It's In The Glass

A chain is only as good as its weakest link.  Often times when people are getting a camera, they think about all the features of their camera (body) and skimp on perhaps THE most important component: the lens.  A good lens will often cost as much or more than a camera body and those good lenses will have a tendency to hold their value - or should I say a used lens will hold its value.  Once you take the lens out of the package it will devalue slightly but as a "used" lens, it's like money in the bank.  In other words, a lens is an investment - so don't worry too much about plunking down a huge chunk of cash for a reputable piece of glass, because you can always resell it (unless you have destroyed it).  On the other hand, a camera body will depreciate dramatically for two reasons: 1) Technological advances "obsolete" your camera body in a short period of time. 2) Your camera body is subject to failure a lot faster than lenses typically are.  This is not always necessarily the case, but it holds as a general rule.

You might look at the long lists of lenses available with befuddlement - wondering why there are so many and which ones are the best quality or best value.  

First, I would say that before making any major purchase (it is not uncommon to pay a couple grand for a good lens) that you go to a dealer's website and read the reviews from other users.  This may give you an indication of whether or not there are problems or if the lens is worth buying.  The thing I do when reading these reviews is to first see who is the user and what their level of expertise is.  Often, one of those writing a review simply does not know how to use their equipment and so they will write a negative review and discredit the product based upon their lack of experience - not the quality of the product.  If there seems to be a consistent problem with the product, then you might look at similar products... or the competition.  

The next thing to consider or action to take is to educate yourself on the types of lenses and the purpose for them.  There are several main types of lenses: 1) There are fixed focal length lenses (some have called these "prime" lenses because they are typically sharper than any other type) of various sizes.  There is a range for lenses (and depending on the sensor magnification of your camera) where each of these lenses falls and is considered in that classification.  This is not necessarily a hard and fast rule because there are different magnification factors for digital SLR cameras.  In the 35mm (film) days, this was a fixed value, but many cameras now have sensors that will magnify the value of the lens typically by 1.5 times.  So in other words, if you get a lens with a 50mm focal length, the sensor will magnify that by 1.5, so in essence you are getting a 75mm lens.  There are some cameras like the Canon 5D Mark II that have a full frame sensor.  This means that the sensor is 1:1 or in other words, there is no magnification factor.  A 50mm lens is a 50mm lens.  By the way, a 50mm lens is what would be considered the normal focal-length lens or one that best fits the magnification of the human eye.  It's pretty much the "vanilla ice cream" lens of photography.  Some have considered this a "portrait" lens - but a more widely accepted lens for portrait photography is 85mm.  There are various other focal lengths within the type of fixed focal lengths - with different purposes.  I would say that unless you are a professional (and meticulous) photographer, you would be best to steer clear of the fixed lenses because you are going to get a better value by purchasing a zoom lens.  2) A zoom lens is one with a variable focal length.  There are numerous ranges of zoom lenses.  Some of them are medium wide-angle lenses (generally around 18-50mm), telephoto lenses (50-300mm) and either end of the spectrum (less than 18mm or greater than 300mm).  Generally, the bigger lens (the greater the focal length) the more expensive the lens, but this is not always necessarily the case.  3) Special purpose lenses: macro lenses, fisheye lenses,  extenders and so forth.  There is often the confusion that the term for an extreme wide-angle lens is a "fisheye lens."  While a fisheye lens IS an extreme wide-angle lens, that doesn't mean that all extreme wide-angle lenses (even for the same focal length) are fisheye lenses.  It has to do with the way the image is distorted.

Lens selection

One thing that is not even possible with a point-and-shoot camera or even a so-called "bridge" camera, is the selection of lenses.  You are stuck with whatever lens came with it - and normally the lenses in these types are not that great.  With DSLR cameras, you have an overwhelming selection.  When it comes to lenses, this is one area where you get what you pay for.  However, sometimes you can get third-party lenses that are just as good as the brand of camera you have (and they are designed to fit them) and I have heard that they are just as good - if not better.  So these resources should also be considered when shopping for a lens.  Another good indicator of the quality of the lens is its f-stop.  Almost invariably, the lower number of the aperture, the higher quality of the lens.  You should also note that in the higher priced lenses, that the lower aperture throughout the entire travel of the zoom is the same, while lower priced lenses have a variable number.  This does not necessarily mean that it is a cheap lens, but just that this a quality of the best lenses.  If a lens starts out with an aperture of say f/3.5 and ends with a number of f/6.3, that is quite a variation of aperture.  You are going to have markedly different exposure when you zoom in your lens - whereas, if you have a lens that is capable of a fixed aperture throughout the entire range, you won't be sacrificing any exposure for closer zoom.  The trade-off is the cost of the lens.  

Beyond providing a wider aperture (the smaller number, the wider the aperture, or hole), the higher quality lenses produce a sharper image.  One of the reasons for this is that the lenses use higher quality optical glass.  This adds clarity simply because the glass is of a higher grade, but also because better lenses are less prone to chromatic aberrations.  These aberrations occur because the makeup of the lens is such that it separates the spectrum of light (like a rainbow) because the light travels at different speeds through the glass.  Higher quality lenses are able to use different materials to compensate for this anomaly and thus you get sharper images with more accurate colors and greater depth.     

The purple aura (chromatic aberration) can bee seen above the horse's head and in the trees.  Part of the reason for this is shooting into bright sunlight.  The other reason is that this is shot with a low-cost lens.  

Some of the other features or traits of lenses that add to the cost (and quality) are: image stabilization, ruggedness, rotating zoom ring (as opposed to sliding-type), faster and more accurate focus, versatility and reputation.  As I get deeper into the subject of lenses, I will break these down further.  

It is entirely possible to get an "all-purpose" lens now.  Nikon makes a pretty good lens that goes from 18-200mm with an aperture of f3.5-5.6.  This is definitely not their best lens, but it is one that is great for travel photography where you don't have to keep changing lenses.  Other than that, most photographers will have two or three good lenses that they take with them: a wide-angle zoom lens and a telephoto zoom lens.  It would also be a good addition to have a macro lens - if you like to shoot very close-up (like insects, flowers and small animals).  Many photographers will also include an extender.  These usually come in 1.4x or 2x magnification.  A 2x extender will turn a 200mm lens into a 400mm lens.  You will sacrifice some quality and exposure potential and will subject your images to vignetting though.  Vignetting is where the corners of the photo are darker than the overall picture.  

When I get ready to actually make the purchase of my lenses, I will post the exact make and model of the lenses that I have selected as well as those that I have researched to be the best lenses.  I will also post any lenses that I find have either had poor reviews or those that I have personally had trouble with.  I will also go into greater depth with lens types, what they're used for and how to properly use them, since there is a LOT more information than I can put in one article - and a lot more that I have to solidify in my mind.