Photography Gear Jargon Demystified

Introduction

Some of the most common questions I've been asked (in no particular order) include:

• "What's the best camera to get?"
• "What sort of lenses do I need?
• "How much money should I spend on a camera kit?"
• "Can I just use my mobile to take photos?"
• "How many megapixels do I need?"
• "Where should I buy my camera gear?"
• "What makes a lens better than others?"

.... and so many more....

So often, these questions show a passing interest in the field of photography... but they clearly have not done their research. Because the answer to every question here is:

It depends.

There is no simple answer, every photographer is different. Their needs, their budget, their interests, and style will need something different. To help you to make the right decision for your particular situation, you have to understand what the sales people are telling you, and for that, the jargon needs to not only understood, but which real-world compromises such a feature would entail.

Sensors, and megapixels.

Cameras come in many shapes and sizes. So do, their sensors. However, before you chase after the most megapixels, there’s a few things you should know.


Ok, so a pixel (short for picture element), is basically a coloured dot. If you make the dots small enough, and numerous enough in close-knit columns and rows, you get increasingly fine-details in your monitor-displayed or printed image. A mega pixel is 1 million pixels so when you buy a 10 megapixel camera, that’s 10 million details put into every image. The official term for the overall arrangement of "dots" is resolution.

Resolution is often used for computer monitors and TV screens.

Those of you who remember TVs back in the 80s might know that the image was 640 pixels wide, and 480 pixels high. (That's a total of 307,200 pixels, or just over 0.3 megapixels). These days, even the cheapest TV has a resolution of 1920 pixels wide and 1080 pixels high (also known as 1080P) which has just over 2 megapixels (that's 6 times the detail). 4K TVs and screens have even higher pixel counts (3840 x 2160 pixels) which has nearly 8.3 megapixels in every frame. That's 27 times the detail of an old TV. Remember, that low resolution is fine for smaller images. TVs back in the 80s were lucky to be 50cm wide. Now they're often 50 INCHES or more wide. If you could go back to old 640x480 TV footage  and watch it on a small screen it'd be fine. However, if watching that safe footage on a modern, and large screen, say 4K (or higher) it would look awfully blurry and low quality on a huge TV by comparison, especially when blowing it up to a much larger screen sizes. Each dot wouldn't be a dot, but a huge single coloured block.

Back to camera sensors....

Digital sensors are getting better all the time, and higher-end cameras are often over 20 megapixels, some professional cameras go above 50, or even 100 million. But of course, you’ll pay for it with higher prices. Most "jack of all trades" cameras that pros use tend to be in the 16-35 megapixel range. However there are situations where going higher or lower is desirable... and other situations where it's a terrible idea.

The pros of having more megapixels:

1. More details means that your photos are sharper.
2. Your photos can be cropped more, (cut bits off) without substantially impacting your shot. However, this comes at a number of downfalls... and discourages careful composition. This is why cheap equipment teaches people to overcome their limits by using skill and thought.
3. You can enlarge your prints without it looking bad.

These three points are huge. So when I explain the downsides in greater detail, don't think that the cons necessarily outweigh the benefits, ok?

The cons of having more megapixels:

