At present, small sensors are named after the dimensions of a hypothetical glass tube that would surround the sensor, as if they were a 1950's Vidicon tube. We will instead focus on actual sensor dimensions.

The way the industry describes small image sensor sizes (eg: 1/2.3"-type) is not just unclear but actively misleading. So, we're going to change the way we describe sensors to make sure readers aren't so easily confused.

Small sensors are currently named after the diameter of the VIdicon Tube they could be substituted for.

Photo: Sphl, CC BY-SA 3.0, via Wikimedia Commons

Every few years a website or YouTube channel discovers or explains that no aspect of a '1"-type' sensor is actually one inch long. Our own article explaining the topic was published nearly twenty years ago, and yet the issue is still causing confusion. This confusion is only made worse when the word 'type' is left out of articles and videos, making the name look like a measurement, rather than a designation of sensor class.

There are two parts to our approach. The first is that, from today, we plan to use drop the reference to inches, and refer to 1"-type sensors as Type 1 sensors.

This way we're not using completely different terminology from smartphone and drone makers, but at least removes the confusion and potential to mislead that exists in the current naming scheme, with its implication that it represents an actual measurement.

As well as changing our own style guide, we've approached a series of major publications and YouTube channels. Imaging Resource, PC Mag, PetaPixel, Cameralabs, Gerald Undone, The Art of Photography and Tony & Chelsea Northrup have all said they'll follow the same approach, and we hope others will follow.

This is an approach Sony Semiconductor, one of the world's largest sensor makers, has already adopted.

The second part of our change is that, in response to our recent poll, we will also specify the approximate sensor dimensions in mm, wherever possible, to make it easier to visualize the size being discussed.

Old naming system New name
1"-type sensor Type 1 (12.7 x 9.5mm) sensor

We will quote sensor area in comparison tables, as it's the difference in imaging area that has the biggest impact on image quality for single-shot photography, and we believe area is the more intuitive way of conveying the magnitude of sensor size difference.

Examples

Designation Dimensions
(Typical)
Sensor area
(Typical)
Diagonal
(Typical)
Crop factor
(vs full-frame)
Type 1/3.4 4.0 x 3.0mm 12mm² 5.0mm 8.6
Type 1/2.3 6.3 x 4.7mm 29mm² 7.8mm 5.5
Type 1/1.28 10 x 7.5mm 75mm² 12.5mm 3.46
Type 1
(4:3)
13.1 x 9.8mm 128 mm² 15.9mm 2.65
Type 1
(3:2)
13.2 x 8.8mm 116mm² 15.86mm 2.72

This same system could, in principle, be applied to larger sensors, but we feel these are alreadry sufficiently well understood that we won't need to change the way we deal with these.

Designation Dimensions
(Typical)
Sensor area
(Typical)
Diagonal
(Typical)
Crop factor
(vs full-frame)
Four Thirds 17.4 x 13.1mm 227mm² 21.77mm 2
APS-C

23.6 x 15.7mm 372mm² 28.4mm 1.52

Full Frame

36 x 24mm 864mm² 43.3mm 1
Medium format
Type 3.4
44 x 33mm 1452mm² 55mm 0.79

We'll apply these changes immediately and update our database soon. This change is likely to have most impact on our drone and smartphone coverage, but we'll aim to be consistent throughout.