DCRP Lens Buyers Guide

Table of Contents
1 Introduction 2 Figuring out your needs 3 What determines price? 4 Apertures and IS 5 Extenders 6 MTF Charts7 Lens Recommendations 8 Conclusion 9 Links/Resources
I. Introduction Buying a lens for your new DSLR can turn out to be a more difficult decision than deciding which DSLR or brand to buy. For each system, there are dozens upon dozens of choices on the market ranging from a lowly $50 all the way up to a bank breaking $10,000+. This guide will help you choose the right lens(es) given your needs and your budget. II. Figuring out Your Needs The first step towards buying a lens is asking yourself what kinds of subjects you shoot the most. That’s where the bulk of your investment needs to go initially. Ask yourself questions like the following… – Do I shoot indoors or outdoors? – Do I take pictures of closer things or farther things? – Do I take photos of fast moving objects (i.e. action, sports)? – Do I want to take portraits or do weddings? – Do I like hiking around to take pictures of wildlife and nature? – Am I into macro photography? – Do I take pictures of landscapes, interiors, and/or architecture? – Do I prefer more compact, convenient lenses or more bulky, inconvenient lenses that will help me take “better” pictures? These are the kinds of questions you need to ask yourself. Once you find out what your needs are, you need to decide what your budget is and how many lenses you plan to buy. If your lens budget is in the range of… Under $300 In this range, a solid 3rd party all-purpose lens will be your best bet. Hopefully, you won’t be in tricky situations like indoor sports, concerts or indoor venues where flash is prohibited. $300-$600 In this range, you have a little more room to work with. You still can’t afford a “premium” first-party (Canon/Nikon) lens, but you can comfortably buy a top-grade 3rd party lens with money to spare for a 50mm prime (for low light situations). Above $600 When you have a little more money to work with, you can start looking at entry-level premium lenses. However, these may not work for tricky situations like indoor, low-light photography. For those situations, you will want to look at lenses with large apertures of at least f/2.8. You may also want to opt for a prime instead. Either way, refrain from buying more than 2 lenses at the outset. Buy slowly and constantly evaluate what you need. You may end up changing your mind once you start shooting. Reminder! Whichever lens(es) you decide to purchase, be sure to actually try them out in the store before buying! Make sure you’re comfortable with the build of the lens as well as its weight. And most importantly, make sure that its optical quality meets your expectations. Bring along a memory card and see how the shots come out at home. There’s no way you can evaluate image quality through the preview LCD, even a 3.5″ one! III. What determines price? If you are looking at lenses and their prices for the first time, you may be quite bewildered at the pricing scheme. It may be counter intuitive at first to see that the lenses with the widest ranges (the highest “optical zoom”) tend to be the cheapest while the ones with the most restrictive ranges tend to be the most expensive. But once you understand how several key factors play into the final cost of a lens, you’ll understand why certain lenses can cost thousands while seemingly similar ones can cost only hundreds. There are two primary factors that determine the price of a lens. These are focal length and aperture. Focal Length The cheapest lenses are the ones that are easiest to make. The easiest lenses to make are those that are close to the 50mm mark*. The farther the focal length deviates from 50mm (percentage-wise), the more costly it will be. It is much trickier to design a 10mm or a 500mm lens than 50mm lens. Moreover, we must take into account the fact that most digital SLR’s use sensors whose area is smaller than that of 35mm film. This is where the crop factor originates and is why people commonly say to multiply a lenses focal length by 1.5x or 1.6x to get its true length. * Precisely speaking, the “normal” focal length is defined as the length of the diagonal dimension of the medium. For film this is approximately 43.2mm (24mm x 36mm). Calibrating this to 50mm is a simplification, so that we can make our calculations easier. (Comparison between a 50mm to a 1200mm lens) Aperture The bigger factor into cost is how large the aperture is. The larger the aperture is (indicated by a small f-number), the more costly a lens is. This is why two lenses with the same focal lengths can differ by $1000. Notice how the lenses with large apertures have huge, fat barrels while the small aperture lenses are skinny and compact. (Comparison between a small aperture and large aperture lens) There are other features that factor into the final cost such as build quality and the inclusion of ED (extra low dispersion) elements for reducing Chromatic Abberation (abbreviated CA and known as “purple fringing”). IV. How big an aperture do I need? Do I need IS? Bigger apertures are better, but they cost you a lot of extra money. Why do you need a bigger aperture anyways? There are several reasons for wanting a big aperture. Bigger apertures are most commonly used in situations where there’s poor lighting and if you cannot use flash. To take a picture, the camera will either need a bigger aperture or it will need to make the shutter speed slower to expose the shot properly. Using a larger ISO value (1600, 3200) will help too, but going too high may sometimes introduce unwanted noise into the picture. If you are handholding the shot in this situation, the need for a bigger aperture is that much more important because a slower shutter speed will lead to camera shake and blurriness. You will also need a bigger aperture when you want to blur the background in a shot. When you use a larger aperture, the depth of field becomes shallow, placing only closer things (to the focus point) in focus, leaving the rest out of focus, or blurred. Conversely, when you use a smaller aperture, the depth of field becomes deeper, making a larger part of the image in focus. Diaphragm Blades and “Bokeh” The other major factor when it comes to