10 facts about lenses you need to know
1. Focal length
Focal length is indicated by ‘mm’ as you can see on the lenses. Small number e.g. 17mm feels like zooming out, where almost things in front of you can be captured by viewfinder in the camera. On the other hand, big number e.g. 200mm feels like zooming in, more or less how binocular works for you. Do note that focal length on certain DSLR bodies does not feel the same. 35mm on Full-frame cameras does not have the same view as crop-sensor camera due to the crop factor. To put it simple, crop-sensor have magnification factor(1.6x for Canon or 1.5x for Nikon) in comparison with full-frame bodies. Therefore, 35mm on crop sensor is more or less equal to 50mm on full frame bodies.
Aperture value of a lens is written on the lens itself e.g. 1:4 which means at any focal length of the lens, the aperture value will remain the same at f4. Some lenses show certain value like this 1:4-5.6. This means at wide open, the aperture varies as you change focal length (zooming in/out). For instance, for a lens 17-85mm f4-5.6, at 17mm, the biggest aperture you can have is f4 and at 85mm, the biggest aperture you can have is f5.6. The reason behind this is all about the cost of constructing a lens. Making a fixed-aperture lens is more expensive than a variable-aperture lens. To be precise, aperture is measured as a fraction of the focal length. 17mm f4 means the aperture opening is 17mm/4 which is 4.25mm wide while 85mm f5.6 means the aperture opening is 85mm/5.6 which is 15.2mm wide. To have a fixed aperture along the focal length would require the aperture opening to be 85mm/4 which is 21.25mm. Given the required aperture openings at the longest focal length, a lens needs to be big in size and that means the cost of building it will be expensive.
3. Focus ring & AF MF button
All lenses have a focus ring on its body. Generally, focus ring should be at the most front of the lenses, while the other is the zoom ring. If you are using autofocus, you don’t have to even bother using this focus ring at all. But when switching to manual focus, you have to do the focusing by yourself. There is a small button in between the focus and zoom rings, stated AF & MF. Switching to MF will activate manual focus and vice versa. Indeed, there are certain circumstances where manual focus work much better for you. Generally, there are two situations where you might consider using manual focus.
1. Autofocus doesn’t focus at where you want
This is so true especially in Macro and Portrait photography. Since these kinds of photography require you to perfectly focus on the eyes of the subject, getting control of the focus will yield you a better result
2. Autofocus keep hunting and couldn’t lock on the subject
This is very obvious in low light situation especially when the background is dark. Some cameras have an AF assist beam to help auto focusing, but if you find it difficult to focus on your subject, switch to manual focus and do the focusing with your own very eyes
4. ‘Fast Lens’ term
This is a term that most people like to use so getting familiar with it is very useful. A fast lens is a lens that have big aperture (small f-number), generally aperture of f2.8, f2.0, f1.8 and so on. Having a lens with these apertures allow you to use ‘fast’ shutter speed especially in low light situation. Sometimes, you may encounter a situation where you want to use fast shutter speed (to avoid blurred pictures) without compromising ISO settings therefore, having a lens with big aperture will be very handy. For more info how aperture affects shutter speeds, you may refer HERE.
5. Prime lens
Prime lens has fixed focal length which means you have to zoom in/out with your own feet! Although it may seem at disadvantage to have a prime lens because it can’t cover variety of focal lengths, it has its own strengths that you may consider to get one
1. Small in size and light in weight
Prime lens is small and light, meaning that you won’t need to have a big bag to carry one, together with your DSLR. I admit, most people quit using DSLR because of size and weight. So, using prime lenses can reduce your burden a lot!
2. Fast lens
Most prime lenses offer big aperture such as f1.8, f1.4, f1.2. Though the world is vastly evolving, a lot of zoom lenses offer f2.8 at fast. Having a fast prime lens will help you a lot especially in low light situation. Other than that, a fast lens allows you to create blurred background or some people call it bokeh. A fast prime lens is a lot cheaper than any other zoom lenses of equal aperture. Cheap, fast and easy bokeh, that’s why prime lens is most favoured by portrait photographers.
3. Image quality
Images taken with the prime lens are usually sharper, especially in the corners. Apart from that, prime lenses are better at dealing with chromatic aberration than zoom lenses.
6. Zoom lens
Zoom lens is what it is; a zoooom. In contrary to prime lens, it has a mix combination of focal length from as low as 8mm to as long as 400mm. Here are some of its good points in comparison to prime lens;
1. It’s a zoom
There might be some instances where you have troubles with zooming in or out with your foot. And the zoom of course save your time from walking to the position where you want you should be.
