Things to Know Before Buying a Lens

If you’re just starting out photography and bought your first DSLR, it’s very likely that you got it with the kit lens. Different camera bodies come with different kit lenses. Higher end bodies usually come with pro grade lenses whereas entry to mid level bodies come with regular lenses. For instance, the Canon 5D Mark III (Canon’s current flagship camera) comes with the EF 24-105mm f/4.0 L IS USM which is an excellent lens. Mid level cameras like the Canon 60D, 70D, or 7D usually come with either the EF-S 18-135mm f/3.5-5.6 IS STM or the EF-S 18-135mm f/3.5-5.6 IS UD or the EF-S 28-135mm f/3.5-5.6 IS USM. Finally the entry level cameras come with the EF-S 18-55mm f/3.5-5.6 IS STM. Although some of these lenses are excellent glasses, they do have their limitations. Of course, you can just buy the camera body and get any lens you want. I do strongly suggest that you play around with your kit lens before you consider getting a new piece of glass because the more experience you have, more easier for you to figure out what type of lens you want to buy next, rather than winging it.

Once you’re either fed up with your kit lens or pushed it to its limits and finally decided to get a new lens, you need to be able to make the choice. What I’m trying to do here is to suggest several things you could do, in order to make a smart choice. Even though I explained a bit about lenses, how they work, and some lens lingo, I didn’t really say what to look for when you’re buying a lens. There are several questions that you need to ask yourself before buying a lens.

What kind of a photographer are you?

Are you the type of person who enjoys taking beautiful sceneries, cityscapes, seascapes etc.? Then you’re looking for a lens with a focal length below 35mm for landscape/architecture photography. If all you take are portraits, you are going to need something in the range of 70-135mm. If you’re fascinated with tiny little details and would like to see a whole new world open up to you, macro lenses are your calling. If birds, wildlife, or sports interest you more than anything, you’re looking at telephoto lenses. This is why I said it’s important to play around with your kit lens for a while, until you figure out what type of a photographer you are. Otherwise you might just buy a lens out of the blue and might end up not getting its money’s worth.  Of course if you enjoy every type of photography (nothing wrong with that), get ready sell couple of body parts unless you’re loaded because it is going to cost you!

When and where will you be shooting most of the time?

Once you finally figure out what type of lens you need, you need to think of the occasions you’re going to use this lens. Is it going to be inside or outside? What kind of light available to you? Do you have the opportunity to use a tripod? If you’re going to be shooting under low light conditions most of the times, you should probably invest in a lens with a wider constant aperture like f/2.8 (or f/4.0 on super telephoto lenses) throughout the focal length range and has image stabilization. Unfortunately these lenses are expensive than the others. Usually wedding photographers and event photographers use these type of lenses. If you’re shooting landscapes etc and getting a wide angle lens, the maximum aperture is not a huge deal because you will be stopping down the lens to get a deeper depth of field anyway. Also, more often than not you can afford to use a tripod. You don’t really need image stabilization with wide lenses or when you’re using a tripod. In fact, it is advised to turn off the IS if you’re using a tripod because the lens will “look” for movement when there is none and create not as sharp images. Most lens manufacturers have couple of different versions of similar lenses. For instance, Canon has four 70-200mm lenses and all of them are pro grade lenses.

  • Canon EF 70-200mm f/4.0 L USM ($709)
  • Canon EF 70-200mm f/4.0 L IS USM ($1349)
  • Canon EF 70-200mm f/2.8 L USM ($1449)
  • Canon EF 70-200mm f/2.8 L IS II USM ($2499)

The prices are from Amazon at the time of writing this. So what makes the difference? The first two lenses can only open up to f/4.0 which means they won’t be ideal for low light situations. The second one has image stabilization. So it would be a little bit better than the first one. These two lenses however, weigh less significantly compared to the other two. Canon doesn’t make the third one anymore because they came up with the second version of that particular lens. That’s what “II” means on the fourth lens. But you can still find the third one if you really want. All four lenses are equipped with USM (Ultra Sonic Motor). This makes the lens focus faster and virtually silent. The bottom line is that these lenses have different functions, different dimensions, and different weights. Knowing what you really need can save you a lot of money because while it is very desirable to get the fourth one, you may not need it.

How much weight are you willing to lug around?

