How to choose the right lens

Choosing the right lens, or lenses, is obviously important when it comes to creating the photographs you love. So, which lens or lens combination is right for you?

This will depend upon the type of photography you do, and here are some questions to ask:

Should I use a prime lens or a zoom lens?
What is the best focal length, or focal length range?
How much can I afford to spend?
How many prime lenses do I need, or should I switch to a zoom lens?
What are the pros and cons for both types?

In addition, it's helpful to understand how a lens is described. For example, you might come across:

RF 100mm F2.8L MACRO IS USM
or
RF 24-240mm F4-6.3 IS USM

Which letters and numbers do you need to know (especially if you order lenses online)?

This podcast answers those questions and gives you some other things to consider.

It's time for another podcast...

Thank you for listening. Please remember to take a look at the website as I have a few things going on, including mini-workshops to help you with your photography: www.ge.photography

Or join the mailing list... and I'll tell you myself!

Transcript

>> Graham: 0:17

Hello again. In this podcast I thought I'd talk a little bit about lenses because I sometimes get asked about different types of lens and what is the best lens to use. So I want to talk about that. But I also want to dive in a little bit deeper and start talking about what the numbers mean. So, so if you've ever looked at ordering a lens or buying a lens, whether online or in a store, ah, you'll see that there are basically a bunch of numbers that you get with each lens and some of those numbers might be obvious, some of them less so. So what I want to do is just talk about that aspect of buying a lens as well. So the first thing I'm going to talk about is focal length. And focal length is essentially how much magnification a lens is going to give you. So if you use as a reference 50 millimeters. So a focal length of 50 millimeters on a 35 millimeter camera system, so the old film system or a full frame sensor, 50 millimeters gives you the same view that you would get using your naked eye. So basically there's zero magnification. It's kind of one to one, representation of what you would see with your eye as you go for a longer focal length. So let's say 100, 200, 300, whatever what you're doing, you're magnifying what you would see with the naked eye. So if you, if you like, think of it as using binoculars, it's the same effect you get grade of magnification. What changes also is the angle of view that you have. because if you think about it, as you zoom in on something, you see less and less of what's to either side or above and below that particular subject. So that's essentially what I mean by the angle of view that reduces as you go longer, ah, as your focal length gets longer and equally if you go the other way, if you go for a focal length shorter than 50 millimeters, you're basically demagnifying. So you're stepping back and stepping back so what you're seeing. Individual elements in that photograph will appear smaller than they do to the naked eye. But it means obviously you can get a broader scene in. So if you're doing landscape, photography for example, you will typically do that with a wide angle lens. And a wide angle is simply a shorter, focal length. But the wide angle refers to the angle of view that you would have. So wide angle lenses give you a wider angle of view than your normal, vision. So the 50 film, 50 millimeter lens as a reference. And then when you go the other way and there we're talking about telephoto lenses, we're zooming in so you're getting some level of magnification. So that's the first part of that. So, as I said, that's the first thing. And that I think is fairly straightforward. I think most people understand to some extent the focal length and what that gives you. And if you go on to certain manufacturer sites and Nikon are one of them, they used to do, I think they still do. And also Canon, I believe, used to do this. There is a page in there somewhere, where you can look at different lenses that will be in their lens area, but it will show you the difference if you look at one scene. So it will give you a kind of reference scene and then it shows you how that scene will change as you use different focal length lenses. So if you don't really understand what the focal length gives you, then something like that is very helpful. Just to make it very clear by demonstrating to you visually what the different lenses will deliver, in terms of magnification or that wide angle, how, how much you're going to, of that full scene. You're going to get into your photograph when you use a particular focal length. So that's the first thing. A couple of other things to think about though when you are choosing your lens. So again this will come back to the kind of photography you're doing as you get wider with your wide angle lens. So as the focal length gets shorter, so let's say you go from a 28 millimeter to a 14 millimeter, which is also referred to as a fisheye. what happens is the angle of view gets wider, but you'll begin to see more and more distortion not only on the edge