I'm kind of clumsy, and given the choice between dropping and breaking a $2500 camera or a $25,000 camera... I'll cry less over having to buy a new $2500 camera.

Moral of the story: think about the kind of photography you want to do, shop around to find the gear that gives you what you want at a price you’re comfortable with, learn everything you can about all the features of your new camera and truly learn how to use them, and be happy with your decision in the knowledge that yours was an intelligent and considered choice. With photographic gear, as in much of life, it’s not so much about getting everything you want, it’s wanting everything you have.

Gear, Part I

Admittedly, I'm still getting accustomed to the whole idea of blogging, so bear with me. I suppose since we're at the beginning, I should start at the beginning: my camera history.


Like most people, my first camera was a cheap hand-me-down, a Kodak Instamatic, as a matter of fact. It took those chunky cartridge-style film rolls that had its own take-up reel, and was about as basic as it got, but I loved that thing. I shot many, many rolls of film, mostly of nothing -- when you're twelve, the things that interest you in that moment when you decide to raise the camera to your eye are not what interest you by the time the film is developed and you look at the prints. Still, there were shots I have from my school years that were actually halfway decent, mostly by virtue of the good fortune to be in the right place at the right time, standing in the right way at just right distance from my subject that it took advantage of the precise focal length of my camera's lens, rather than by any intent or forethought on my part. I rarely considered how the final print would look, and I only invested in one of those disposable cube flashes once, just to see what the camera could do with night photography (with rather uninspiring results, I must admit) -- most of my photography was the result of one little corner of my brain taking over and saying, "Ooohpretty*click*"


Noticing that I seemed to enjoy snapping photos of every random thing that crossed my path, one of my sisters gave me a Pentax P3 SLR, with a 50mm 1:1.7 lens; I think she hoped that better equipment might at least make some of those random things look a little better. In high school, I took an actual photography class, and this introduced the concept of composition, that maybe if you THINK about the shot before pressing the shutter button, you might be more pleased with the results. For some projects, I borrowed my brother's 70-200mm telephoto zoom lens (which seemed, to someone like me who had gotten accustomed to little lenses with a single focal length, to be just ridiculous to lug around, but cool all the same), but mostly I concentrated on portraits and landscapes, which suited the 50mm lens just fine. I still shot a lot of film with only a few prints worth keeping, and I had yet to develop any real sense of composition or style, but I like to think I did better work as I got older and that I was refining my own aesthetics over time.


I dragged that P3 with me into my Navy years, and considering how much time it spent rattling around the cramped, cluttered and somewhat fetid environs of my rack, it's a wonder it continued to function at all, let alone well. Yet as I travelled the world and arbitrarily documented my various misadventures, it did just that, despite smashing into a hundred different hard surfaces in fifteen or twenty different countries, being subjected to temperatures ranging from around 5F (Alaska) to 110F (Bahrain) and humidity from 0-100 (and more, since it actually got submerged in water twice), never having quite all of the sand removed from its internals or the internals of the lens such that focusing on a subject made an intermittent ratcheting sound like a fishing reel with stripped gears, and actually getting smeared with a mixture of peanut butter and Sriracha hot sauce (don't ask). The trouble was, since the photographer was also getting smashed, frozen, fried, submerged and smeared right along with the camera, there was a certain lack of attention to little details like lighting and exposure, focus, depth of field, and framing, not to mention overall composition. It was costing me a lot of money to keep buying and developing film when I wasn't getting shots worth keeping, and I soon began to think about making the transition to digital -- at least with pictures that only existed on a computer screen, you could delete all the garbage shots and not be out potentially hundreds of dollars in developing fees. You could snap away with impunity and not feel that bad about it.


The first digital camera I bought was an Olympus C-300. It was a 3.0 megapixel point-and-shoot, and was... not sexy. Bigger and better digital cameras were available even at the time, but out of my price range (and to be honest, out of my skill range as well). To be honest, I paid way too much for this camera, but it turned out to be a little workhorse for quite a while, certainly good enough for the family photos I was taking.


