post

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.

post

Deciphering The Camera Jargon – Part 3 – Loose Ends

This is the third and the final part of the Camera Jargon series. Hopefully, I explained most of the popular terms in such a way that a beginner can understand. I left out some of the technical details when I felt that they are not necessary to understand the concept. Some of these terms are only explained briefly and has much more to it. As I keep writing this blog, I intend to go in to details in depth.

Depth of Field

Depth of Field or DoF for short is the area of an image that appears reasonably sharp or in focus. I discussed about DoF in the previous article in brief and I mentioned how the aperture affects the DoF. There are couple of other factors contributing to the DoF. However, I think I’m going to leave out most of the technical details out in this discussion.

Aperture – No point in repeating myself. See the previous post.

Sensor Size – Have you ever noticed when you’re taking pictures with your phone or your pocket camera, everything seems to be in focus no matter what you do? Hence the increased popularity in the Instagram and its blur feature. But when you’re using a DSLR, it’s much easier to achieve a blurred background and a sharply focused subject. FYI the blurred out background is called bokeh and nobody knows how to pronounce it (or to spell it). Anyway, the DSLRs have a much larger image sensor compared to mobile phones or pocket cameras. Larger image sensors allow shallower DoFs.

Camera to Subject Distance – When you’re up close and personal to the subject, you get a shallower DoF and if you step back couple of feet, you get a deeper DoF.

Subject to Background Distance – If the distance between your subject and the background is greater, you will get a much blurred background. If the said distance is smaller, you will get a deeper DoF. Just think of a person standing right next to a wall. The wall will almost always will be in focus. But if your subject is standing out in an open field, the far away mountains will almost always will be out of focus.

Focal Length – This gets a little tricky to explain without going into technical details. Contrary to the popular belief, focal length does not contribute to DoF. But there’s a reason why I included it here. It APPEARS to have a significant impact on DoF. There is an apparent change in DoF with a long lens vs. a short lens because the length of the lens changes the perspective in the scene – longer lenses render the background larger in relationship to the subject making it seem more blurry thus creating the impression of less depth of field. This is because when you’re shooting at a very wide focal length (say 16mm), your field of view is much greater. But when you’re shooting at a telephoto length (300mm or so), you field of view gets narrower. Thus your subject occupies different fractions of your image. Tele lenses magnifies the subject and therefore, they occupy a greater portion of your image whereas in wide angles, the subject appears smaller and they only occupy a smaller portion of the image. If the subject occupies the same fraction in both scenarios, the DoF will be the same. In order to do this, you have to step back a lot when you’re shooting with the telephoto lens. But that kind of defeats the purpose of a telephoto lens, doesn’t it? So the take home message is that technically, focal length does not have an effect on DoF. However, artistically it does. Since photography is an artistic medium, I will leave it up to you to interpret this one. It has been raining in Sri Lanka like crazy for the last couple of days. I will demonstrate this with an example the first chance I get and post it here. Bare with me until then.

White Balance

I think it would be fair to say that white balancing is a way to reproduce the colors as accurately as possible. Each light source has a different temperature (or a color) associated with it. Day light, tungsten lights, candle light, fluorescent etc. has different colors. However, modern DSLRs are more than capable of doing a decent job when the available light is uniform, or you have one type of light source. When you’re using couple of different types of light sources, it gets a little tricky. Imagine you’re shooting inside a room that is lit by fluorescent bulbs and tungsten bulbs. Your pictures are likely to have an unnatural color cast on them.

White Balance_1

Left – White Balanced. Right – Not White Balanced.

Have you ever taken pictures, specially with a compact digital camera, inside a room and all of your pictures had an amber color to them and you wondered why? This is because your camera gets confused under these conditions unlike human eye, which does a fantastic white balancing job. Simply put, white balancing is telling your camera what white looks like, hence the name white balancing. When you tell your camera what white looks like, it automatically puts all the other colors in to their proper places and thus produces an accurate image. If you’re mathematically inclined, you can think of this as a circle centered at origin (0,0) on a XY plane. The radius is irrelevant here. Imagine that inside the circle is all the colors you need. When the camera is not properly white balanced, the circle shifts its position. So what’s supposed to look like white, does not look like white anymore. When you white balance your camera, the circle shifts back to its proper place, and you have all the natural colors again.

