07. Camera Lenses and Focal Length
Lenses play an important part in photography — some may even argue that they’re equally, if not more important, than the choice of camera.
As we touched on in chapter one of this course, different lenses produce different results depending on the configurations within the lens barrel. These configurations determine the magnification and angle of view and allow us to create different effects, depending on the lens.
How camera lenses work
Lenses focus the light onto the recording medium, which allows an image to be recorded. As you’ll see from the illustration of a DSLR camera below, light enters the lens and passes through the front element (2) before reaching several lens elements (3, 5 & 6). These elements serve to direct the light to a single focal point so that it can accurately be recorded by the sensor (9) once the mirror (7) flips up (which is triggered by pressing the shutter button). Mirrorless cameras work the same way, but do not have the mirror or prism.
Lens quality is determined by factors such as its maximum light gathering ability (f-stop number written on the lens), its resolving power (how sharp the images produced are), the colors it can focus (quality of the glass), the contrast it achieves (also the quality of the glass) and the type of material the lens is made from - all part of lens design.
What the numbers on a lens mean
Now that you understand the basics of how a lens works, you might be wondering what all the numbers (and letters) on a lens mean. Typically, lenses are written in a format like this: Canon EF 24-70mm f/2.8L II USM Lens or Nikon AF-S 50mm f/1.8G. Each of these numbers and letters tell you essential information such as focal length, maximum aperture, lens version and focusing motor. Other features specified can include stabilisation, filter diameter and focusing distances.
When looking to buy a lens, it’s important to consider each of these points as these will, in part, tell you about the characteristics and capabilities of the lens.
Types of camera lenses
When it comes to lenses, there’s no shortage of options. Quite simply though, lenses can be categorised into two main groups — prime or zoom lenses, both of which come in different focal lengths.
Prime vs zoom lenses
Prime (or fixed) lenses feature a fixed focal length. Available in a range of focal lengths, prime lenses are known for delivering high quality images. They also generally offer much wider apertures compared to zoom lenses.
Zoom lenses, on the other hand, provide a variety of focal lengths in one lens. This makes them very versatile and also reduces the need for multiple lenses.
Focal length
The focal length is one of the defining characteristics of a lens as this determines the angle of view as well as magnification. How focal length is determined requires an understanding of the physics of light and concave or convex lenses, but very simply, when light enters a lens, glass elements within the lens serve to converge the light to a single point, known as ‘focus’. The distance between this point and the centre of the lens is the focal length.
The focal length is usually indicated both on the side of the lens barrel and sometimes on the front of the lens, along with the lens diameter. Ranging anywhere from 8mm to 2000mm, there is a wide variety of focal lengths for photographers to choose from, each of which are better suited to different genres of photography. Lenses with shorter focal lengths provide a much wider angle of view and are therefore better suited to landscapes than product photography as well as less magnification. The opposite is also true for longer focal lengths, which may be better suited to sport or wildlife photography than architectural photography. Lenses with shorter focal lengths also provide less magnification than those with larger focal lengths.
In addition to influencing the angle of view and magnification, focal length can also impact camera shake. Longer focal lengths are more susceptible to camera shake due to greater magnification — the tiniest movements become magnified and can result in blurred photos. Generally, I recommend shooting with a shutter speed equal to or greater than the focal length as this can help prevent this from happening.
Aperture
Although not specifically a type of lens, aperture is another important feature of lenses.
As you’ll already know from the previous chapters, aperture refers to the opening in the lens that controls how much light reaches the sensor. This is indicated in the format 1:2.8, for example, with the second set of numbers indicating the maximum aperture. Some lenses will feature two maximum apertures (shown as 1:4-5.6). What this means is that as you zoom, the aperture capability changes. So at the shortest focal length, you may be able to shoot at f4, but once you zoom to the longest focal length the widest aperture you’ll be able to shoot at will be f5.6. Generally lenses with wider apertures are favourable due to their increased light capturing capabilities.
There is also a category of lenses that feature a fixed aperture. Catadioptric, or mirror lenses, which used to be fairly common, usually feature a longer focal length, such as 500mm at a fixed aperture of f6.3. Most telescopes are catadioptric.
