Transcript 06_sensorChip_8

Digital Photography I
Teacher: Kenji Tachibana
.
Sensor Chip
8 slides
Copyright © 2003 – 2009 Kenji Tachibana
Digital Photography I
Teacher: Kenji Tachibana
Sensor Chip: Compact Digital
Evolving Technology:
1. Next to the lens, the chip is the heart and
the most expensive part of all compact
digitals.
2. The compact digital sensor chip is about
the size and weight of a postage stamp.
4. Imagine dividing the stamp into 10 parts
as shown to the right. Divide it 10 more
times vertically creating 100 discrete parts.
5. Dividing it into 1,000 sections and seeing it would
take a microscope, which I can still imagine.
6. Today’s chips have 10 million discrete light sensitive
pixels on a postage stamp size area. That’s totally
unimaginable!
Digital Photography I
Teacher: Kenji Tachibana
Sensor Chip: Compact Digital
Enough Already:
7. 10 million means over crowding which results in
excessive heat. And heat is the enemy of all
electronic devices.
8. 5 megapixel ran a lot cooler and it is more than
adequate for most practical purposes. So, many
photographers would rather see R&D put into
getting more real image quality improvements.
For the camera maker, selling bigger numbers is
an easy-sell.
Digital Photography I
Teacher: Kenji Tachibana
Sensor Chip: Compact Digital
Practical Size: 5 MP
9. The 5 MP is capable of producing an excellent
8x10 or a good 11x14 print.
10. It’s the bases for the assignment required 2547
x 1955 image size.
11. It produces approximately 2 to 2.5 MP file size
which is easy to process and store.
12. Larger file sizes becomes harder to handle,
slower to process, and storage space can
easily become as issue even with current
cheaper storage devices.
Digital Photography I
Teacher: Kenji Tachibana
Sensor Chip: DSLR
DSLR: Pro & Con
1. DSLR sensor chips are about 5x larger. And
even the pixels are larger.
2. The larger chip size helps to reduce over
crowding, which also reduces the over heating
problem. For the DSLR’s, the 10 MP doesn’t
does not means over crowding.
3. Besides heat, dust is another huge enemy of the
chip. Current flock of DSLR camera bodies
comes with assortment of dust fighting
mechanisms. Some work better than others.
Compact digitals are sealed. They don’t have dust issues.
Digital Photography I
Sensor Chip: Generic information
Pixel Array
1. Sensor chips contains a 16 pixel checker
board arrangement (Bayer Pattern) of
light sensitive receptors (pixels).
2. Receptors are photo diode which
responds to light by producing
electricity.
Sophisticated circuitry interprets and amplifies
the signals to ‘process’ the digital image in
conjunction with the camera software referred
to as firmware.
All DSLR and high end compact digitals are
capable to updating the firmware.
Teacher: Kenji Tachibana
Digital Photography I
Teacher: Kenji Tachibana
Sensor Chip: Generic information
Chip Types: 2 main types with variations
1. CCD (charged couple device) is the most popular
sensor type found in digital cameras.
2. CMOS produces less heat and is cheaper to
make. For those sensible reasons, it is starting to
replace CCD’s. It was first successfully used in the
Canon Rebel DSLR cameras.
3. Sony was the first to use the CMOS chip for its
prosumer digital CyberShot R-1 with a 10 MP
pixel count on a APS size chip.
4. Foveon is another kind of sensor chip design. It
sounds great on paper but only Samsung has put
it into a production digital camera. I am looking
forward to seeing its development.
Digital Photography I
Teacher: Kenji Tachibana
Sensor Chip: Generic information
Sensitivity: ISO
1. Most compact digitals have light sensor sensitivity
ranging from ISO 100 to 800. Some have a higher
numbers such as 1200 or 1600.
2. From an image quality point of view, only the ISO
100 is recommended for assignment shoots. Use
the ISO 200 for a one-stop gain in aperture or
shutter speed under emergency situations.
3. Don’t use speeds higher than 200 because of
image quality loss. The ISO has also fallen prey to
the false notion that ‘bigger numbers are better’.
Digital Photography I
Teacher: Kenji Tachibana
Out take from the book: One Digital Day by Rick Smolan
Microprocessor: Background
The modern microprocessor contains as many as 20
million transistors, and each finished chip is the product
of processes more complicated than those used by the
Manhattan Project in building the atomic bomb.
Yet despite an extraordinarily sophisticated
manufacturing process, microchips are produced en
masse at the rate of more than a billion each year. To
put this complexity in perspective, imagine that within
each tiny chip there exists a structure as complex as a
mid-sized city. Now imagine that throughout that same
city, millions of people are racing around at light speed
and with perfect timing in an intricately choreographed
dance.
Digital Photography I
Teacher: Kenji Tachibana
x
End