The sensor is the surface that records light, and its physical size shapes image quality, depth of field and the size of the camera. This chart compares the common formats using approximate figures, which vary slightly by maker.
Quick Comparison
| Format | Approx. size | Crop factor | Strength | Trade-off |
|---|---|---|---|---|
| Small phone or compact sensor | Few millimeters across | Above 5x | Tiny devices, deep focus | Struggles in dim light |
| One-inch type | 13 x 9 mm | About 2.7x | Compact bodies with fair quality | Limited background blur |
| Micro Four Thirds | 17 x 13 mm | 2x | Small lenses, good range | More noise than larger formats |
| APS-C | About 23 x 15 mm | About 1.5x | Balanced size and quality | Slightly less light than full frame |
| Full frame | 36 x 24 mm | 1x | Strong low-light and shallow focus | Larger, heavier kit |
| Medium format | Larger than full frame | Below 1x | Fine detail and tonal range | Bulky and slower to use |
What Size Changes
- Light gathering: a bigger sensor collects more light per picture, which usually lowers visible noise.
- Depth of field: a bigger sensor at the same framing and aperture gives a shallower focus zone.
- Equipment size: larger sensors need larger lenses to cover them.
What Size Does Not Decide
Lighting, lens quality, technique and editing often matter more than format. A well-lit scene with a smaller sensor can look better than a poorly lit one with a larger one. Pixel count is a separate matter from sensor size.
Using Crop Factor
- Find the crop factor in the maker’s guide.
- Multiply the lens focal length by it to get the equivalent view.
- Multiply the aperture value by it for an approximate equivalent depth of field.
Sizes in the chart are approximations, and makers name formats differently. The one-inch label, for instance, refers to an old tube measurement, not the actual width. Check the maker’s guide for exact dimensions if you need precise numbers for lens coverage or crop calculations.
When comparing two cameras, look at the whole package: the lenses available for the mount, the size of the body and how the camera behaves at the settings you use most. A smaller sensor with a wide choice of compact lenses can beat a larger one that you leave at home.
Dynamic range, the span from dark shadows to bright highlights that a sensor can record, also tends to improve with larger sensors, although recent designs have narrowed many gaps. Read user comparisons carefully and focus on the situations you shoot in.
FAQ
Is full frame always better?
Not for everyone. It offers advantages in dim light, but size and weight are real costs for travel and long days.
Do more megapixels mean a bigger sensor?
No. A small sensor can hold many pixels; the pixels are simply smaller.
The Short Version
Larger sensors help in low light and give softer backgrounds, while smaller ones keep kits compact. Choose the format whose size and reach fit how you shoot.