Why constant-aperture ZOOM Lenses are the best

The main difference between a constant aperture lens like an f/2.8 zoom and a variable aperture lens like an f/3.5-5.6 zoom is how the aperture changes as you zoom in and out.

A constant aperture lens maintains the same aperture throughout its zoom range, meaning that regardless of the focal length you set, the aperture remains the same. For example, an f/2.8 lens will have a maximum aperture of f/2.8 throughout its entire zoom range. The 70-200 can be F2.8 at 70 and 200mm.

In contrast, a variable aperture lens changes its aperture as you zoom in and out, meaning that the maximum aperture changes depending on the focal length you set. For example, an f/3.5-5.6 lens will have a maximum aperture of f/3.5 at its widest zoom setting, but as you zoom in, the maximum aperture will decrease to f/5.6.

The advantage of a constant aperture lens is that you can maintain a consistent exposure and depth of field as you zoom in and out. This can be particularly useful in low-light situations where you need a wide aperture to let in more light.

The price difference…

The disadvantage of a constant aperture lens is the price – it tends to be more expensive than a variable aperture lens, due to the complexity of the lens design required to maintain a constant aperture throughout the zoom range.

The weight difference…

The advantage of a variable aperture lens is it requires less complex lens design, so it can also be lighter and more compact than a constant aperture lens. Better for travel perhaps.

The practical difference…

The disadvantage of a variable aperture lens is that as you zoom in, the aperture decreases, which can make it more challenging to maintain a consistent exposure and depth of field. This can be particularly problematic in low-light situations where you need a wider aperture to let in more light. Additionally, a variable aperture can make it more difficult to achieve a pleasing bokeh effect (the blurred background), as the aperture changes with the zoom range.

It’s never straightforward forward is it!

Better quality but heavier and more expensive, versus lower quality but portable and cheaper.