Tutorial Lenses E-mail

Lens tutorial imageLenses determine more than anything else the technical quality of a photograph.  While it is possible to take interesting pictures with any type of camera and lens, the sharpness of the image is, at the end of the day, determined primarily by the quality of the lens.  The lens decides how close you have to get to your subject, it decides how large the angle of view will be, it decides how sharp your picture will be, the severity of optical distortions  and of course how much you'll have to carry around.  This tutorial helps you understand the basics so you know what you're looking at.


Lenses are the single most important piece of equipment you'll invest in (yes, they are in fact to some extent more important than the camera itself).  They are also the most expensive piece of equipment outside of professional studio flash/aggregator systems (which are not discussed on this site).  For instance a good telephoto lens will easily cost $5000+, but fortunately for most of your needs you're looking at $100 - $1000 for each lens.


Criteria for evaluating lenses - what to look for

This is a section that could drag on into infinity with techical details, but I'm going to cut it short.  The things to look for in a lens are the focal length, the aperture and the auto-focus speed. Focal length basically decides how many degrees of your current positions view is included in the picture.  The smaller the focal length the larger the degree (great for landscapes), and the higher the focal length, the lower the degree (great for closeups of distant objects).

The aperture decides how much light comes through the lens.  It's simply the size of the hole through which light passes to your camera's sensor.  Aperture is measured in F-stops, as in f1.4, f2.8, f5.6 ...f16...f32 etc.  The smaller the f-stop, the larger the aperture/hole, and the more light comes through the lens.  This translates directly to quality and price, a lens with equal focal length at for instance f1.4 will be significantly more expensive than one at f5,6 witht the same focal length.  This is all about the quality of the glass, as it indicates how much light manages to come through the optics.  Note that the aperture advertised on the lens is the smallest it can go, so if your lens says f5,6 you can shoot at f5,6 or f16, but not at f2,8.

The final element of note is the speed of the auto-focus, it should be self-evident why this is of interest.  If you AF is very slow you might just end up not getting the picture.  The other element to note with AF is whether it's noisy or not.


Typical Lenses

Now before you do anything at all you need to know the basic types of lenses out there:

The Normal Lens is probably the first you'll want/need.  This is the lens that allows you to take decent photos of people etc. at a length of a few meters.  Typically you're looking at a focal lenth of 40-70mm depending on the camera's sensor, for a full-format sensor (35mm film equivalent) a 50mm lens is a normal lens.  See the children statue photo analysis for example with normal lens.

The Wide-angle Lens allows you to take pictures that include more of the surroundings, this is the ideal for sweeping landscapes, but can also be used for indoor shooting if you want ot include a lot of surrounding, e.g. a person in a room with lots of fun details scattered around the room.  At typical wide-angle lens is 10-30mm, the lower the number, the more you get into the frame.

A Telephoto Lens allows you to shoot closeups of distant objects (think eagle in the sky, or a celebrity on the beach).  Typically you'll see lenses that go from 100 - 1000mm, and typically they are very heavy and very expensive.  However, if you want nice large prints of distant objects this is the only way to go.  For the typical sparrow-in-a-tree shot you're looking for a lens of 200 - 400mm which can come at reasonable prices.  See the crocodile photologue for samples with telephoto lens.

For closeups of small things like insects, plants or pennies you really want a Macro Lens. A macro lens allows you to shoot on a 1-to-1 scale, and allows you to focus on objects that are very close to the lens (typically just a few centimeters), this makes for brilliant "closeups" of insects etc.  See the bee photo analysis for example with macro lens.


Personal favourites

The Zoom lenses are lenses that allow a range of focal lengths, e.g. 100 - 300mm.  That means they can physically grow longer/shorter to accommodate the focal length from 100 (short barrel) to 300 (long barrel).  Generally speaking fixed-lens alternatives offer higher price/quality gains, but the fact that one good zoom-lens can replace several non-zoom lenses make then my personal defacto standard as I don't do studio photography.  The last thing you really want is lots of lenses to carry around.  Unfortunately the wider the gap between top and bottom the worse the lens generally, so my recommendation is to go for a wide-angle zoom (e.g. 14mm - 28mm), a  normal-zoom (28mm - 70mm) and a telephotozoom (70 - 400mm) as your first lenses, then if you really need the extra hassle of individual focal lengths, buy what you need.

There are other more specialized lenses like the Fisheye which gives you a very wide angle, but also very distorted image where the center is enlarged and the surroundings are distorted as if pulled over a sphere.  Stereoscopic lenses give you a dual image, used for 3D photography and there are a few others, but the ones you really need to "know" are the above mentioned normal, wide-angle, telephoto and macro.



So, now that you know which lens to use, make sure you know how to compose a picture and also know the basic camera modes for best results.

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