1. Increased noise: Sensors usually come in particular sizes. As the megapixel count goes up, the sensor's pixels (also called "sensels", "photo sites", "photo-sensitive cells") have to become smaller, and more tightly packed to fit. This means that the amount of light falling onto each sensel becomes smaller. Just as a small window lets in less light than a bigger window, the sensor at each site has less light to deal with. Consequently, has to work harder or longer to quantify the light falling on it. Similarly, because the sensels are placed so closely together, the electric current can leak from one sensel to another. This is a form of electrical miscommunication that is present in all sensors, and even if you shot a completely black scene (say with the lens cap on), you get randomly coloured pixels, or bright spots in the recorded image. Noise appears as a "grainy", effect on photos, and it looks a lot like a dusty old picture.  Increased noise means the camera will perform worse in low light conditions than a camera with fewer pixels. So huge megapixel counts are best used in bright conditions like a studio, or outdoors during daylight hours.
2. Increased file sizes: As the amount of detail goes up, so does the data storage and processing requirements. Going from a 10 megapixel camera to a 30, or even 50 megapixel camera means that each photo can take the commensurately increased amount of space for both short term (memory cards) and long term storage (hard disk), and require a more powerful computer to process. As soon as I bought my 4K capable drone, my workflow computer had to have a substantial upgrade in order to process the video. Then my long term storage had to be upgraded, as 1 minute of 4K video uses at least the same amount of data as 20 raw images from my 23 Megapixel Canon 5D Mk III. Now I take a lot of photos, but even when I'm traveling, I don't take 20 shots per minute on average.
3. You often need faster memory cards and longer term storage: Imagine you're photographing birds in flight, and an eagle drops toward a lake and snaps up a fish. Getting the exact moment in something happening so fast is unlikely. So, wildlife photographers often put their camera on "rapid fire", and combine the "spray and pray" mentality with some serious leg work, skill and/or preparation to improve their odds of success. Now think about that, if your camera can shoot 10 shots per second, at 24 megapixels per shot (roughly 24MB per shot in raw), the data-handling parts of your camera is going to need to able to process and write 240MB of data per second to keep up. If your camera or memory card can't keep up, that means the buffer in the camera fills up and then the camera slows down to a crawl, because it's waiting for it's "backlog" of work to finish before it takes more shots. This slowing makes missing that key fish and eagle moment far more likely. Even if you have a top end camera, the memory card is a key part of this process. The difference between a class 10 and ultra-high-speed (UHS-I or UHS-II) memory card is substantial, both in performance, and price.  Obviously, if you're a landscape photographer or do product photography in a studio, then you're probably not worried about speed at all. Your subject matter isn't likely to be moving, and even if it is moving, you can simply retake the shot if you're not happy with it.
4. You need better lenses: As detail goes up, the accuracy of the lenses needs to go up too. Imperfections in the glass starts to show up more readily as the resolution goes up. When Canon introduced it's two 50+ megapixel cameras (5Ds and 5Dsr) they had to include professional grade lenses as their kit lenses, the cheap ones just looked... sad.
5. You need better technique: Strapping more pixels into a finite space makes each pixel on the sensor smaller. Which means smaller movements by subject or camera will result in blurring. This is made exponentially worse as the focal length of the lens goes up. As such, you're going to need to increase shutter speed, use a tripod to reduce camera shake, or some combination of both in order to get a usable image. In short, higher megapixel cameras need better skills to use effectively.

So now you know that more megapixels isn't a universally "better" option. I should point out that there are cameras where they have actually decreased the number of megapixels in the newer generation to improve image quality. As is the case of the Olympus TG-5 and TG-6, which were the latest two generations of an underwater camera at the time of writing. Since it is used where they know that the light might not be very good. The newer models have only 12 megapixels, whereas the previous model (the TG-4) had 16 or so.

So how many megapixels is enough?

Please note that if you use the entire frame of your shot (no cropping in post processing) then 12 megapixels is more than enough detail to print to A3 at a studio printing level. Think, fashion magazine with glossy cover! So more pixels only count when:

1. You want to print the image bigger than A3.
2. You often work in bright conditions, or in a studio where lighting is controlled.
3. The absolute pin-sharp detail of the image is somehow important (for research photography)
4. You want to crop your images a lot. (With better technique and perhaps longer lenses, this might be completely unnecessary).
5. Your skill can match the needs of a high-resolution camera.

The Four Types/Classes of Camera: Phones, Compact, Mirrorless, & Digital Single Lens Reflex (DSLR)

In this day and age where most people are happy with the cameras in their phones, I'm going to briefly describe the differences, and what each category is good for, as well as comment on the latest trends.

Phone-based cameras:

Phones have come a long way in recent years. With offerings from big and smaller manufacturers installing one, two or even three cameras into portable devices like tablets and phones. For sheer convenience, and posting images and videos on social media, phone and tablet cameras destroy the other types of camera classes. They've got their own Internet access, apps for basic-yet-surprisingly-effective in-device editing, and let's face it most people carry these things around all the time. They also often store photos for long periods of time, so you can have your photos on hand whenever you need it.

