When shopping for cameras, you’ll quickly encounter sensor size terminology. Full frame, APS-C, Micro Four Thirds, crop factor – it sounds complicated, but the basic concepts are straightforward once explained properly.
Understanding sensor size helps you make smarter purchasing decisions and explains why cameras at similar price points can perform quite differently.
What Does Sensor Size Actually Mean?
The sensor is the part of your camera that captures light and creates your image. Think of it like the film in old cameras – it’s where the picture is actually recorded.
Sensors come in different physical sizes, measured in millimetres. A larger sensor captures more light information, which generally (though not always) translates to better image quality, particularly in low light.
Full Frame: The Reference Standard
A “full frame” sensor measures 36mm x 24mm. This matches the size of traditional 35mm film, which is why it’s called full frame – it’s the full size of what photographers have used for decades.
Advantages:
- Best low-light performance
- Shallowest depth of field (more background blur)
- Generally highest image quality
- No crop factor on lenses
Disadvantages:
- Largest and heaviest cameras and lenses
- Most expensive bodies and glass
- Can be overkill for casual use
Full frame cameras are typically aimed at professionals and serious enthusiasts. In Australia, you’re looking at $2,500 to $4,000+ AUD for an entry-level full frame body, with professional models exceeding $6,000.
APS-C: The Sweet Spot for Many Photographers
APS-C sensors measure approximately 22mm x 15mm (exact dimensions vary by manufacturer). They’re about 1.5 to 1.6 times smaller than full frame.
This creates what’s called a “crop factor” of 1.5x (Nikon, Sony, Fujifilm) or 1.6x (Canon). A 50mm lens on an APS-C camera gives you the equivalent field of view of a 75mm lens on full frame.
Advantages:
- Excellent balance of quality and size
- More affordable bodies and lenses
- Smaller and lighter systems
- Extra reach is useful for wildlife and sports
Disadvantages:
- Less background blur at equivalent settings
- Slightly less low-light capability
- Crop factor can be confusing initially
APS-C is where most beginners should start. Cameras like the Sony A6400, Fujifilm X-T50, and Canon EOS R50 use APS-C sensors. In Australia, expect to pay $1,000 to $2,500 AUD for quality APS-C bodies.
Micro Four Thirds: Compact and Capable
Micro Four Thirds (MFT) sensors measure 17.3mm x 13mm, with a crop factor of 2x. This format is shared by Panasonic and OM System (formerly Olympus).
Advantages:
- Smallest and lightest complete systems
- Excellent in-body stabilisation
- Deeper depth of field (easier focusing)
- Outstanding video capabilities
- Most affordable lens ecosystem
Disadvantages:
- Less background blur potential
- More noise in low light
- Smaller sensor can feel limiting to some
MFT cameras excel for travel, video, and situations where portability matters. The crop factor actually helps for telephoto work – a 150mm MFT lens gives 300mm equivalent reach. Prices in Australia range from $800 to $2,500 AUD for bodies.
How Sensor Size Affects Your Photos
Low-Light Performance
Larger sensors have bigger individual pixels (or can fit more pixels at the same density). Bigger pixels capture more light, which means cleaner images when light is scarce.
In practical terms: a full frame camera at ISO 6400 will typically look cleaner than an APS-C camera at the same setting, which will outperform Micro Four Thirds.
However, this difference matters less than it once did. Modern sensor technology has improved dramatically. Current APS-C cameras handle low light better than full frame cameras from five years ago.
Depth of Field
Depth of field refers to how much of your image is in focus. Larger sensors naturally produce shallower depth of field at equivalent settings.
For portraits, this means more background blur (bokeh) is easier to achieve on full frame. For landscapes or product photography, smaller sensors can actually be advantageous – keeping everything sharp requires less stopping down.
Size and Weight
Sensor size directly influences overall system size. Full frame lenses must project a larger image circle, requiring more glass. This makes them bigger, heavier, and more expensive.
A complete Micro Four Thirds kit for travel might weigh half what an equivalent full frame setup weighs. Over a long day of shooting, this difference is significant.
Price Comparison in Australia (2026)
Full Frame Options:
- Sony A7C II: ~$3,100 AUD body only
- Canon EOS R8: ~$2,500 AUD body only
- Nikon Z5 II: ~$2,200 AUD body only
APS-C Options:
- Sony A6700: ~$2,100 AUD body only
- Fujifilm X-T5: ~$2,700 AUD body only
- Canon EOS R7: ~$2,100 AUD body only
Micro Four Thirds Options:
- OM System OM-5: ~$1,700 AUD body only
- Panasonic Lumix G9 II: ~$2,500 AUD body only
- Panasonic Lumix GH6: ~$2,900 AUD body only
Where to buy:
Which Sensor Size Should You Choose?
Choose full frame if:
- You regularly shoot in very low light
- Maximum background blur is important to your work
- You’re a working professional or serious enthusiast
- Budget isn’t a primary constraint
Choose APS-C if:
- You want excellent quality without full frame size/cost
- You’re a beginner building your first serious kit
- You photograph wildlife, sports, or anything needing reach
- You want a good balance of everything
Choose Micro Four Thirds if:
- Portability and weight are top priorities
- You travel frequently with your camera
- Video is as important as stills
- You want access to affordable quality lenses
The Truth About Sensor Size
Here’s what camera marketing doesn’t emphasise: sensor size matters far less than skill, composition, and lighting.
A talented photographer with a Micro Four Thirds camera will produce better images than a beginner with a full frame body. The sensor doesn’t compose your shot, find the light, or tell a story.
Modern cameras across all sensor sizes are remarkably capable. The “full frame is better” mentality often leads to people buying more camera than they need, spending money that could go toward lenses, travel, or education.
Consider your actual needs, not theoretical maximum performance. For most photographers, APS-C delivers everything they’ll ever need at a sensible price and weight.