Digital Camera Sensor Technology - Part 3 CCD Sensors explained

Continuing with my review of camera sensor technology I attempt to show how this CCD sensor captures and shifts out the electrons to a capacitor/amplifier before being sent to the analogue to digital convertor which gives a digital value proportional to the light which fell on that pixel during the exposure cycle. It is quite a complex operation and I have tried to keep it as simple as possible yet still retain some of the key points of this technology. It is my understanding of how the device works and may not fully represent a real world device as manufacturers quite often change designs to improve efficiency and reduce noise.
my photoblog site: www.grahamhoughton.com

[@AsaadFSaid]

Thanks Graham!. That was really helpful and a great explanation of CCD in digital Camera.

[@sirtedley]

Thank you Graham
I've learned so much by watching your videos
I must say. I didn't know very much about digital cameras
But thanks to you I've learned a lot even though I watch your videos
More than ONECE believe me.
Thank you
Ted.

[@GrahamHoughton12]

Its a hard topic to explain, never mind try and understand but quite a few people had requested it so I scheduled the series

[@moveinmaldives2080]

this is so well explained :D thanks

[@Trumpyfilip]

This was great, thank you ! But what about the video about CMOS sensors ?

[@oculushut7205]

Hi Graham - great video. Thank you for sharing. Did you get around to creating the CMOS video in the end?

[@QuinnWaters]

thank you!

[@adidnda]

amazing and good

[@jasimahmed6623]

Thanks

[@darthvader5300]

Charged Couple Devices works just like our LRD "Light Receiving Diodes" or LRRD "Light Receiving Receiver Diodes" in our military satellites. CCDs in digital cameras and telescopes or zoom lens cameras works just our LRD and LRRD systems.

[@hofmannwaves1525]

Thank you

[@fab123fab]

great

[@SonjaWilliamsB]

Thanks for this explanation. It looks to me like the charge is amplified after it is collected and if I understand right, the ISO determines the amplification. Can you explain why there is more noise in the image as amplification (ISO) is increased? Thank you!

[@davidmorgan2699]

Sonja, I think you are right that ISO determines the amplification. When the camera is operated at the lowest ISO's, there are enough photons that the potential wells may be totally filled or unfilled. When ISO is increased, the amount of light hitting the sensor decreases. Then there really is not enough light to totally fill the well, and the amplifier gain is increased to compensate for that, so you still get the same range of analog signal to the A-D converter. So even though the well cannot now be filled, it is still possible for the output of the amplifier to be at its maximum level and get 'white', or a digital value of 255.
However, every sensor has some amount of noise that leaks into the image sensor cells from unwanted sources. When the ISO is low, and the amplifier gain is low, this noise is amplified the least, and shows up the least in the photo. Another way to look at it is that it is small compared to a potential well that can be fully filled by incoming photons. When you increase the ISO, you increase the amplifier gain. This increases output of the CCD cell, both signal and noise. But now you are dealing with less signal, fewer photons, and the noise becomes more apparent. It has now been amplified more when it gets to the A-D converter.
In reality, there is noise introduced into all circuitry, so noise gets into the signal both before and after the amplifier. It is the circuit designers job to insure that the noise from the rest of the circuitry is insignificant compared to what comes from the sensor.

[@indio007]

I know this video is old but maybe you could answer a question. Are the indiviual pixels in the sensor squares or rectangles?

[@drumcoveraddict]

rectangles

[@salimkumar1414]

Nice

[@GrahamHoughton12]

thank you!

[@terenas1986]

Hmm.. let's point out one thing though. While CCD is read out pixel-by-pixel, the image in whole is read "all at once" by the processor, thus not creating the screen-tearing effect that of which the CMOS sensor suffers greatly. (Only when doing videography of course.)

[@Kudlaty771]

interesting... i thought this was the playback medium causing this, not the sensor in the camera itself

[@DrN007]

How does an analog shift register work though?!

[@kirtisingla55]

It's useful information but it'll make more clear if we'll have it's subtitles..... please upload it's subtitles

[@soufmaro502]

shift registers should not exits anymore
there a parallel or synchron electrical circuits that exits already like in the 1960´s
i still cant see why they would be used today, that electrical circuit problem is a very old known problem
while cpu´s longly use both, background wireing and paraellel/synchron circuits
that works for anything that has a charge or electric flow, therefore that works on any electric circuit
people that might say you dont see the diffrens that is simply not true, special now in 2021 you more and more can see this problems

[@iosef3337]

But can i make one homemade?

[@SianaGearz]

If you don't mind it having just a handful of pixels of resolution and being rather huge, like where every pixel is a few millimeters in size rather than the whole camera sensor being a centimeter in size, I can't see why not. There are even potential practical uses for that kind of thing, like an optical position encoder or a display calibration device, though in both of these cases you're actually better off buying a small image sensor IC off Texas Instruments or whomever.

[@iosef3337]

Ok

[@kadhemalhasan3810]

What is the meaning of p + and n +

[@qkasriel]

P type and N type silicon.

[@1ksubswithnovideos534]

ccd