Note: A little known-benefit is that taking a photo of documents on your phone and emailing it... is often better than using a full-blown office grade photocopier, with colour-capable document scanner! Particularly on faded or low contrast documents.

Despite the convenience, there are down sides. The flash is awful (given that it's effectively a single LED or Light Emitting Diode) that is both limited in range, and usually unflattering to say the least. Much of the camera is automated, you do not have much control over the lighting, focus, and newer phones like Apple's latest offerings store their images in a new-but-relatively unsupported format of HEIC (High efficiency image compression) instead of the established JPEG. Apple realizes that this is a problem outside of their products, so once you "share" a picture by sending it through email, it is automatically converted to JPEG for compatibility's sake. Unfortunately for Apple "Air Drop" fans, if you use "Air Drop" it'll stay in HEIC, which is not supported much at all on web sites... at least at the time of writing. So you'll need to convert HEIC images to JPEG/PNG with your favourite photo editing software. (Or you can use Automator, and create a convenient "Quick Action" to copy, resize and/or convert HEIC files to your preferred format).

Despite having multiple cameras in many mobile devices, they all use very small sensors, so they struggle in low light environments. The mobile device's software can compensate for that a bit (particularly on the newer iPhone/Android offerings), often by stacking multiple shots together, and adjusting and combining shots in any number of weird and wonderful ways... but in the dark or other challenging conditions, using a phone is hobbling the image quality from the outset... no matter what the marketing gurus say. That said, they are getting better.

Compact cameras:

Compact cameras are becoming a bit of a rare beast. Phones are really taking over the market for this type of camera these days (and other categories). However, a compact camera (particularly higher end ones) have almost all of the features and benefits of larger cameras. Sony makes a compact with the same huge sensor as a full-framed DSLR. Of course, to achieve this amazing feat of electronic origami in such a small package, the cost is more than most high end DSLRs and mirrorless cameras. Also, being a compact camera, there is no ability to change lenses. This isn't always a negative, since dust and debris are far less likely to work their way into the camera. I have taken some amazing (and award-winning) shots with my little compacts. I like them over phone cameras because my last few compact cameras have featured greater creative control, they interface nicely with my phone over WiFi, and still fit into my pocket.

Compacts range in features, depending on the cost. Most have tiny sensors (still often larger than phone equivalents), most have an actual optical (not digital) zoom lens (since no phones have this yet), and the remainder have amazing prime lenses that leave phone lenses for dead. Of course, being a dedicated device, your average compact camera has more options and controls for actually taking photos. Since it is not a "smart" device, it does not offer the editing, long-term storage and viewing options, and internet connectivity found with phones and tablets. However, newer and higher-end models often have Wi-Fi connectivity so you can use your phone as a wireless release/intervalometer/improvised cinema screen and more. Interestingly, I find that some of the third-party apps are better than Sony's "Play Memories" app, and are cheaper.

In short, you need to take your shots off the camera to process and share them with some sort of intermediary device (tablet, laptop, or desktop). However, that is likely to change in the future... if it hasn't already on some models.

Compacts, while unpopular as "primary" cameras, are great for certain functions. Video content/VLOG creation, street photography, travel photography, and action/extreme sports photography are common uses. Afterall, they're a pocketable device that provides the photographer with all the controls you'd expect from most higher end cameras. If you just want a "pocketable" device, compacts extend the conditions in which you can shoot (such as low light environments) over most phones and tablets. Whether you like Canon's rugged G series, or Sony's RX 100 (Versions 2,3,4,5, 6 & 7 (still all sold since they are aimed at different photography styles), or a little Panasonic for their highly-regarded video image quality. Being able to just toss it in the bag, or run as a backup camera is really handy!

DSLRs (Digital Single Lens Reflex) Cameras:

I'm going to skip mirrorless cameras for a moment, and jump straight to DSLRs so I can better clarify the difference later. When most people think of professional photography, they're thinking of people who use this type of camera. The "Single Lens Reflex" means that the photographer can see the actual light coming through the lens, which is achieved by using a mirror to reflect that light to the viewfinder window on the back. In short, it's somewhat like looking through a telescope, or perhaps more accurately, a periscope. The mirror moves out of the way when the photo is taken so the light hits the film/sensor in the back. 