White Balance

If those red straight lines are our X and Y axis, the one on the left is when you have your camera properly white balanced for the situation and one on the right is when you don’t have your camera properly white balanced. Note: This does not represent all the colors your camera can produce. This image is only used to illustrate my point. I grabbed the color wheel from PemaMendez in DeviantART. Kudos to him for making it.

There are several methods to white balance properly. You can shoot RAW format and adjust your white balance later during post processing. This is what I personally do. If you shoot JPEGs, you limit your ability to properly white balance during post processing because you burn your white balancing profile into the image and doesn’t collect enough data to do it later. You can adjust it a little bit but not as much as shooting RAW. If you want to get it right in the camera, you can use something called an 18% grey card. As the name suggests, it’s simply a card that is grey. What so important about the color grey? Well grey has equal amounts of each primary color and reflects natural light and the camera can use it as a reference point. What you do is, you place the grey card against the subject you want to shoot and take a picture of the card, properly exposed, filling the entire scene. Then use this image as a reference custom white balance image. Refer to your camera manual on how to achieve this on your camera. When you do this, your camera will produce accurate colors.

Aspect Ratio

Aspect ratio describes the ration between the width and the height of an image. This is something often ignored by many people because the aspect ratio is something that is fixed. This ratio reflects the width to height ratio of your camera’s image sensor. Canon, Nikon, and Pentax have a 3 : 2 ratio whereas Olympus and Panasonic have a 4 : 3 ratio. The 3 : 2 ratio comes from the 35 mm film where the area that records the image is 36 mm wide and 24 mm tall. This becomes a very important subject when you’re going to print your pictures. If your camera’s aspect ratio is 3 : 2, you can make 2 x 3, 4 x 6, 10 x 15, 16 x 24, 20 x 30 prints or anything that matches the 3 : 2 ratio without cropping out your image. However, the problem is that most of the popular print sizes, like 5 x 7, 8 x 10, 11 x 17 don’t match with this ratio. There are some places that will make prints that matches with your ratio, so don’t fret. I don’t like to throw away pixels but most importantly, when you crop your picture, it changes the composition of the image. So when you’re out there taking pictures, and if you plan to print these pictures with anything other than the native ratio of your camera, you need to take into account the fact that you have to crop this image later. Personally, I always stick with  3 : 2 ratio because that’s what my camera gives me.

FPS

In photography, fps stands for frames per second, not first person shooters. When you look at a camera’s specifications, this number is often under continuous mode or burst mode. This mode allows you to take a series of shots by holding the shutter button. This is mainly used when taking action shots, like sports or birds in flight. This increases the chance of getting a sharp shot and later you can discard the rest of the images if you want to. Thank goodness we’re shooting digital. The fps depends on several things. Buffer, the temporary memory where the images are stored before they are transferred into the memory card. Higher the buffer, high the fps. Image processor is another factor. If your camera has a faster image processor, the fps is higher too. The megapixel count has an indirect impact on fps. Since more megapixels mean bigger file sizes, it fills up the buffer really fast and thus results in a lower fps. This is why the Nikon’s the D800, fully equipped with all the other modern features, still shoots at a very low 4 fps because it has a unnecessarily large 36.8 megapixel count.

Image Stabilization

Remember I mentioned the one over focal length rule? Now that I have discussed the effective focal length, I should say that it’s actually one over effective focal length. This rule gives you a rough idea of how much your minimum shutter speed should be to handhold your camera in order to obtain a sharp image. This is of course not a rule written in the stone and it varies from person to person. However, the Image Stabilization (IS) technology gives you the option to handhold the camera at lower shutter speeds. Usually a lens would say that it has 2 stop IS or 4 stop IS. What this means is that you can shoot either 2 or 4 stops of shutter speed lower than the regular shutter speed when handholding the camera with an image stabilized lens. There are two main ways of stabilizing images.

Lens – Based

This is accomplished by introducing gyroscopic sensors. It would move the lens elements to counter the movement of the camera due to hand shake and direct the light into the sensor. There are two gyroscopic sensors, one to detect horizontal movement and the other to detect vertical movement. Some high end lenses come with a secondary mode of image stabilizing which allows you to turn off the horizontal gyroscopic sensor. This is useful when you are panning your camera to follow a subject, like a moving car.

