Going Fast. Why You Should Have At Least One Fast Lens


We all feel the need, the need for speed. When it comes to photography going fast is not about speed, it’s about the amount of light you can get through the aperture of your lens.

We are constantly bombarded by photographic advertising telling us about the latest and greatest, super fast zoom and why we should own one. The problem is of course, faster glass means bigger glass and when you have more of something, it's going to cost more.

Today, we are going to look firstly at why you should consider a fast lens and secondly what your options are, including budget alternatives to big fast zooms.

What Is A Fast Lens?

A fast lens is one that has a relatively large maximum aperture compared to lenses of a similar focal length. In the region of 50-100mm fast would be considered less than f.2, typical 50mm lenses being f1.8 and fast portrait 85mm going down to f1.4.

Outside this range maximum aperture tends to be a little slower, f2.8 being considered fast for anything above moderate telephoto or moderate wide. Prime lenses will faster than zooms for a similar focal length.

As fast as you can go, the Noctilux is an f1.0 50mm. By Dino Quinzani

This course ‘Understanding Composition‘ is an excellent introduction to how you can understand and improve on your technique as a photographer. Why? Because when you're using a fixed lens (i.e. a “prime”) learning and understanding how to compose images is a fundamental part and your skills will improve as a result.

Why Go Fast Then? 

There are two primary reasons for shooting with a large aperture lens, low light and depth of field. The obvious advantage to a wide aperture fast lens is that it allows you to shoot hand held at lower light levels without having to boost the ISO. The upshot of this is less unwanted noise in your image.

The other reason is to get a shallow depth of field and it’s associated bokeh. Shallow depth of field is the when the areas in front of and behind the main subject are out of focus, isolating that subject.

The wider your aperture, the shallower your depth of field. This is also dependent on the focal length of the lens used. Telephoto lenses will have a shallower depth of field than wide angles for the same aperture.

Bokeh is a strange name give to define the softness of the out of focus regions in shots with shallow depths of field.

Perfect petals of brilliant color seen in Chaoyang Park in Beijing, China

Shallow depth of field. One very good reason for a fast lens. By Bryon Lippincott

What Are My Fast Lens Options?

The camera companies will always hard sell their top of the range fast zooms. Often called the holy trinity of lenses, the combination of 14-24, 24-70, 70-210mm f2.8s are the staple of professional photographers.

They are also relatively expensive and comparatively heavy. Pros use them because they are often working to tight deadlines and in difficult light conditions. The wide aperture gives them both the ability to work in low light and to get shallow depth of field shots.

For many of us though, the holy trinity is not something we require even if we could afford it. For starters, a fast wide angle lens is not necessarily a must-have option. It is more difficult to achieve shallow depth of field with wider lenses and is a technique that is not often required.

Also, hand-holding speeds with wide lenses are lower than with longer lenses. The extra glass required for a wider aperture will add weight and negate the hand holding advantage.

A fast wide zoom. Expensive and possibly not the best choice for the average user. By Marco Galasso

Stepping up to 50mm and above, a fast lens becomes a viable option for the average enthusiast photographer. Perhaps one of the better options here is to purchase a prime lens rather than a fast zoom.

The advantages are that primes are usually not only significantly cheaper but also have a better maximum aperture to their zoom equivalents. A term you may have heard of is the “nifty fifty” – it's a great name for a versatile lens, a fast, f1.8 or f1.4 50mm prime that works well as a general purpose lens for low light and shallow depth of field. They are also amongst the best value of all lenses.

The Nifty Fifty is “best bang for buck”. By Jeff Golden

Stepping up a little we get to the classic portrait prime, the 85mm f1.8 or f1.4. More expensive than the nifty fifty but in f1.8 form at least significantly cheaper than an equivalent fast zoom.

Beyond that focal length, primes tend to get much more expensive. Using either a 50mm or 80mm fast prime gives you great options for low light and bokeh.

For those on a tight budget or comfortable with manual focus and manual exposure, there is a whole world of fantastic fast old lenses. Retired lens systems like the Canon FD series have some great fast primes available for very low prices secondhand similarly, there are some great M42 screw mount lenses.

You will need an adapter to mount the lenses to your camera but these are inexpensive and as they contain no optics do not degrade image quality.

A Canon FD 50mm f1.4 on a modern Fuji. By Conal Gallagher

Adding just one fast prime to your kit bag is an inexpensive way to increase the range of creative shooting possibilities that are open to you.

Remember, using a Prime lens can really improve your photography…it's true. One of the main reasons for this is because you have to think about Composition and move your feet!
Getting the angle and photograph you want sometimes takes a little more thinking ahead, but your skills will come on leaps and bounds as a result! This course ‘Understanding Composition‘ is an excellent introduction to how you can understand and improve on your technique as a photographer.

Further Resources

About Author

Jason has more than 35 years of experience as a professional photographer, videographer and stock shooter. You can get to know him better here.

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