blurring the background is how many diaphragm blades there are. This affects the the “bokeh” (a Japanese word which literally means “blur”), describing how well a lens handles out of focus areas of an image. Having more blades (7-9) is better than having fewer (5). Bad bokeh can be characterized by the presence of distinct geometric shapes (like pentagons or hexagons) instead of smooth circles when certain elements are blurred out. Do I need IS? Image Stabilization (IS) is a technology that can reduce the need for a larger aperture if you are handholding shots in low light. In layman’s terms, it is a “virtual tripod.” In situations where you cannot bring along a tripod, IS can make a difference between a photo that’s a keeper and one that heads to the trash bin. In practice, IS will gain you about 2 full stops (3-4 for newer generation lenses), but your mileage will vary depending on how advanced the technology in the lens is and technique. To put things into context, I’ve heard of people who were able to handhold shots at shutter speeds of 1/4 sec! (Right – IS off, Left – IS on) Beware that IS does NOT help when the subject moves. While IS may still help you handhold the shot, you will still need a fast lens to obtain a faster shutter speed that will freeze the action. Like everything else, IS is a useful tool but is not a substitute for skill. You still need to hold your camera still and use proper technique. What apertures do I need? If you are doing available-light indoor photography, f/2.8 is the bare minimum. I recommend f/2.0 or larger. If you are doing indoor sports or action photography, f/2.0 and larger is virtually required, so you can get fast shutter speeds to freeze the action in addition to bumping up the ISO to 800 or 1600. If you are working in decent light (i.e. outdoors), f/4 will work just fine. If you work mostly outdoors in great lighting, f/5.6 and above will suffice. If you plan on bringing a monopod or a tripod to stabilize things, you can even get away with even smaller apertures. V. What is an extender? An extender is a special kind of lens which mounts itself between the main lens and your camera. As its name suggests, an extender increases the focal length of your lens by some set amount. At this moment, there are two kinds of extenders, 1.4x and 2.0x. As a quick example, if you have a 100mm lens, the 1.4x and 2.0x extenders will transform the focal length into 140mm and 200mm respectively. For this reason alone, extenders can be quite useful in extending the reach of your lenses at a relatively lowcostwhile taking less space. As always though, there’s a tradeoff when you gain convenience. You sacrifice image quality, and the lens becomes “slower.” Here’s an explanation for both points. 1) You might recall that f-stop is a simple ratio between the diameter of the aperture of the lens (how big the hole is) and the focal length of the lens. For example, a 50mm lens with a 25mm diameter has an f-stop value of 2, hence the f/2 branding. Naturally, this means then that doubling the focal length will double the f-stop value, causing you to lose TWO whole stops. Using a 1.4x extender makes you lose ONE stop. If the f-stop value gets too high, sometimes auto focus will no longer function. Check with your manufacturer for exact details. 2) Extenders also degrade image quality, especially if you use a 2x extender. Think of an extender as a magnifying glass for a moment. If an extender is a magnifying glass, all of the “faults” in a lens will effectively become that much more noticeable. For examples, images may be softer, be more distorted or may lack contrast. But this is the price you pay for convenience. I’m sure that most of us would be happy lugging around a 200mm lens with an extender rather than a 400mm lens and a tripod. To sum it up, extenders are useful tools for getting more utility out of your lens collection. I personally recommend buying a 1.4x converter as the degradation in speed and image quality is less noticeable in practice. If you start with a very good lens, you may not notice a difference at all! VI. How do I read MTF charts? (For the Adventurous) MTF stands for Modulation Transfer Function. You don’t need to understand what the heck that means to read an MTF chart. An MTF chart gives us a visual representation of how well a lens performs. It gives us a good idea of howcontrasty and sharp a lens is in laboratory testing. Here are two sample MTF charts from Canon. For simplicity, I have chosen 2 primes. The first chart is for the 135 f/2 L. The second chart is for the 50mm f/1.8. (Source: Canon USA) The vertical axis represents contrast, ranging from 0% to 100%. An ideal lens would take in 100% of the light, but that never happens in practice. So, the higher a line is, the more contrast the lens has, which is good. The horizontal axis represents the distance for a sample point from the center of the image in millimeters. It is typically the case that quality suffers as you move towards the edge, but that isn’t always true as you can see with the 135L. Ignore the dotted lines for a moment. The black lines represent the lens performance wide-open. The bluelinesrepresent its performance at f/8. Obviously, stopping a lens down will result in better contrast and sharpness. The best lenses will differ little when stopped down, meaning they can be used wide-open! This means you want theblack and blue lines to be as close to each other as possible as you can see once again with the 135L. If you look carefully, you’ll notice that for each pair of lines (black and blue), there is a thicker line and a thinner line. The thick line tells you specifically about contrast while the thin line tells you specifically about sharpness. Finally, what do the dotted lines represent? Rather than go into the technical jargon of what they are, you are looking for these lines to be close to each other. They represent the quality of the “bokeh.” MTF charts shouldn’t be taken as the ultimate word on everything as they are yet just another bunch of numbers, but they are usually pretty accurate. Their weakness though is that they don’t reveal everything about a lens. BOTTOM LINE: A good MTF chart doesn’t necessarily lead to great performance in real world photos and vice-versa.