Before the advent of digital sensors and "live view", this was the closest to "What you see is what you get" (a.k.a: WYSIWYG). However, it does not account for shutter speed, depth of field, or intended exposure (brightness of the shot). Some DSLRs have a depth of field preview, but this isn't what you'll see in the end photo. Most DSLR's can run a "live view" these days, where the screen on the back will show the overall brightness of the photo (exposure), depth of field. However, I should warn you that the screen is very small, and does not show out-of-focus shots very well at all unless you use the image zoom function.

DSLR cameras are still considered by many as "the best" in terms of sheer versatility, and ease of use. DSLRs have the biggest range of lenses by far and offer the greatest versatility in focal lengths, quality, and cost (especially second hand). However, individually or combined, DSLR equipment is relatively more heavy, bigger, and new DSLR-grade gear can be very expensive. DSLRs have mechanical shutters which wear out, making them less attactive to people who take a lot of photos. (Time lapses and slow motion videos are two cases where DSLRs aren't well suited). My bag for travel is considered "too heavy for carry on", with two DSLRs, three lenses, a flash, and laptop. However, this is nothing, compared to the kit I'll take when I'm driving around Australia.

DSLR's have started to fall out of favour in the semi-pro, and well funded, enthusiastic amateur market due to the convenience of allegedly lighter options in the mirrorless alternatives, which I'll discuss below. What most people fail to consider is that the lenses on most mirrorless camera setups are slightly smaller in the shorter focal lengths.. but things change as the lenses themselves get longer (and larger). In fact, professional grade, mirrorless telephoto lenses can be larger, heavier, and more expensive than the DSLR equivalents... if mirrorless cameras do have equivalents... which isn't always true... yet.

Mirrorless cameras:

Honestly, I have a love/hate relationship with mirrorless cameras, mostly because most people switch to them for reasons that aren't necessarily appropriate or true. However, outside of phone cameras, mirrorless is the only other growing category of cameras and while they do have their downsides, offer a fantastic option for some.

By removing the optical viewfinder from an DSLR, these cameras do not need a mirror between then lens and the sensor. As such, mirrorless cameras opt for the "Live view" method to help with composition. "Live view" is just using the sensor itself to send a video signal of what it sees to the screen on the back of the camera. This has some significant advantages, because you will only see what the camera sees. Live view, as stated above, shows you the end product of your shot by depicting changes brightness, depth of field, and colour... but not so much for motion blur. (There had to be a limitation somewhere, right?)

Some mirrorless cameras have a second optical viewfinder for "snap shots" but this isn't common, so if a viewfinder is present, it's likely that the camera just uses a second, smaller "live view" screen inside an eyepiece to create the effect of an optical viewfinder. 

Since the camera relies on live view, the batteries are drained faster due to powering both the screen and the sensor more often during composition and focusing. By taking out the mirror and the mechanical shutter, you can reduce the size of the camera itself, which has some weight benefits I suppose, but it also makes the mirrorless cameras more cramped/harder to use for people with bigger hands. It also means batteries have to be made smaller to fit inside, reducing the number of shots between charges.

Power is a real issue for mirrorless models, batteries are made smaller, and expected to do more. Things get even worse in cold climates, as all batteries perform less well in lower temperatures, and there's less battery material overall, so they cool down even faster than larger DSLR equivalents. All to reduce the size of the camera, so photographers have to carry even more batteries to get through a solid day of shooting.

Ironically, after sacrificing so much to get a smaller camera, the most common response photographers have to these problems, is adding a battery grip and a second/larger battery which basically undermines the whole point of buying a smaller camera in the first place. Sigh.

