A few days ago I watched a video of a photographer talking about CMOS versus CCD sensors*. Nearly all digital cameras nowadays have CMOS sensors, and the advantage of them apart from any other consideration is the speed with which the signal can be taken off the sensor and stored on the card.
The faster the signal can be taken off the sensor, the faster the camera can take photos one after another. It is not uncommon now for cameras to be able to take anywhere from ten to twenty frames a second.
And a photographer might want to take many photos in rapid succession for rapidly-changing events such as gymnastics, or wildlife in motion.
CMOS sensors can transfer information of the card in one batch. In comparison, CCD sensors are read line by line, so cameras cannot read photos from the sensor to the card at the same rate. If the information is still on the sensor, the photographer cannot take the next shot until the data has been transferred.
So why the interest in CCD sensors?
Well, the photographer in the video thought the photos from CCD sensors had a certain quality, a more film-like quality than photos from CMOS sensors.
I decided I wanted to find out for myself. I have Nikon lenses, so it made sense to buy a used Nikon camera with a CCD sensor.
In fact I used to have a Nikon D70, which has a CCD sensor. It was the second digital camera I owned.
So I turned to eBay. The camera was very cheap. After all it only has six mega-pixels. Smartphones have twice as many pixels (albeit smaller ones).
Here is a list of Nikon cameras with CCD sensors
The photo at the top of this article is a sample shot from the D70. For the technical info – I shot at 1/125th of a second at f5.6 and ISO 200 with a 35mm f1.8 lens.
What do you think? Is the photo quality pleasing?
CMOS stands for ‘complementary metal-oxide semiconductor.’ A CMOS sensor converts the charge from a photosensitive pixel to a voltage at the pixel site. The signal is then converted by row and column to multiple on-chip, digital-to-analog converters that can transfer voltage read-outs at high speed, with low sensitivity, and high, fixed-pattern noise.
CCD stands for ‘charged coupled device’. A CCD sensor is a silicon chip that contains an array of photosensitive sites It is an analog device and its output is immediately converted to a digital signal by an analog-to-digital converter. The voltage is then read from each site to reconstruct an image.
The bottom line is that CCDs are slower to read out, consume more energy than CMOS sensors, and are more expensive to make – but they have higher capability to send a clean signal to the card.