Chapter 2
Wednesday, September 26, 2012 at 2:27PM Cameras, sensors and a lot of pixels
When it comes to talking about sensors, it is very easy to go propeller hat on the subject, but I will save that for a later project and will try my best as i did in Chapter 1 to keep it basic and simple.
The lens and sensor on a camera are the two most important parts for the technical quality of the image and this chapter is mostly about sensors, but it's necessary to talk a little about cameras, not brands but types, and here I will mention and go through the four types most people know and use.
Please pay no attention to the brand in the following examples they are only chosen because it is what I have around me and use, and is not a testimony of the necessarily best available on the market, they are chosen for their example value alone.
What are pixels?

Each of the small squares you see in the picture represents a pixel and are the light emitting points (LEDs) you are seeing on your screen right now and together they are forming the picture. On the sensor it's, the number of photosensitive points which collects light and make the electronic representation of the image you are shooting and can be displayed on a screen or printed on paper.
The following examples is four test shots taken with different cameras under the exact same lighting conditions and with all the cameras in macro mode, in order to compare the importance of sensor sizes, and what we're looking for is, 1 dynamics, 2 depth of field (DOF), 3 low light performance and 4 ISO noise.
It should be mentioned already here that the lenses also have a significant impact on the sensor capability, but I will get into to that in Chapter 3.
Canon EOS 5D Mark II:

This camera has a large sensor (Full Frame) with 21.000.000 light sensitive pixels spread over 864mm2 a large surface that can receive a lot of light.
1 Good dynamics throughout the tonal range.
2 Good shallow deep of field and a beautiful fade.
3 Good low light performance and still maintain a large dynamic range.
4 Not much noise when amplifying the sensor's sensitivity to 800 ISO.
Konica Minolta DiMAGE A2:

This Compact Camera, which is a $1000 camera from 2003, I put in here to show two things, first that even a small sensor with good glass in front can do some good things, and second to show the noise this old sensor produce when you turn up the ISO to 800 which is the max.
The modern version of this type of camera has a much larger sensor, some even a Full Frame and good interchangeable lenses, a camera type, I think we will see much more of in the future.
1 Good dynamics throughout the tonal range.
2 A reasonable shallow deep of field, would have been better in more light, and it must be mentioned that the aperture only goes down to f 3.5 in macro mode, even in manual.
3 Not a good low light performance, but if on a tripod and you give it enough exposure, in this case an entire second and nobody moves, it still has good dynamics.
4 Here it ends in a disaster, even a good noise reduction filter would find it difficult to cope with this one, it is not useful to increase the ISO to more than 200 at this sensor, but it's also 10 years old,
a very long time in sensor years.
Canon IXUS 120 IS:

Now we are down to the very small sensors and it starts to have a cost, but I am impressed with how good they are, I know that not only is there 12.000.000 pixels on this small area but there are the same number of corresponding electronic circuits each of which produces noise, all electronic components in a circuitry produce noise, still they managed to control it, and I know something about how difficult that is, this is jaw dropping technology!
These type of cameras I think has their future behind them, there's no real reason to buy such a camera when smart phone cameras has the quality that they have now, and are becoming better for each release, I don't think there are many who will carry both a compact camera and a camera phone.
1 Fairly good dynamics throughout the tonal range in good light.
2 Nice but not great shallow deep of field.
3 Reasonably good low light performance, but loses some of the dynamics in the tonal range.
4 Not much noise when amplifying the sensor's sensitivity to 800 ISO.
Samsung Galaxy Note:

This smartphone camera has the smallest sensor of the four, but after all they've got room for 8.000.000 pixels in this small area, and however they did it they got away with it in a good way.
1 Good dynamics throughout the tonal range.
2 Not so great shallow depth of field, but better than one would expect of a lens and sensor in this size.
3 Great low light performance for the sensor size.
4 Lower than expected noise for the sensor size, when amplifying the sensor's sensitivity to 800 ISO.
Summary:
I hope that what you got out of this chapter is that size does matter when it comes to sensors, but not so much when it comes to the number of pixels. I would also like if it told you that most modern cameras is able to take technical great pictures and if not "you're holding it wrong" :)
Next chapter will be about lenses.