Let’s be honest here. There are so many people who will get a DSLR but rarely use it because it’s too heavy. Until you get used to your camera, it does seem a little heavy. However, the lens can make all the difference in the world. This is especially true for pro grade telephoto lenses because they are built like tanks. Pro grade telephoto lenses are made with metals unlike regular lenses which are made with high grade plastic. They have a lot of lens elements contributing to their weight too. These can easily weigh anywhere between 3.5-4.5 kilograms (~8.5-10 pounds). These lenses are near impossible to handhold due to their weight and magnified camera movement. So you’re going to have to carry a tripod – a tripod that is capable of holding these beasts. A $30 tripod won’t cut it. These tripods are heavy and expensive too. It may sound easy to carry around but remember that you will most likely to have this around your neck for couple of hours at least. Therefore, weight is a serious thing to consider before buying a lens. So if you think weight is not going to hinder you from taking photos, by all means get these lenses. They produce very high quality images. Although I’m going to be very sad if I see a $12,000 lens sitting on a shelf unused.

Do your homework

Reading reviews is a great way to find out about a particular lens. There are so many unbiased reviews out there and there is no reason why you shouldn’t read them. Not only the professional reviews, read reviews from consumers to see what they think about the lens. Most online stores, such as Amazon, has customer reviews. They are usually very helpful. If you want to justify buying this lens, go to flickr and search for the lens you have in mind. This will bring up pictures taken using that particular lens. Make sure it’s the correct lens because sometimes flickr tags can be misleading. You will either inspired by the results or look for another lens. You’re about to spend your hard earned money and lenses are not cheap. So it’s important to be well-informed.

Try it out before you buy it

There are so many services/companies that rent out lenses for a reasonable price. Take your potential choice on a “date”. See how you like it. All the reviews can be positive but only you can decide if it’s the right choice for you because you might just find something annoying about the lens. Renting out lenses is a great way to learn a lot about lenses. This is also very useful if you’re a portrait photographer but you need to get that one landscape shot or similar situations. It’s obvious that you don’t want to spend couple hundred dollars on a wide angle lens if you are not going to use it often. Renting a lens is the smart choice here (or borrowing it from a friend).

General purpose lenses

This may be the solution for those who want a “do it all” lens or for those who are too lazy to change their lenses. These lenses have a big focal length range, from wide angle to telephoto. If it sounds too good to be true, it’s because there is a down side too. The downside is that these lenses sacrifice a little bit of optical quality for convenience. Of course these lenses come in several levels too. So if you buy a pro grade general purpose lens, the optical quality would be much better than a regular general purpose lens. But if you want to do a specialized type of photography like macro or fish eye, general purpose lenses won’t cut it. You wouldn’t go to a gynecologist for a brain surgery, would you? Lenses are kind of like doctors in a sense. If you want a fantastic job done, a specialized lens is the way to go. Others may or may not screw you over, although not to the same level a doctor would.

There are some lenses that can do multiple jobs. I think it would be fair to call them “multi purpose lenses” rather than general purpose lenses. The 100mm f/2.8 macro lens for instance makes an excellent portrait lens specially when coupled with a full frame camera. You won’t be sacrificing any optical quality here.

MTF chart

This could very well be the most technical way to compare two lenses or even learn how a particular lens performs. If you want an objective point of view on a lens, it is vital that you take a look at its MTF chart. MTF stands for Modulation Transfer Function and it measures the optical performance of a lens compared to a hypothetical perfect lens. You can find the MTF chart of a lens usually in the camera manufacturer’s website or in some review websites. Keep in mind however that different manufacturers may use different measurement standards. Therefore it won’t always be possible to compare two lenses from two different companies. But this would hardly be a problem because most of the time you’re sticking with one camera brand anyway. Explaining how to read an MTF chart is a very lengthy process. So I’m simply going to redirect you here where they have done an excellent job explaining all the details.

Hopefully this will help you to make an educated choice when it comes to buying a lens. If you have specific questions, I would be happy to help you out in any way I can.


Deciphering The Camera Jargon – Part 2 (Focal Length and Lens Choices)

This is the 2nd part of the camera jargon series. Once you finally pick out your first DSLR then you are faced with another challenge. How can you possibly pick out a lens from all those lenses available to you? Which lens is right for you and what are some of the limitations that you may face? This article aims to answer some of those questions.

Focal Length

Focal length is probably the most basic description of any given lens and is usually represented in millimeters. It is horrifying to hear that some people think this is the actual length of the lens. If it was, imagine the size of a 10mm lens. While it would be so nice to have such tiny lenses, that is not the case. So what is it then? The focal length of a lens is the distance from the optical center of the lens (where light rays converges to form a sharp image when focused at infinity) to the image sensor of the camera. Without discussing physics behind this, it is easier to think of the ways certain focal length ranges affect the image. Note that the focal lengths described here are in terms of full frame cameras. The sensor size of the camera determines the effective focal length of a lens as mentioned in a previous article.

Sorry about the crappy scene. I'll update this as soon as I get the chance.

Sorry about the crappy scene. I’ll update this as soon as I get the chance. Click on the picture for a better view.

