Understanding Camera Lenses

by Ion Paciu
(London, United Kingdom)

Before investing in a camera lens you first need to know if it will work for you. This article aims to improve your understanding of camera lenses by providing useful information about the main categories of camera lenses, their features and how can they enhance the quality and the beauty of your photographs.

Briefly, there two main categories of lenses:

Prime lenses or fixed focal lenses (no zoom e.g. 50mm, 80mm, 100mm, etc.)

Zoom lenses - versatile lenses that can change their focal length (e.g. 55-200mm, 70-200mm, etc.)


Prime Lenses have the following main characteristics:

- convey a better image quality;
- are sharper;
- are smaller and lighter;
- have larger maximum apertures;
- have a better light-gathering ability, being recommended for both low-light and fasCam shutter speeds, ideal for sports / theatre / events photography;
- can achieve shallower depth of field;
- are simpler in terms of construction;
- are cheaper;
- make you more proactive;
- are less versatile;

popular focal lengths of prime lenses are: 20mm, 24mm, 28mm, 35mm, 50mm, 80mm, 105mm, 135mm, 200mm, 300mm, 400mm, 600mm.


Zoom Lenses have the following main characteristics:

- portability;
- are great when covering an event while unable to move around at will;
- ideal for shooting groups of people indoors;
- entails speed when adjusted to framing;
- instant capability to get a tighter shot when the moment dictates;
- easier to achieve a variety of compositions or perspectives (since lens changes are not necessary);
- using a zoom lens does not necessarily mean that one no longer has to change their position - zooms just increase the flexibility.

Lenses categorised by focal length (a rough guide, actual uses can vary)

Typical focal lengths and their uses
Less than 21 mm Extreme Wide Angle Architecture?
21-35 mm Wide Angle Landscape
35-70 mm Normal Street & Documentary
70-135 mm Medium Telephoto Portraiture & Event
135-300+ mm Telephoto Sports & Wildlife


Please note that these focal lengths apply only to 35 mm equivalent cameras.

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Other lenses that you may come across include things like and teleconverters and extension tubes.

Teleconverters (TC):

Are optical devices which can be attached to the rear of a lens increasing the effective focal length.
The most common are:
- 1.4x (stops down the lens by 1 stop of light);
- 2x (stops down the lens by 2 stops).

How do TC operate:

-work better with fairly long focal lengths and prime lenses;
-do not produce good results while used with short focal length lenses and zoom lenses;
-some TCs can only be used with certain types of lenses(you might need to check when you buy them);
-the autofocus does not operate for all apertures(you need to check your body camera when you buy a TC).

Are Teleconverters worth it?
The answer is yes, as long as you use them(preferably) with a prime lens / long focal length. However, they are not useful with zoom lenses and short focal lengths.

You can also consider an extension tube which:
- simply moves the lens farther from the sensor;
- does not contain optical elements;
- gives you closer focus (very useful for macro work);
- gives greater magnification;
- stops down the lens (1 or 2 stops);
- those without electrical contacts disconnect the lens from the camera (there is no AF).

I hope this helps. However, there are many other types of lenses (macro, tilt shift, etc.) and so much more to be said about them. I consider this information helps you find the type of lenses that best suites your camera and your needs.

Ion Paciu

web courses: http://londondigitalphotographycourses.co.uk
online portfolio: http://www.photoion.co.uk/

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