Sensor – Shift

In this method, the sensor is shifted to compensate for the movement of the camera. The advantage of this method is that the image is stabilized irrespective of what lens is used. The disadvantage is that the effectiveness of stabilization is limited to the movement of the sensor and that if your camera has an optical view finder (most DSLRs do) the view finder won’t be stabilized. Sensor Shift IS is also called the in body image stabilization.

IS

Effect of Image Stabilization. The left one was taken with the IS on and the right one was taken with the IS off. Both were taken using the same camera, lens, and settings. The shutter speed was 1/50th of a second at 300mm (480mm effective focal length). As you can see, the IS makes a huge difference specially when shooting in such slow shutter speeds at higher focal lengths.

Different lens manufactures like to call this feature different names.

  • Canon – Image Stabilization (IS)
  • Nikon – Vibration Reduction (VR)
  • Olympus – In Body Image Stabilization (IBIS)
  • Sony Cyber Shot – Optical Steady Shot (OSS)
  • Leica and Panasonic – MegaOIS
  • Sony – Super Steady Shot (SSS)
  • Sigma – Optical Stabilization (OS)
  • Tamron – Vibration Compensation (VC)
  • Pentax – Shake Reduction (SR)

Olympus, Sony, and Pentax uses sensor shift stabilization whereas the others use lens-based stabilization. Image stabilization only works to compensate for the camera movement. If your subject is moving, you will still get a blurry image if you don’t use a fast enough shutter speed. IS is specially useful when shooting in low light conditions where handholding the camera is necessary.  

This does not obviously conclude all of technical terms used in the wonderful world of photography but some of the most important ones. Other terms will be explained as they come along in our discussions.

post

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.

post

Deciphering the Camera Jargon – Part 1 (Sensors and Megapixels)

When you’re going to buy your first DSLR, it’s so easy to get lost within the technical terms. Without knowing what they mean, it’s difficult to make a choice. Even when you read reviews online, they often don’t make any sense if you don’t know what they are talking about. In an effort to explain some of these terms that tend to appear over and over again, I’ve decided to write a series of posts. I’m going to publish this in several parts to keep each post relatively short. It’s near impossible to explain one term without relying on other terms as they are inter-connected with one another. So if you run into something unfamiliar here, it’s very likely that it will be covered in a future post.

DSLR

This goes without saying but I thought I’d add this here anyway. DSLR stands for Digital Single Lens Reflex. The reflex mechanism is the main difference between a DSLR and a compact digital camera. The light travels through the lens and hits a mirror, which reflects it to the view finder through either a pentamirror or a pentaprism. When you click the shutter button, the mirror flips up, allowing the light to hit the image sensor. The term “single lens” here can be a bit confusing because DSLRs use many different lenses. However, the term refers to the fact that the light travels to both the viewfinder and the image sensor via a single lens as opposed to having a different lens for the viewfinder.

Full Frame vs Crop Sensor

Different Sensor Sizes. Image courtesy - Wikipedia

Different Sensor Sizes. Image courtesy – Wikipedia

In photography, we use the 35mm standard film SLR camera as the reference point. Of course the digital cameras don’t use film but instead full frame cameras have an image sensor with the same dimensions as the 35mm film, which is 36mm x 24mm. Now, why on earth is this called 35mm if the width of the film is actually 36mm? It’s because it actually refers to the full height of the film which is 35mm, including those tiny little holes on the sides. And if you think this is bad enough, it is also called the 135 photographic film format. Why? Because Mr Kodak said so and ain’t nobody’s messing with him. All in all, any DSLR with a 36mm x 24mm image sensor is considered a full frame DSLR. But there are so many different sizes of sensors out there. Technically speaking, a crop sensor is anything smaller than a full frame. But we don’t hear people referring to their pocket cameras as crop sensors even though the image sensor in those cameras are significantly smaller than full frame sensors. This language is mainly used to describe DSLRs.

