Some things to consider before you go lens shopping...

The better title for this article probably would have been: "The lens I love to hate".

For me this is my Zeiss Distagon 21mm f/2,8. Inbetween other more pressing issues I will soon write a bit more explaining my love hate relationship with this lens I bought with my Canon EOS5D Mark III back in 2012. Now you might wonder what I am smoking? How could you possibly hate a Zeiss lens? To answer this question I need to bore you with some background detail. But not now. I will, however, use some qualities of this lens as a reference point in planning future lens purchases.

The first decision is probably that of Zoom lens versus Prime lens. The Zeiss is a 21mm fixed focal length (Prime) lens.

I probably should have mentioned brand first, right? So you shoot a Nikon or a Canon but there are some third party lens manufacturers like Sigma, Tamron and others who offer great alternatives. No worries, everything in this article applies to all of them so it really does not matter too much.

With a Prime lens there is no zoom and therefore no variable perspective. For the camera perspective to change you need to change position or lenses. What you see is what you get. They are considered limiting in this regard. They are also mostly faster than Zoom lenses in that they are capable of smaller f/numbers which allow more light in due to larger internal openings. In 35mm or 135 systems they also nearly always yield better image quality and sharpness.

Now the 21mm Zeiss is a fairly wide lens but HOW wide is it really? To have an understanding of this we have to talk numbers. Very confusing and rather boring numbers for anyone with a life beyond collecting useless information.

Some time back I did an article on the 50mm lens and you can find it here if you like. Now this 50mm lens is also a prime lens.

I start with the 50mm lens because this, in full frame (for D-SLR cameras) or 35mm film camera terms is the border between wide angle (shorter than 50mm) and telephoto (longer than 50mm).

Schoenies Sunset shot with a 50mm lens

Now Prime lenses are described by their focal length in mm and maximum aperture. You will find lenses such as the 35mmf/1,4 or the 300mm f2,8 or the 600mm f/4 or the 85mm f/1.8 and many many more. If the number in mm happens to be smaller than 50 it is considered a wide angle lens. How and why this came about is a story for another day.

The problem is that a totally new set of numbers came into existence along with the D-SLR cameras and their younger cousins, the mirrorless systems. If you would like to know more about this click through the orange text for a great explanation of crop sensors, full frame sensors and how the numbers game got complicated.

If landscapes and nature scenes are your thing, a wide angle lens is often (but not always) called for. A wide angle lens is any 35mm camera system lens with a focal length shorter than the 50mm standard lens. Should you wish to know more detail about the history of the 35mm camera system, please click through the orange text for a good start read about the history of the 35mm or 135 format film camera systems.

Stormy sunset sky near Komga shot with a 50mm lens.

Now 21mm is very wide by most standards.

The wider the lens (and therefore logically the smaller the focal length number in mm) the more distant your subject matter will become but at the same time anything close to the camera will appear very large by comparison.

When we get to zoom lenses the numbers of options are, at best, much more confusing and even intimidating. Now we have to deal with two mm number descriptors and often two f/numbers too. Let's use the typical 18-55mm kit lens as an example. One example, and there are many, is the 18-55 f/3,5 - 5,6. This broadly means that the lens zooms between 18mm and 55mm perspectives (for crop sensor Canon D-SLR). At the wide end of 18mm perspective the maximum aperture is f/3,5 and fully zoomed to 55mm the maximum aperture is f/5,6.

Now there are big-boy zoom lenses out there with a "constant aperture". An example that comes to mind is Canon and Nikon's 70-200 f/2,8 lenses. At 70mm it can be shot at f/2,8 and at the 200mm long end it can still be shot at f/2,8. This is a benefit that often lightens the wallet considerably too.

This is worth knowing about because it has a very real influence on exposure settings. No, your camera is not broken. The f/2,8 or f/3,5 or f/4 you got at the wide end had to drop to f/5,6 at the long end of the zoom. Either the ISO setting or the shutter speed might need to be adjusted to get a good exposure.

For the sake of our collective sanity I deliberately chopped off all the alphabet soup in front of and behind. This too is a story for another day.

Now, with all of this having been said, I trust that I demystified a little bit of the way lenses are described. Please feel free to leave a comment and I will happily respond as soon as I can.

Coming soon will be Part One of my adventure with a friend who recently bought himself a very nice Canon EF-S 10-22 wide angle zoom to go with his Canon EOS 100D and 18-55 kit lens.

Be sure to check back or subscribe to my feed to find out soon what that old classic in the background is doing there.

Happy shooting!

Anton