As I mentioned above, lenses for mirrorless and DSLR cameras aren't necessarily all that different in weight and size. Sure, you can have a range of small, light-weight lenses which will be more than sufficient for many people. However things can change pretty quickly, particularly when you want fast, telephoto lenses which are always considerably larger than the camera itself anyway, even on DSLRs. Mirrorless cameras do nothing to change the size of the lenses. Since a 600mm telephoto lens for a DSLR will be nearly identical in size/design to a 600mm lens for a mirrorless, it's hard to change the physical dimensions of the glass elements, and general construction of larger lenses without compromising image quality or lens speed. Weight is perhaps the only exception, where the quality of the materials, and design can lead to tangible differences. However, the cost of some of these large mirrorless lenses are noticeably higher than the DSLR equivalents... and many of the mirrorless lenses at this extreme telephoto end of the spectrum are heavier than their DSLRs equivalents.

DSLR cameras range between 200-900g heavier than their mirrorless camera counterparts. (Not including any lenses) This is completely offset by the larger lenses if the mirrorless lens is 1-2Kg heavier than the DSLR's equivalent.

That's not to say that mirrorless cameras aren't good. Some of them are amazing, with hundreds of focal points, lightning fast electronic shutters, and some of the best sensors I've ever seen can be had in mirrorless cameras....but it's important that you go into it with realistic expectations. Don't let the "mirrorless is so much smaller and lighter" argument sway you more than warranted, especially if you plan on using larger lenses.

How do they compare to compact cameras?

Mirrorless cameras are often a major step up from compact models. Their sensors are more often comparable to DSLRs, and they're a good intermediate point between compacts which have no option to change lenses, and the potentially intimidating DSLR range. If you do a lot of high-speed, rapid fire work, using hundreds of focal points to lock onto moving subjects with speed and precision, the lack of a mechanical shutter not only increases the burst rate, but improves the longevity of the camera itself. So that makes mirrorless models a good option for wildlife and sports photographers. Perhaps less commonly, it also makes mirrorless cameras a compelling case for time lapse photographers, and those who shoot high speed (or slow motion) cinematography.

Now while I've "harped on" about the misleading "mirrorless is always smaller and lighter" impression. There are times when a mirrorless camera with a few small lenses is going to be lighter and smaller than an SLR model. But there's overlap here. A mirrorless photographer with lots of lenses and accessories is going to have a bigger kit than a DSLR user with only one lens. So while the average size and weight of a mirrorless kit is typically lower than the average DSLR kit, the bell-curve of each is going to have a pretty decent overlap.

The quality of shots from a mirrorless, even in challenging conditions is often as good as, and can be better than DSLRs, but as you might imagine, those models are often more expensive than DSLRs. However, they still need a computer to process and store your shots long term.

In conclusion:

So I strongly urge you, to consider the best style of camera by trying models in each category first. Always try to "have a go" with some cameras before buying. Whether you borrow, beg, rent, or just go to a shop for a demonstration, the experience will tell you what it's like to actually use, hold, carry, and set reasonable expectations of what it can and cannot do.

I've been taking photos since my relatively early childhood, and while I can get distracted from the hobby by work, family, and life, I keep coming back to it. I'm not going to say buy one type of camera, because in all honesty, each have their strengths and weaknesses. Over the years, as technology changed and my skills (and budget) increases, I've ended up with multiple types of cameras. I own two phones, two tablets, three compacts, a Go Pro, a mirrorless, and three DSLRs. I use the "best one I have at the time" but I definitely have my favourites for different styles of photography.

Lens related jargon:

Let's get the spelling right!

Not technically jargon, but lets get the word right. Lens is a four letter word in English. The plural is lenses. English is inconsistent at the best of times, and dropping that last "s" from lenses might seem right, but it isn't. Don't worry I am not judging you, English might not be your first language, or you may never have been taught. Regardless of your reason, so many English speakers get it wrong too. So despite doing everything else to look professional, many amazing photographers undermine themselves a little when add an e to the end of lens. It just shows people that they don't want to use spellcheck. (Now I know there's a lot of typos on this site, but hey I can at least get this bit right... I hope).

The purpose of a lens:

A lens bends, gathers, and focuses light toward a sensor at the back of your camera (at least, when attached). With an in-built iris, the lens can also reduce or increase the amount of light entering the camera. Now, the physics of light is beyond the scope of this article. (Again, whole books on the subject), but there are a few terms, acronyms, and other confusing relationships which beginning photographers might like clarified.