An example of aperture blades that are partially closed to approximately f8. © Karl Taylor
Pinhole cameras
Throughout this course, we’ve referred to six essentials of photography. However, at this point, it is important to mention that this could in fact be five. This is because images can be recorded without a lens. These cameras are known as pinhole cameras (or camera obscuras). However, recording an image without a lens is far more complex and doesn’t afford the photographer the same creative freedom as when using lenses. Essentially, without a lens, you're shooting at a very small fixed aperture. Lenses, due to the variations in magnification, allow us to shoot many different objects, which simply wouldn’t be possible with a camera obscura. For more information about this, refer to the complimentary e-book.
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Comments
Hi Karl, I would like some advice from you. I already have a prime 100mm macro lens which is a wonderful lens. I wanted to purchase a new one to take photos of larger products, do shooting for restaurants (not just details or food), and start portrait photography (business, beauty, families…) so I bought a 24-70 2.8 lens because I heard it’s very versatile, but I’m not sure I made the right choice… Do you think I should return it and buy a prime lens? If so, which one? Thank you!
Hi, the 24-70 is not suited to portraits, it is suited to more general scenes. For interior wide angle shots and landscapes I’d be looking at a 16-35 and for dedicated portraits then your 100mm macro is good but also a fixed 85mm 1.4 would be great. Another versatile lens for portrait and distant work is the 70-200 f2.8. I’ve never really liked the 24-70 as for me it’s neither wide enough or close enough if you know what I mean. My lenses for a 35mm FF camera are, 90mm macro, 85mm (portrait) 16-35 wideangle/landscapes/interiors, 70-200 f2.8 portraits/distant subjects, 2x convertor for the 70-200.
Hello Mr Taylor. Please for me using APS-C Canon SL2 Camera. What lenses would you recommend. Though I am planning to buy sigma 18-35 f1.8 but which is best for photography on APS-C type camera
Hi, I think you should consider a fixed focal length lens around 70 or 80mm in f1.4 so that you have a lens that is good for portraits. The 18-35 will be a medium wideangle which is better for street and landscapes.
Hi Karl. For product & food photography you mention that you use 100mm focal lenth often. But I have a APS-Crop Sensor Canon body. That said, for closer product shots, should I look at a 60mm macro lens to bring me closer to the 100mm after the math for the crop sensor?
Many Thanks!
Hi, yes a 60mm macro would be a good option in that case.
Excellent. Thank you so much! Really enjoying all of your courses!
Hello Karl! I’m excited to join this program a ton. I do have a question here, I’ve heard lots of different opinions for the best lenses for product photography, and I’m wondering what do you think is best for that. I’ve recently ordered the 85mm/ f/2.8 G OSS macro lens for my Sony camera.
Hi Mahmoud, thanks for joining us. If you check our Introduction to Product Photography section you will find good advice there.
My question is: a 28mm lens is not going to give your picture/video the same look as a, say 135mm lens even if you walk up to the subject because the wider lens(es) have a more curved shape and perspective than the more telephoto lenses – is my understanding correct?
Hi, yes perspective changes dramatically depending on focal length and therefore the choice of lens is important to the style of story telling.
In this case then I suppose a 35mm lens does NOT give the same look on a cropped sensor than a 50mm lens on a full frame, even though in theory they both have equivalent focal length (the 35mm on cropped sensor will give a more distorted picture than the 50mm on full sensor?)
Hi, yes that’s exactly correct because one would be a cropped picture and the other would not and then if you moved to make the subject the same size then perspective has changed.
Hi Karl – what kind of Flash are you using?
Hi, in this lesson I think it was a 580 EX Canon Speedlite.
Hello Mr Taylor i am getting ready to purchase a dedicated landscape lens. i am currently looking at the Canon 24-70 and a 24-105, (both L lens) from what I have seen the 24-70 seems to be the standard, so what is the main difference besides aperture and focal lengths and what would you recommend ? thank you
Hi, if you are looking at a dedicated landscape lens then why 24-70 or 24-105? I would be looking at 16-35 for Landscape. Please watch the rest of this course.
Hi Karl,
I’m new to photography and have already learned so much from you, so thank you! I have just purchased a Canon R5 with a 100mm RF 2.8 Macro IS USM lens. My passion is product photography.
I want to photograph some general scenes (like some books on old wood with a bottle of whisky etc.) and one or two portraits, so I was thinking more generally.
I asked my local photographic store, and they don’t recommend an 85mm lens and should go with a 50mm. They say I’m already in that area with a 100mm, so why have two lenses with a similar focal distance/range?