The size of the image sensor is directly related to the effective focal length of a lens. What is the effective focal length you ask? The advertised focal length of a lens is always in terms of a full frame camera because it is our reference point. But if you put that same lens on a crop sensor body, the lens does not behave the same way it does on a full frame body. Since the crop sensor bodies only capture a portion of the image a full frame body would, it narrows the viewing angle and thus it has a magnifying (zoom) effect. While there are so many crop sensors out in the market, there are several popular ones. Canon APS-C (22.3mm x 14.8mm), Nikon DX, Pentax K, Sony (23.6mm x 15.6mm), Canon APS-H (27.9mm x 18.6mm), Olympus and Panasonic Four Thirds System (17.3mm x 13.0mm). There’s an awesome table in Wikipedia which includes all these numbers and the associated crop factor. Crop factor, or the focal length multiplier, as the name suggests is the factor by which you multiply your focal length to get the effective focal length (full frame equivalent focal length). For instance, the Canon APS-C system has a crop factor of 1.6 which means if you put a 50mm lens on a Canon APS-C body, you have to multiply 50mm by 1.6 to get the effective focal length. 50mm x 1.6 = 80mm and therefore this 50mm lens would behave like an 80mm lens on a full frame body. Thus the effective focal length of a 50mm lens on a Canon APS-C body is 80mm. As you might have already guessed, the full frame sensors have a crop factor of 1.0 just for book keeping purposes. Now that I mentioned APS-C, it stands for Advanced Photo System type C (Classic), in which the sensor size is approximately 60% of the size of a full frame sensor. APS-H stands for  Advanced Photo System type H (High Definition), in which the sensor size is approximately 75% of the size of a full frame sensor. There’s also an APS-P (Panoramic) albeit not very common.

So it all comes down to choices again. Which one is best for you? Well, that I cannot tell. What I can do is to tell you some advantages and disadvantages of each system. I’m going to limit this comparison to full frames and classic crop sensors because they are the most popular out there.

Full Frame Advantages

  • Improved dynamic range and better low light performance leads to higher quality pictures (larger pixels compared to a crop sensor with the same megapixel count).
  • Lenses behave the way they are supposed to. Although this is not a huge advantage due to the large range of available lenses.
  • Easier to achieve a shallower depth of field. If you keep all the other factors the same and shoot the same scene using a full frame and a crop sensor camera, the full frame camera will have a shallower depth of field. The sensor size is a factor determining the depth of field. This is why it’s near impossible to achieve a shallow depth of field with your point and shoot camera despite the fact that it has a f/1.8 lens.
  • Brighter view finder. Comes in very handy when focusing manually.
  • Larger field of view. If you use a 14mm lens on a full frame, you would capture a wider view than using a crop sensor body. Especially useful in landscape and architecture photography.

Full Frame Disadvantages

  • Expensive. That large sensor is sure going to cost you a lot more.
  • Generally heavier and bulkier than crop sensor bodies.
  • Shallower depth of field. I wouldn’t say it’s difficult to achieve a deep depth of field with a full frame because that would be a lie. There are many ways around this. But like I mentioned before, if you use the same settings, a crop sensor body will give you a greater depth of field. There are many occasions where you would want a deeper depth of field.
  • To fully exploit the advantage of a full frame camera, you need those expensive lenses. Mind you, I’m talking about the image quality here, not the photographic quality.
  • Higher quality pictures mean bigger file sizes. But this is hardly a problem now that storage options are dime a dozen.

 Crop Sensor Advantages

  • Cheaper. Most of the entry-level and mid-level DSLRs are crop sensor cameras. They are more affordable than those expensive full frame bodies. This was a reason why photography opened up for so many people, including me. Heck, I still can’t afford a full frame camera.
  • Light weight and less bulky.
  • Extra reach. While crop sensor bodies have a disadvantage on the wide end, they have an advantage on the tele end. This comes very handy especially in wild life, bird, sports photography due to the focal length multiplier. Crop sensor bodies magnifies the subject like I mentioned before.
  • Smaller file size.
  • Specially designed lens series. Canon has EF-S lenses and Nikon has their DX lenses specially designed for their crop sensor bodies. These lenses tend to be cheaper than their full frame counterparts while delivering amazing results at the same time. Crop sensor bodies can also use the lenses you put on a full frame (Canon EF and Nikon FX) but the reverse is not true. The full frame bodies cannot use EF-S or DX lenses. So there’s a wide variety of lenses available for crop sensor bodies.
  • Vignetting and soft focus at the edges are less likely due to the cropped field of view.

Crop Sensor Disadvantages

  • Well this section should be pretty obvious by now after you read everything else I said. So I will refrain from stating the obvious.