As seen in the picture, short focal lengths allow a wider viewing angle whereas longer focal lengths gives you a narrower viewing angle (Field of View – FOV) and magnifies the subject. So the focal length and FOV are inversely proportional. If you really want to know, FOV = 2 arctan (x/2f) where x is the diagonal length of the image sensor and f is the focal length. But that’s just bonus information. Strictly technically speaking, anything lower than a 50mm is considered wide angle and anything higher than 50mm is considered telephoto. However, in popular culture, this is not the case. We put lenses into several categories.

Normal Lenses – If the focal length of the lens is equal to the diagonal length of the image sensor, it is said to be a normal lens for that particular camera. For instance, a full frame sensor has a diagonal length of 43.3mm but there are no such lenses. So on full frame cameras we consider 50mm (or between 35mm – 70mm) lenses as normal lenses. Normal lens roughly gives you the same field of view as your eyes. Thus everything looks normal. These lenses are used for documentary, journalism, and street photography.

Extreme Wide Angle Lenses – Lenses with focal length less than 21mm is considered extreme wide angle. These lenses have a very large field of view. Mainly used in architecture photography, although I use a 10mm (16mm effective focal length) for landscapes.

Wide Angle Lenses – Focal length between 21mm – 35mm are considered wide angle and are used in landscape photography.

Medium Telephoto Lenses – Lenses with focal lengths between 70mm – 135mm belong to this category. Specially used for portraiture.

Telephoto and Super Telephoto Lenses – Anything between 135mm – 300mm and above are considered telephoto lenses. These are mainly for sports, birds, and wildlife photography.

Macro Lenses – This is an entirely different domain on its own. These lenses come in various focal lengths. In a very technical sense, a true macro lens has a 1:1 magnification. This means, the reflection that is created on your image sensor has the same dimensions as the actual object. For instance, if you’re focusing on a penny that has a, say 10mm, diameter. The reflection of this penny will also have a 10mm diameter. But some lenses are designated as macro lenses using a less strict definition if they achieve a reasonable magnification. The Sigma AF 70-300mm f/4.0-5.6 APO DG Macro is such an example. It’s not a true macro lens but it achieves a 1:2 magnification. Meaning, the diameter of the reflection of that penny would be 5mm instead 10mm if you use this lens. Macro lenses generally have a very small nearest focusing distance. So you can get very close to the subject and still focus fine. Macro photography opens up a whole new world for photographers. You can see amazing details on tiny little things. However, this requires an advanced understanding of the medium, proper equipment, patience, and adequate technical knowledge. Taking close ups and taking true macro photos are two entirely different things. Perhaps I will cover this subject in depth in a future article.

This was taken with the Sigma AF 70-300mm f/4.0-5.6 APO DG Macro. It's not a true macro lens. But these types of lenses are not too bad either.

This was taken with the Sigma AF 70-300mm f/4.0-5.6 APO DG Macro. It’s not a true macro lens. But these types of lenses are not too bad either.

Now, I should also mention that these categories are just to get an idea. This does not mean that you cannot use a 50mm lens to take portraits. In fact one of the most popular portrait lenses is the 50mm f/1.8 AKA the nifty fifty. Perhaps the reason is that it’s available for almost any brand of camera, it’s fast, light weight, considerably cheap (probably the cheapest, I know it is with Canon not sure about other brands), and still delivers amazingly high quality pictures. A must have lens for anyone, beginner and professional alike.

To illustrate the point, here are three portraits I took using three different lenses. Experiment with different focal lengths to get your desired result.

Taken with the Canon EF 50mm f/1.8, the nifty fifty.

Taken with the Canon EF 50mm f/1.8, the nifty fifty.

Taken with the Canon EF-S 10-22mm f/3.5-4.5 USM at 15mm. This is a self portrait, well a combination of 3 self portraits taken in my room. I had little space. So I had to use a wide angle lens to get a large field of view.

Taken with the Canon EF-S 10-22mm f/3.5-4.5 USM at 15mm. This is a self portrait, well a combination of 3 self portraits taken in my room. I had little space. So I had to use a wide angle lens to get a large field of view.

Taken with the Canon EF 70-300mm f/4.0-5.6 L IS USM at 200mm

Taken with the Canon EF 70-300mm f/4.0-5.6 L IS USM at 200mm

Inside The Lens

A lens is constructed using several lens elements, apart from the lens barrel. The main role of these lens elements is to focus the ray of light on the image sensor as accurately as possible and recreate the image in front while minimizing any distortions and aberrations. This determines the optical quality of a lens and ultimately dictates its price tag. Lens manufacturers are constantly trying to build high quality lenses using least expensive elements.