Having a zoom lens means you can save your money from buying a lot of fixed lenses and save your beg spaces. For instance, a lot of lens manufacturers do produce 18-200mm which covers the common focal lengths that everybody uses. Instead of carrying a lot of lenses, you can just carry one! How handy is that? You can also save all the hassles from changing one lens to another.
7. Type of lenses
Lenses come in various type, though it doesn’t specifically mention in its manual. Generally, lenses serve different purposes
1. Normal lens
Normal lens generally ranges from 17mm to 70mm (for crop sensor body) or 24mm to 80mm (for full frame body). Most kit lenses fall under this category such as Canon/Nikon 18-55mm. These focal lengths suit general purpose photography like travel, family occasion etc.
2. Ultra wide angle lens
Any focal length falls below 17mm or 24mm (for full frame body) is considered ultra wide angle lens. This lens is massively used by landscape photographers, while some wedding photographers also use it. Lenses with strong distortion is called as fisheye lenses, in which the term is given based on how a fish would see an ultra-wide hemispherical view. Mastering this lens is a bit tricky as you need to carefully control the distortion that this lens produce.
3. Telephoto lens
Any focal length fall above 70mm or 80mm(for full frame body) is considered telephoto lens. This lens is famously used by wildlife photographers where you don’t want to get too close to the animals and scare them away (or scare you away). This lens is also good for portrait because you will get less distortion on the faces, and it is much easier to create bokeh.
4. Macro lens
Macro lens doesn’t have a specific focal length. What makes it different than any other lenses is its ability to take extreme close-up image, particularly very small subjects, in which the size of the subject in the image is greater than its actual size in real world.
8. Lens filter
Filters are put at the front on the lenses, more or less how sunglasses work for you. A lot of filters are available out there in the market, so here are basic knowledge you need to know about filters
1. Type of filters
The most commonly used filters are UV filters & Polarizing filters. While there are numerous debates regarding the usage of UV filters vs image quality, it is normally used for lens protection. Polarizing filters are used to reduce reflection on the water, and enhance colours and contrast of the sky.
2. Filter size
When purchasing any filters, always match the filters with your lenses size. The info is written on the body itself. However, you may save your money by using a step up/step down ring. For example, you have 2 lenses with filter size of 67mm and 77mm. Instead of buying two polarizing filters, you may just buy a 77mm polarizing filters and a 67mm-77mm step up ring!
9. Third party lenses.
Third party lenses are made by those companies that specialize in making lenses only, means that they don’t produce camera bodies with Sigma, Tamron and Tokina being the top third party manufacturers. Instead of looking at first party lenses such as Canon or Nikon, you might as well consider this third party lenses when buying a new lens.
Some third party lenses offer slightly different focal length than those that are offered by first party lenses like Sigma 30mm f1.4, Tamron 15-30mm f2.8 and Tokina 11-16mm f2.8. This is maybe one of their selling points and as an example, Sigma offers 30mm while Canon offers 28mm and 35mm prime lenses. If 28mm is too wide and 35mm is too tight for you, getting this 30mm might be a good choice.
Third party lenses is well known for its price. Cheap and affordable. Third party lenses is suitable for those who are on budget, especially students. Tamron 18-200mm is $199 while Nikon 18-200mm is $600 and Canon 18-200mm is $700. Of course the cheapest will be your choice!
3. They are now going fast
Nowadays, third party lenses do not only focus on making cheap lenses, rather now they are shifting themselves in making fast lenses like Sigma 35mm f1.4, Sigma 18-35mm f1.8 and Sigma 120-300mm f2.8 but the cheapness still stay in it. The Sigma 35mm f1.4 cost $899 while Canon 35mm L f1.4 cost $1479. Cheap vs no cheap, both offer f1.4, which one would you choose?
4. Compatibility issue
This is the main reason why some photographers prefer first party lenses over third party lenses. Some lenses do not work on some bodies, especially the newer ones due to upgrades in software. So, before buying any third party lenses, do check on its compatibility on your camera.
10. Lens hood
Lens hood is an extension that you put in front of your lenses. It comes in round and petal shapes, depending on the focal length of the lenses. The main purpose of using a lens hood is to block out light that is coming into the lens from the side, causing lens flare thus reducing contrast and colour of the images. Though lens flare can be avoided by shooting at different angles, photographers often use lens hood for lens protection, especially those who don’t use UV filter as lens protection. It is not necessary to have one, but it is a good practice to have one.