Focal Length:

Focal length is the primary feature you're going to be looking at when buying a lens. If you want to capture the entire sky in one shot, you're going to need a wide angle of view. Wide angle lenses have the shorter focal lengths. Alternatively, if you're trying to shoot pictures of a bird 30+ metres away, then you're going to want a really narrow field of view to focus only on that bird, so you'll want a telephoto lens (think, small scale telescopes if that helps). Naturally, telephoto lenses have longer focal lengths. Commercial telephoto lenses can go up to 1200mm long, but they'll cost more than some people's homes. Ordinary mortals who aren't BBC documentary photographers, will usually have lenses (for DSLRs) between 10mm and 600mm.

You might be wondering, "What focal length separates the wide from the telephoto?". That's a good question, and one that doesn't have a simple answer, because the sensor size in the camera plays a role. Cameras with larger sensors have longer focal lengths appear as "normal". (Roughly the field of view of one eye... Not too wide, but not telephoto either). A full frame camera (usually the higher end DSLR and mirrorless cameras) will have a normal view point at 50mm focal length. APS-C sensor cameras get a little more complicated, because Canon makes a slightly smaller APS-C sensor than Nikon, so the range is somewhere between 33mm for Nikon, and somewhere around 31mm for Canon. Go down into Micro Four Thirds sensors (smaller again) and you're looking at the 25mm mark. Smaller sensors still, found in your phone, might genuinely have a normal perspective at focal lengths of only a few millimetres.

With all this confusion, comparing focal lengths for different sensor sizes, it's hard to get an idea of whether a particular focal length is wide, normal or long. So the "effective focal length" is an adjusted value which compares lenses as though they're all being attached to a full frame sensor camera.

As such, here's how to interpret full frame length, "effective focal length" or just "effective length":

• <14mm is extremely wide (most likely a fish eye or 360 degree lens with lots of warping)
  
•  14-24mm extremely wide (but likely to be a normal rectilinear lens, less warping).
• 24-49mm wide.
• 50-60mm Normal
• 61-200mm Telephoto
• >200mm Extreme Telephoto
• >=1200mm you could buy a house.. or a lens... you decide.. but you probably can pick a window from over 1000-1600m away.... but you won't have anywhere to live. Does that make you a Peter Pan, or your everyday stalker?
  

Please note: That it's entirely possible that lenses designed for full-frame cameras can be used on crop factor cameras too. Naturally, their official focal lengths will be assuming the full-frame camera. However, if you put a 400mm full frame lens on a crop factor camera, then this changes the effective focal length. On Canon APS-C DSLRs, the multiplier is 1.6x, and Nikon APS-C sensors, their cameras have a multiplier of 1.5x. So if you run a Canon 400mm lens on a APS-C cropped sensor camera like the 7D, you're effectively shooting with an effective length of 640mm. This is great if you're a wildlife photographer, you just got 240mm of extra "reach" without paying for it. However, things aren't so great if you take lots of photos with shorter focal lengths (wide angles). All of a sudden your Canon 24mm lens is "less wide" with an effective length of 38mm or so.

Focal length also affects your images. As focal length increases:

1. For most aperture settings, the depth of field will reduce (easier to blur backgrounds... or harder to keep subjects in focus)
2. If you're not blurring your background, your background will look much closer to your foreground. (An effect called "compression").
3. It gets harder to hold your camera steady enough to avoid blurring due to camera shake. You'll need to up your shutter speed if shooting hand-held. A common guideline is that divide 1 second of shutter speed by your effective focal length. So if you have an effective focal length of 200mm, then you should shoot at 1/200th of a second as the SLOWEST shutter speed when shooting hand-held. If you're shooting with an effective focal length of 640mm, then 1/640th of a second is a good estimate.
4. It also gets harder to keep a fast moving subjects in your shot as your field of view narrows.
5. Lenses seemingly go up almost exponentially in cost, and weight.

