Equivalence is a way to compare a final exposure of lenses across different sensor formats. A lens’s focal length is measured in millimeters, an inherit property of a lens that determines the field of view it can capture. However, the focal length is not the only property in a camera system that can affect the field of view, sensor size is another. The larger a sensor is, the wider a field of view you can capture. Because of this, comparing two focal lengths made for different sensor sizes, a conversion needs to be made to equally compare their final field of view.
Fujifilm has a great line up of fast lenses with focal lengths that match many popular full frame lenses from Canon, Nikon, and Sony. This article goes over some things to watch out for when comparing them.
With the immense popularity of the 35mm film format, photographers were already familiar with the given look of a focal length on that film size. This became the baseline for manufacturers to compare their lenses too. Today, when buying a lens for a crop sensor, like the one found in the Fujifilm X system cameras, a 35mm or full frame equivalent focal length is usually listed.
And this is how we get to the real point of this article. Simply doing a conversion of the focal length will give you an understanding of what the field of view will be, but one thing manufacturers don’t like to remind you of, is this also affects the f‑number. A 56mm ƒ/1.2 APS‑C (1.5x crop factor) lens is equivalent to an 84mm ƒ/1.8 full frame lens, not an 84mm ƒ/1.2 lens. It can be deceiving buying a crop sensor lens and thinking you will get the same amount of background blur as the full frame equivalent with the same f‑number.
To learn more about equivalence, please read this excellent article by DPReview.
The 56mm ƒ/1.2 is the fastest lens in the Fujifilm X line up, it isn’t the largest aperture, meaning there are lenses that will give you more blur. That award will go to the yet‑to‑be‑released XF200mmF2, with an aperture that is over two times as wide as the XF56mmF1.2. Depth of field and blur are more complicated than just aperture size, and many more variables should be taken into account, but this is a good starting point to look at when comparing different focal lengths.
Depth of field is not bokeh, bokeh is the quality and look of the blur from the out of focus parts of an image.
This table will help you find the true 35mm equivalence of native Fujifilm X lenses.
Focal Length (35mm)
|XF16mmF1.4 R WR||24mm||ƒ/2.1||11mm|
|XF16mmF2.8 R WR||24mm||ƒ/4.2||5.7mm|
|XF18mmF1.4 R LM WR||27mm||ƒ/2.1||13mm|
|XF23mmF1.4 R LM WR||35mm||ƒ/2.1||16mm|
|XF23mmF2 R WR||35mm||ƒ/3||12mm|
|XF27mmF2.8 R WR||41mm||ƒ/4.2||9.6mm|
|XF33mmF1.4 R LM WR||50mm||ƒ/2.1||24mm|
|XF35mmF2 R WR||53mm||ƒ/3||18mm|
|XF50mmF1.0 R WR||75mm||ƒ/1.5||50mm|
|XF50mmF2 R WR||75mm||ƒ/3||25mm|
|XF56mmF1.2 R APD||84mm||ƒ/1.8||47mm|
|XF60mmF2.4 R Macro||90mm||ƒ/3.6||25mm|
|XF80mmF2.8 R LM OIS WR Macro||120mm||ƒ/4.2||29mm|
|XF90mmF2 R LM WR||140mm||ƒ/3||45mm|
|XF200mmF2 R LM OIS WR||300mm||ƒ/3||100mm|
|XF8-16mmF2.8 R LM WR||12-24mm||ƒ/4.2||2.9-5.7mm|
|XF10-24mmF4 R OIS WR||15-36mm||ƒ/6||2.5-6mm|
|XF16-55mmF2.8 R LM WR||24-83mm||ƒ/4.2||5.7-20mm|
|XF16-80mmF4 R OIS WR||24-120mm||ƒ/6||4-20mm|
|XF18-55mmF2.8-4 R LM OIS||27-83mm||ƒ/4.2-6||6.4-14mm|
|XF18-135mmF3.5-5.6 R LM OIS WR||27-200mm||ƒ/5.3-8.4||5.1-24mm|
|XF50-140mmF2.8 R LM OIS WR||75-210mm||ƒ/4.2||18-50mm|
|XF55-200mmF3.5-4.8 R LM OIS||83-300mm||ƒ/5.3-7.2||16-42mm|
|XF70-300mmF4-5.6 R LM OIS WR||110-450mm||ƒ/6-8.4||18-54mm|
|XF100-400mmF4.5-5.6 R LM OIS WR||150-600mm||ƒ/6.8-8.4||22-71mm|
|XC15-45mmF3.5-5.6 OIS PZ||23-68mm||ƒ/5.3-8.4||4.3-8mm|
|XC16-50mmF3.5-5.6 OIS II||24-75mm||ƒ/5.3-8.4||4.6-8.9mm|
|XC50-230mmF4.5-6.7 OIS II||75-350mm||ƒ/6.8-10||11-34mm|