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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.

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