I note you use 50mm and 85mm on product photography. My problem is with the 100mm macro lens, I need to be quite far away from the subject or scene, and sometimes that’s impossible for me. I’m looking and buying a Canon RF 85mm F1.2L USM DS lens. What are your thoughts on this, please?
Many thanks
Nick
Hi Nick, good choice on camera and lens, you will see Anna and I using the 100 2.8 on lots of food shots. The 85mm isn’t really good for product work as it’s designed as a portrait lens but it is a better for portrait than the 100mm. For product work your 100mm is perfect for smaller products but yes you might want to consider the 50mm for larger sets but check what its closest focusing distance is. The 50 will also be a good choice for full length fashion, especially on location.
Hi Karl, thank you for your reply, especially on a Saturday evening. It’s greatly appreciated! You’ve been a great help and enabled me to make a much more informed choice. Many thanks, take care, Nick.
Hello Karl. I was just watching the video about lenses and I have a question on the 50 mm. I have the 50 but not the prime one. Will it give me the same results as the prime? What’s the difference between the two?
Hi, no it won’t give the same ‘look’ as the prime. It will give the same field of view but the appearance of the image may look different because of the characteristics of the glass and elements that make the lens as well as the aperture blades and the maximum aperture size.
Dear Mr. Taylor,
I am relatively new to photography and just discovred your educational program, which is amazing! I finally understand the relation between aperture, shutter speed and the balance to get the correct exposure. I cannot believe how easy and logical it is :))) But this only if you have someone who knows how to explain it. I enroled in the hope that I’ll be able to take good photos of the jewelry I make. I am not looking to become a professional photographer, but would really love to take some good photos of my products. I have an old Nikon DSLR D3000 with a 18-55 mm lens, which is obviously not suited for this kind of job. What lenses would you recommend? Being on a tight budget I was wondering if a 50mm prime do the job? And also if extension tubes would help in any way.
Thank you in advance!
Johanna
Hi Johanna, thank you and i’m very happy to hear you are enjoying our classes. This is the section you should watch it covers information relating to product photography and lenses –
https://visualeducation.com/section/getting-started-in-product-photography/ you will also find other classes in the main ‘product’ section relating to jewellery.
Hi Karl,
What are good lenses for group or family photography? Also, lenses that are good for group portraits as well?
Thank you
Hi Candace, this depends on a couple of things, the first is how much room do you have to move back. If it’s outdoors or in a big studio then I’d still go with around 80-100mm or 50mm at the widest – that’s based on full frame 35mm cameras.
Hey Karl, would I get the same result with 85mm prime lens and 70-200mm lens (shot at 85mm focal length)? If you say yes, then why 85mm prime lens is also called Portrait lens, and is also a darling for many fashion photographers
Hi, because the 85mm prime has less elements and is optimised for that focal length only in terms of distortion, aesthetic and usually has a larger maximum aperture for shallower depth of field or lower light work when needed.
Hi Karl!
I just noticed that in your Camera Lenses graphic (above) you listed Short Telephoto as from 85-135mm and angle of view from 28°-12°. I believe you meant 28°-18° (assuming your next category, telephoto is correct from 135-200mm and 18°-12°). I only noticed because I thought the numeric info was worth remembering and was writing it down in my notes!
I joined KTE recently and have really enjoyed your recent live shows! I am really glad that I joined!
Hi Don, thanks for the info I will pass that on to our video editor to check and clarify. Glad you are enjoying the shows and content! Cheers Karl.
Hello Mr. Karl I am just starting out and have a couple of questions I use Nikon and would like to know what essential lens are needed for portrait shots and how would you capture someone in motion like doing something like painting?
Hi, for portrait work I’d recommend something around 85mm and with a maximum aperture of f1.4. (this is for a full frame 35mm format camera as you didn’t say which Nikon you have).
You’re a braver man than me Mr T.
I don’t think I’d be lining up all my expensive lens on a sea wall 🙂
Excellent content throughout your website. I’m very happy to have renewed my subscription.
Thanks Paul.
Your Introduction to Photography videos, in combination with E-books is in my opinion an excellent educational platform with I visited more than ones. The Introduction to Photography videos prepares the student for the live streaming classes that deal with the subtle differences of the photographic mysteries. I sympathies with the students that don’t experiment with the equipment they have on hand, to emulate the techniques you demonstrate in the live classes.