VII. Lens Recommendations These recommendations are geared towards a budget-minded DSLR buyer. I’ve also included some nicer lenses that are popular choices for those who’ve outgrown kit lenses and wish to upgrade. The prevailing theme is: Less is more. Spend your money on fewer lenses rather than spreading your money out. It’s better to acquire lenses slowly but steadily. Buy one lens at a time and evaluate your needs. Never buy a lens for the sake of buying a lens! Disclaimer: Prices are estimates taken from Amazon.com as of the time of this post. I do NOT count rebates in the price, so please check with your preferred merchant before buying. A) Starting Out? —————————————————————————— The following 4 setups are the among the most common starting kits I’ve come across. Setup A ($250 and up) – Single Convenience Lens Recommended for those who want one lens to handle it all. These are perfect lenses for traveling when portability is a concern. These lenses compromise some quality because of the large range, but the upside is that you can figure out what focal lengths you use the most and work from there. Sigma 18-125mm f/3.5-5.6 ($250) Cheap and good price-performance. A great traveling lens. Sigma 18-200mm OS f/3.5-6.3 ($450) A solid and versatile lens for non-Nikon users. Nikon 18-200mm VR f/3.5-5.6 ($680) The current king of convenience lenses. It’s not flawless, so make sure you try this lens out before you buy. Setup B ($300 and up) – Single “Walkaround” Lens A walkaround lens is another name for standard zoom lens. These lenses are faster and better in optical quality than convenience lenses, but they lose range and portability. They also cost more. Sigma 17-70mm f/2.8-4.5 ($350) A solid replacement for a kit lens.Great optical quality (sharp!) and fairly fast. Tamron 17-50mm f/2.8 ($450) This Tamron lens is widely regarded as the cream of the crop for third party lenses. Highly recommended if you are after a constant aperture zoom lens. Setup C (add $80) – “Walkaround Lens” + Prime Pair any of the lenses above with the 50mm f/1.8 prime. The prime is ideal for portraits, available-light photography and more. Setup D ($700 and up) – Prosumer Lenses For those who want something more than the entry level. These lenses aren’t cheap, but they are lasting investments that will serve you well. Canon 17-40mm f/4 L ($700) A popular choice for those who want to splurge on a quality wide-angle lens with top-notch build quality and autofocus. As good as this is, consider the EF-S 17-55 if you are not using a full-frame body. Canon 70-200mm f/4 L ($600) Arguably Canon’s most popular lens. It’s one of the best zoom lenses on the market (optically speaking) and comes at a moderate price. If f/4 is OK for you, look no further. The IS version costs $1100. Canon 17-55mm f/2.8 IS ($1000) The best of the best when it comes to a standard zoom lens. L-class optical quality, L-class autofocus and an L-class price to boot. Alas, build quality is a bit weak relative to the price point, but this is the best lens for an APS-C body at the moment. Canon 24-105mm f/4 IS ($1100) A convenient standard zoom lens at a premium price. The focal length is a little awkward to use on an APS-C body, but if it fits your needs better than the 17-55, it’s a good choice. B) Convenience Lenses —————————————————————————— The rest of this guide splits up lenses into various categories. This category contains compact, super-convenient lenses which are good for outdoor shots and for budget-minded photographers. Sigma 18-125mm f/3.5-5.6 ($250) – It’s not without its flaws, but it’s a convenient starter lens and also good for vacations. For $100 more, you can get the 18-200, a similar lens with longer reach. For $100 more, you can add image stabilization to either lens. Canon EF-S 17-85mm f/4-5.6 IS ($550) – A popular alternative to the kit lens. It has its flaws, but it’s a convenient lens for traveling and general use. Nikon 18-200mm f/3.5-5.6 VR DX ($680) – This is a very good lens relative to other “convenience lenses,” but it still has its shortcomings. Try before you buy. C) Walkaround Lenses —————————————————————————— If you want a wide or standard zoom lens, put these at the top of your list. These are less versatile than the do-it-all lenses, but they are faster and have better optics. Sigma 17-70mm f/2.8-4.5 ($350) – An excellent alternative to a kit lens at a slightly higher price. This lens is sharp throughout its range and roughly