Conversely, as focal length decreases:

1. Depth of field will extend (easier to get entire landscapes in focus, but smooth creamy blurred backgrounds might be harder)
2. Foreground objects appear a long way from the background. (I don't know if it's an official term, but I call it "expansion")
3. Lenses become lighter, and shutter speeds can be reduced and you'll still get sharp hand held images. However, go wide enough, and distortion and other issues become more apparent.
4. Wider lenses make getting moving things "in the shot" easier, but their impact on the overall image will be diminished.
5. Lenses are considerably lighter than extreme telephoto lenses... but lenses at the extreme wide end start getting expensive and heavy again too.

Prime Lenses:

Are just lenses without any zoom capability. They're are usually sharper compared to zoom lenses. If you want to "zoom" with a prime lens, you have to get closer, or further away. (Zoom with your feet, by walking closer/further away).

Zoom Lenses:

Lenses that have the ability to shift focal length. Giving the effect of being closer/further away without moving. These generally offer a great deal of convenience, but as the zoom range goes up, the image quality at either the wide or telephoto end (or both ends) will drop.

Aperture/F Stops:

Lenses have an iris to control how much light is let in (much like curtains on a window). Lower F-stop values indicate a wider iris, allowing more light in, and allows equivalent brightness to be done in less time. This is why lenses that have really wide apertures (low F-stop values below F4) are considered "fast". Wider apertures allow shots to be taken in darker conditions, or in other cases, blur the background more, and allow faster shutter speeds, and/or lower ISO settings, which is always a nice option to have. However, to make lenses capable of handling wider openings, the precision needed to make them is often much higher, so they can be considerably more expensive.

When you read the specs on most lenses, only 1 aperture value is shown. This is the fastest/brightest setting. Regardless of how fast the lens is "wide open", most lenses have a range of slower/darker settings, usually to F22 or F32. You'll find weird number sequence. Like:

F1, F1.4, F2, F2.8, F4, F5.6, F8, F11, F16, F22, F32.

Each of these settings is 1.4 times the preceding number. 1.4 is roughly the square root of 2. By dividing the diameter of the iris' hole by 1.4, you halve the area of the hole, and thus halve the amount of light going through the lens. So F1 is twice is bright/fast as F1.4, which is twice as bright/fast as F2, which is twice as bright/fast as F2.8... and so on.

That means F1 has to be halved 10 times to get to F32. Meaning that F1 is 2¹⁰ = 1024 times brighter than F32. Please note that there are lenses faster/brighter than F1, and other lenses that offer settings slower/darker than F32.

In short, we need this exponential ability to halve/double the light to cover the huge range of brightness the real world can throw at a camera without spending weeks dialing it in. Every time you halve or double a setting, you've changed it by one "stop" or "exposure value" (EV). If you wanted to shoot after the sun has disappeared over the horizon you might reduce your aperture to F4 from F8, this is two stops (one stop to F5.6, then another to F4) which means F4 is 2² or four times brighter. As it gets darker, you may further decrease the F value to something like F2.8, just so you don't have to adjust your other settings, and deal with the negative consequences of those adjustments.

On zoom lenses, occasionally you'll see two aperture values mentioned in the specs, such as:

Canon 100-400 F4 - F5.6

The best value (lowest F number) is always at the wide end. So this lens, when you set the focal length to 100mm, gives you the option to set the aperture as low as F4. However, as you zoom in toward the 400mm end, the lens can't gather enough light to maintain the max aperture of F4, and loses a stop to F5.6. That might not sound like much, but a stop on a long lens can substantially impact the conditions you can shoot in. Even going from sunny to cloudy days (or simply moving into deeper shade) may make things difficult. Some lenses lose more than a stop from wide to telephoto/long end. Also, the transition from one max value to another, may be gradual, or a sudden change somewhere in between the extreme ends. It doesn't have to be in the middle at all, it may only switch to a darker max aperture near the long end, or it could go the other way, and move a few millimetres from the short end, and it may change.

Clear as mud? Ok, but now you know more about aperture than most people.

Image Stabilization (IS) Optical Stabilization (OS) and Vibration Reduction (VR)

Different manufacturers offer lenses that have a system designed to compensate for "camera shake". Slow down your shutter enough, move the camera fast enough, or use lenses with long enough focal lengths, and you'll run into blurring the entire image, simply because you're not still enough.