Thank-you, Maestro Karl Taylor
Gerardo D. Duran Jr. a.k.a. PhotosGerardoDD
“Using technology to cope with Dyslexia,
and find my Dyslexic Advantage.”
Presently I’m a widower, in my 80th decade of life and retirement active, a practicing photography enthusiast.
Thank you very much for your comments Gerardo.
Karl, I noticed you used a flash attached to your camera in this outdoor shoot? can I just use this type of camera flash for outdoor shoots instead of buying the more powerful outdoor flashes such as the AD200 AD400 or AD600. Thank you.
Hi, you can but they are not as versatile. If you do though make sure you find a way to get it off camera.
Hi Karl. What lens would you buy to take very close-up portraits of faces, that accentuate wrinkles, lines and are often seen in print journalism? I have a Nikon D3100 DSLR but am on a tight budget. I currently have a kit lens 18-55mm f5.6 and a n 18-70mm f3.5 lens, which is again an older kit lens.
Hi Tim I’d go for a portrait lens such as an 85mm focal length.
Hi, I’m thinking about buying a camera+lenses, which one would you recommend for portrait photography, Nikon D5600 + 18-105 AF-S VR or Nikon D5600 + AF-P DX 18-55 VR + AF-P DX 70-300 VR. The price of the second set doesn’t differ that much, but I would like to hear yor opinion. Thank You.
Hi Krzysztof, I’m very sorry but I can’t really offer any advice in areas like this as I don’t know these camera models well as I’ve not used them. There is only one rule I’d stick to, Full Frame sensor (medium format even better) 18mp minimum. Good quality lenses.
Karl,
You dispensed with the fill in flash for the tele photo side lit shots? Yor backlit shots were TTL flash? What focal length do you find gives the natural portrait on a tele-zoom say on a 28 – 300mm lens?I`m thing the manufacturer would try to limit extortion on 85mm length on these.
My first fill in flash shots on natural side lit shots the highlights overexposed as the speckles of light were dispersed unevenly over the face (light between tree leaves). The shadows were just about right. Again it highlighted the learning curve we go through. Needed to reposition the model or dispense with flash but I wanted some eye sparkle. 🙂
I love it how you can keep the language simple, introduce new terms and concepts clearly! Really enjoying the series
Thank you Tim, glad you are enjoying our platform!
Hi Karl,
I´m currently using an Sony a7 II with a Sony Macro 90mm (for portraits and macros) and a Rokinon 14mm wide angle for landscape, any recommendation for a new lens, so I can shoot a different style in my photography?
Thanks you
Hi Gustavo, well you have super-wide angle and portrait focal lengths covered. Really you’d be looking at 28-40mm wide-angle as a less distorted wide-angle option and maybe a telephoto in the 200+ range for the long shots or compression of the perspective.
Hey Karl, im currently using the Nikon D3200 and switching off between 35mm lens and a 70-200 zoom lens. I have been debating picking up a new camera or maybe saving up some money and buying into some nicer lenses. I feel like i have kind of hit a wall with using my D3200 but i keep hearing from every forum i read or person i talk to that its better to stick with my body and get some nicer lenses. Any thoughts? Thanks in advance.
I’d agree the lenses are more important in giving you more versatility.
Thank you Karl! That was kind of my thought too. It’s most likely a better quality glass that comes with the lens and there is this other argument people have mentioned.
By using a full frame lens on the crop body you will be effectively shooting through the center sweetspot of the lens which reduces vigneting and gives you a sharper image.
Hi Karl,
I have a question! hopefully you can help me out. I have a crop sensor camera Nikon d7100 which normally uses dx crop lenses but can also use fx full frame lenses.
i want to buy a new lens which is full frame because in the future I want to get a full frame camera body also.
will a picture be sharper, less sharp or is there no difference in using a full frame lens on a crop sensor body? Perhaps any other advantage or disadvantages?
I have tried finding the answer all over the internet but I have not managed to find a satisfying answer. A lot of people have an argument for either side of the debate.
Hi Jacques, there will be no difference in image quality at all, in fact you may find the full frame lenses sharper. The only difference is the size of the image circle which will be bigger to accommodate a full frame sensor.
Hi Karl what can I use my 50mm lens for?
Hi Ross, lots in fact it is a great all round lens. It can be used for portraits, even landscapes and with a simple extension tube it makes a good macro alternative.