Buying len guide

You have switched from compact camera to digital SLR and you realized that you have a huge range of len to choose from and you are not sure which len to get for photography. This section will introduce the different types of len that you need to know and certain features that manufacturers will introduce in their len.

Telephoto len

Telephoto len refers to len that is more than 200mm. Telephoto len is usually good for taking object where:

1. The place the object in is inaccessible. 2. You want to achieve a shallow depth of field when taking portraits (i.e you want to blur the background and make your people stand out). 3. You want to shoot the object from a distance such as candid shot. Telephoto lens are very vulnerable to handshake. You can try to experiment with the len and zoom at the tele end of the len and you will find that handshake is obvious when you try to hold your camera. Some high end lens offer image stabilizer ability and they are very expensive. Such feature is extremely useful especially when you are faced with low shutter speed or you don’t have any form of support to help stabilise your camera.

Normal len

Normal len usually have range from 40mm to 100mm. This type of lens is usually good for walk about len where you may want to take the surrounding place that does not require telephoto or wide angle len. Normal len can also be used for portrait and other aspects of photography that requires the range mentioned. The advantages of using a normal len are it eliminates the need to switch the len and also reduces your camera equipment load.

Wide angle len

Anything less than 28mm can be considered a wide angle len. Wide angle len is mostly used for scenery shot (e.g mountain, sunset on a beach) or the space area is very limited. Wide angle offers a deep depth of field so an average photographer can get decent and relatively sharp pictures.

Zoom VS prime len

Zoom lens are gaining in popularity since they eliminate the need to change len and help to reduce camera load. Still len makers are making prime lens for different focal length. You may wonder why this is so and this is because traditionally, prime len produced sharper images than the zoom len. But with the improved in technology, the difference in sharpness produced by zoom len and prime len are almost on par with each other.

Len speed /aperture

By saying a len has fast speed, it means the len has low aperture (i.e the size of the len hole is bigger, thus more light can be captured by the camera). This enables you to use fast shutter speed, hence the term fast len. You need low aperture if:

1. You want to achieve a shallow depth of field so as to isolate your object from the background. 2. You find yourself in low light condition and the need of small aperture is crucial. 3. You want to get more shutter speed to freeze a moving object by setting a low aperture. When taking the aperture into consideration, you have to ask whether you need a fast len as it is more expensive than slow len. If you are pursuing a general photography, then a fast len is not probably needed and an aperture of f/3.5 – f/5.6 should be sufficient.

Len Compatibility

Most len made in the past are for film body (i.e they are made for 35mm format). But this does not necessarily mean it cannot be used in a digital body. Digital body can also take in len that is made for full frame but their focal length will increase. This is known as the crop factor and most digital SLR have crop factor from 1.3x to 2x depending on the manufacturers. This is another factor you need to take into consideration. For example, to achieve a 15mm in 35mm format, you will need to get a len that is 10mm with a crop factor of 1.5x. There are also some lens that are made exclusively for digital camera with crop factor and cannot be used in full frame body. The common acronyms used for len designed for crop body are DC for Sigma, EF-S for Canon, DX for Nikon and Dii for Tamron. If you are going for full frame body soon, it might not worthwhile to invest in such len.

Additional stuff and acronyms for len

Some lens come with a len hood which you can mount on top of your front len element to reduce flare as well as to protect your len. It is recommended to purchase a UV filter to protect your front len element because some lens doesn’t come with len hood and you may not need a len hood all the time and also if there is no UV filter on, your front len element will be prone to scratches. Some additional filters such as polarizer, warm or cool filter, infrared filter that you might also want to consider to purchase but is optional if you are very new to digital SLR system.

You might also be interested to know some common acronyms used by different manufacturer to describe the len. Image Stabilizer (IS), Vibration Reduction (VR), Optical Stabliser (OS) lens are used to describe lens that have image stabilizer ability. APO, ED, SLD and LD are terms that used to describe lens with special low dispersion glass introduced to improve colour sharpness, contrast and accuracy. Lens that have Ultrasonic motor (USM) and Hyper-Sonic motor (HSM) have the ability to zoom quietly and achieve faster autofocus.

Conclusion

For a person that is new in photography, it is advisable to get a len that covered wide angle to telephoto len and a cheap prime len like 50mm f/1.8. This allows you to get a feel of the different range of the len as well as discover the range that you normally used so as to purchase a more specialized len in the future. A 50mm f/1.8 will allow you to play with different aperture to achieve creativity. It is also important to read reviews of the len that other people have experience in order to make a good len purchase.

See also other acronyms.