Lens based stabilizers usually consist of some sort of computer controlled optic inside the lens. If your camera moves up, it moves down to compensate for it, so no matter which direction you move, the lens compensates for it... at least, somewhat. Canon calls it "image stabilization". Nikon calls it "Vibration reduction", Sigma calls it "Optical stabilization". I'm sure every lens and camera manufacturer have some sort of trade-marked term for it, but no matter what it's called, it basically works on the same principles.

One of the best things about new lenses is the ability to compensate the inherent shake of "hand held" shots. Stabilization means that you can use longer lenses, slower shutter speeds (to a point) and in some situations, shoot with the freedom of not being tethered to a tripod or some other support, at least somewhat protected from the blur caused by jittery hands (whether it's cold, caffeine overdose or withdrawal, or a nervous disposition). Now, please note that stabilization does absolutely nothing to compensate for a moving subject, just a moving camera+lens. If the subject is moving in it's own way, IS/OS/VR won't help at all.

Not all lenses have stabilization. So if you're in the market for a 70-200mm lens. Canon offers four different models. Max aperture of F4, and F2.8, and both of these models can come with... or without stabilization. F2.8L IS (F2.8, L for professional grade lenses, and IS for stabilization) is the most expensive and capable, while the F4L (note the lack of IS) is the cheapest, and lightest. I've never seen a non-IS 2.8, but I know it exists, but there's also the IS capable F4 as well.

The effect stabilization has, will depend on the particular lens. Older generation lenses like my original Canon 100-400, released in the 90s, included early-generation stabilization that was only good for 2 stops. Modern lenses are able to provide 4,5 or even 9 stops of stabilization.

Please note that some newer cameras provide the stabilization in the camera body, rather than in the lens. This means that it doesn't matter what compatible lens you use, they all get stabilized by default. This has a financial benefit, as you don't have to keep buying one stabilizer system after another in each of your lenses. However, I've not tested any body IS system with lens based system comparisons.

Ultra-Sonic Motor (USM)

This is the motor that drives the auto focus of the lens. USM are the almost completely silent, and ridiculously fast to focus. However, they do add cost, so they're found in higher-end lenses.

Stepper Motor (STM)

On cheaper lenses, stepper motors drive the auto focus function in the lens. There's nothing wrong with this system, but they tend to be relatively noisier, and a little slower to focus.

Mount Type:

This just describes what type of camera the lens can plug into. Canon EF and EF-S mounts are for their DSLRs. (EF-S mounts cannot be connected to full-frame Canon DSLRs, but EF mount lenses can be used on any Canon DSLR). Canon RF mount is for their new mirrorless. Canon M mount is for their early generation mirrorless. Nikon has a few mounts as well, as do most of the other brands. If you're buying a third-party lens (Sigma, Zeiss, Tamron, Tokina, etc) they might make one model of lens for several different cameras. Make sure you are ordering the right one.

Filter Size:

Filters are optional accessories aimed at changing the light coming into the lens somehow. Filters are usually attached in one of two ways. On the front of the lens, using a fine screw-in thread, which varies wildly from 25mm wide, to huge behemoths like 105mm. After the front element gets bigger than that, it becomes cheaper to make a smaller filter that can be inserted between the lens and sensor using a "drop in" system. This is limited to very expensive lenses, usually the longer prime telephoto models, like the 400mm F2.8 and beyond.

Many higher-end filter companies also offer an adaptor, where you might buy the screw-in ring for each lens, and then you simply plug the "filter holder" to that ring and use the one square/rectangular filter+holder for any lens you want.

Please note, that if you are trying to put a filter on wide-angle lenses (particularly 20mm and below) the circular filter ring may actually cut off the corners of your 16-35mm, in this case you either need to opt for a "slim profile" filter, or opt for a filter holder rig with sufficiently "low profile" construction. Really wide angle lenses (fish eye's and the like) often have convex glass front elements (the front of the lens). Because the lens sticks out so far, there might not be a nice way to attach any front-attached filters.

I hope this intro has de-mystified some of the jargon, there are whole sections of libraries dedicated to photography. I'm just trying to offer a condensed version of my most commonly received questions.

Have fun!

Ham.