Elizabeth Halford Photography {the blog} » photography in plain English

Making sensor of it all {APS-C, CMOS, CCD, etc}

One of the most baffling features of choosing a new camera {or understanding your existing one} is sensor size and type. Are you baffled by the terms CMOS or APS-C? I was! And as usual, there’s a plain English explanation for this in the world of techie-jargon.

First, let’s clear up some of the jargon. There are terms that refer to the sensor’s size like APS-C. Like you can see in the image to the right –> APS-C sensors in Canon cameras are slightly smaller than those in Nikon cameras. And of course, full frame is nearly the largest while medium format sensors are the cream of the crop. But then there are terms which relate to a sensor’s type or material used and these can often be seen in terms like ‘CCD’ or ‘CMOS’. Again, this refers to the material of the sensor and not the size. I read in one forum that asking the difference between APS-C vs CMOS was like asking someone to “define the difference between plastic and a centimeter”. Two completely different, incomparable, things.

{CMOS vs CCD}

So now that you’ve seen that fancy little graphic and explanation above, you know the difference between the terms that describe the size of a sensor and the type of a sensor. So now let’s talk about different sensor types. Neither is superior to the other. Both have advantages and disadvantages.

CCD – …stands for ‘charge-coupled device’. These sensors were invented in the 1960′s and weren’t originally formulated for recording photographic images, but rather, storing computer data. In the 70′s and beyond, CCDs began making their appearance in film and still cameras. One of the disadvantages of CCD sensors is cost. These sensors are considerably more expensive for various highly-jargon-related reasons.  And they are known to suffer from the slower way in which they read-out the information to solidify it as an image on your memory card. But of course, what they consider ‘slow’ is actually just the splittest of seconds. CCD sensors are renowned for creating the highest quality, lowest noise images, however, they consume 100x the battery power of a CMOS sensor.

Some cameras in which you will find CCD sensors are:

  • Canon PowerShot compact cameras like the G1 {2000} to the G12 {2010}
  • The Nikon d3000 DSLR has a CCD sensor while all of their others hold a CMOS.
  • Nikon’s newest compact camera, the p7100 holds a CCD sensor.
  • I’ve seen conflicting information about the sensor in Canon’s pro series 1DmkIV and 1Dx cameras. In many articles and forums, I see claims that this camera holds a CCD sensor. While Canon’s own website says they employ CMOS sensors in those cameras.

CMOS – CMOS stands for ‘complementary metal oxide semiconductor’. They are considerably cheaper to produce than CCD sensors and are the type of sensors found in mobile phone cameras but also in higher end prosumer models like the Canon 5DmkII. These sensors are sometimes called ‘active pixel sensors’ in contrast with the CCD sensors which are sometimes known as ‘passive pixel sensors’. The reason they’re called ‘active’ pixels is that each pixel on the sensor has its own amplifier. One of the benefits of this is that CMOS sensors are faster at reading the information gathered when you open your shutter and expose it to light. They are known to suck up less power from your battery, thus enhancing battery life.

Some cameras in which you will find a CMOS sensor are:

  • The one camera in the Canon PowerShot series of compact cameras which uses a CMOS sensor is the G1x which was just released this month
  • All Canon DSLRs hold a CMOS sensor.
  • All Nikon DSLRs hold a CMOS sensor, apart from the d3000 model

{If it produces more noise, why CMOS in a DSLR?}

So now that we’ve seen that, basically, DSLRs have CMOS sensors while compact digitals have CCD sensors, you’re probably wondering why. I found it especially confusing to note that the same sensor type you’ll find in your mobile phone is the type you’ll find in your DSLR. Weird, eh? And that a full-frame camera is known for having less problems with noise while it holds a sensor known for producing the most noise.

This is why you shouldn’t judge a camera based on the sensor type alone. You also need to consider the size of that sensor. Because, for example, a Canon 5DmkII has a CMOS {more noise} sensor, but the 35mm equivalent, full-frame sized sensor {read this for a post all about what that means} means that there’s room for more pixels on the sensor. So while each pixel may produce more noise, they are bigger and there are more of them which compensates. Also, many DSLRs employ other in-camera methods for counteracting or reducing noise.

Just down from full-frame sized sensors {see the image at the top of this post} you have APS-H sized sensors like in the Canon 1DmkIV which will be replaced by the full-frame 1dx this spring. So then just down from that, you have the size APS-C and these are the size sensors you’ll find in, for example, a Canon 7D or 550D {known as T2i in America}.

{Conclusion}

You might still feel confused about sensor size and type, but at hopefully now you know more than you did before you read this!

{further reading}

 

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  • Jsonsteby

    Thank you! This was easy to understand and something that I have wondered for awhile now!

  • Rivergull

    It takes a woman to explain things in a simple yet technically comprehensive way. Thanks Elizabeth!

  • http://www.facebook.com/JPOC226 Joseph Jpoc Comeau

    Ok this is all fine and dandy but my friends SONY A100 uses a 10MP CCD sensor, and my D90 uses a 12MP CMOS. BUT the Sony at ISO400 is nosier than the Nikon at ISO3200.

    My thoughts are that the Processor on the Nikon is better than the Sony.
    And the Sony is a 2005 Camera and the Nikon is a 2008 Camera.

  • Patrick Byrne

    Very helpful!! “define the difference between plastic and a centimeter”…perfect!

  • Sammy

    I’m new in digital photography and found this very helpful article that helped clarify my confusion. I wanted to read more and went to your first link from teledynedalso but I see that it was published in Jan 2001. Is that information still relevant? Thanks. =)

  • elizabethhalford

    Hi Sammy! Any information with definitions will still be relevant but any information concerning the most up to date technology will obviously be outdated within only months of this post going live. Tech changes so quickly! But the principles remain the same :)

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