of the frame, that's where it will start to show first. But if you have, let's say a row of fence posts and you shoot that with a very wide angle lens, you'll see that those fence posts are no longer straight, they're all curved to some extent or another. So what happens when you start going wider and wider with the angle of view you get shorter and shorter with your focal length, is that you begin to introduce more and more distortion into the image. And something like a 14 millimeter lens, which is regarded as a fisheye, is where things are very, very curved. So that becomes a different style of photography really in its own right, because of just the amount of distortion you get. So that's what happens as angle of view widens, you get more distortion in the image. if you go the other way with telephotos, what telephoto lenses will do is they will begin to compress perspectives. What I mean by that is if you imagine you're watching, some people running a race on a, let's say, 100, meter track, if you are standing sort of past the finish line, looking back down that 100 meter track at the athletes, if there's a big gap between them, it will become less obvious as you lengthen your, focal length. So if you're at shooting them, say, a 100 millimeter focal length, you might see that one person is clearly some distance behind the other because they're a bit smaller in the frame in the image, they look a bit smaller as you go longer. So as you go to 200 to 400 to 600, that person in the background gets magnified more relative to the person in the foreground. So they look like they're really close to one another. And you may have seen this if you watch athletics on television, when they shoot down a straight, it might look like one. Let's say the second person who's second is very close to the person who's first. But when you look at that same part of the race from the side, you can actually see there's quite a big difference between the, where they are. So that's what I mean by compressing perspective. It gets rid of that sense of depth. It essentially flattens the image so that something that can be quite a long way in the background looks much closer to your subject than it would appear in real life. So again, at 50 millimeters the way your eye would normally see it. So I'm hoping that makes a bit of sense. Okay, so that briefly is focal length. It's simply how much. So it's influencing two things. What's the angle of view and how much magnification are you adding to what you would see with your naked eye. Now, the next thing that coupled very closely with this is aperture. And this will be on the spec of the lens as well. So the aperture is simply the opening in the lens that allows light through. And basically, the, bigger the aperture, the more light you get. And aperture also controls depth of field. So what I mean by that is what's in focus. So how much of what's going on behind your subject and in front of your subject is in focus? And that area that's in focus is referred to as depth of field. And, and you control that with aperture. So if you want a very narrow depth of field, let's say you're taking, a portrait of somebody and you focused on their eye and you want the tip of their nose to be in focus, maybe their ear to be in focus, but everything beyond that out of focus, then you would control that depth of field using the aperture. So that's two functions. That aperture provides how much light and then what your depth of field is, and the way that's achieved in lenses is that there are aperture blades within the lens. And if you rotate, if it's an old lens where you've got a rotating, sort of, bezel on the, the outside of the lens, you can see those blades in operation. If you look down the lens with it off the camera, you can clearly see where, you've got a big aperture when you've got a small one. And that's controlled by these blades, or it might be controlled by software in the camera. So that's all good. Now that's where we get F numbers coming in. So you'll not. They're normally expressed. And F shows you how wide the aperture is. And you'll normally see a number. And it could be something like F 2.8. So that would be the aperture number. Now, the way to think of this is that F2.8 is actually quite a big aperture, quite a big hole. Large amount of light might be the maximum for that particular lens and the narrowest depth of field. Alternatively, you might have a number like F22, which is a very small aperture. So very little light coming in, but very big depth of field. Now this can seem confusing. So small number equals a big aperture, and a big number, small aperture. But the way to remember this is that that number, that 2.8 or that 22 is actually a fraction. So in reality what you're looking at is 1.2.8. So 1 over 2.8, one of the maximum diameter of the lens. So you've got 1 2, 1 8, which is obviously a large fraction. And 1 over 22 to 1 22nd of the, maximum, aperture is obviously quite a small number. Or it might be 1/16 of the maximum aperture or 1/8 of the maximum aperture. So that's where those numbers, they can be a little bit counterintuitive, but that's where they come from. So it is actually a fraction. And then it