There is so much information rolling around about lenses that it can become overwhelming for somebody starting out in photography.
Kit lenses, prime lenses, zoom lenses, telephoto lenses, wide angle, ultra-wide angle, focal length, f-stop, auto-focus, extension tubes, bellows, field of view, depth of field, aperture, shutter speed, leaf shutter, pincushion distortion, barrel distortion, sharpness, transmission, chromatic aberration, vignetting and on and on.
How much did I miss? Likely a lot. More importantly where did I loose you! More importantly what do you need to know and how does it impact your photographs? Well actually you don’t need to know it all, but most of it can impact your photographs in one way or another. Some are rather complex and nothing you can do about them. Chromatic aberration for example is one you likely never have even heard of, yet can impact quality of image. It is something that is close to being perfect in the professional lenses and does taper off in more budget friendly lenses. But what is it? Essentially it is a failure of a lens to focus all colours accurately at the same place. It is caused by light dispersion as the the refractive index of the lens elements varies with the wavelength or colour of light. While even the worst lenses are only very small in the errors it does impact the ability of a lens to be really crisp and sharp in focus. Is it important to you? Really it depends on what you do with your lenses and how critical you are of their performance ability.
We won’t cover them all here in this blog, but I do have workshops from time to time where topics like this can be discussed.
Lets go through a few though today. First are the differences between prime lenses and zoom lenses. You have one or the other and very likely have both if you have many lenses. Years ago all cameras came with a prime lens from the store and today more often then not they come with a zoom lens, and often one referred to as a kit lens. What is the difference between prime and zoom lenses? Well, prime lenses are the ones with a fixed focal length and zoom lenses have variable focal lengths, it is in a nutshell that simple. The real advantage of any zoom lens is its versatility. The zoom lens is ideal when moving around and the subject size or distances is constantly changing. When I do bird photography as an example a zoom lens is often very beneficial, not essential but certainly is very useful. Using a zoom lens reduces the changes in lenses, the time lost and the missed images. It can also reduce wear and tear on the lenses in changing constantly and will help keep dust and dirt out of camera body and sensor. There are however disadvantages to zoom lenses which are generally size, weight, maximum aperture size (or f-stop) and sharpness. Now higher end zoom lenses do have better or wider apertures (are faster or smaller f-stop numbers) and are sharper for sure. In fact using Nikon as an example, their “holy trinity” of lenses (which are 3 zooms ranging from 14-24mm – 24-70mm and 70-200mm) has aperture as wide as f/2.8 and sharpness that meets or exceeds most any prime lenses. In fact the 14-24mm f/2.8 Nikon was better than pretty much any prime ultra-wide for years and the barrel distortion even at 14mm was almost non-existent. But that does come at a cost in dollars invested in the lens and even at that generally the very best primes can beat the very best zoom lenses. The advantage of the prime or fixed focal length lenses are their compact size and weight and as stated their maximum aperture! But to beat the best zoom lenses you are often looking at five digit prices figures for the top prime lenses (especially in the longer focal length lenses). This means that good prime lenses are almost always better in low light as they generally allow higher shutter speeds and less likelihood of shake or blur in image. Using a high end prime lens with large apertures also means you can get a shallow depth of field which can be useful for portraiture providing a pleasantly softer or blurred background (also known as bokeh).
Enough for tonight more in another blog. If you need to know more then ask or join one of my workshops.