replicates a classic 28-105 lens. Tamron 17-50mm f/2.8 ($450) – A spectacular lens for APS-C cameras. If you’re in the market for a quality standard zoom with a fixed aperture but can’t splurge on the Canon 17-55 IS, this is the one to get. Canon 17-40mm f/4 L ($700) – Arguably Canon’s most popular lens, this great wide-angle walkaround lens can be used everywhere as long as the lighting is good. While third party alternatives are budget friendly, the Canon still trumps them in focus speed/accuracy and build quality. Canon/Nikon 28-105mm f/3.5-4.5 ($230) – One of the best bargains out there and is easily one of the best consumer zooms available. It beats a kit lens by a long shot, but it’s less convenient due to the crop factor. Do not confuse with the f/4-5.6 variations which are cheaper and far worse in quality. D) Telephoto Zooms —————————————————————————— Need that extra reach to capture distant subjects? If you are on a tight budget, I highly recommend buying a decent walkaround lens first and then dealing with telephoto later. In addition, you’ll learn how to use the camera and be able to better evaluate your situation when the time comes to buy your second lens. There are lots of choices, but my top recommendations are the Sigma 70-300 APO for budget users, the 70-200 f/4 L for discerning users, and the Canon 70-300 IS for everybody else. APS-C Telephoto Zooms Sigma 50-150mm f/2.8 EX ($600) – A compact and economical alternative to a classic 70-200 lens for APS-C cameras. Optically sound, but early adopters are reporting front focusing issues. Try before you buy. Tokina 50-135mm f/2.8 EX ($700) – A similar lens to the Sigma, without the front focusing issues but with a reduced range. Up to 200mm Canon 70-200mm f/4 L ($600) – An entry-level L lens which is a big leap up from consumer telephoto lenses. Stunning optical quality as long as you aren’t taking low light shots. Lightweight and compact enough to bring everywhere. One common use of this lens is for zoo/short-range wildlife photography. Nikon 55-200mm f/4.5-5.6 VR ($250) – A cheap telephoto kit lens that has image stabilization. Recommended for those starting out. Don’t expect much, but having VR at this price is a boon. Canon has a similar lens (55-250 IS). 300mm+ Sigma 70-300mm f/4-5.6 APO DG ($200) – If you need a telephoto lens and only have $200 to spend, this is the lens to buy. Be sure to buy the APO version. Canon 70-300mm f/4-5.6 IS ($550) – Canon has replaced its popular 75-300 IS with a brand new version that contains a UD element, an updated IS mechanism and an updated body. This is a much sharper and better lens than the old version. Some consider it to be close to the 70-200/4 L mentioned above. Nikon 70-300mm f/4.5-5.6 VR ($530) – Similar to the Canon lens, with some of the same strengths and flaws. Worth a Mention (Good but flawed choices) Sigma 70-200mm f/2.8 EX DG ($750) – An alternative to the first party offerings for hundreds less, IF you get a good copy. Be sure that your merchant accepts exchanges, or be ready to send to Sigma for calibration. I’m only including this here because it’s a nice lens when it works properly. Tamron 70-200mm f/2.8 ($700) – A cheap and fairly lightweight alternative to first party offerings. Optically equivalent to first party offerings, but early reviews and user reports find that autofocus speed and accuracy are disappointing. Try before you buy. E) Ultra Wide Zooms —————————————————————————— With the advent of digital bodies with a crop factor came the need for ultra-wide lenses to make up for lost coverage at the wide end. Consequently, almost all of these lenses are only suitable for such bodies and if used on a full-frame camera, will exhibit vignetting. In general, there are a lot of ultra-wide lenses on the market, and most of them are pretty good. The first party offerings are better, but like always, they may not be worth twice the price. What may sway your decision most (besides price) may be how each lens fits into your current lens lineup. Because each one starts and stops at different focal lengths, what works for one person may not work for you. Canon EF-S 10-22mm f/3.5-4.5 ($700) – This is a sharp, relatively distortion-free (for this focal length) lens that has L-class optics. Don’t be misled by the f/3.5-4.5 designation. It’s f/3.5 up to 20mm and f/4.5 for the last 2mm. Tokina 12-24mm f/4 ATX-PRO ($470) – This lens is a great alternative to first party ultra wide lenses. Build