DSLR /Mirror-less camera Lens information that everybody must know.

   

    

    Eyes play very important role in our life by letting us see beautiful environment around us. Right now you are reading this post because of them only. The light in front of us enters our eyes and after analyzing it, we get to see things. 

Same important work is done by lenses in cameras. Sensor collects light falling on it, but lenses concentrate the light on sensor. This post describes importance of lens in photography.  

When do we take photo? When we want to capture the moment happening in front of us for ourselves or when we want to share it to somebody else. The work of lens starts from here. Actually the ‘photo taking process’ starts with the lens. 

There are some parts of lens which we have to study to know working of lens. They are Glass elements, Aperture, Image stabilization system, Auto focus system, Focus ring and Zoom ring, lens cap, lens hood, weather sealing and Tripod or lens collar. Let us see them one by one now.

1. GLASS ELEMENTS

        Every lens has a set of glass elements which are either concave or convex in shape. Depending upon lens type and quality, the number and size of these glass element may change accordingly.  They are setup in the lens in such a way that, every ray of light should fall on the sensor as we expect it to be. The quality of light should remain intact even after passing through all these glass elements. For this very reason, some glass elements may be coated with special chemicals to get desired effect. Due to this, refraction and reflection of light is controlled. 

   

2. APERTURE

Aperture means the door for light, in the lens. Aperture is located at the back side of the lens, which is towards camera when attached to it. We can control its size based on the light quantity required in photo. It’s work is same as that of pupil in our eye, i.e., to control the amount of light entering the body, based on light quantity present in surrounding. Aperture opening is enclosed by thin metal or plastic blades, which slide on each other to make the aperture small or big. There may be 7 or 9 aperture blades in a lens.

3. IMAGE STABILIZATION SYSTEM

While taking photos, our hands may not remain rock steady and because of that, the photo may come out a bit blurry. To eliminate this user error, in some lenses there is a provision of image stabilization system. For this system to work, there is a glass element in the lens which is kept floating. This can be moved by some margin according to need. This glass element is moved in the direction opposite to that of our hand movement. Due to this, our hand movement gets cancelled in the lens and we get sharp photo. 

4. AUTO FOCUS SYSTEM

The term auto focus is so huge that, it can’t be explained and understood in short. But still, if it is to be done so, it works like this. Camera recognizes if the subject is in focus or not. If it is not, then it decides what should be done to get the subject in focus. After that, this information/analysis is provided to lens and then after the lens system moves it’s glass elements to and fro and achieve the focus in photo. 

Focusing has three types as PDAF (Phase Detection Auto Focus), CDAF (Contrast Detection Auto Focus) and Laser AF (Laser Auto Focus). Out of these, PDAF is latest and performs best in the field. 

5. FOCUS RING AND ZOOM RING

Every lens has a focus ring. It is used to focus on the person, subject or scene that we want to photograph. The smoother it is, the better it is. Because in this way, it allows us to focus accurately and easily. 

The lenses which have ability to zoom, have zoom ring in addition to focus ring. It the zoom ring is smooth, it is useful in videography work. The amount of rotation required to achieve full zoom in a lens is also important, because it decides ease in usability of that lens. 

6. LENS CAP

As the name suggests, the lens cap provides cover to lens, against direct light. Lens is covered by lens cap to avoid accumulation of dust particles on lens and to protect the front glass element, when not in use. 

The front glass element has some chemical coatings on it, to retain quality of incoming light. If it is not covered by lens cap when idle, it may get spillage of some liquid or may get physically damaged by some hard objects. 

        If the front element gets smudges, they are going to show up in every image we take. Also when we put the lens in lens bag, in absence of lens cap, any hard objects can scratch the front element and ruin it entirely. So use of lens cap is very much essential. 

7. LENS HOOD

When we go in bright sunlight, we have to cover or shade our eyes to see clearly, in better contrast. Or many times we cover upper part of the eyes, to prevent bright light in upper part of the scene (like sky), from entering our eyes. 

Lens hood does the same work for lens. The light coming from directions other than from front side, may ruin the photo by adding light flares and reducing the contrast in it. So lens hood avoids all these problems and help to get clearer, sharper and punchy picture. 

Different lenses have different shapes and sizes of lens hoods. It depends upon whether the lens is a wide angle lens, a standard lens or a telephoto lens. Lens hood eliminates extra unwanted light from side.

8. WEATHER SEALING

Dust and water are the enemies of lens. If they enter your lens, be prepared to repair of even replace it. Many times we have to take photos in extreme weather conditions, like windy dusty places, places with more moisture in air, etc. In these times, weather sealing proves to be helpful. 

For this, the area where lens attaches to the camera body, a rubber gasket ring is provided, so that it closes the gap between lens and camera completely, when attached. Also in lenses where two parts move in & out externally, the moving parts are sealed in such a way that, dust particles and moisture should not enter the camera body. 

But I should mention one thing here that, lenses are always splash proof and not water proof. Means, they can only handle water falling over them. But if they are submerged in water, then they are likely to get damaged. 

9. TRIPOD COLLAR

Some lenses are larger and heavier than the camera body itself. Telephoto lenses uses for wild life photography and sports photography, are mainly included in this category, which weigh from 1.5 kg to 4.5 kg. Also consider the fact that largest camera is having a weight of 1.5 kg.

        So these lenses when mounted on camera, may harm the mount assembly, due to their weight. To avoid this and to reduce some load of lens on camera body, they are provided with tripod collars. So, when we want to use these lenses, the lenses are actually mounted on tripod with the help of these collars and the camera is attached to them, hanging at the back end. In this case, lens carries the weight of the camera.

    

       Every lens definitely has minimum required parts like glass elements, aperture, focusing ring and a lens cap, in it. Because without them, no any lens can be made. But other features/parts of lenses are found in some lenses, for which you have to pay extra money. But for that money, you get ease in working and enhanced quality of photo. 

For every work, there is a lens made to fulfill it’s specific requirements. Let’s hope that more features get added in lenses, in future. Because advancement in technology is the key to happiness. At least in photography.

    

- Prasanna Joshi

       

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'TYPES OF LENSES'

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