It should be pointed out that over the years camera manufacturers have closed the gap between full frame cameras and crop sensor cameras. For instance, there are specially designed lenses to battle the wide angle problem in crop sensor bodies now. Both systems deliver amazing results. There are good enough reasons to pick either one. While most professionals stick to high end full frame cameras, there’s a good amount of professionals who still prefer crop sensor bodies and they are in no way inferior. It’s just a personal choice and depends on what kind of work you do with your camera. For photography enthusiasts like myself, it makes much more sense to use a cheaper crop sensor system because I don’t earn any money from my camera. 99% of the time, each system would deliver similar results. But sometimes you have to push your camera to its limits and then the advantages one system offer over the other becomes important. A professional bird photographer would have to use a $20,000 system to get the results just because anything less wouldn’t deliver exactly what he needs. If you’re still unsure what you need, I suggest that you rent out some equipment and try it out for yourself. If you’re just starting out photography, I would suggest you just get an entry to mid level camera and some decent lenses. But that’s just me.

Megapixels

Where do I even begin? I think in the digital camera world, megapixels have the highest number of myths associated with it. I’ll try to keep it short. The smallest element of a picture is called a pixel (PICture ELement –> pixel, get it?). I’m not gonna go into sub-pixels because it’s not very relevant here. Just so you know, there is something called sub-pixel as well. If you zoom in on a picture, you’ll start seeing individual pixels. Remember the late 90s and early 2000s when digital cameras were gaining popularity? I’m sure you’ve heard a conversation somewhere along the lines of “hey, my camera is 3 megapixels. how many megapixels does yours have?” “five” “woah!”

Now, let us back up here for a moment. Does the number of megapixels really matter? Not really! Let me put it this way. Imagine a 2 cm x 2 cm square (note: most DSLR image sensors have an aspect ratio of 3 : 2 but for the sake of this argument, we’ll consider a square). This square has an area of 4 cm2. If we are to fill this square with 1 cm2 little squares, we need 4 of those. We’ll call each of these 1 cm2 squares a pixel. However, if we are to fill this 4 cm2 square with 0.25 cm2 little squares, we’re going to need 16 of those. Now imagine that the bigger square is the image sensor. This is exactly what happens when they cram in more pixels into the same sized sensor. Simply the size of a pixel goes down. Mega stands for 1 million (106). So a 10 megapixel camera has 10 million pixels. So why does the size of a pixel matter? Larger pixels have more light gathering capabilities, which means at a given time interval, the larger pixel will collect more light compared to a smaller pixel. This results in less noise (little grainy stuff you see when you take a picture, especially under low light. See ISO) and sharper, more detailed images. Hence, what determines the image quality of a camera is not its pixel count but the size of a pixel. This is one of the distinguishing factors between DSLRs and compact digital cameras (and one of the reasons why DSLRs are expensive) because DSLRs have larger image sensors and thus larger pixels when comparing the same number of megapixels.

So why all the hype? It’s one big marketing strategy! The megapixel count was used by camera manufacturers as a primary way of competing with other brands. Don’t you love it when a salesman keeps exaggerating this? If they feel like you don’t know what pixels are, almost always they are going to push this. Sometimes they just don’t have any idea what it actually does either. Once I was on the phone with AT&T and I wanted to get an upgrade. When I asked about different phones, he kept coming back to the number of megapixels. I told him I’m looking for a phone, not a camera. Funny how that works.

Does the number of megapixels matter at all? Very little. If you want to crop out an image and still print it big, a higher pixel count would come in handy. This leads to another discussion on print resolutions. I promise I’ll keep it short this time. Two terms keep popping up. PPI (Pixels Per Inch) and DPI (Dots Per Inch). These are two different terms, although some people use them interchangeably. This page explains the difference in great detail. I promised I’d keep this short 🙂 Anyway, back to the matter at hand, a 15 megapixel camera will allow you to print 10 x 15 images at 300ppi without artificially enlarging (using algorithms) the image. If you want larger prints, you simply reduce the ppi and when you do, it appears pixelated, you know like when you really zoom in on a picture. However, it doesn’t really matter because the larger your print is, greater the normal viewing distance. For instance, you’re not going to make a print 2 meters tall and stand right next to it. You step back. This is how large bill boards work. They are printed at very low resolutions but since you’re viewing them from a greater distance, you don’t notice the pixelation. Of course, if you stand very close, it would look horrible but then you don’t see the bigger picture, do you?

I think I’ve covered most of the important facts about megapixels. Now repeat after me, “I’m not going to be fooled by megapixel count again!”