quality is superb, and the image quality is similar. The newly released 11-16/2.8 is even better. The other good third party lens to look at is the Sigma 10-20mm f/4-5.6 EX ($470). It’s not perfect, but it’s similar to the Tokina. I would avoid the Tamron 11-18 which is more expensive and has more faults than the Tokina and Sigma. Nikon has a similar lens that is similar to the Canon and Tokina, but it’s priced close to $1000, putting it out of range for most. F) Primes —————————————————————————— Primes are the best bangs for the buck if you need them. You lose flexibility, but you gain it all back in sharpness (especially wide-open), low distortion, less lens flare, and less ghosting. Do you shoot indoor sports like hockey or indoor action? Do you shoot indoors in low-light in places where flash is prohibited? If you work in these kinds of tricky conditions, consider these lenses. Primes are also superb for portraits though high grade zooms also do the trick. I am only listing shorter primes (less than 200mm) here. 50mm f/1.8 (< $100) – Should be part of everybody’s collection. If you use this prime a lot and you own a Canon body, step up to the f/1.4 version for the better build quality and better optics. 85mm f/1.8 ($360) – An ideal lens for candids and portraits. Also works as a short range telephoto lens in low light. Canon offers a similar 100mm f/2 lens for a little more if 85mm is too short for you. Canon 135mm f/2 L ($900) – This is one of Canon’s best lenses. This gem will serve you extremely well if you shoot indoor sports or concerts. It’s also a superb portrait lens. Nikon has a similar lens, but it costs more. Canon 200mm f/2.8 L ($700) – This lens is very similar in quality and size to the 135 and is a great, compact alternative to a 70-200 f/2.8 zoom which is heavy and attention grabbing. You may notice that I have not listed any wide primes here. Generally speaking, consumer-grade wide primes aren’t a whole lot better than quality wide zooms. You are better off buying a quality zoom instead. G) Macro Lenses —————————————————————————— In a gist, macro lenses let you get closer to your subject than a normal lens can, effectively letting you fill up the frame with a small subject. This is how small subjects like bees and flowers can appear “magnified.” Macro lenses can also double as standard lenses. The downside? They tend to have higher f-stop numbers than an equivalent lens, and they also tend to hunt a bit in low light. Sigma 50mm f/2.8 EX Macro ($230) – A good bang for the buck. This lens renders life size images (1:1) as opposed to the Canon model which only has 0.5x magnification (1:2). Canon EF-S 60mm f/2.8 Macro ($370) – Although it’s an EF-S lens, this is a spectacular macro lens made to replicate a classic 100mm macro lens. Sharpness is top notch. Great for product photography. I personally use it for taking pictures of food. Tamron 90mm f/2.8 Macro ($400) – Popular telephoto macro. The Canon/Nikon 100mm versions are better (particularly in focusing) but cost more. The Sigma 105mm f/2.8 EX ($350) is also very similar to the Tamron. Sigma 180mm f/2.8 EX APO Macro HSM ($650) – Sharpness is undeniably good though focusing speed is lacking compared to first party choices. Sigma also makes a popular 150mm macro lens if 180mm is a bit too long. Summary: It’s hard to go wrong with any dedicated macro lens. Just pick the focal length(s) you need, and you’re set! VIII. Conclusion I hope that you now have a better idea of what lenses to get for your brand new DSLR. Even if you are still unsure about what to get, you should now be a more informed buyer, and you will make a better decision about what lens to buy in the end. IX. Resources These are sites that supply ratings and/or reviews for various lenses. Take what they say with a grain of salt. They’re good for doing a “sanity check” and making sure the lens you want isn’t a dud, but don’t take what they say as the absolute truth. Look for general trends in what users say and see if those comments really affect you. Lens Specification Charts – Canon – Nikon Lens Reviews – Our lens reviews (DCRP) – Lightrules (Detailed Lens Comparisons) – Photozone (Full reviews) – The Digital Picture (Full Reviews and Comparisons) – Fred Miranda (numbers and user comments) – Photodo (all numbers) – William Castleman (lens comparisons)

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Siddharth Shah

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