begins to make more sense that, yeah, 2.8 is you know, it's just under well, 2.8 of the maximum diameter. So that's quite a large amount of the of the maximum diameter that that is available there. And 1 16, say is M, clearly much smaller. So that's how to remember how those individual numbers correlate to physically how much, how wide that hole is. Now the way that this gets expressed in a lens, I'm going to talk through this because this is I'm going to use Canon just as an example. So when you start looking at lenses, you might see something like RF 100 millimeter F2.8L macro is USM. So that's a bit of a mouthful, but that's not unusual, as the kind of nomenclature you use that is used on lenses by anybody. And it's actually quite a standard format that different manufacturers use. And that's both camera manufacturers and independent lens manufacturers. So let's just break it down. So the first thing I mentioned was rf. So the letter R, the letter F and what that refers to is that the mount that that lens is designed for. So if you're not familiar, it's probably a good idea to get familiar with the mount that your camera body is using because they will vary from brand to brand. You'll have a Canon mount, you'll have Nikon mount. But even within the different manufacturers they have different mounts available because they're designed to take different families of lenses, which is probably different generations of lenses. So RF is the newer lens mount for Canon that's designed for mirrorless cameras. So that's where you would find that. Or it might be an MD mount or something like that. But that's what those first letters are. So you'll start with the mount. So we've got RF and then we've got a number 100 millimeters. And that's your focal length. So that's pretty straightforward. It's a 100 millimeter focal length. The next thing you get is F2.8 and the F AH2.8 is the maximum aperture that you will get on that lens. So that's what's normally specified because the maximum aperture is in many ways the more important thing to know than the minimum aperture, which might be F22, for example. So F2.8 is important to know. And then in this case we've got, so we've got RF 100 millimeter, so that's RF 100mm F2.8L.L in this instance simply refers to their professional series of lenses. And this is the way Canon differentiate between their standard lenses and their professional lenses. it's then followed by the word macro. A macro is simply ah, a lens that's designed for very close focusing. And I'm going to talk about macro photography in a few minutes. Then the letters is and in Canon that stands for image stabilization. So it means that this particular lens has some sort of image stabilizing built in. And that's just to remove the effects of camera shape. Particularly if you're doing a lot of photography in low light environments where you might have to shoot with a very low shutter speed. So if you remember, as a general guide, the slowest shutter speed you can use when you're hand holding your camera is one over the focal length. So if I've got say this 100 millimeter focal length lens, the minimum shutter speed for me to handhold that lens is 1 over 100. So that's 100th of a second shutter speed. Anything slower than that I'm likely to get camera shake. Anything faster than that I should be okay. But these are guidelines only because it depends on you, how steady you are, all sorts of other factors. So that's what is stands for. And the other advantage of image stabilization if you have it on your lens is that it does mean that you can take longer exposures then if to some extent similar exposures to if you had a tripod. So those situations where you can't take a tripod for whatever reason, having image stabilization is definitely a bonus. And then this particular lens has USM M on the, the final letters on it and that stands for ultrasonic motor. So that, that basically means it's a quiet focusing system that they use on that particular lens. So just going back over that lens name again, Excuse me. So that's RF 100mm, F2.8L. Macro M is USM. So just to review, the RF is the mount type. So you do need to know that if you're going to buy lenses for your camera. The focal length, well you'll need to know what focal length that you want to use. The maximum aperture generally get, have that number as small as possible. So 2.8 is fine. If you can get 2 that's better. the L. So F2.8 L L just means it's the professional lens for Canon macro close focus and is for image stabilization. And USM is this particular quiet motor system, these focusing. So that's what that all means on a Canon. So depending on the lens you're looking at, the nomenclature might be slightly different, but it will be about that. So it will be the mount type, the focal length, maximum aperture, and then particular characteristics of that lens. that will generally relate to how that lens manufacturer defines them. Okay, so that is on what we call the prime lens. So prime lens is simply a lens that only has a single focal length. Now your alternative is to use a zoom lens. So really the advantage of a prime lens is often, you'll get a much wider aperture than you will with a zoom