How Much Does Sensor Size Really Matter?

Zack Arias of Dedpxl.com posted a YouTube video recently on the difference between full frame and APS-C camera sensors.

The title "Crop or Crap".



His take, there is negligible difference between the sensors (and the photographer matters more than the sensor.)


He doesn't actually get into any numbers, so I thought I would.  (One of my first posts involves a comparison of sensor size so I have easy access to the numbers involved.)


A full frame digital sensor measures 36 x 24 mm.  APS-C sensor size varies based on manufacturer.  Its roughly 22 x 15 mm.  The full frame sensor has a surface area of 864 sq. mm versus about 330 sq. mm. for the APS-C sensor.

Micro 4/3 sensors are 17.3 x 13 mm, for a surface area of 225 sq. mm.


It's the surface area number that's important.  That number reflects the actual space available for individual photosites or pixels. There is a limit on how small individual photosites can be shrunk.  (Too small results in introducing an unacceptable level of noise.)

Based on the numbers, there is actually a very large difference between APS-C and full frame sensors, with the full frame sensor offering roughly 2.5 times the surface area. 


Given the same pixel count, a camera with an APS-C sensor will have to use smaller photo sensors and have those sensor located closer to each other.  This increases the likelihood of noise.  Eventually, you get to a point where the photosites are so small and so close together that it is impossible to fit photosites onto the sensor.

Neither Micro 4/3" or APS-C sensors seem to have reached their theoretical maximum pixel count right now.  Those systems will eventually reach a point where they can't offer the same resolution as full frame cameras, and any future conscious photographer should consider this when investing in a new camera. 

(Frankly, the theoretical limit on resolution is high enough when it comes to Micro 4/3" and APS-C systems that most photographers won't care.  For those that do, the limit for full frame cameras will be 2.5 times that for APS-C cameras.)


For those willing to accept this theoretical limit, systems using the smaller sensors do offer some advantages.

The smaller sensor size equates to smaller camera bodies.  It also means smaller lenses.  Smaller cameras and lenses mean these systems are lighter and easier to carry.  The lenses also tend to cost less as they contain less glass.

The weight and monetary savings make these systems very attractive compared to full frame DSLR cameras.  They also happen to be capable of producing high image quality.  (There are minor differences when it comes to things like depth of field.)

There seems to be very little reason to avoid these systems right now.  That might change in the future if manufacturers start increasing the resolution offered by these systems, especially if they start reaching the theoretical maximum resolution (whatever that turns out to be).