I got more serious about my photography only very recently. Before taking a trip to southern Africa, I bought another Olympus, an SP-550UZ 7.1MP digital camera with an amazing 18x optical zoom, and I still have this camera for simple vacation photos or to document things around the house -- the files are much smaller than my professional camera, and it's much lighter so it's easier to carry around. This really opened my eyes to what was out there in the market; the greater resolution and zoom capability, coupled with better in-camera software and image stabilization meant my shaky, tentative photography produced much clearer images than I had ever shot before. This camera made it look like I knew what the hell I was doing, and perhaps for the first time in a long while, I actually enjoyed taking photos and invested a lot more energy in trying to make them more visually interesting. Of course, with all the automatic functions within the camera taking care of me, I got technically sharp and well-exposed shots, but I struggled to defeat those functions when I actually wanted to do something a little more artistic, partly because I'm kind of a big-thumbed ape when it comes to technical details and partly because I was still trying to figure out what I wanted out of any given shot and how I should go about actually getting it.


Taking better photos inspired me to... well, take better photos. After I returned from my Africa trip, I realized just how much I enjoyed photography, and that I wanted to take it further, so I bit the bullet and invested in a Canon EOS 50D digital SLR. It came in a package deal with a selection of lower-end lenses: a 50mm fixed lens, an 18-55mm telephoto, a 70-300mm telephoto, a wide angle and a macro lens, along with a handful of filters, a cheap flash I never used, a camera bag and a few odd and sundry bits and pieces. This gave me a lot more functionality than the Olympus, better resolution, and was a little easier to fiddle with to get long exposures or to under-expose when I wanted it, or to get soft focus when I wanted that. I also still have this camera, and I've gotten several years of use out of it, and it has proven to be suprisingly rugged -- I have yet to see anything fail, despite many inadvertent attempts to break it, and actually continued to perform well in environments where more expensive cameras simply gave up (a particularly heavy rain on the Olympic Peninsula comes to mind). The shots I got from the 50D were clear enough and composed well enough (especially after futher education, including a few sessions under the tutelage of Art Wolfe) that I felt confident enough to actually put my work up for sale.


For a professional photographer, the 50D has some limitations, of course (which is why Canon lists it as a "semi-professional" model). It's obviously not the highest resolution camera Canon makes, but in this case, it's really size that matters: it has a 3/4 frame CMOS, meaning the sensor is not the same size as a piece of 35mm film. So all those megapixels have to be crammed in closer to one another, and at least theoretically, that means a higher probability of signal noise in the final image. Since I'm interested in getting photos that are tack sharp and with as little noise as possible, I need to do everything I can to reduce digital errata, so I made the upgrade to a full-frame sensor and bought a Canon EOS 5D and some better glass (which one will improve my images more is a subject for further debate, but I'll take whatever does the trick and not lose sleep over it). I haven't had it long enough to report fully on its plusses and minuses, but I know a lot of professional photographers who swear by it. (We'll have the Canon vs. Nikon disussion at a later date, when we have much more time and a bit more alcohol on board)


Where will I go from here? Hard to say; technologically, I've reached a point that many professional photographers are comfortable settling at. There may at some point be a need to get a medium- or large-format camera for detailed work that I'll want to blow up to mural sized prints, but for the moment, I can't justify it (not at current market prices, particularly) and I'm pretty comfortable with what I'm using. We'll see; if somebody invents a digital camera that takes pictures in 3-D, I might have to jump on that bandwagon, but until we start doing holographic field photography, I'm happy with my 5D. I'm done buying toys for a while... until someone shows me something else that bright and shiny.

Stock photo site

Oh, by the way, my new stock photo site is up on Photoshelter. I'm still tweaking it, but it's available for viewing -- sometime very soon, people will also be able to buy prints and licenses as well. It's located at http://uyyek.photoshelter.com/

Welcome!

My name is Michael Uyyek, and I am a wildlife and landscape photographer based in Seattle, Washington. I hope that as time goes on, you will join me as I continue to travel the world and see new wonders of nature and places that still remain untamed. I'm also interested in documenting scenes a little closer to home, and am equally drawn to more man-made images as well. I'd like to share with you some of the lessons I learn along the way as I become a more seasoned photographer and traveller, and in a way, you'll be coming with me everywhere I go. Thanks for joining my journey, and you'll hear from me again soon!