lens. And often in terms of size and weight, they're smaller and lighter than the equivalent zoom lens. Because if you think of it, the zoom lens has to have multiple elements in it to cover the different focal lengths. So that there's basically more, mechanical system in there, if you like, to achieve that, ability to change focal length. Whereas a prime lens doesn't have that. It's simply one focal length. And that's how it sticks. Obviously, the advantage of a zoom lens is it's versatile. And, it means with a single lens you've got quite a range of different magnifications you can use, when you're putting your photograph together. So I've just gone through the lens name for a, prime lens. And what I will say actually is just the subject of fast lenses. You might have heard the phrase fast lens. It basically means that the aperture is very wide. So that number. So let's say 2.8 or 2 or even smaller than that, those would start falling into the category of a fast lens. And the reason it's fast lens is that that big aperture lets in a lot more light. So it means that you can use a much faster shutter speed for a given lighting situation than you can do with a lens that isn't able to open up as wide. So let's say it has, a maximum aperture of 5.6. So that hole is physically smaller. So it's physically reducing the amount of light that can come in. So that means you need to really compensate with a slower shutter speed. So that would be a slower. A, slower lens. So again, hope that's making sense. So I've mentioned the zoom lens. So going back to the, specifications on a zoom lens, how does that differ from the prime. Well, you'll see a few more numbers there. So here's another example. And this is another Canon lens. So the Number here is RF24, 240 millimeters F4.6.3 is USM M. So what does that mean. Well, hopefully you've recognized that the RF is the mount type again. So that's the same but instead of a single number, against the millimeter, so the focal length, we've actually got a range it's 24 to 240 millimeters. So it's quite a long length. in fact 10 times used to be known as super zooms. I think they still are. But anyway, it's a 10 times magnification. So you go from that 24 sort of a wide angle through to 240, which is quite a reasonable telephoto. So the magnification, range and difference for that lens and the change in angle you can see is quite marked 24 to 240 millimeters. Then I've got the numbers F4 to 6.3. So that means the maximum aperture for the two focal lengths, one end of the focal length range and the other are the numbers that are put there. So at 24 millimeters that you take, so that's the first number in the focal length. You then look at that first number for the aperture and it's f4. In other words, one quarter of the aperture. so that's at 24 millimeters. As you zoom in that number the fraction will get smaller so that number reduces. So it's actually 6.3 or 1 over 6.3 at 240 millimeters. So it means that as you zoom in your lens gets slower. It's another way of thinking about it. So when you're thinking about lens, the lens that you want to use, you do need to start thinking about how much light you want to have. Because if you're in a situation where you're shooting in low light or it might be, let's say dawn and dusk, if you're doing wildlife, an aperture of 6.3 might be pushing you a little bit. And that means, if you remember your exposure triangle, it means you have to compensate with the ISO, which means you risk grainy photos and all that stuff. So this is when understanding the lens nomenclature comes. Pardon me, it comes in very handy. And then at the end of that I had is again for image stabilizing and usm, which is the quiet motor. So that hopefully has given you a little bit of insight into how the number systems work when you're specifying a lens. And if you look at any of the lens manufacturers, any of the camera, manufacturers, you'll see that type of nomenclature and, and maybe we'll explain what it means. But the key things that you need to know are your mount, the focal length you want and what sort of aperture you're likely to have available. And if it's a zoom lens at both ends of the zoom range, image stabilizing does tend to make the lens a little bit more expensive. But a lot of the certainly pro lenses will tend to have it anyway and it can be quite useful. But again you've got to think about the sort of photography you're doing and is image stabilization like this be useful? So if you're pushing how the sort of shutter speed you're using when you're hand holding, if you're getting below that one over focal length guide, then you definitely want to be thinking about image stabilizing. If you can't use a tripod. So for example, when I'm photographing humpback whales, I'm on a boat, that's moving, the whales are moving, I don't know where they're coming up. So I'm having to come up fast. It's impossible in my opinion to do that effectively using a tripod. So image stabilizing is very helpful to me in that situation. So it's a very useful thing to have on my lens. And you may even find with some cameras, first of all you might see a switch for image stabilizing on and off. because that can