Light, however, does not behave exactly the way we want. Visible light is a very small fraction of the electromagnetic spectrum. The wavelength of visible light ranges from about 390nm to 700nm. Each wavelength refracts differently when going through different medium. This is why we see rainbows. Due to this phenomenon, when light travels through the lens, each lens element refracts each wavelength (different color) differently. This leads to false alignment of colors and results in chromatic aberration.

A ray of light being refracted in a plastic block. Image courtesy - Wikipedia

A ray of light being refracted in a plastic block. Image courtesy – Wikipedia

Chromatic aberration is just one measure of optical quality. There’s also vignetting (darkening of edges), loss of contrast, blurring, and distortion. This is why your lens is more important than your camera body. If you’re to exploit your camera to its full potential, it’s vital that you have a good piece of glass in front of it. Otherwise your high end professional DSLR won’t deliver the results you would expect. High quality lenses have various techniques to battle these problems. Therefore, they are more expensive. That is why you see lens manufacturers have several lenses covering the same focal length range. One is either optically better or faster or both than the other and is more expensive. However, it should be mentioned that lenses have come a long way since the beginning. Even the consumer grade lenses now deliver decent results. You wouldn’t notice a quality difference until you make a side by side comparison  with a professional grade lens.

See that purple line along side the tree branch? That's chromatic aberration. Click on the image for a better view.

See that purple line along side the tree branch? You’re going to have to click on the picture to see this. That’s chromatic aberration. Also note that this is a 400% crop. This picture was taken with an L grade lens. So the chromatic aberration is minimal. I had to hunt for an example.

Different lens manufacturers have their own methods to designate or identify their top quality lenses. Canon has their “L” series (luxury) with a red ring at the end of the lens barrel. Nikon has a gold ring at the end of the lens barrel. Sigma designates them as “EX” for excellence. Tokina has AT-X Pro so on and so forth. From my experience, the most noticeable difference between consumer grade and pro grade lenses is the frequency of getting sharp images. Consumer grade lenses will still give you sharp results, but not as often as a pro grade lens would. But this is just one side of the story.

Zoom vs Prime Lenses

In the good old days, there were only prime lenses. These lenses have fixed focal lengths. Therefore, the only way you can change the composition or the perspective of a picture is by moving in or out. Zoom lenses on the other hand offers a predefined focal length range. This allows you to change your composition or perspective without physically moving. Thus zoom lenses are very versatile. But there are many reasons why prime lenses are still around.

Advantages of Prime Lenses

  • Cheap – Prime lenses generally tend to be cheaper due to the fact that it has less lens elements. This does not mean that there aren’t any expensive prime lenses though.
  • Faster – I mentioned the speed several times already. So what does it mean that a lens is fast? It refers to the maximum aperture of the lens. As you already know, if a lens can open up more, it lets in more light. Thus you can use faster shutter speeds. Prime lenses are almost always faster than their zoom counterparts. Very handy in low light situations. This also makes your view finder a little brighter.
  • Weight – Prime lenses are smaller and light weight compared to many zoom lenses, again due to less lens elements.
  • Sharp Images – While cost, speed, and weight are the three main advantages of prime lenses, they tend to produce sharper images. There are less moving parts inside a prime lens (less lens elements). Therefore, it’s easier to accurately focus light which results in sharper images.
  • Bonus – Prime lenses have the potential to make you a better photographer. This is because you’re limited to one focal length and you’re forced to move around a lot to get the shot you want. This teaches you how to compose properly and forces you to think a little bit harder. Zoom lenses are likely to make people a little lazy but that’s just what I think.

Advantages of Zoom Lenses

  • Versatility – Like I said before, these give you the option to change the composition and perspective without moving. This doesn’t mean you shouldn’t move though.
  • Keeping up with the subject – If you’re shooting dynamic subjects, a zoom lens is the way to go, so you can follow your subject without too much of a hassle.
  • Bang for the buck – I know I said that the prime lenses are cheaper. But if you want to constantly use several different focal lengths, you’re going to need several different prime lenses or one zoom lens. So it depends on your needs.

When zoom lenses first came into play, the optical quality was far inferior than prime lenses. However, with the advancement of technology, the gap has been narrowed significantly. Now they make remarkable zoom lenses that deliver high quality pictures to a point that an untrained eye is unable to say the difference between the two.

So, zoom or prime?

Well I think by now, you already know the answer I’m going to give. It’s up to you. I will say this though, I think everyone should have the 50mm prime. It’s inexpensive and extraordinary. That is the only prime lens I’m carrying at the moment. Give this lens a try. Then you get to experience the mesmerizing qualities of a prime lens. If you think primes are not for you, you can always sell it with very little loss.

I hope I answered some of the questions you may have had. If you still have questions or need a little more help, leave a comment and I will get back to you. Stay tuned for the next part of this series.