drain your battery or slow down your maximum burst rate and all these kind of things, you need to just see how it impacts your system or it might have different features. So there might be a choice of is mode depending on how that particular lens is set up. So just some things to be conscious of. So having said all of that, what is relevant to you and the kind of photography you're doing? So if you're doing more general photography, so you're not. And what I mean by that is it's maybe a range of different subjects, but normally you're in a situation that's fairly well lit, you're not kind of pushing the camera particularly in terms of getting correct exposure. And that's obviously what we're going for here, correct exposure and correct focus. Then something that gives you the kind of apertures I've been talking about. So the F4 to 6 point three might be fine as a sort of general purpose lens. If however you need to be photographing in low light situations and in situations where you don't have the option to use a tripod. And I've given you an example of one of those, then ideally you want to have a faster lens because it just means that you can, maybe freeze the action. So if you're photographing wildlife at night that's moving, obviously the better the shutter speed, the faster the shutter speed, the better. if you're photographing sport, again, with sport photography, you often want two things, actually. You want a fast shutter speed and you want a fairly narrow depth of field. Because if you've got somebody, say, kicking, a football and you want to be focused on them, maybe it's a full body shot, but you want the background to be a little bit out of focus, that, at the very least, so that the person who's looking at that photo, their eye is drawn to the subject and not distracted by all the stuff that's going on in the background. You can imagine, that you might have hoardings with adverts on, people running about all this kind of stuff that you get at that kind of event. So, equally motorsport, something like that. Again, you might want to get quite a fast shutter speed. so again, something like thousandths of a second to freeze the action, or hundreds of seconds if you want some degree of movement in your image. And what that shutter speed finally ends up being will depend on situations such as the aperture on the lens. So these are reasons why this is relevant and at least why it's useful to know. But as you go for bigger apertures, what happens is the lens physically gets bigger, particularly if you're looking at a zoom lens. So a zoom lens will always have a lower performance than a prime lens. But if you need to have several focal lengths in order to get the degree of magnification you want. So for me and wildlife, I often shoot at 400mm, but if I was to photograph birds, I really want 600 mil. Now I, can get a prime, 600mm lens, which will have a very good aperture. And that will allow me to really shoot some cracking photographs, even in low light. But, I don't want to be carrying around four or five different lenses. So this is where primes sort of have their downfall. If you might need a range of lenses. So if that's the case, my recommendation is you go for a zoom lens, but really do look at the apertures and get the best you can. Another thing to bear in mind is if you start using lens doublers, so these are, ah, little attachments that go on the mount of the lens and then into the body of the camera and they magnify the focal length of your lens, it might be by a factor of two or some other factor might be 1.6 or something like that. But remember, when you put one of those things in, you usually reduce the effective maximum aperture of the lens as well. So you're actually reducing even further the amount of light that you can that will be hitting the sensor or the film. So if you're thinking about using one of those, I would suggest caution. And in my experience they're probably not worth it unless you are able to live with these very small apertures that result from using something like that. Okay, so I think that covers primarily what I wanted to cover with this. So just to review, I guess what, what are the key things here? The two things to really think about when you're buying a lens are, focal length, because that's the degree of magnification that you have on your subject compared to how you normally see them and the angle of view that you have. And there are two. And of course you've got your aperture, which is how much light that that lens will let into the camera and onto the sensor. So if you're going to be working in low light situations, you really want that aperture to be as physically large as possible. And remember, the F number is a fraction. So F, two is basically one over two of the basically half the aperture. Maximum aperture, if it's f5 point, 6, it's 1 over 5.6. So it's around a fifth of the maximum aperture. So these give you an idea. So you really want to get that number to be as close to one as you can is probably the best way to think of that because that will give you lots of light. And the more light you have coming into the camera, then the more options you've got on shutter speed, depth of field and the more creative control you've got. If you're really struggling with a smaller aperture, what's likely to happen is you're gonna have to push your ISO up to compensate, which means you're gonna get grainy or you have the risk of grainy images. And you're going to have less creative control, you're going to have fewer options. However, it also comes down to how you're using these lenses. So if you're going to have if you've got the money and you're able to practically carry a lot of different lenses around with you and you've got time to change them, then great. Prime lens is Perfect. But for most of us we need to use telephoto lenses because we don't have the money or the muscles to carry around a lot of different lenses. And maybe we need to react fairly quickly to a situation in order to get the photograph. So in that case the zoom lens is the way to go. And that's where just remember on the specification for the zoom lens you're going to see two F numbers. One is at the wide end so the shortest focal length and the second one is at the longest focal lengths so the narrowest so the maximum magnification. And probably if you're anything like me, the number that you want to be paying most attention to is the aperture size at maximum magnification. Because if you're doing, certainly if you're doing wildlife and to a similar degree if you're doing a lot of sports photography, you're probably going to be zoomed in to some degree to get that photograph. So you want to have as many options as possible when it comes to selecting your shutter speed. beyond that, what are you doing? So if you're doing what if you're doing mostly landscapes, then wide angle zoom or maybe a 28mm prime, something like that, or 24. If you're not using full frame you can go to a shorter focal length. That's subject for another talk. because a cropped frame, it simply is effectively zooming you in a little bit anyway because it's not, not the full, physically not the full size of a 35 mil piece of film, which is what a full frame sensor will give you effectively the same size. if you're looking at APS C or a cropped sensor of any sort, then you're using a smaller physical area to capture the image which is the same as zooming in a little bit, compared to 35mil. So hopefully that hasn't baffled you. but yeah, so landscapes probably the aperture is less important. Action stuff. Definitely it is important. macro is good if you want to do close up photography and particularly if you're photographing things like insects or anything where you're really close to the lens because then that lens is able to magnify quite often what you're seeing so you'll get a really good image. So macro photography is another style of photography which has well really its own demands. But if you are possibly thinking of macro or even if you might want to focus quite close to your lens, then I definitely recommend getting a lens with a macro that is macro capable. The wide angle zoom, lens that I use is a macro lens and I find that very useful. I don't shoot macro very often, but it is useful to have that, that ability, that capability there when I need it. Image stabilizing, yeah, look, if you, again it depends what you're shooting, if you're going to be in bright daylight all the time or if you've got the option to use a tripod, and that none of that's a, problem. So if you're doing studio photography, then image stabilizing isn't really relevant. I would suggest, however, if you are out in the open and you're in a situation where you can't use a tripod or a tripod isn't practical, or you might have to react very quickly, then I would suggest image stabilizing is worthwhile. And with all of these things, if you're looking at a lens and you're not familiar with it and you don't know anyone who's using one, just have a look online and look at just these reviews of different lenses and how different people have found them. If I'm reviewing a lens, if I'm doing that kind of research, I'll generally look for two or three reviews and just look for consistency in those reviews. And sometimes I'll look for a review by the same person on a lens that I'm using because then I've got my experience of using that lens and I can compare it to what they're saying. So there you go. that's pretty much it. I hope that's demystified some of the really what lenses are all about and the things you need to know about lenses and, and more importantly the way a lens is specified because I know if you present with a bunch of letters and numbers and they don't mean anything, that can be a bit confusing. So hopefully that's a bit clearer for you and enjoy photography. So I will speak to you in the next podcast. Bye for now. Well, I hope you enjoyed that. Now, I just want to say thank you for tuning in and joining me in the, wildlife and Adventure Photography podcast. If you have enjoyed today's episode, please give me a, like a subscribe, maybe tell your friends, and by all means leave a comment. And if there is a subject you would like me to cover in the future, please let me know and I'll be very happy to do my best. So thanks again. For joining, me. And I look forward to seeing you again. Next podcast. Bye for now.